Effect of Adding Pulses to Replace Protein Foods and Refined Grains in Healthy Dietary Patterns

Pulses are dry seeds of legumes which are high in fiber and contain plant protein and several important macronutrients. Our aim was to model the nutritional effects of substituting servings of protein foods and/or refined grains with servings of beans and peas in the Healthy U.S.-Style Pattern identified in the Dietary Guidelines for Americans, 2020–2025. Dietary modeling was accomplished by substituting nutrients of protein foods and/or refined grains with nutrients of the USDA’s beans and peas (pulses) composite in the 2000 kcal Healthy U.S.-Style Pattern. A 10% or more change was used as an indicator of meaningful differences. Cost implications were computed by adding the cost of pulses and subtracting the cost of protein foods/refined grains according to the modeling scenario. The substitution of 6–8 oz/week protein foods with 1.5–2.0 cups/week pulses increased fiber and decreased cholesterol. Higher amounts of pulses replacing refined grains or combinations of protein foods and refined grains generally increase fiber, iron, magnesium, potassium, and copper depending on the modeling scenarios. All modeling scenarios of substituting the servings of protein foods alone or in combination with refined grains with the servings of pulses were associated with cost savings. Our results suggest that encouraging increased pulse consumption may be an effective strategy for improving diet.


Introduction
Pulses are the dry seeds of legumes (e.g., dry peas, lentils, chickpeas, and dry beans) which are high in fiber, plant protein, and several important macronutrients, which are important components of healthy diets.Pulses are defined as dry harvested legumes, beans, peas, lentils, and chickpeas; however, legumes with a high amount of moisture or fat/oil at harvest, such as fresh beans, peas, edamame, and peanuts, are not considered as part of pulses [1][2][3][4].Pulses are a nutrient-dense food that contain many nutrients, such as complex carbohydrate, protein, fiber, folate, iron, magnesium, potassium, choline, zinc, selenium, and phosphorus, and also contain phytochemicals or bioactive nutrients [3][4][5][6].In a recently published analysis of the National Health and Nutrition Examination Survey (NHANES) data, a regular consumption of pulses was found to improve the diet quality and nutrient density of the diet of U.S. adults [7].Recent scientific evidence also suggests a beneficial role of pulses in reducing the risk of chronic diseases such as CVD [8][9][10][11], cancer [12][13][14], diabetes [15], and obesity [16,17], and the overall mortality risk [18].Pulses have also been identified to play a potential role in sustainable food systems [19].
Pulses are consistently included in food-based dietary guidelines globally as part of the vegetable and/or protein food groups or as a separate food group [2,3,20].In the U.S., the Dietary Guidelines for Americans 2020-2025 (DGA) indicated that the beans, peas and lentils (pulses) can be considered as part of the vegetable or protein food groups, but should be counted in only one food group [21].The USDA's Choose MyPlate [22] considers beans, peas, and lentils (pulses) as a part of the vegetable group and also a part of protein foods as they are an excellent source of fiber, folate, and potassium, like vegetables, and are excellent sources of plant protein that also provides iron and zinc like other protein foods.DGA recommend consuming 1.5 cups of pulses per week as part of healthy diets [21].Specifically, the USDA's Healthy Dietary Patterns (Healthy U.S.-Style Pattern, Healthy Vegetarian Style Pattern, and Healthy Mediterranean Style Pattern), that were released as part to DGA to help individuals follow the DGA recommendations, include 1.5 cups of pulses per week as part of the vegetables group.In the Healthy Vegetarian Style Pattern, 6 oz eq/week (or 1.5 cups/week) of pulses are also recommended as a part of the protein foods [21,23].The recent Eat Lancet Commission Planetary Health Diet recommended consuming 100 g/day or 0.5 cups/day (50 g of dried beans, lentils, and peas; 25 g of soybeans; and 25 g of peanuts) as a part of nutritious and environmentally sustainable dietary patterns [24].However, only ~27% of adult Americans consume pulses on any given day with an average daily consumption of less than 0.5 cup equivalent per day, according to a recent analysis of the NHANES 2013-2014 data [7].
We hypothesize that since pulses have high amounts of protein and are rich in carbohydrate, they could be used as a replacement of animal protein and refined grains.A key objective of current research was to model the effect of increasing the amounts of pulses (dry peas, lentils, chickpeas, dry beans, and canned beans) in the Healthy U.S.-Style Pattern identified in the Dietary Guidelines for Americans 2020-2025 from 1.5 cups/week to up to 3.5 cups/week as a replacement of current protein foods.Additional objectives included examining the impact of pulses replacing refined grains since pulses also contain high amounts of carbohydrates and also simultaneously replace a combination of refined grains and current protein foods.

