Grain foods collectively, whether through enrichment and/or fortification practices, are an integral part of American dietary practices. Grains represent a key component of energy and nutrients in the 2015–2020 Dietary Guidelines for Americans (2015–2020 DGA) dietary patterns, such that at the 2000 calorie level, both the Healthy U.S.- and Healthy Mediterranean-Style patterns recommend six ounce-equivalent (oz. eq.) servings, daily, of grains, with half of those servings being whole grains, while the Healthy Vegetarian eating pattern recommends 6.5 oz. eq. daily servings of grains, with 3.5 oz. eq. stemming from whole grains [1
]. The 2015–2020 DGA places emphasis on increasing consumption of whole grains and concurrently limiting consumption of refined and/or enriched grain foods. While certain grains foods may contain higher levels of nutrients to limit, including added sugar, saturated fat, and sodium, many grain foods contribute positive nutrition to the American diet, and are important contributors of the shortfall nutrients. Recently, secondary analyses of the National Health and Nutrition Examination Survey (NHANES) 2005–2010 identified several grain food patterns of consumption in U.S. adults and reported an association between grain food consumption and nutrient intakes, such that several grain food patterns were linked with greater nutrient intakes, including higher intake of shortfall nutrients and nutrients of public health concern as identified by the 2015–2020 DGA [2
]. Similarly, certain grain food patterns in children and adolescents, including both whole and refined grains were associated with greater intakes of shortfall nutrients and/or nutrients of concern, including iron, magnesium, vitamin D, dietary fiber, and folate when compared to children and adolescents consuming non-grain dietary patterns [3
Classifying all grains that are not whole grains into the one category of refined grains may not be a justified representation of the nutrient contribution provided by many nutrient-dense enriched grain foods, including breads, rolls, cooked cereals, and ready-to-eat cereals. Since less than 5% of Americans consume the minimum recommended amount of whole grains, with the average American consuming less than one oz. eq. of whole grains per day [1
], it can be assumed that the predominant type of grains consumed by Americans, as collected by NHANES, are refined/enriched grains. Recent analyses using NHANES 2009–2012 demonstrated that grain foods are contributors of the 2015–2020 DGA underconsumed nutrients and nutrients of public health concern [5
], including dietary fiber, folate, magnesium, calcium, and iron. When considering sub-categories of grain foods, breads, rolls and tortillas, and ready-to-eat cereals were meaningful contributors (i.e., ≥10% in the diet) of dietary fiber, thiamin, folate, iron, zinc and niacin to the American diet of children and adolescents.
The nutritional contribution of specific grain foods in the diet of American adults by gender is limited, thus, the objective of the present analyses was to determine sources of energy and nutrients, with particular focus on shortfall nutrients, from commonly-consumed grain foods in U.S. adults using data from NHANES, 2009–2012.
All grain foods, collectively, in addition to specific grain food groups, are meaningful contributors of nutrient density and provide sources for several shortfall nutrients and nutrients of public health concern (i.e., dietary fiber) as identified by the 2015–2020 DGA. All grain products contributed 14.2% or 285 kcal per day in the total U.S. diet of both genders combined. When considering nutrients to limit as outlined by present and previous dietary guidance [1
], grain foods contributed 7.2% total fat, 5.4% saturated fat and 14.6% sodium, and 7.9% total sugar. Similarly, when considering nutrients to encourage (i.e., underconsumed nutrients and nutrients of public health concern), grain foods are meaningful contributors to the daily diet. Additionally, breads, rolls and tortillas, and ready-to-eat cereals are meaningful contributors of dietary fiber, thiamin, folate, iron, zinc, and niacin to the American diet of adults, while certain grain foods alone provide minimal contributions to the diet, including sweet bakery products. Thus, indulgent grains should be consumed in moderation with attention to limiting total caloric intake. Cumulatively, a variety of grain food groups routinely consumed by adults contribute to nutrient density in the total diet and can be encouraged as part of a healthy dietary pattern, while adhering to authoritative recommendations to limit calories, saturated fat, sodium, and added sugar intake.
