The growing popularity of plant-based diets has sparked immense public interest. The whole-food plant-based (WFPB) and vegan diets have gained traction as potentially healthier alternatives to the standard American diet. This article delves into the components of a well-structured plant-based diet plate, examining its nutritional strengths and weaknesses, and comparing it to standard dietary recommendations.
Introduction to Plant-Based Diets
The public interest in popular diets is increasing, in particular whole-food plant-based (WFPB) and vegan diets. A variety of professional organizations in the US and elsewhere have now issued dietary guidance statements on vegetarian or vegan diets. While many recipes and cookbooks written for vegans do emphasize fruits, vegetables, whole grains, and legumes, they also tend to be less rigid with respect to avoiding refined foods or ingredients.
WFPB and vegan diets similarly exclude all animal products, including red meat, poultry, fish, eggs, and dairy products. However, although also a vegan diet, a WFPB diet places a greater emphasis on minimizing or excluding all processed foods made with refined grains and added sugar, refined fats and oils, and salt.
Data from NHANES 2009-2010 suggests that Americans consume 60% of their calories from ultra-processed foods such as breads, cakes, cookies, pizza, French fries, salty and sweet snacks, and desserts, with only 5% and <1% of calories from fruits and vegetables, respectively. WFPB and vegan diets generally promote practices consistent with higher dietary quality, such as an emphasis on greater intakes of whole grains and vegetables and avoidance of added sugars and refined foods. Thus, there is growing interest in these diets as healthier alternatives to the standard American diet.
Methodology: Assessing WFPB and Vegan Meal Plans
To assess the nutritional adequacy of these diets, thirty representative days of meal plans were created for each diet. Weighted mean food group and nutrient levels were calculated using the Nutrition Data System for Research (NDSR) and data were compared to DRIs and/or USDA Dietary Guidelines/MyPlate meal plan recommendations. The Healthy Eating Index (HEI-2015) scores were calculated.
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Top sources of diet information were captured from the Adhering to Dietary Approaches for Personal Taste (ADAPT) Feasibility Survey. In brief, this was a short, web-based survey designed to recruit self-identified popular diet followers. The survey was open for 8 weeks in 2015, from 14th July to 14th September, and a total of 13,787 participants consented to enroll. Participants identified the specific diet they followed by selecting a single diet from among multiple choice answers with a write-in option if their diet was not listed. A total of 6372 responded to this optional question and listed at least one book source, and the two largest self-identified groups were selected for this analysis. Of the total responses to this question, 29% self-identified as WFPB followers (n = 1856) and 19% as vegan (n = 1218). We used data on sources of dietary information from a random sample of 200 participants’ responses from each of the WFPB and vegan diets.
Foods and nutrient levels in each of the diets were calculated in a multi-stage process. The majority of responses included two or more unique sources. A five-day meal plan from each of the six sources was created, for a total of 30 representative days, for both WFPB and vegan diet groups. Similarly, MyPlate plans posted online (Sample Two-Week Menus and Sample Menus for a 2000 Calorie Food Pattern) were used to create 21-day USDA compliant meal plans. Meal plan data were collected and analyzed using Nutrition Data System for Research software version 2016 (NDSR 2016) developed by the Nutrition Coordinating Center (NCC), University of Minnesota, Minneapolis, MN. NDSR provides a complete nutrient profile for all foods in the database. Ingredients consistent with recipe instructions were selected whenever possible. When recipe instructions were ambiguous, NDSR data-entry rules were used to select generic ingredient choices and standard portion sizes to maintain consistency. Food plans and recipes were generated and entered in full to NDSR (Micaela C. Karlsen) and subsequently divided by the number of servings to obtain single-serving portions. The accuracy of recipes and meal plans entered into NDSR was confirmed by a second reviewer (Akari Miki). Dietary supplements that were advised by at least two meal plan sources were entered as part of the WFBP or vegan meal plans using the 24-h supplement intake module in NDSR. Vitamin B12 (µg) was included in all six meal plan sources and five of the six sources included daily vitamin D (calciferol, µg) supplements. Specific doses of supplements that were specified by the meal plan sources were entered, however when doses were not provided a generic supplement was selected (~1000 µg of B12 and 25 µg of vitamin D based on typical available products). Both total (food plus supplements) and diet only nutrient levels were calculated.
Food and nutrient data from the meal plans was generated by NDSR and analyzed using SAS 9.4 (SAS Institute, Cary, NC, USA). Mean intakes for selected nutrients and food groups were calculated for each diet. The percent for weighting each source was calculated as the number of mentions of the source out of the total number of mentions of the top six sources. Interestingly, the top six sources mentioned were the same among both WFPB and vegan diet followers; however, the percent of mentions for these sources differed slightly, leading to minor differences in weight between the two groups. This weighting approach was chosen because the nature of the question was open-ended, and most respondents cited multiple sources of information, so accounting for multiple data sources captures a more representative estimate of the overall diet guidance followed. Since the meal plan sources were identical between the two diets, and the weighting scheme applied only differed slightly, marginal differences were observed in the mean composition of the vegan versus WFPB diets after applying the weighting. Therefore, to avoid redundancy of results, only WFPB meal plans results are presented in the main text, and vegan meal plan results are presented in Tables S2-S5. Mean nutrient and food group levels from meal plans were compared to mean nutrient levels from MyPlate. For those items in which the standard deviation is 50% of the point estimate or more, we examined the median difference with similar findings (data not shown). Nutrient content of the meal plans was compared to the relevant Dietary Reference Intakes (DRIs) from the Institute of Medicine [30] for male and female adults (ages 19-70 years) for the Nutrients of Concern as identified by the US Dietary Guidelines Advisory Committee [31]. The Nutrients of Public Health Concern [31] are those nutrients for which a majority of Americans have been found to have intakes below either the Estimated Average Requirement (EAR) or the Adequate Intake (AI), or above the Upper Limit (UL). To determine the theoretical nutritional quality of the meal plans, we applied the following criteria to estimated nutrient levels: (1) EAR and RDA for vitamin A (RAE, µg), vitamin D (calciferol, µg), vitamin E (mg), folate (µg), vitamin C (mg), calcium (mg), magnesium (mg), and iron (mg); (2) AI for potassium (mg) and fiber (g); (3) UL for sodium (g); and (4) recommendation from the 2015 US Dietary Guidelines for Americans [29] to limit saturated fat and added sugar to less than 10% of calories. Percent differences are expressed as the percent greater or lesser for the meal plans’ mean nutrient content as compared to the DRIs and MyPlate. These differences were calculated as % difference = (mean meal plan value/recommended value) * 100 − 100.