Materials and Methods
To achieve the objectives of this study, we used the USDA's dietary modeling approach [23].Briefly, the USDA's Food Patterns provide amounts of foods from the five major food groups and subgroups, including (1) Fruits; (2) Vegetables (dark green, red, and orange, beans and peas, starchy, and other); ( 3) Dairy (milk, cheese, yogurt, includes calcium-fortified soy beverages); (4) Grains (whole grains and refined grains); and (5) Protein Foods (meats, poultry, and eggs; seafood; nuts, seeds, and soy products).The USDA creates food item clusters of the food groups and then determines the amounts of energy and nutrients that would be obtained by consuming various foods within each group.With this basic information, the USDA then develops dietary patterns with the suggested levels of consumption of each food group/sub-group and confirms that the patterns meet the caloric and nutrient needs for numerous sub-population groups.We chose to focus on making changes to the protein foods consumed (decrease other protein food amounts and increase pulses amount) and/or refined grains (decrease refined grain amounts and replace with pulses).Thus, the following dietary modeling scenarios were used for modeling the 2000 kcal Healthy U.S.-Style Pattern: 1.
Replacing 1, 2, 4, 6, and 8 oz eq/week of current protein foods (mix of protein foods: meat, chicken, fish, eggs, nuts, etc.) as provided by the USDA's Food Pattern Modeling Report [23] with 0.25, 0.5, 1.0, 1.5, and 2.0 cups/week, respectively, of pulses.Since 2000 kcal Healthy U.S.-Style Pattern includes 1.5 cups/week of beans and peas (pulses), this additional 0.25 to 2.0 cups/week would increase the total amount of beans and peas to 1.75 to 3.5 cups/week.2.

3.
Replacing the combinations of 2 oz eq/day of current protein foods and 1, 2, and 3 oz eq/day of refined grains with 1, 1.5, and 2.0 cups/day of pulses.

4.
Replacing the combinations of 4 oz eq/day of current protein foods and 1, 2, and 3 oz eq/day of refined grains with 1.5, 2.0, and 2.5 cups/day of pulses.
The base nutritional profile of 2000 kcal Heathy U.S.-Style Pattern was obtained from the Food Pattern Modeling Report [23] and is presented in Table 1.
The nutrient profile of the USDA's Beans and Peas (pulses) composite was obtained from the Food Pattern Modeling Report [23].The USDA's Beans and Peas composite (with representative food in parentheses) includes 14.3% black beans (Black, brown, or Bayo beans; dry, cooked, fat not added in cooking); 5.4% chickpeas (Chickpeas; dry, cooked, fat not added in cooking); 0.3% cowpeas (Cowpeas; dry, cooked, fat not added in cooking); 12.1% Kidney beans (cooking); 7.6% lentils (Lentils; dry, cooked, fat not added in cooking); 0.5% lima beans (includes fava and mung beans, lima beans; dry, cooked, fat not added in cooking); 41.9% pinto beans (includes pink beans, yellow beans, Pinto, calico, or red Mexican beans; dry, cooked, fat not added in cooking); 1.3% soybeans/Edamame (Soybeans; cooked, fat not added in cooking); 0.8% split peas (Green or yellow split peas; dry, cooked, fat not added in cooking); 2.7% unknown legumes (White beans; dry, cooked, fat not added in cooking); and 13.0% white beans (White beans; dry, cooked, fat not added in cooking).However, Soybean/Edamame included in the USDA's composite was in the pods of green legumes (not dried like other beans and peas); therefore, we used a modified USDA's beans and peas composite which was developed by proportionally subtracting the nutritional contribution of edamame (nutritional profile obtained from the USDA's FoodData Central, FCD ID: 2342911) [25] and adjusting the calories from the rest of the composite.The nutritional composition of the revised composite without edamame are also presented in Table 1.The amounts of pulses in cups/day used in different modeling scenarios are presented in Supplemental Table S1.The protein foods composite in the USDA's Food Pattern Modeling Report [23] includes 38.21% Red meats, 29.39% Poultry, 2.71% High omega 3 fish, 5.95% Low omega 3 fish, 9.44% Eggs, 1.78% Soy Products, and 12.51% Nuts/Seeds.The nutritional profiles of each component were obtained from the Food Pattern Modeling Report [23] and the nutritional composite of protein foods was computed by adding the nutrients of each individual component in the above proportion and is provided in Table 1.The nutrient profile of Refined Grains was also obtained from the USDA's Food Pattern Modeling Report [23] and is also provided in Table 1.
Dietary modeling was accomplished by substituting the nutrients from protein foods and refined grains (alone or in combination) with the nutrients from pulses in the desired amounts and modified nutrient profiles were created using Microsoft Excel (Version 2019, Microsoft, Inc., Redmond, WA, USA).A change of 10% or more in nutrients due to the dietary modeling analyses of the 2000 kcal Healthy U.S.-Style Pattern was used as an indicator of meaningful differences.
The cost of beans and peas (pulses) replacing current protein foods and/or refined grains was estimated by linking the Purchase to Plate National Average Prices (PP-NAP) database [26] (from the USDA's Economic Research Service) for 2015-2016 with the food codes from the Food Patterns Equivalent Database (FPED) 2015-2016 [27] for the representative foods provided in the Food Modeling Report [23].Cost implications were computed by adding the cost of pulses and subtracting the cost of protein foods/refined grains according to the modeling scenario.