Our current analyses also assessed the sources of energy and nutrients from specific grain foods, of which included breads, rolls and tortillas, and ready-to-eat cereals. While breads, rolls, and tortillas contributed less than 9% of all sodium, less than 4% of total fat, and less than 3% saturated fat, breads, rolls, and tortillas provided greater than 10% for dietary fiber, folate, and iron in adult men and women. Similarly, ready-to-eat cereals provided minimal daily contributions of energy (<3%), sodium (<2%), total sugar (<3%), total fat (<1%), and saturated fat (<1%), but meaningful contributions of folate, iron, magnesium, thiamin, vitamin B12
, vitamin A, vitamin D, vitamin E, niacin, and zinc relative to the daily contribution of energy (calories). Since previous data has established that nearly the entire U.S. population consumes a diet with fewer whole grains than recommended [4
], the assumption with the current NHANES analysis is that most of the grains consumed are enriched grain food products. Thus, the nutrient contribution of all whole and refined grain food products, including breads, rolls and tortillas and ready-to-eat cereals, can play a key role in helping American adults meet recommendations for underconsumed nutrients and nutrients of public health concern.
The current adult data are aligned with results found from our data previously published in children and adolescents [5
]. In particular, for children and adolescents 2–18 years-old, all grain products contributed 14% or 263 kcal per day. In analyses focused on nutrients to encourage (i.e., underconsumed nutrients and nutrients of public health concern), NHANES 2009–2012 data provided evidence that grain foods were meaningful contributors of nutrient density in the American diet of children and adolescents throughout the various age groups examined. The data also showed breads, rolls and tortillas, and ready-to-eat cereals to be meaningful contributors of several nutrients, including dietary fiber, thiamin, folate, iron, zinc, and niacin to children and adolescents. The research concluded that a variety of grain food groups consumed by American children and adolescents contribute to nutrient density in the total diet and should be encouraged as part of a healthy dietary pattern.
It has been recently stated that food processing as an industry may be the stepping stone to urbanization [13
]. However, in recent years, a negative perception of processed foods, including many foods within the grains food group, have been misperceived as non-nutrient dense foods that are not compatible within a healthy dietary pattern. Indeed, in recent years processed foods have been reformulated to be lower in total and saturated fat, reduced calories, less sodium, and added sugars [14
]. A previous NHANES analysis evaluating the contribution of processed foods to nutrients to encourage and nutrients to limit, as recommended by dietary guidance over a 30-year period in individuals ≥2 years-old, found that energy and sodium intakes significantly increased since the 1970s, but have remained constant since the 1980s and 1990s, while saturated fat, measured as grams per day or as a percentage of calories, significantly declined from the late 1970s to the 2000s [13
Consumers may also be questioning nutrient bioavailability and the public health value of enrichment and/or fortification practices. The 1998 mandatory folic acid fortification of cereal grain products labeled as enriched in the U.S. contributed to a 36% reduction in neural tube defects from 1996 to 2006 and prevented an estimated 10,000 neural tube defect-affected pregnancies, leading the Centers for Disease Control and Prevention to identify folate fortification as one of the top ten public health achievements in the U.S. [15
]. Similarly, an expert working group in the U.S. and Canada found that wheat flour fortification which provided an additional intake of approximately 100–150 µg/day of folic acid significantly lowered prevalence of neural tube defects at birth. The report also found that most adverse effects associated with folic acid overconsumption in adults was related to supplement use and not mandatory food fortification [16
]. The International Life Sciences Institute North American committee on Fortification in collaboration with the American Society of Nutrition indicated that future directions in discretionary fortification requires monitoring across all age groups and genders, particularly individuals who are more likely to consume both fortified foods and supplements [17
]. Micronutrient malnutrition can have adverse outcomes on health, even at moderate levels of deficiency and in industrialized countries, like the U.S., factors that contribute to reducing the risk and prevalence of micronutrient malnutrition includes greater access to nutrient-rich and fortified foods, high-quality health services and higher income levels [18
]. Indeed, food fortification has a long history in the U.S. and other industrialized countries, and provides several advantages when properly administered. Food fortification of commonly-consumed and widely-available foods, such as grain-based foods, have the potential to improve the nutritional status of a substantial portion of the population, independent of income status, with the caveat that fortified foods are included as part of a healthy dietary pattern [15
