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Article

Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts

by
Bradley Ridoutt
1,2,*,
Danielle Baird
3 and
Gilly A. Hendrie
3
1
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Clayton, VIC 3169, Australia
2
Department of Agricultural Economics, University of the Free State, Bloemfontein 9300, South Africa
3
CSIRO Health and Biosecurity, Adelaide, SA 5000, Australia
*
Author to whom correspondence should be addressed.
Dietetics 2025, 4(3), 35; https://doi.org/10.3390/dietetics4030035
Submission received: 30 May 2025 / Revised: 17 July 2025 / Accepted: 8 August 2025 / Published: 11 August 2025
Browse Figure
Versions Notes

Abstract

Protein-rich foods, such as meats, eggs, nuts, legumes, and dairy foods, can be important sources of micronutrients, especially those micronutrients that tend to be widely under-consumed. The source of dietary protein, animal or plant origin, is therefore a relevant consideration in the transition to healthier and sustainable diets. In this study, 1589 Australian adult diets with higher diet quality and lower environmental impact were isolated from Australian Health Survey data. These diets were primarily differentiated by lower intake of energy-dense/nutrient-poor discretionary foods. These diets were grouped according to the proportion of total protein obtained from animal and plant sources. On average, 55% of protein was from animal sources and 45% was plant derived. As the proportion of animal protein increased, total dietary protein intake also increased, and total energy intake decreased. Diets with between 60 and 80% of protein from animal sources met the greatest number of Estimated Average Requirements (EARs). Furthermore, diets with this ratio of animal protein were closest to benchmarks when assessed as a proportion of EAR met. That said, across all identified “sustainable healthy diets”, calcium, vitamins B6 and A, zinc, and magnesium were at risk of inadequate intake. This evidence suggests that a diet with around 60–80% of total protein coming from animal sources can reduce the risks of inadequate intake of micronutrients in a sustainable diet.

Graphical Abstract

1. Introduction

Proteins are an important component of the human diet, especially those proteins that contain the essential or indispensable amino acids that the body is not able to synthesize on its own [1,2,3,4]. Amino acids play a critical role in tissue growth and repair and are used by the body in a range of functions. Deficient intake of protein and the required essential amino acids can lead to growth retardation, loss of muscle mass, cognitive impairment, weakening of the immune system, among many other conditions [5,6,7,8]. Not all sources of dietary protein are alike in terms of amino acid composition and digestibility. Generally, proteins from animal-sourced foods are more complete and digestible than those from plant-based sources [9,10,11]. However, combinations of plant-based foods are able to provide all the necessary amino acids. Globally, protein energy malnutrition remains a common problem [12]. However, in many high-income regions, inadequate intake of protein relative to dietary recommendations is uncommon, except in the case of older population subgroups. For example, in Australia, greater than 99% of adults below 70 years of age meet the estimated average requirements for protein intake [13]. However, 14% of males and 4% of females above 70 years were found not to achieve adequate protein intake. As such, there has been a special focus on protein intake across older generations [14,15,16,17]. In addition, attention has been directed toward micronutrient intake associated with the choice of protein-rich foods [17,18,19,20], as protein-rich foods can be an important source of micronutrients for which the prevalence of inadequate intake can be high. Inadequate intake of micronutrients, sometimes referred to as hidden hunger, can be widespread across life stages [21,22,23,24].
Consideration of protein sources and the associated intake of micronutrients is especially relevant in the context of efforts to pursue dietary patterns with lower environmental footprints. Oftentimes, recommendations to make diets more environmentally sustainable involve limiting the intake of animal-sourced foods [25,26,27,28,29,30], thereby shifting the balance of protein obtained from plant and animal sources, a so-called protein transition [31,32]. Diets in high-income countries are typically found to have an animal/plant protein ratio in the order of 65/35 [33]. Animal-sourced protein foods can be rich and bioavailable sources of essential micronutrients that can be difficult to obtain from plant-based sources alone or are less available in plant-based foods [14,17]. These include minerals such as zinc, phosphorus, calcium, heme iron, and selenium, vitamins such as B12, B6, riboflavin, niacin, retinol, and vitamin D3, as well as nutrients DHA, EPA, and choline. Concerns have been raised about the potential for a protein transition to exacerbate micronutrient gaps [14,34,35,36,37,38,39,40,41,42,43], particularly in relation to the predominantly plant-based Planetary Health Diet [44] developed by the EAT-Lancet Commission [45,46,47,48,49,50,51,52,53,54,55,56]. This dietary pattern was identified by Beal et al. [45] as lacking sufficient vitamin B12, calcium, iron, and zinc for some life stages, and, in particular, for women of reproductive age. Furthermore, these authors highlighted the high phytate intake of the Planetary Health Diet that could negatively impact micronutrient bioavailability [45]. Oxalates are a further consideration, having the potential to reduce micronutrient bioavailability. As a general recommendation for adults, one study has suggested that a minimum of around half of all protein intake should be from animal-based sources to achieve adequate intakes for all micronutrients [57].
The point has been made that sustainable healthy diets need to be defined at the local level in order to reflect local food sources and production practices, local environmental conditions, local food cultures, and the importance of specific foods in supplying individual nutrients, especially those nutrients where inadequate intake is common [58]. For the Australian food system and dietary context, global recommendations and evidence obtained in other countries may not be directly relevant. In this study, we evaluate micronutrient adequacy in relation to protein source in Australian adult diets identified as having higher diet quality and lower environmental impacts. In previous research, life cycle assessment (LCA) was used to characterize environmental impacts for 9341 individual Australian adult daily diets obtained from the National Nutrition and Physical Activity Survey [59,60,61,62]. Using this data resource, quadrant analysis was used to isolate a subgroup of healthier and more environmentally sustainable diets [63]. This subgroup of diets is important because it represents existing food habits within the Australian community which already have more desirable characteristics. These are not conceptual diets or diets obtained using an optimization algorithm that may not reflect common food intake patterns currently consumed in the population. Furthermore, such diets may not reflect the way foods naturally combine into familiar recipes and meals, and depend upon assumptions about total dietary intake across the day [58]. Our goal was to describe the micronutrient characteristics of Australian adult diets with different animal/plant protein ratios and make practical recommendations relevant to public health nutrition and dietetics practice.

2. Methods and Data

2.1. Background Data

The dietary intake data used in this study were obtained from a nationally representative nutrition and physical activity survey [64] conducted in 2011–2012 by the Australian Bureau of Statistics (ABS) as part of an Australian health survey [65]. A detailed description of the methodology has been published by the ABS [65]. These data were collected using a 24 h recall process over a 13-month period and across all days of the week and included 9341 adults aged 19 years and above. The survey was designed to provide comprehensive coverage of the Australian population, enabling the dietary intake estimation according to demographic subgroups through the application of population weighting factors. The survey also included a second 24 h recall. However, the response rate was only 64% of the original sample, and significantly lower energy intakes were reported. Therefore, to maximize the sample, only data from the first 24 h recall were used in this study. In relation to the issue of potential inaccuracy in the recall of foods and beverages and portion sizes during the survey, the ABS also published estimates of the prevalence of under-reporting of food energy (17% and 21% for males and females, respectively) [65]. These factors were applied uniformly across the dietary intake data to avoid systematically underestimating dietary environmental impacts. This process also enabled a reliable comparison with recommended daily intakes of foods [66] and estimated average requirements for nutrients [67].
Data concerning the environmental impacts of foods in the Australian food system were sourced from previous studies. These data, developed using life cycle assessment, covered four environmental aspects: cropland scarcity [60], climate impact [61], pesticide toxicity [62], and water scarcity [68]. Selected climate impact data were revised where recent reports indicated large changes in values [69,70]. For each food, these four indicators were used to develop an integrated environmental impact score using weighting factors, as described previously [63,71], with capping minimum values for individual indicator scores at zero. Briefly, the weighting factors were developed on a distance-to-target basis [72]. In such an approach, environmental indicators that require large improvement are given a larger weight relative to indicators that require less improvement. Weighting factors are presented in Supplementary Table S1, and environmental impact scores for foods that were revised are presented in Supplementary Table S2. Lower environmental impact scores imply lower overall environmental impacts.