Results
Substituting 6 and 8 oz eq/week of protein foods with 1.5 and 2 cups/week of beans and peas (pulses) without edamame increased fiber and decreased cholesterol by more than 10% from the baseline.However, changes in the other nutrients did not reach our a priori defined 10% cutoff point.Substituting protein foods with lower amounts of pulses did not result in changes in any nutrients by more than 10% from the baseline (Table 2).Substituting 1 oz eq/day of refined grains with 0.5 cups/day of pulses increased fiber, magnesium, potassium, and copper by more than 10% from the baseline; substituting 2 to 4 oz/day of refined grains with 1 to 2 cups/day of pulses increased protein, fiber, iron, magnesium, phosphorus, potassium, zinc, copper, vitamin B 6 , and choline, and decreased sodium by more than 10% from the baseline (Table 3).Additionally, replacing 3 and 4 oz eq/day of refined grains with 1.5 and 2.0 cups/day of pulses also increased vitamin E and decreased niacin by more than 10% from the baseline.Selenium also decreased by more than 10% from the baseline in replacing 4 oz eq/day of refined grains with 2 cups/day of beans and peas without edamame (Table 3).Substituting 2 or 4 oz eq/day of protein foods in combination with 1 to 3 oz eq/day of refined grains with 1.0 to 2.5 cups/day of pulses consistently increased carbohydrate, fiber, iron, magnesium, potassium, and copper, and it decreased cholesterol, sodium, selenium, niacin, and vitamin B 12 by more than 10% from the baseline (Table 4).Substituting 4 oz/day of protein foods in combination with 1 to 3 oz eq/day of refined grains with 1.5 to 2.5 cups/day of pulses additionally increased thiamine and decreased total fat, saturated fat, and riboflavin by more than 10% from the baseline.Total fat and saturated fat also decreased, and protein increased for the replacement of a combination of 2 oz eq/day of protein foods and 3 oz/day of refined grains with 2.0 cups/day of pulses.Additionally, phosphorus increased in the substitution scenarios involving the combinations of 2 oz/day of protein foods and 1.5 and 2.0 oz eq/day of refined grain, and 4 oz eq/day of protein foods and 2.0 and 2.5 oz eq/day of refined grain; zinc increased in 2 oz eq/day of protein foods and 3.0 oz eq/day of the refined grain substitution scenario; vitamin D decreased in all modeling scenarios except for the substitution of 2 oz eq/day of protein foods and 1 oz eq/day of the refined grain combination; and choline decreased for the substitution of 4 oz eq/day of protein foods and 1 to 2 oz eq/day refined grain (Table 4).The substitution of protein (alone or in combination with refined grains) with pulses were also associated with cost savings whereas the substitution of refined grains with pulses were associated with additional costs (Tables 2-4).