]. This implies that fortified foods play an important role in the American diet, provided that dietary recommendations are met. Importantly, all grain food consumption, whether whole or enriched grains, should be incorporated as part of a recommended dietary pattern. Dietary guidelines promote consuming healthy eating patterns at appropriate calorie levels for age and gender, of which includes choosing a variety of nutrient-dense foods across and within all food groups in recommended amounts. Dietary guidance also promotes increasing whole grains, fruits and vegetables, low-fat dairy foods, and lean protein foods while limiting added sugars, saturated fat, sodium, and total energy [1
Previous work using NHANES 2003–2006 has examined the nutrient contribution of processed foods, where nutrients were added via enrichment (i.e., replacing nutrient in the food lost during processing) or fortification (i.e., adding nutrients to the food at higher levels than naturally present). Enriched foods included grain products, with particular focus on breads, while fortified foods included ready-to-eat cereals (i.e., fortified with folate, iron, and other nutrients) and milk (i.e., fortified with vitamins A and D). The researchers found that if enrichment and fortification practices were not utilized in the food supply, large percentages of the American population would have inadequate intakes of vitamin A, vitamin C, vitamin D, vitamin E, thiamin, folate, calcium, magnesium, and iron. In contrast, when nutrients from enrichment and fortification were added to the dietary analysis, the percentages of the population with inadequate intakes was meaningfully decreased for vitamin A, vitamin D, folate, and iron [19
]. Likewise, an analysis with 2007–2010 NHANES data to model the potential impact of a lack of fortification on overall dietary intake in children and adolescents (2–18 years-old) and adults (19–99 years-old) verified the important role ready-to-eat cereal fortification provides to help achieve nutrient recommendations. Among children and adolescents with intake below the estimated average requirement (EAR), significant nutrient increases resulting from consumption of fortified ready-to-eat cereals ranged from 3.3% for vitamin D (D2
) to 161.5% for folate. There were also significant increases in iron, thiamin, riboflavin, vitamin A, vitamin B6; vitamin E, niacin, and zinc. Similarly, in adults, significant percentage increases for nutrients below EAR ranged from 8.3% for magnesium to 84.8% for folate. Iron, riboflavin, thiamin, vitamin A, vitamin B12
, vitamin B6
, zinc, niacin, and vitamin E also significantly increased as a result of ready-to-eat cereal fortification [16
]. Previous work in Americans aged ≥2 years-old, identified significant amounts of vitamins A, B6
, C, and D, as well as thiamin, riboflavin, niacin, folate and iron were from enriched and/or fortified foods, suggesting that without enrichment and/or fortification, nutrient recommendation shortfalls may be further exacerbated [20
], further providing evidence to advocate for the beneficial role processed foods can play in promoting public health. Data from the National Health and Nutrition Examination Survey (NHANES) 2003–2006, showed fortification of grain foods provides nutrient adequacy for U.S. children and adolescents, without concern for excessive intakes for most vitamins and minerals [21
]. Others have shown that without fortification and enrichment, 20% of the U.S. population would fall below the EAR for iron, with this percentage being lowered to approximately 6% when including enriched and fortified foods [20
]. The most robust effects of enrichment and fortification practices have been documented with thiamin and folic acid, nutrients typically added to grain foods through enrichment and fortification practices. Data have shown that without enrichment and fortification, 50% of the U.S. population would have inadequate intakes compared with only 5% when enrichment and fortification are included. Similarly, for folic acid, when not considering mandatory and discretionary enrichment and fortification, nearly 90% of Americans would have inadequate intake versus only 10% with enriched and fortified food consumption [14
]. Thus, fortified and enriched foods [19
], including the grain food category, are a key component of healthy dietary patterns and may provide indispensable benefits to eating patterns by helping individuals attain dietary adequacy.
The current analyses have limitations inherent within observational research and have previously been documented. The results are dependent on self-reported dietary data for foods, which may involve study participants under- or over-estimating food consumption, leading to inaccuracies in energy and nutrient intakes. Data were also obtained using a 24-h dietary recall, which relies on study participant memory and while validated methods are used to gather the data, recall information is subject to inaccuracies and bias from memory challenges and other potential measurement errors experienced in epidemiological investigations using large datasets [23
]. Caution should be administered when comparing the current findings to previous studies as food groupings can impact sources of energy and nutrient outcomes, specifically where there are differences in the level of aggregation (i.e., the number of food groups) or disaggregation methods used by researchers. A significant benefit of using NHANES data for the current analyses includes access to a large and nationally representative dataset of adults in the U.S. and corresponding food, energy and nutrient intake data.