2.2. Quadrant Analysis

A subset of adult daily diets was isolated with higher scores for diet quality and lower scores for environmental impact. Diet quality scoring used the Diet Quality Index [73]. With this Index, scores range from 0 to 100, whereby higher scores describe a higher level of compliance with the Australian Dietary Guidelines [66]. Briefly, the Australian Dietary Guidelines identify five food groups: fruits, vegetables, grain (cereal) foods, fresh meats and other protein rich foods like tofu, nuts and eggs, and dairy foods, which include dairy alternatives made from soy, nuts, etc., provided they contain at least 100 mg of calcium per 100 mL [66]. In addition, the Australian Dietary Guidelines describe “discretionary choices”, which are energy-dense and nutrient-poor foods and beverages high in added sugars, salt, and saturated fats. Alcoholic drinks are also described as discretionary choices. The discretionary choice category includes sugar-sweetened beverages, biscuits and cakes, dairy desserts, processed meats, potato chips, confectionaries, extruded snacks, along with many other types of processed foods that are widely consumed in Australia.
As described previously [63], the 9341 daily diets were stratified by sex and age group (i.e., 19–30, 31–50, 51–70, and 70 years and above), and each stratum was sorted into quadrants according to diet-quality score and environmental-impact score. Stratification was undertaken because total dietary energy intake and environmental impact scores have previously been shown to be positively correlated [58,74]. Without stratification, a subgroup of diets with higher diet quality scores and lower environmental impact scores would have been biased toward diets of females and older adults who typically have lower total energy intake. To create greater contrast, daily diets within 0.25 standard deviation of the mean for each parameter were also excluded. Accordingly, a subset of 1589 daily diets having the characteristics of a higher diet-quality score and lower environmental impact score (HQLI diets) was isolated for further analysis. The composition of this subgroup, by age group and sex, is presented in Supplementary Table S3.

2.3. Analysis of Animal/Plant Protein Ratio

For each of the 1589 HQLI diets, total daily protein intake was assessed along with the amount of protein of animal and plant origin. For all foods within the Australian food composition database [75], the proportion of protein coming from animal or plant sources was determined. The proportion of protein from animal and plant sources was calculated as the average proportion of foods and beverages consumed across the day. The 1589 HQLI diets were subsequently divided into five groups according to the proportion of total protein derived from animal sources, i.e., less than 20%, 20 to less than 40%, 40 to less than 60%, 60 to less than 80%, and greater than 80%. These groups were assessed in terms of protein-rich food choice and whether estimated average requirements (EARs) for nutrients were achieved [67].

2.4. Analyzing Nutrient Adequacy

The AUSNUT 2011–13 food and dietary supplement database provides 53 nutrient values for 5740 foods and beverages [75], enabling estimation of nutrient intake based on the reported dietary intakes of individuals falling into the HQLI quadrant. Nutrient adequacy was assessed for 16 nutrients using the published Nutrient Reference Values for Australia [67]. Micronutrient intakes were compared to the Estimated Average Requirements (EARs) for each nutrient, with both the proportion of diets meeting the EAR and the percentage of the EAR met (capped at 100%) calculated. Diets in the HQLI subgroup were also compared to the population average in terms of nutrient density (i.e., nutrient content per megajoule).

2.5. Statistical Analyses

Statistical analyses were conducted using IBM SPSS Statistics (Version 29.0.2.0). Survey weights were applied to calculate population estimates representative of the Australian population, with an additional adjustment to account for uneven sampling across the days of the week. Baseline characteristics were assessed by comparing the HQLI subgroup to population means using one-sample t-tests (continuous variables) and chi-squared goodness-of-fit tests (categorical variables). The HQLI subgroup was excluded from the overall population sample (n = 7752) prior to these comparisons. Differences in nutrient composition between groups defined by the animal-to-plant protein ratio were also tested using t-tests. All p-values are reported in the results.

3. Results

3.1. Characteristics of the HQLI Subgroup

The HQLI subgroup of daily diets had a diet quality score that was 37% higher than the average Australian adult diet (58.5 compared to 42.6; Table 1). This subgroup of diets also had a 38% lower environmental impact score (0.050 compared to 0.087), with lower environmental impacts across all four of the individual environmental indicators. For example, climate impacts were 38% lower and water scarcity impacts were 36% lower (Table 1). The primary factor distinguishing the HQLI subgroup of diets from the average Australian adult diet was a much lower intake of discretionary foods (2.1 servings compared to 6.8 servings; Supplementary Table S4). Vegetable intake was 23% higher (3.2 servings compared to 2.6 servings), and the intake of dairy foods and alternatives was 20% lower (1.1 servings compared to 1.4 servings). Smaller differences were observed for other food groups, although within the meat and alternative food group there was a greater intake of seafood and red meat and a lower intake of other choices. The HQLI subgroup of diets was associated with Australians who were less likely to smoke cigarettes and had a marginally higher avoidance of dairy foods (Table 1). Differences in weight status, activity level, and other socio-economic indicators were significant, but the direction was unclear.
Consistent with the lower intake of discretionary foods, the HQLI subgroup of adult daily diets had markedly lower total dietary energy intake (7331 kJ compared to 10,458 kJ for the average Australian adult diet). The nutrient density was also higher for many beneficial nutrients (Table 2). For example, nutrient density was more than 20% higher in the HQLI subgroup for long-chain omega-3 polyunsaturated fatty acids, dietary fiber, dietary folate, retinol equivalents, thiamin, and iron; and more than 10% higher for zinc, magnesium, potassium, protein, and several other nutrients. In addition, nutrient density was significantly lower for sugar, trans-fatty acids, and alcohol.

3.2. Animal/Plant Protein Ratio

Within the HQLI subgroup, diets were categorized according to the proportion of total protein derived from animal and plant sources (Table 3). On average, for the HQLI subgroup, 55.2% of protein was from animal sources and 44.8% was plant derived. As the proportion of animal protein increased, total dietary protein intake also increased (r = 0.453, p < 0.001). As shown in Table 3, for diets with less than 20% animal protein, total protein intake was 66.8 g. This compares to 115.4 g of protein for diets with greater than 80% animal protein. A weaker positive correlation also existed between the proportion of animal protein and total energy intake (r = 0.123, p < 0.001). Total dietary energy intake was more than 20% lower for diets with the highest proportion of animal protein compared to diets with the lowest proportion of animal protein (6385 kJ compared to 7804 kJ; Table 3).

3.3. Protein-Rich Food Choices

According to Australian Dietary Guidelines, the two protein-rich food groups are lean meats and alternatives, and dairy and alternatives. The minimum recommended number of servings of lean meats, poultry, seafood, eggs, and other protein-rich plant-based alternatives, such as nuts, seeds, and legumes, ranges from two servings for women aged above 70 years to 3 servings for men aged between 19 and 50 years. For the HQLI subgroup, the average minimum recommended number of servings was 2.5, which was met only by the groups having higher proportions of animal-sourced protein (Table 4). Among these groups with higher animal-sourced protein, red meat (i.e., beef and lamb) was consumed in the greatest amount, followed by poultry (Table 4). The recommended number of servings of dairy foods ranges from 2.5 servings for those aged 19–50 years up to 4 servings for women aged 51 years and above. Intake of dairy foods across groups ranged from 0.72 to 1.19 servings (Table 4), all below the recommended minimum intake for adults.