Key Components of a Plant-Based Diet Plate
A well-balanced plant-based diet plate should emphasize the following components:
- Vegetables: These should form the foundation of every meal, with a variety of colors and types to ensure a broad spectrum of vitamins, minerals, and antioxidants.
- Fruits: Opt for whole fruits over juices to maximize fiber intake and minimize added sugars.
- Whole Grains: Choose whole grains like brown rice, quinoa, oats, and whole-wheat bread over refined grains for their higher fiber and nutrient content.
- Legumes: Beans, lentils, peas, and chickpeas are excellent sources of protein, fiber, and iron.
- Nuts and Seeds: These provide healthy fats, protein, and essential minerals.
- Healthy Fats: Include sources of healthy fats like avocados, nuts, seeds, and olive oil.
Nutritional Strengths of WFPB Diets
WFPB meal plans provide more total vegetables (180%), green leafy vegetables (238%), legumes (460%), whole fruit (100%), whole grains (132%), and less refined grains (−74%) in comparison to MyPlate. Fiber level exceeds the adequate intakes (AI) across all age groups.
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The WFPB meal plans exceeded the MyPlate meal plan targets with respect to total vegetables, green vegetables, and nuts and seeds, as well as several nutrients including vitamin A, vitamin E, vitamin C, and folate. The calculated HEI-2015 scores were 88 out of 100 for both WFPB and vegan meal plans.
Estimated theoretical nutrient levels from the WFPB plans meet or exceed the RDAs for vitamin A, vitamin E, folate, vitamin C, magnesium, and iron for adult men and women.
Theoretically, if a person adhered to a WFPB or vegan diet, the quality of their diet would be superior to the typical American diet.
Potential Nutritional Deficiencies and How to Address Them
Certain concerns have been raised with respect to nutrient adequacy for diets that exclude all foods of animal origin. Without supplementation or the consumption of fortified foods such as plant milks and nutritional yeast, diets with no animal foods may provide inadequate levels of vitamins B12 and D. Without emphasis on sea vegetables and/or inclusion of iodized salt, they also may provide inadequate levels of iodine.
WFPB meal plans failed to meet the Recommended Dietary Allowances (RDA)s for vitamin B12 and D without supplementation, as well as the RDA for calcium for women aged 51-70.
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Estimated vitamin D levels are inadequate for vitamin D from food only (data not shown); however, when consuming supplements, the RDA is exceeded. EARs for calcium are met for men and women, and the RDA is met for men but not for women ages 51-70 years. Meal plans meet or exceed the AIs for potassium and fiber for men and women. Estimated sodium intake exceeds the UL for adult men and women.
To ensure nutritional adequacy, individuals following a WFPB diet should pay attention to the following:
- Vitamin B12: Supplementation is crucial, as vitamin B12 is primarily found in animal products.
- Vitamin D: Consume fortified foods or consider supplementation, especially during winter months or in regions with limited sunlight.
- Calcium: Include calcium-rich plant foods like leafy green vegetables, fortified plant milks, and tofu.
- Iodine: Use iodized salt or consume sea vegetables like kelp.
WFPB vs. MyPlate: A Comparative Analysis
Percent energy from macronutrients differed between the theoretical WFPB and MyPlate. Macronutrient content (% of total energy) in MyPlate and whole-food plant-based WFPB meal plans. The fiber content for MyPlate is 28 g/day and 70 g/day for WFPB. Percent energy from added sugar is estimated to be 6% for MyPlate and 2% for WFPB. Medians and interquartile ranges for food and nutrients are presented in Table S5 (both WFPB and vegan). Comparisons with recommended intake levels for the Nutrients of Public Health Concern are presented in Table 3 (Table S4 for vegan).
The lower HEI score of the WFPB diet is primarily due to the exclusion of dairy products. The contribution of energy from fat and carbohydrate differs substantially for WFPB relative to MyPlate, with WFPB displaying a “low-fat, high-carbohydrate” profile (17% fat, 73% carbohydrate).
Practical Considerations and Potential Pitfalls
While WFPB diets offer numerous health benefits, it's important to be mindful of potential pitfalls:
- Over-reliance on Processed Vegan Foods: Some vegan products can be high in unhealthy fats, added sugars, and sodium. Focus on whole, unprocessed plant foods.
- Inadequate Calorie Intake: Plant-based foods tend to be less calorie-dense than animal products, so ensure you're consuming enough calories to meet your energy needs.
- Lack of Variety: Eating the same foods repeatedly can lead to nutrient deficiencies and boredom. Experiment with different recipes and ingredients.
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