Discussion
The results of the present dietary modeling analysis indicate an additional 1.5 to 2 cups of pulses per week replacing protein foods would increase fiber and decrease cholesterol by more than 10% from the baseline while higher amounts of pulses replacing refined grains or combinations of protein foods and refined grains would consistently increase fiber, iron, magnesium, potassium, and copper in the 2000 kcal Healthy U.S.-Style Pattern.
Replacing pulses for current protein sources only increased dietary fiber and decreased cholesterol when larger amounts were replaced.There were changes in the energy intake and in other nutrients, but those changes were less than 10% of the bench mark.Dietary fiber is an essential and important component of a healthy diet and is associated with several health benefits [28].However, more than 90 percent of women and 97 percent of men do not meet the recommended intakes for dietary fiber and DGA has identified it as a dietary component of public health concern for the general U.S. population because low intakes are associated with health concerns [21].In the present modeling analysis, 1.5-2.0cups of pulses per week were needed to improve the fiber intake, which equates to about a 1  4 cup of pulses per day.We think providing information about how much beans and peas to consume on a daily basis is likely to be better received by consumers, which may help with behavioral changes to consume more pulses (e.g., its only 1 /4 c per day).Replacing higher amounts of pulses for refined grains or combinations of protein foods and refined grains consistently increased fiber, iron, magnesium, potassium, and copper by more than 10% from the baseline.Potassium and iron (especially for pregnant women) are also identified as a nutrient of public health concern [21].However similarly, at a higher level of pulses replacing combinations of protein foods and refined grain, while beans, peas, and lentils may be thought of as either a vegetable or a protein food when aiming to meet the recommended intakes since they have a similar nutrient profile to the foods in both the vegetable group and the protein foods group [21].However, the 2005 dietary guidelines advisory committee conducted a comprehensive review of the literature and acknowledged that legumes along with dark green vegetables were relatively high in the nutrients needed to meet the unmet nutrient goals, recommending to preferentially increase their amounts and proposed three cups of legumes/week [32].Subsequently, the Dietary Guidelines 2005 [33] also recommended three cups of legumes/week as part of the vegetable group.However, for unknown reasons, the Dietary Guidelines 2010 and 2015 decreased the recommended amount to 1.5 cups/week as part of healthy dietary patterns [34,35].While 1.5 cups/week is recommended as part of vegetables in dietary patterns that also include meat (Healthy U.S.-Style Pattern and Healthy Mediterranean Style Pattern), an additional amount of 6 oz eq beans, peas, and lentils per week is recommended as part of the protein foods in the Healthy Vegetarian Style Pattern [21,23].The NHLBI's DASH (the Dietary Approaches to Stop Hypertension) diet recommends the consumption of 4 to 5 servings (one serving = 0.5 cup) of nuts, seeds, and legumes per week [36].Regular consumption of 100 g/day or 0.5 cups/day (50 g of dried beans, lentils, and peas; 25 g of soybeans; and 25 g of peanuts) as part of nutritious and environmentally sustainable dietary patterns was also recommended by the recent Eat Lancet Commission Planetary Health Diet [24].In multiple systematic reviews, 2 to 3.5 cups per week (1/2 cup or 100 g per day) was found to be the optimal intake amount associated with a positive health outcome [8,17,37,38].
There has been a consistent and ongoing debate in the scientific community to increase the proportion of plant-based foods (including plant protein foods) in the diets to enhance environmental sustainability and to decrease the chronic disease risk [24,39].Sustainable diets are diets with low environmental impacts, contributing to food security and healthy life, protecting biodiversity and ecosystems, and are affordable and nutritionally adequate [40].Plant-based diets are reported to be more sustainable and have a lower environmental impact [41].In a recent prospective cohort study, healthier plant-based dietary patterns containing legumes were associated with a lower environmental impact and a decreased CVD risk [42].Legumes and pulses are sustainable plant-based foods [19,43] as they contribute to lower greenhouse gas emissions [44], are water efficient [45], and are beneficial for biodiversity and soil health [46].Our results show that pulses are a more affordable source of dietary protein than the current mix of dietary protein in the Healthy U.S.-Style Pattern.
Future research might include modeling increases in pulses using large national representative databases like the NHNAES in the U.S. to assess the specific impact to various sub-groups of the population (e.g., by race/ethnicity, by age/gender groups, by socioeconomic status, etc.).Continual monitoring of the current intake of pulses also seems meritorious, especially given the recent interest in increasing plant-based foods.
The major strengths of our study include the use of the USDA approach on dietary modeling, leveraging pulses' contribution to both protein and carbohydrates (e.g., modeling simultaneous changes in protein and refined grains), and converting to possibly more communicable metrics (per day rather than per week).The major limitations of this study were some dietary modeling scenarios call for a large increase in pulses which may not be achievable for some consumers, though vegetarians do tolerate much higher levels of pulses in their diet; and we only highlighted changes of at least 10% or more, though smaller changes might also be useful.Additionally, as in any dietary modeling study, our results evaluated the maximum effect of dietary modeling and may not reflect actual individual dietary behavior.