3.4. Nutrient Adequacy

HQLI diets with between 60 and 80% of protein from animal sources were most common within this subgroup of diets (Table 3) and also the most likely to achieve the recommended levels of intake of a variety of vitamins and minerals (Table 5). In contrast, HQLI diets with less than 20% of protein from animal sources were least likely to achieve recommended intakes of nutrients. Diets with greater than 80% animal protein were also less likely to achieve EARs than diets with between 60 and 80% of protein from animal sources (Table 5). For some nutrients, recommended intakes were largely met regardless of the source of protein, such as niacin and phosphorus. However, other nutrients were found to be at high risk of falling below the recommended intake, such as calcium, vitamins A and B6, as well as zinc and magnesium. Vitamin B12 was also at risk of inadequate intake for HQLI diets with less than 20% of protein from animal sources (Table 5). HQLI diets with between 60 and 80% of protein from animal sources were also closest to achieving EARs (Table 6). For these HQLI diets, nutrient intake averaged 93.3% of EARs. HQLI diets with less than 20% of protein from animal sources were farthest from achieving EARs (87.9%; Table 6). There are important differences between the data presented in Table 5 and Table 6. In theory, at least, it is possible for a diet to meet none of the EARs but be very close to meeting all. As such, EARs were assessed in two ways. Number of EARs met, and proportion of EAR achieved.

4. Discussion

4.1. Desirable Animal/Plant Protein Ratio

This study has focused on a subgroup of Australian adult diets with higher diet quality and lower environmental impacts. This subgroup is relevant because it reflects the diets of Australians who already have more desirable dietary habits. These diets are prevalent in the community and are thought to be realistically able to be adopted by Australians with poorer quality diets and by those whose diets presently have a higher environmental burden. Importantly, this study used dietary intake data obtained through a nationally representative survey, which represents real food choices, food combinations, and total dietary energy intake across the day. This is a critical element of the research methodology since food choice can influence total dietary energy intake across the day [58]. Often, sustainable diet studies are based on iso-caloric comparison of conceptual dietary alternatives, which overlook one of the primary determinants of a sustainable healthy diet—avoidance of food overconsumption [63,76]. In this study, the HQLI subgroup of daily diets had around 30% lower total energy intake. The overconsumption of food energy is a major health issue in Australia. According to the Australian Institute of Health and Welfare, two-thirds of adults are living with overweight or obesity [77]. Overconsumption of energy is also an environmental concern because total dietary energy intake and dietary environmental burden are positively correlated [59,60,61,71].
One particular concern about more environmentally sustainable diets is the potential for inadequate intake of micronutrients. This study has addressed this concern through the lens of the animal/plant protein ratio, finding that more sustainable diets in the Australian context have better micronutrient characteristics when they contain 60–80% of protein from animal sources. This subgroup of diets had the greatest likelihood of achieving EARs (Table 5). They were also found to be closest to achieving EARs (Table 6). These diets also achieved the Australian Dietary Guideline [66] minimum recommended number of servings from the “Fresh meats and alternatives” food group, which was not the case for diets within the HQLI subgroup with a lower animal/plant protein ratio (Table 4). Furthermore, since higher ratios of animal/plant protein were positively correlated with total protein intake (Table 3), diets with 60–80% of protein from animal sources met the EAR for protein in almost all cases (Table 5). In addition to higher total protein, these diets also had lower total energy intake than diets with a lower animal protein ratio (Table 3), which is generally beneficial since overconsumption of food energy is common in Australia, as mentioned above. In contrast, diets with the lowest percentage of animal protein (i.e., less than 20%) had the poorest nutrient adequacy (Table 5 and Table 6), were well below the recommended intake of protein-rich foods (Table 4), met the EAR for protein in only 75% of cases, and had higher total energy intake. Also noteworthy was that diets with greater than 80% animal protein were well below the EAR for folate, vitamins A, B1, and C, as well as magnesium and calcium, suggesting that extreme categories of animal/plant protein ratio risk various nutrient deficiencies.
These results are broadly consistent with other studies. For example, Vieux et al. [57] used mathematical modeling based on French dietary intake data and concluded that around half of the total protein should come from animal sources to meet micronutrient requirements. In another optimization study, a lower ratio of 40/60 animal/plant protein was suggested [78]; however, this study did not use dietary intake data, instead modeling conceptual iso-caloric dietary options based only on agricultural commodities. Beal et al. [45] identified potential micronutrient shortfalls in the EAT-Lancet Planetary Health Diet, which has around 30% intake of protein from animal sources, for vitamin B12, calcium, iron, and zinc, and suggested greater consumption of animal-sourced foods. In contrast, in another modeling optimization study, Fouillet et al. [79] suggested the theoretical possibility of obtaining adequate micronutrients with diets containing up to 80% plant protein. Other authors have suggested fortification to achieve adequate micronutrient intake for highly plant-based diets [80,81]. Mathematical optimization naturally creates a wide range of potential solutions; however, the iso-caloric assumptions underpinning these models and the relevance to actual dietary preferences within populations must be questioned.

4.2. Nutrients at Risk of Inadequate Intake

While the diets with 60–80% animal protein were most nutritionally adequate, there was significant variation in the nutrient content of diets within the HQLI subgroup (Table 5 and Table 6). Generally, HQLI diets were at risk of inadequate intake of calcium, vitamins B6 and A, zinc, and magnesium (Table 5 and Table 6). This is consistent with a recent systematic review of Australian evidence concerning diet and environmental sustainability [58]. And, as noted in this review, the practical implication is that foods that are nutrient-dense and bioavailable sources of these specific nutrients need to be prioritized in a healthy, sustainable diet [58]. It is also worth noting that these nutrients are among the nutrients most widely under-consumed across the Australian adult population generally [24]. Elsewhere, it has been demonstrated that nutrient density increases as the percentage of energy from protein-rich foods increases [82], consistent with the finding from the present study, as HQLI diets with a higher percentage of animal protein also had higher total protein intake (Table 3) and greater intake of protein-rich foods (Table 4). In addition, a greater variety of protein-rich food intake has been shown to be beneficial for micronutrient intake [83]. Animal-sourced proteins, therefore, play an important role in a sustainable, healthy diet as the Australian evidence suggests a higher percentage of animal protein is correlated with higher total protein intake and lower overall energy intake, and a nutrient profile that aligns more closely with estimated requirements. Much of the sustainable diet literature suggests avoiding or limiting animal-sourced foods, e.g., [44], but the evidence presented in this study suggests that higher intake of animal-sourced foods, within the context of a healthy dietary pattern with lower environmental impacts, can reduce the risks of inadequate intake of micronutrients.
Beal et al. [45] also draw attention to the high levels of phytate that can be present in diets with a high proportion of plant-sourced protein, such as the Eat-Lancet Planetary Health Diet. Phytic acid can interfere with nutrient absorption, especially minerals like iron, zinc, calcium, and magnesium [84,85,86,87]. Oxalates, present in plant foods, can similarly reduce the bioavailability of these nutrients. As discussed above, these nutrients are among the nutrients at highest risk of inadequate intake in a sustainable diet in Australia. While it is possible for individuals to manage their food choices to achieve adequate nutrient intake with a diet high in plant-based protein, for dietary guidance aimed at the general population, the Australian evidence presented here does not support recommendations to avoid or limit animal-sourced protein foods to achieve a healthy and sustainable diet.

4.3. Limitations and Future Directions

The results reported in this study are relevant to Australia as they are based on Australian dietary intake data and environmental data, particular to foods in the Australian food system. The results may not be directly relevant in other regions where food cultures and preferences differ, or where food production practices differ, or where environmental concerns differ. It is recommended that, where possible, locally relevant evidence is used to inform the transition to more sustainable and healthy diets. The study used the highest-quality available data sources. Dietary intake data came from a large, nationally representative survey undertaken by the Australian Bureau of Statistics that used a 24 h recall methodology. While the survey was conducted 12 years ago, it is the latest and most comprehensive dietary intake data available for the Australian population. That said, with the 24 h methodology, there is potential for under-reporting, and estimates of under-reporting prevalence developed by the Australian Bureau of Statistics [65] were applied to the data accordingly. The uniform application of these factors across all types of foods may have led to an underestimation of discretionary food intake if there was a bias toward under-reporting of these specific types of foods [88]. Environmental assessment was based on four environmental indicators, meaning that not every environmental aspect was covered. However, four indicators are a reasonable number and certainly provide for much more robust evidence than when a single environmental aspect is studied, such as GHG emissions alone, or water scarcity alone [89]. This study did not include an assessment of food waste, which is an important environmental issue [90]. The reason for exclusion was a lack of reliable data describing food waste patterns at the individual food item level in Australia. Similarly, food packaging was not included since similar foods can be packaging in many different formats, and the dietary intake data did not include information concerning packaging.
When assessing the nutrient adequacy of daily diets between groups, all nutrients for which an EAR is available in Australia were included [67]. No discrimination was made between the importance of one nutrient compared to another. Nutrient adequacy was assessed using both the proportion of EAR met and the percentage of EAR achieved. Consistent results were achieved with these two measures. We discuss the potential implications of higher phytate content of diets with a higher proportion of protein from plant sources; however, phytate content was not directly assessed. Nor was the content of other antinutrients assessed. This topic remains an opportunity for future research. Also, in future it would be valuable to assess nutrient adequacy in relation to source of protein for specific lifestages, such as men and women in later lifestages (70 years and above), women of childbearing age, and young adults who are often more concerned about environmental issues and can be early adopters of alternative plant-based foods and diets.

5. Conclusions

This study focused on a subgroup of Australian adult diets determined to have higher compliance with Australian Dietary Guidelines and lower environmental impacts, i.e., sustainable healthy Australian diets. In summary, among these diets, those that included 60–80% of total protein from animal sources were most likely to meet nutrient Estimated Average Requirements (EARs). Further to this, the most nutrient-dense dietary pattern was actually, also the most common animal/plant protein ratio among HQLI diets, with almost 40% of Australians in this subgroup eating this way. As the proportion of animal protein increased, total dietary protein intake also increased. Consequently, these diets achieved the recommended number of servings of protein-rich foods described in the Australian Dietary Guidelines and almost all contained adequate protein. With a higher proportion of animal protein, total dietary energy intake was lower, which is generally beneficial, as overconsumption of dietary energy is common. This evidence suggests that higher intake of animal-sourced protein foods, around 60–80% of total protein, is beneficial and can reduce the risks of inadequate intake of micronutrients in a sustainable diet in Australia.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/dietetics4030035/s1, Table S1: Weighting factors applied to footprint indicators to develop the environmental impact score; Table S2: Updated environmental impact scores; Table S3: Sample size for the higher diet quality and lower environmental impact (HQLI) subgroup according to age group and sex; Table S4: Food intake (servings/person/day) for the HQLI subgroup of adult diets.

Author Contributions

Conceptualization and study design, B.R., D.B., and G.A.H.; data compilation and modeling, B.R. and D.B.; writing—original draft preparation, B.R.; writing—review and editing, D.B. and G.A.H. All authors have read and agreed to the published version of the manuscript.

Funding

This research received funding from Meat and Livestock Australia (https://www.mla.com.au/) under grant number D.NRE.2502.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Ethics approval was not required as the study involved secondary analysis of data published by the Australian Bureau of Statistics.

Data Availability Statement

The dietary intake data are available from the Australian Bureau of Statistics (https://www.abs.gov.au/statistics/health/health-conditions-and-risks/food-and-nutrients/latest-release#data-downloads Accessed on 31 August 2017).

Conflicts of Interest

Funding received from Meat and Livestock Australia (MLA, https://www.mla.com.au) is acknowledged. The authors declare no conflicts of interest. The authors exercised freedom in designing the research, performing the analyses, and making the decision to publish the research results. MLA did not have any role in the design of the study, the analysis of the results, or the interpretation of the results. The decision to publish was made prior to funding and before the results were known. MLA had no role in the preparation or approval of the manuscript.