Conclusions
In conclusion, the results of this modeling study provide insight into the nutritional benefits of adding pulses as a replacement for the servings of protein foods and/or refined grains in the 2000 kcal Healthy U.S.-Style Pattern.Depending on the amount, the addition of pulses replacing protein foods, refined grains, or combinations of protein foods and refined grains increase fiber, iron, magnesium, potassium, and copper in the 2000 kcal Healthy U.S.-Style Pattern.Our results suggest that encouraging increased pulse consumption may be an effective strategy for improving diet quality and achieving a healthier dietary pattern.However, observational and controlled feeding trials are needed confirm the results of our dietary modeling study.
[25]ient profile of pulses was computed by using USDA's beans and peas composite (nutritional profile obtained from Food Pattern Modeling Report[23]), proportionally subtracting the nutritional contribution of edamame (1.3%, nutritional profile obtained from FoodData Central, FCD ID: 2342911)[25]and adjusting calories from rest of the composite.Nutritional profile of USDA's protein foods composite was computed by proportionally adding nutrients of each individual components (38.21%Red meats, 29.39% Poultry, 2.71% High omega 3 fish, 5.95% Low omega 3 fish, 9.44% Eggs, 1.78% Soy Products, and 12.51% Nuts/Seeds).Nutritional profiles for each component of USDA's protein foods composite and of Refined grains were obtained from Food Patterns Modeling Report[23].RAE, retinol activity equivalents; ATE, alpha tocopherol equivalents; IU, international units.

Table 2 .
Effect of replacing 1 to 8 oz eq/week protein foods (PF) with 0.25 to 2.0 cups per week pulses in 2000 kcal Healthy U.S.-Style Pattern (baseline).

Table 2 .
Cont.Baseline nutritional profiles of 2000 kcal Heathy U.S.-Style Pattern was obtained from Food Pattern Modeling Report[23].Nutrient profiles after replacing protein foods (PF) with pulses were computed by removing the nutrients of protein foods and adding the nutrients of beans and peas (Table 1) from the nutrients of the 2000 kcal Healthy U.S.-Style Pattern.Since 2000 kcal Healthy U.S.-Style Pattern includes 1.5 cups/week of pulses this additional 0.25 to 2.0 cups/week of would increase total amount of pulses to 1.75 to 3.5 cups/week.* Indicates ≥10% change from baseline; values in bold indicate increase and values in italics indicate decrease from baseline.RAE, retinol activity equivalents; ATE, alpha tocopherol equivalents; IU, international units.

Table 3 .
Cont.Baseline nutritional profiles of 2000 kcal Heathy U.S.-Style Pattern was obtained from Food Pattern Modeling Report [23].Nutrient profiles after replacing protein foods (PF) with pulses were computed by removing the nutrients of protein foods and adding the nutrients of pulses (Table 1) from the nutrients of the 2000 kcal Healthy U.S.-Style Pattern.*Indicates ≥10% change from baseline; values in bold indicate increase and values in italics indicate decrease from baseline.RAE, retinol activity equivalents; ATE, alpha tocopherol equivalents; IU, international units.

Table 4 .
Effect of replacing combinations of protein foods (PF) and refined grains (RG) with pulses in 2000 kcal Healthy U.S.-Style Pattern.

Table 4 .
Cont.Baseline nutritional profiles of 2000 kcal Heathy U.S.-Style Pattern was obtained from Food Pattern Modeling Report[23].Nutrient profiles after replacing combinations of protein foods (PF) and refined grains (RG) with pulses were computed by removing the nutrients of protein foods and refined grains and adding the nutrients of pulses (Table 1) from the nutrients of the 2000 kcal Healthy U.S.-Style Pattern.*Indicates ≥10% change from baseline; values in bold indicate increase and values in italics indicate decrease from baseline.RAE, retinol activity equivalents; ATE, alpha tocopherol equivalents; IU, international units.