References

  1. Wolfe, R.R.; Church, D.D.; Ferrando, A.A.; Moughan, P.J. Consideration of the role of protein quality in determining dietary protein recommendations. Front. Nutr. 2024, 11, 1389664. [Google Scholar] [CrossRef] [PubMed]
  2. Calvez, J.; Azzout-Marniche, D.; Tomé, D. Protein quality, nutrition and health. Front. Nutr. 2024, 11, 1406618. [Google Scholar] [CrossRef] [PubMed]
  3. McAuliffe, G.A.; Takahashi, T.; Beal, T.; Huppertz, T.; Leroy, F.; Buttriss, J.; Collins, A.L.; Drewnowski, A.; McLaren, S.J.; Ortenzi, F.; et al. Protein quality as a complementary functional unit in life cycle assessment (LCA). Int. J. Life Cycle Assess. 2023, 28, 146–155. [Google Scholar] [CrossRef]
  4. Adhikari, S.; Schop, M.; de Boer, I.J.M.; Huppertz, T. Protein quality in perspective: A review of protein quality metrics and their applications. Nutrients 2022, 14, 947. [Google Scholar] [CrossRef]
  5. Semba, R.D. The rise and fall of protein malnutrition in global health. Ann. Nutr. Metab. 2016, 69, 79–88. [Google Scholar] [CrossRef]
  6. Sato, H.; Tsukamoto-Yasui, M.; Takado, Y.; Kawasaki, N.; Matsunaga, K.; Ueno, S.; Kanda, M.; Nishimura, M.; Karakawa, S.; Isokawa, M.; et al. Protein deficiency-induced behavioral abnormalities and neurotransmitter loss in aged mice are ameliorated by essential amino acids. Front. Nutr. 2020, 7, 23. [Google Scholar] [CrossRef]
  7. Lewicki, S.; Lesniak, M.; Bertrandt, J.; Kalicki, B.; Kubiak, J.Z.; Lewicka, A. The long-term effect of a protein-deficient-diet enriched with vitamin B6 on the blood parameters in unexercised and exercised rats. Food Agric. Immunol. 2018, 29, 722–734. [Google Scholar] [CrossRef]
  8. Granic, A.; Mendonça, N.; Sayer, A.A.; Hill, T.R.; Davies, K.; Adamson, A.; Siervo, M.; Mathers, J.C.; Jagger, C. Low protein intake, muscle strength and physical performance in the very old: The Newcastle 85+ study. Clin. Nutr. 2018, 37, 2260–2270. [Google Scholar] [CrossRef]
  9. Day, L.; Cakebread, J.A.; Loveday, S.M. Food proteins from animals and plants: Differences in the nutritional and functional properties. Trends Food Sci. Technol. 2022, 119, 428–442. [Google Scholar] [CrossRef]
  10. Kaur, L.; Mao, B.; Beniwal, A.S.; Abhilasha; Kaur, R.; Chian, F.M.; Singh, J. Alternative proteins vs animal proteins: The influence of structure and processing on their gastro-small intestinal digestion. Trends Food Sci. Technol. 2022, 122, 275–286. [Google Scholar] [CrossRef]
  11. Herreman, L.; Nommensen, P.; Pennings, B.; Laus, M.C. Comprehensive overview of the quality of plant- and animal-sourced proteins based on the digestible indispensable amino acid score. Food Sci. Nutr. 2020, 8, 5379–5391. [Google Scholar] [CrossRef]
  12. Grover, Z.; Ee, L.C. Protein energy malnutrition. Pediatr. Clin. N. Am. 2009, 56, 1055–1068. [Google Scholar] [CrossRef] [PubMed]
  13. Australian Health Survey: Usual Nutrient Intakes. Available online: https://www.abs.gov.au/statistics/health/health-conditions-and-risks/usual-nutrient-intakes/latest-release#macronutrients (accessed on 11 April 2025).
  14. Morgan, P.T.; Carson, B.P.; Witard, O.C. Dietary protein considerations in a sustainable and ageing world: A narrative review with a focus on greenhouse gas emissions and skeletal muscle remodelling and maintenance. BMC Musculoskelet. Disord. 2024, 25, 1030. [Google Scholar] [CrossRef] [PubMed]
  15. Li, S.-Y.; Lu, Z.-H.; Leung, J.C.S.; Kwok, T.C.Y. Association of dietary protein intake, inflammation with muscle mass, physical performance and incident sarcopenia in Chinese community-dwelling older adults. J. Nutr. Health Aging 2024, 28, 100163. [Google Scholar] [CrossRef] [PubMed]
  16. Vázquez-Fernández, A.; Caballero, F.F.; Yévenes-Briones, H.; Struijk, E.A.; Baylin, A.; Fung, T.T.; Lopez-Garcia, E. Plant and animal protein intake and transitions from multimorbidity to frailty and mortality in older adults. J. Cachexia Sarcopenia Muscle 2025, 16, e13729. [Google Scholar] [CrossRef]
  17. Beal, T.; Manohar, S.; Miachon, L.; Fanzo, J. Nutrient-dense foods and diverse diets are important for ensuring adequate nutrition across the life course. Proc. Natl. Acad. Sci. USA 2024, 121, e2319007121. [Google Scholar] [CrossRef]
  18. Tedeschi, L.O.; Beauchemin, K.A. Galyean appreciation club review: A holistic perspective of the societal relevance of beef production and its impacts on climate change. J. Anim. Sci. 2023, 101, skad024. [Google Scholar] [CrossRef]
  19. Givens, D.I. Animal board invited review: Dietary transition from animal to plant-derived foods: Are there risks to health? Animal 2024, 18, 101263. [Google Scholar] [CrossRef]
  20. Drewnowski, A. Perspective: The place of pork meat in sustainable healthy diets. Adv. Nutr. 2024, 15, 100213. [Google Scholar] [CrossRef]
  21. Beal, T. Big environmental gains from small dietary tweaks. Nat. Food 2023, 4, 935–936. [Google Scholar] [CrossRef]
  22. Mchiza, Z.J.; Ortenzi, F.; Parker, W.-A. Editorial: Nutrient density: Evidence of multisectoral approaches for improved nutrition. Front. Nutr. 2024, 11, 1542624. [Google Scholar] [CrossRef] [PubMed]
  23. Wang, X.; Dou, Z.; Feng, S.; Zhang, Y.; Ma, L.; Zou, C.; Bai, Z.; Lakshmanan, P.; Shi, X.; Liu, D.; et al. Global food nutrients analysis reveals alarming gaps and daunting challenges. Nat. Food 2023, 4, 1007–1017. [Google Scholar] [CrossRef] [PubMed]
  24. Ridoutt, B. An alternative nutrient rich food index (NRF-ai) incorporating prevalence of inadequate and excessive nutrient intake. Foods 2021, 10, 3156. [Google Scholar] [CrossRef]
  25. Tukker, A.; Goldbohm, R.A.; de Koning, A.; Verheijden, M.; Kleijn, R.; Wolf, O.; Dominguez, I.P.; Rueda-Cantuche, J.M. Environmental impacts of changes to healthier diets in Europe. Ecol. Econ. 2011, 70, 1776–1788. [Google Scholar] [CrossRef]
  26. Aleksandrowicz, L.; Green, R.; Joy, E.J.M.; Smith, P.; Haines, A. The impacts of dietary change on greenhouse gas emissions, land use, water use, and health: A systematic review. PLoS ONE 2016, 11, e0165797. [Google Scholar] [CrossRef]
  27. Wilson, N.; Cleghorn, C.L.; Cobiac, L.J.; Mizdrak, A.; Nghiem, N. Achieving sustainable and healthy diets: A review of the results of recent mathematical optimization studies. Adv. Nutr. 2019, 10, S389–S403. [Google Scholar] [CrossRef]
  28. Clark, M.A.; Springmann, M.; Hill, J.; Tilman, D. Multiple health and environmental impacts of foods. Proc. Natl. Acad. Sci. USA 2019, 116, 23357–23362. [Google Scholar] [CrossRef]
  29. Rabès, A.; Seconda, L.; Langevin, B.; Allès, B.; Touvier, M.; Hercberg, S.; Lairon, D.; Baudry, J.; Pointereau, P.; Kesse-Guyot, E. Greenhouse gas emissions, energy demand and land use associated with omnivorous, pesco-vegetarian, vegetarian, and vegan diets accounting for farming practices. Sustain. Prod. Consum. 2020, 22, 138–146. [Google Scholar] [CrossRef]
  30. Ruett, J.; Hennes, L.; Teubler, J.; Braun, B. How compatible are Western European dietary patterns to climate targets? Accounting for uncertainty of life cycle assessments by applying a probabilistic approach. Sustainability 2022, 14, 14449. [Google Scholar] [CrossRef]
  31. Jaisli, I.; Brunori, G. Is there a future for livestock in a sustainable food system? Efficiency, sufficiency, and consistency strategies in the food-resource nexus. J. Agric. Food Res. 2024, 18, 101496. [Google Scholar] [CrossRef]
  32. Jenkins, W.M.N.; Trindade, L.M.; Pyett, S.; van Mierlo, B.; Welch, D.; van Zanten, H.H.E. Will the protein transition lead to sustainable food systems? Glob. Food Secur. 2024, 43, 100809. [Google Scholar] [CrossRef]
  33. Drewnowski, A.; Hooker, K. The protein transition: What determines the animal-to-plant (A:P) protein ratios in global diets. Front. Nutr. 2025, 12, 1518793. [Google Scholar] [CrossRef] [PubMed]
  34. Fulgoni, V.L., III; Agarwal, S.; Marinangeli, C.P.F.; Miller, K. Impact of plant protein intakes on nutrient adequacy in the US. Nutrients 2024, 16, 1158. [Google Scholar] [CrossRef]
  35. Huppertz, T.; Blom, L.; van Est, L.; Peters, S. Exploring nutrient-adequate sustainable diet scenarios that are plant-based but animal-optimized. Nutrients 2025, 17, 343. [Google Scholar] [CrossRef] [PubMed]
  36. Leonard, U.M.; Kiely, M.E. Can micronutrient requirements be met by diets from sustainable sources: Outcomes of dietary modelling studies using diet optimization. Ann. Med. 2024, 56, 2389295. [Google Scholar] [CrossRef] [PubMed]
  37. Frank, S.M.; Jaacks, L.M.; Adair, L.S.; Avery, C.L.; Meyer, K.; Rose, D.; Taillie, L.S. Adherence to the Planetary Health Diet Index and correlation with nutrients of public health concern: An analysis of NHANES 2003–2018. Am. J. Clin. Nutr. 2024, 119, 384–392. [Google Scholar] [CrossRef]
  38. Gil, M.; Rudy, M.; Duma-Kocan, P.; Stanisławczyk, R.; Krajewska, A.; Dziki, D.; Hassoon, W.H. Sustainability of alternatives to animal protein sources, a comprehensive review. Sustainability 2024, 16, 7701. [Google Scholar] [CrossRef]
  39. Leonard, U.M.; Leydon, C.L.; Arranz, E.; Kiely, M.E. Impact of consuming an environmentally protective diet on micronutrients: A systematic literature review. Am. J. Clin. Nutr. 2024, 119, 927–948. [Google Scholar] [CrossRef]
  40. Nordhagen, S. Animal-source foods for nutrition, environment and society: Finding a balance. Proc. Nutr. Soc. 2025, 6, 1–11. [Google Scholar] [CrossRef]
  41. Qaim, M.; Barrangou, R.; Ronald, P.C. Sustainability of animal-sourced foods and plant-based alternatives. Proc. Natl. Acad. Sci. USA 2024, 121, e2400495121. [Google Scholar] [CrossRef]
  42. Soh, B.X.P.; Smith, N.W.; von Hurst, P.R.; McNabb, W.C. Evaluation of protein adequacy from plant-based dietary scenarios in simulation studies: A narrative review. J. Nutr. 2024, 154, 300–313. [Google Scholar] [CrossRef] [PubMed]
  43. Viroli, G.; Kalmpourtzidou, A.; Cena, H. Exploring benefits and barriers of plant-based diets: Health, environmental impact, food accessibility and acceptability. Nutrients 2023, 15, 4723. [Google Scholar] [CrossRef] [PubMed]
  44. Willett, W.; Rockström, J.; Loken, B.; Springmann, M.; Lang, T.; Vermeulen, S.; Garnett, T.; Tilman, D.; DeClerck, F.; Wood, A.; et al. Food in the Anthropocene: The EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 2019, 393, 447–492. [Google Scholar] [CrossRef] [PubMed]
  45. Beal, T.; Ortenzi, F.; Fanzo, J. Estimated micronutrient shortfalls of the EAT-Lancet planetary health diet. Lancet Planet. Health 2023, 7, e233–e237. [Google Scholar] [CrossRef]
  46. Stanton, A.V. Plant-based diets—Impacts of consumption of little or no animal-source foods on human health. Front. Nutr. 2024, 11, 1423925. [Google Scholar] [CrossRef]
  47. Stanton, A.V. Unacceptable use of substandard metrics in policy decisions which mandate large reductions in animal-source foods. NPJ Sci. Food 2024, 8, 10. [Google Scholar] [CrossRef]
  48. Tucci, M.; Martini, D.; Vinelli, V.; Biscott, P.; Porrini, M.; Del Bo’, C.; Riso, P. The MED_EAT-IT approach: A modelling study to develop feasible, sustainable and nutritionally targeted dietary patterns based on the Planetary health diet. Curr. Res. Food Sci. 2024, 8, 100765. [Google Scholar] [CrossRef]
  49. Uriza-Pinzón, J.P.; Verstraete, F.F.; Franco, O.H.; Artola Arita, V.; Nicolaou, M.; Van der Schouw, Y.T. Planetary Health Diet compared to Dutch Dietary Guidelines: Nutritional content and adequacy. Nutrients 2024, 16, 2219. [Google Scholar] [CrossRef]
  50. van de Locht, K.; Perrar, I.; Paris, J.M.G.; Schnermann, M.E.; Oluwagbemigun, K.; Alexy, U.; Nöthlings, U. Environmental sustainability of diets among children and adolescents in the German DONALD cohort study: Age and time trends, and nutrient adequacy. Am. J. Clin. Nutr. 2024, 120, 92–101. [Google Scholar] [CrossRef]
  51. Gu, X.; Bui, L.P.; Wang, F.; Wang, D.D.; Springmann, M.; Willett, W.C. Global adherence to a healthy and sustainable diet and potential reduction in premature death. Proc. Natl. Acad. Sci. USA 2024, 121, e2319008121. [Google Scholar] [CrossRef]
  52. Kavanaugh, M.; Rodgers, D.; Rodriguez, N.; Leroy, F. Considering the nutritional benefits and health implications of red meat in the era of meatless initiatives. Front. Nutr. 2025, 12, 1525011. [Google Scholar] [CrossRef]
  53. Klapp, A.L.; Wyma, N.; Alessandrini, R.; Ndinda, C.; Perez-Cueto, A.; Risius, A. Recommendations to address the shortfalls of the EAT-Lancet planetary health diet from a plant-forward perspective. Lancet Planet. Health 2025, 9, e23–e33. [Google Scholar] [CrossRef]
  54. Pan, W.-H.; Wu, S.-Y.; Chang, P.-C. Is nutrient quality of the locally-existing, EAT-Lancet-like plant-based diet better or worse than the average diet in Taiwan? An example of local translation. Nutrients 2024, 16, 2775. [Google Scholar] [CrossRef]
  55. Santos-Guzmán, A.; Rivera, J.A.; Unar-Munguía, M.; Ramírez-Silva, I. Addressing infant and young child feeding recommendations from a planetary health perspective. Adv. Nutr. 2024, 15, 100303. [Google Scholar] [CrossRef] [PubMed]
  56. Elliott, P.S.; Devine, L.D.; Gibney, E.R.; O’Sullivan, A.M. What factors influence sustainable and healthy diet consumption? A review and synthesis of literature within the university setting and beyond. Nutr. Res. 2024, 126, 23–45. [Google Scholar] [CrossRef] [PubMed]
  57. Vieux, F.; Rémond, D.; Peyraud, J.L.; Darmon, N. Approximately half of total protein intake by adults must be animal-based to meet nonprotein, nutrient-based recommendations, with variations due to age and sex. J. Nutr. 2022, 152, 2514–2525. [Google Scholar] [CrossRef] [PubMed]
  58. Ridoutt, B. Diet and environmental sustainability: A review of Australian evidence. Dietetics 2025, 4, 5. [Google Scholar] [CrossRef]
  59. Ridoutt, B.G.; Baird, D.; Anastasiou, K.; Hendrie, G.A. Diet quality and water scarcity: Evidence from a large Australian population health survey. Nutrients 2019, 11, 1846. [Google Scholar] [CrossRef]
  60. Ridoutt, B.; Anastasiou, K.; Baird, D.; Navarro Garcia, J.; Hendrie, G. Cropland footprints of Australian dietary choices. Nutrients 2020, 12, 1212. [Google Scholar] [CrossRef]
  61. Ridoutt, B.; Baird, D.; Hendrie, G.A. Diets within environmental limits: The climate impact of current and recommended Australian diets. Nutrients 2021, 13, 1122. [Google Scholar] [CrossRef]
  62. Ridoutt, B.; Baird, D.; Navarro, J.; Hendrie, G.A. Pesticide toxicity footprints of Australian dietary choices. Nutrients 2021, 13, 4314. [Google Scholar] [CrossRef]
  63. Ridoutt, B.; Baird, D.; Hendrie, G.A. Diets with higher vegetable intake and lower environmental impact: Evidence from a large Australian population health survey. Nutrients 2022, 14, 1517. [Google Scholar] [CrossRef] [PubMed]
  64. Australian Bureau of Statistics. 4364.0.55.007—Australian Health Survey: Nutrition First Results—Foods and Nutrients, 2011–2012; Australian Bureau of Statistics: Canberra, Australia, 2014. [Google Scholar]
  65. Australian Bureau of Statistics. 4363.0.55.001—Australian Health Survey: Users’ Guide, 2011–2013; Australian Bureau of Statistics: Canberra, Australia, 2013. Available online: https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4363.0.55.001main+features12011-13# (accessed on 15 July 2025).
  66. National Health and Medical Research Council. Australian Dietary Guidelines Summary; National Health and Medical Research Council: Canberra, Australia, 2013. [Google Scholar]
  67. Nutrient Reference Values for Australia and New Zealand. Available online: https://www.nrv.gov.au/introduction (accessed on 4 September 2019).
  68. Ridoutt, B.G.; Baird, D.; Anastasiou, K.; Hendrie, G.A. An assessment of the water use associated with Australian diets using a planetary boundary framework. Public Health Nutr. 2021, 24, 1570–1575. [Google Scholar] [CrossRef] [PubMed]
  69. Mayberry, D. Red Meat Greenhouse Gas Emissions Update 2021; Meat and Livestock Australia: Sydney, Australia, 2024; Available online: https://www.mla.com.au/contentassets/5466704f42844b80b1ebea0cd40dacd5/red-meat-emissions-update-2021.pdf (accessed on 22 July 2024).
  70. Ridoutt, B. Equivalence—A useful yet complex concept in natural resource science. Resources 2024, 13, 145. [Google Scholar] [CrossRef]
  71. Ridoutt, B.G.; Baird, D.; Hendrie, G.A. Diets within planetary boundaries: What is the potential of dietary change alone? Sustain. Prod. Consum. 2021, 28, 802–810. [Google Scholar] [CrossRef]
  72. Pizzol, M.; Laurent, A.; Sala, S.; Weidema, B.; Verones, F.; Koffler, C. Normalisation and weighting in life cycle assessment: Quo vadis? Int. J. Life Cycle Assess. 2017, 22, 853–866. [Google Scholar] [CrossRef]
  73. Golley, R.K.; Hendrie, G.A. The Dietary Guidelines Index for children and adolescents: What is the impact of the new dietary guidelines? Nutr. Diet. 2014, 71, 210–212. [Google Scholar] [CrossRef]
  74. Vieux, F.; Darmon, N.; Touazi, D.; Soler, L.G. Greenhouse gas emissions of self-selected individual diets in France: Changing the diet structure or consuming less? Ecol. Econ. 2012, 75, 91–101. [Google Scholar] [CrossRef]
  75. Food Standards Australia New Zealand. Australian Food Composition Database. Available online: https://www.foodstandards.gov.au/science/monitoringnutrients/afcd/pages/default.aspx (accessed on 15 February 2021).
  76. Hendrie, G.A.; Baird, D.; Ridoutt, B.; Hadjikakou, M.; Noakes, M. Overconsumption of energy and excessive discretionary food intake inflates dietary greenhouse gas emissions in Australia. Nutrients 2016, 8, 690. [Google Scholar] [CrossRef]
  77. Overweight and Obesity. Available online: https://www.aihw.gov.au/reports/overweight-obesity/overweight-and-obesity/contents/about (accessed on 2 May 2025).
  78. Simon, W.; Hijbeek, R.; Frehner, A.; Cardinaals, R.; Talsma, E.F.; Van Zanten, H. 40:60: The Optimal Ratio Between Animal and Plant-Based Proteins for Health and Environment. Preprint 2023. (Version 1). [Google Scholar] [CrossRef]
  79. Fouillet, H.; Dussiot, A.; Perraud, E.; Wang, J.; Huneau, J.-F.; Kesse-Guyot, E.; Mariotti, F. Plant to animal protein ratio in the diet: Nutrient adequacy, long-term health and environmental pressure. Front. Nutr. 2023, 10, 1178121. [Google Scholar] [CrossRef] [PubMed]
  80. Grasso, A.C.; Besselink, J.J.F.; Tyszler, M.; Bruins, M.J. The potential of food fortification as an enabler of more environmentally sustainable, nutritionally adequate diets. Nutrients 2023, 15, 2473. [Google Scholar] [CrossRef] [PubMed]
  81. Messina, M.; Duncan, A.M.; Glenn, A.J.; Mariotti, F. Perspective: Plant-based meat alternatives can help facilitate and maintain a lower animal to plant protein intake ratio. Adv. Nutr. 2023, 14, 392–405. [Google Scholar] [CrossRef] [PubMed]
  82. Liyanapathirana, N.N.; Grech, A.; Li, M.; Malik, A.; Lenzen, M.; Raubenheimer, D. Nutrient-sensitive approach for sustainability assessment of different dietary patterns in Australia. Am. J. Clin. Nutr. 2022, 115, 1048–1058. [Google Scholar] [CrossRef]
  83. Ridoutt, B.G.; Baird, D.; Hendrie, G.A. The importance of protein variety in a higher quality and lower environmental impact dietary pattern. Public Health Nutr. 2022, 25, 3583–3588. [Google Scholar] [CrossRef]
  84. Larvie, D.Y.; Armah, S.M. Estimating phytate intake from the US diet using the NHANES data. J. Food Compos. Anal. 2021, 102, 104050. [Google Scholar] [CrossRef]
  85. Ma, T.T.; Sun, Q.; Ba, G.N.; Wu, X.; Pei, X.W.; Sun, C.; Tan, S.J.; Wan, Z.X. Effects of low phytate soymilk intake on calcium, iron and zinc status in male Sprague-Dawley rats. J. Funct. Foods 2023, 106, 105595. [Google Scholar] [CrossRef]
  86. Amirabdollahian, F.; Ash, R. An estimate of phytate intake and molar ratio of phytate to zinc in the diet of the people in the United Kingdom. Public Health Nutr. 2010, 13, 1380–1388. [Google Scholar] [CrossRef]
  87. Schlemmer, U.; Frølich, W.; Prieto, R.M.; Grases, F. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis. Mol. Nutr. Food Res. 2009, 53 (Suppl. S2), S330–S375. [Google Scholar] [CrossRef]
  88. Grech, A.; Hasick, M.; Gemming, L.; Rangan, A. Energy misreporting is more prevalent for those of lower socio-economic status and is associated with lower reported intake of discretionary foods. Br. J. Nutr. 2020, 125, 1291–1298. [Google Scholar] [CrossRef]
  89. Ridoutt, B.G.; Hendrie, G.A.; Noakes, M. Dietary strategies to reduce environmental impact: A critical review of the evidence base. Adv. Nutr. 2017, 8, 933–946. [Google Scholar] [CrossRef]
  90. Hall, K.D.; Guo, J.; Dore, M.; Chow, C.C. The progressive increase of food waste in America and its environmental impact. PLoS ONE 2009, 4, e7940. [Google Scholar] [CrossRef]
Table 1. Characteristics of the higher diet quality and lower environmental impact (HQLI) subgroup (n = 1589) compared to the population estimate (n = 9341).
Table 1. Characteristics of the higher diet quality and lower environmental impact (HQLI) subgroup (n = 1589) compared to the population estimate (n = 9341).
CharacteristicHQLI SubgroupPopulation Estimatep-Value
Diet-quality score (out of 100)58.542.6<0.001
Climate footprint (kg CO2-e day−1)1.272.06<0.001
Water-scarcity footprint (L-e day−1)254394<0.001
Cropland-scarcity footprint (m2y-e day−1)4.476.89<0.001
Pesticide-toxicity footprint (points day−1)13.725.1<0.001
BMI category (%) <0.001
  Underweight1.01.5
  Normal range27.930.7
  Overweight29.731.3
  Obese23.621.9
Dairy avoidance (%)5.74.70.022
Activity level (past week) (%) 0.056
  Inactive18.220.4
  Insufficiently active28.326.4
  Sufficiently active52.752.5
Smoking status (%) <0.001
  Current daily smoker11.215.8
  Current occasional smoker1.21.9
  Ex-smoker29.430.8
  Never smoked58.151.6
Level of highest education (%) 0.002
  Postgraduate9.18.8
  Bachelor18.518.2
  Certificate/Diploma30.834.8
  Without post-school qualification39.636.7
Socio-Economic Index (%) 0.011
  Lowest 20%18.017.9
  Second quintile21.620.4
  Third quintile20.520.0
  Fourth quintile20.519.3
  Highest 20%19.522.3
Table 2. Nutrient density of the higher diet quality and lower environmental impact (HQLI) subgroup (n = 1589) compared to the population estimate (n = 9341). Listing is by order of % difference.
Table 2. Nutrient density of the higher diet quality and lower environmental impact (HQLI) subgroup (n = 1589) compared to the population estimate (n = 9341). Listing is by order of % difference.
NutrientHQLI SubgroupPopulation EstimateDifference (%) 1
LCn3 (mg MJ−1) 248.334.639.5 **
Dietary fiber (g MJ−1)3.62.730.8 **
Dietary folate equivalents (μg MJ−1)93.974.426.3 **
Retinol equivalents (μg MJ−1)126.9100.825.8 **
Thiamin (B1) (mg MJ−1)0.230.1823.1 **
Iron (mg MJ−1)1.581.3120.7 **
Zinc (mg MJ−1)1.541.3018.6 **
Magnesium (mg MJ−1)46.840.515.7 **
Potassium (mg MJ−1)39734614.8 **
Protein (g MJ−1)12.110.712.6 **
Vitamin E (mg MJ−1)1.371.2212.3 **
Iodine (μg MJ−1)23.320.812.3 **
Riboflavin (B2) (mg MJ−1)0.250.2212.0 **
Niacin (B3) equivalents (mg MJ−1)5.454.8911.6 **
Caffeine (mg MJ−1)24.021.710.8 **
Selenium (μg MJ−1)11.810.89.2 **
Phosphorus (mg MJ−1)1891739.2 **
Calcium (mg MJ−1)105968.9 **
Alpha-linolenic acid (g MJ−1)0.170.167.7 **
Vitamin B12 (μg MJ−1)0.570.536.3 **
Vitamin C (mg MJ−1)13.312.56.3 **
Vitamin B6 (mg MJ−1)0.190.185.2 **
Total carbohydrates (g MJ−1)27.126.23.6 **
Polyunsaturated fatty acids (g MJ−1)1.341.302.9 **
Linoleic acid (g MJ−1)1.081.080.7
Sodium (mg MJ−1)285287−0.8
Monounsaturated fatty acids (g MJ−1)3.073.18−3.5 **
Total fats (g MJ−1)7.98.3−5.5 **
Sugars (g MJ−1)11.111.9−7.4 **
Trans-fatty acids (mg MJ−1)136156−13.2 **
Saturated fatty acids (g MJ−1)2.693.11−13.4 **
Alcohol (g MJ−1)0.471.56−69.9 **
1 ** p < 0.01. 2 Long-chain omega-3 polyunsaturated fatty acids.
Table 3. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia (1589 diets): Protein intake and source.
Table 3. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia (1589 diets): Protein intake and source.
Animal/Plant Protein RatioHQLI Diets
(%)		Total Protein (g)Total Energy Intake (kJ)
<20% animal protein6.266.87804
20 to <40% animal protein16.165.37494
40 to <60% animal protein31.080.67512
60 to <80% animal protein38.196.77246
80% animal protein and above8.5115.46385
Table 4. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Mean servings of protein-rich food choice (servings per person) according to animal/plant protein ratio 1.
Table 4. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Mean servings of protein-rich food choice (servings per person) according to animal/plant protein ratio 1.
Food Group 2% Animal Protein
<2020 to <4040 to <6060 to <8080+
Meats and alternatives1.300.891.722.853.96
 Seafood0.000.130.190.390.41
 Beef and lamb0.020.170.451.412.23
 Poultry0.020.100.410.600.93
 Pork0.020.020.130.090.07
 Eggs0.020.050.150.160.20
 Other plant choices1.220.430.400.210.14
Dairy and alternatives0.720.961.191.181.00
1 Animal/plant protein ratio refers to % of total dietary protein intake. 2 Protein-rich food groups include meats and alternatives (including seafood, eggs, tofu, nuts and seeds, and legumes/beans) and dairy and alternatives (including milk, yogurt, cheese and/or their plant-based alternatives provided they contain at least 100 mg of calcium per 100 mL).
Table 5. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Percent of the subgroup meeting Estimated Average Requirements (EARs) 1 according to animal/plant protein ratio 2.
Table 5. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Percent of the subgroup meeting Estimated Average Requirements (EARs) 1 according to animal/plant protein ratio 2.
Nutrient% Animal Protein
<2020 to <4040 to <6060 to <8080+
Niacin (B3) 398.799.699.7100.0100.0
Phosphorus94.095.297.799.899.9
Protein75.685.393.898.699.8
Folate 489.581.488.188.570.5
Iron86.283.379.687.281.4
Vitamin C83.587.785.181.868.3
Iodine66.975.982.382.071.4
Vitamin B1239.758.884.692.395.6
Riboflavin (B2)62.564.581.483.276.2
Selenium56.057.477.886.686.6
Thiamin (B1)67.967.170.073.346.9
Magnesium74.960.158.355.938.9
Zinc46.045.052.468.574.3
Vitamin A 555.763.054.655.335.3
Vitamin B641.143.945.551.445.2
Calcium26.125.935.832.919.4
Average66.568.474.277.369.4
1 EARs are as defined by the Nutrient Reference Values published by the National Health and Medical Research Council in Australia [67]. 2 Animal/plant protein ratio refers to % of total dietary protein intake. 3 Niacin equivalents. 4 Dietary folate equivalents. 5 Retinol equivalents.
Table 6. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Mean percent of Estimated Average Requirements (EARs) 1 met according to animal/plant protein ratio 2.
Table 6. The higher diet quality and lower environmental impact (HQLI) subgroup of adult (19 years old and above) daily diets in Australia: Mean percent of Estimated Average Requirements (EARs) 1 met according to animal/plant protein ratio 2.
Nutrient% Animal Protein
<2020 to <4040 to <6060 to <8080+
Niacin (B3) 399.899.9100.0100.0100.0
Phosphorus98.599.299.799.9100.0
Protein95.596.799.299.8100.0
Folate 497.395.896.596.389.6
Iron95.595.995.197.195.3
Vitamin C89.195.593.993.587.4
Iodine87.693.095.595.390.1
Vitamin B1264.884.595.098.099.5
Riboflavin (B2)90.089.995.195.994.1
Selenium86.590.495.497.797.0
Thiamin (B1)93.892.592.993.782.1
Magnesium93.790.591.191.484.4
Zinc85.282.787.892.293.2
Vitamin A 579.685.983.081.868.4
Vitamin B680.379.682.686.282.5
Calcium68.969.974.573.161.3
Average87.990.192.393.389.1
1 EARs are as defined by the Nutrient Reference Values published by the National Health and Medical Research Council in Australia [67]. 2 Animal/plant protein ratio refers to % of total dietary protein intake. 3 Niacin equivalents. 4 Dietary folate equivalents. 5 Retinol equivalents.
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Ridoutt, B.; Baird, D.; Hendrie, G.A. Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts. Dietetics 2025, 4, 35. https://doi.org/10.3390/dietetics4030035

AMA Style

Ridoutt B, Baird D, Hendrie GA. Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts. Dietetics. 2025; 4(3):35. https://doi.org/10.3390/dietetics4030035

Chicago/Turabian Style

Ridoutt, Bradley, Danielle Baird, and Gilly A. Hendrie. 2025. "Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts" Dietetics 4, no. 3: 35. https://doi.org/10.3390/dietetics4030035

APA Style

Ridoutt, B., Baird, D., & Hendrie, G. A. (2025). Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts. Dietetics, 4(3), 35. https://doi.org/10.3390/dietetics4030035

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