One of the trends of the 21st century is the growing popularity of plant-based diets. And while there are many conflicting estimates of the vegetarian and vegan population in the United States, it is clear that the ranks of plant-based individuals is increasing every year. One 2015 poll found that 3% of Americans adhere to a vegetarian diet, while about 1% avoided all animal-based food (Le & Sabaté, 2014). Besides strictly abstaining from meat, many Americans are trying to reduce their meat, egg, and milk intake. For example, the plant-based milk market is growing at a rapid rate of 10.18% a year (Business Wire, 2020). Even though most Americans still consume dairy, they are still drinking this stereotypically vegan food. Further, meat substitutes such as Beyond Meat and Impossible Meat have made recently many appearances in restaurants and fast food chains. In the coming years and decades, vegetarianism and veganism is only going to continue growing.
So what do all these terms mean? For the purposes of this article, “vegetarianism” refers to the practice of not eating any animals, including fish; “veganism” refers to a more restrictive diet of no animal products, including meat, eggs, and dairy; and “plant-based” refers broadly to all these varying diets. There are many reasons to choose any form of plant-based diet, including a love for animals, concern for the environment, personal health, and religious practices. However, meat is the cornerstone of the majority of humans’ diets. Most Americans don’t go a meal without consuming animal products. This has caused some to speculate about whether cutting out this near-ubiquitous group of foods could negatively impact one’s health. With more and more Americans becoming vegetarians and vegans every day, this is a question of extreme importance. Can you really stay healthy while saying no to this wide source of fats, protein, and vitamins?
In a word, the research says “yes.” The Academy of Nutrition and Dietetics (the AND) is the United States’ leading authority on nutrition, and is the largest organization of food and nutrition professionals in the U.S.. In a 2015 review, this organization concluded that “well-designed vegetarian diets ... meet current nutrient recommendations and are appropriate for all stages of the life cycle” (The AND, 2015). Other groups, such as the German Nutrition Society, the British Dietetic Association, and Dietitians Australia, have made similar conclusions (Richter et al, 2016; BDA, 2017). The AND included sample daily meal plans for vegetarian and vegan diets in their review, each of which contained more than 75 g of protein and 55 g of fat. According to the AND, these are examples of simple and affordable plant-based meals everyone can follow to construct a healthy vegan or vegetarian diet. In fact, the AND further wrote that a diet of only plants reduces risks of “atherosclerosis, type 2 diabetes, hypertension, and obesity.”
This paints a very flattering picture of diets with no animal products. Is it true that a vegan lifestyle is as simple to maintain as an omnivorous one?
Not quite. While it is certainly possible to eat a vegan diet and be perfectly healthy, this requires some careful planning and diet supplementation. In particular, the AND and other organizations point out that vegans are at risk for deficiencies in both certain macronutrients and select vitamins and minerals. This article will now examine some of these specific nutrients and if/how a vegan diet can incorporate healthy amounts of them.
Firstly, because meat is an excellent source of protein, many believe that plants cannot provide the same quality or variety of this crucial macronutrient. However, this claim is unsubstantiated. Legumes (including soy, lentils, and chickpeas), nuts, oil seeds, and wheat gluten (i.e. seitan) are all excellent sources of protein for vegans. For example, one pound of chicken breast contains 139 g of protein; in comparison, one pound of peanuts contains 118 g of protein, and one pound of seitan contains 340 g p of protein (USDA, 2020). One sports nutrition study found that a vegan diet has enough protein to support even athletes, who need much more protein than the average person (Rogerson, 2017).
However, the variety of proteins consumed matters just as much as the quantity consumed. Proteins are built from 20 distinct amino acids, 11 of which can readily be produced by the body. The remaining nine, however, must be absorbed through consumption of food and drink (Hou & Wu, 2018). Therefore, it is crucial to ensure adequate levels of these nine “essential” amino acids in one’s diet. Sources of protein that contain all nine of these essential amino acids are said to be “complete,” while sources which lack one or more are “incomplete.” While some vegan foods, such as tofu, do technically qualify as complete protein sources, they typically only hold a small fraction of at least one essential amino acid (in contrast, complete proteins are present in all beef, chicken, dairy, and eggs) (McGrane, 2020). Because of this, vegans have to take special care to eat a wide variety of protein sources, in order to consume all nine essential amino acids. However, it is not necessary to have all nine essential amino acids at every meal, or even every day (The AND, 2016). All in all, it is not difficult for vegans to consume healthy amounts of these essential amino acids, just by varying the legumes, nuts, and seeds they eat.
Another macromolecule to consider is the omega-3 fatty acid. This form of unsaturated fat is found in fish, plant oils, nuts, and seeds, and is an important component of cell membranes (Salvador et al., 2019). These fats are divided into three categories, all of which are important to bodily function: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA can be readily found in walnuts, flax seed, and other vegan sources. However, studies examining vegans’ blood composition have found that vegans are often lacking in EPA and DHA fats (Salvador et al., 2019). While a small amount of EPA and DHA are produced by the body from ALA, this amount is not enough to meet an individual’s daily needs. Moreover, seaweed and algae are the only common vegan foods that contain significant amounts of these two vital nutrients. Therefore, vegans must usually take artificial supplements (in the form of a pill or tablet) to consume their recommended daily values for EPA and DHA (The AND, 2015).
Besides these two macronutrients, three micronutrients are of particular concern in a vegan or vegetarian diet. The first is calcium. According to the AND, vegans consistently show calcium intakes lower than the recommended daily value (2015). Vegans’ experiences with bone fractures seem to support this statistic. In a long-term study, researchers studied a total of 34,000 individuals, including 9,420 vegetarians and 1,126 vegans. Among other data points, they tracked the participants’ bone fractures over the course of the study’s five year duration. While the incidence of fracturing was similar between meat eaters and vegetarians, vegans were 25% more likely to have suffered a bone break (Appleby, 2007). However, soy products, beans, and certain leafy greens are substantial sources of calcium. For example, tofu contains 434 mg of calcium per one-half cup serving, about half of the recommended daily allowance (USDA, 2020). Many foods, such as plant-based milks, are also fortified with calcium. Thus, it is not difficult to obtain enough calcium a day under a plant-based diet, with proper planning.
A micronutrient related to calcium is Vitamin D. Vitamin D helps the body to absorb calcium; therefore, it is important for bone health and nerve function (Eyvazzadeh, 2020). Inadequate levels of Vitamin D may also contribute to the increased rate of vegan bone fractures found in Appleby et al.’s study. While fish and eggs are common sources of Vitamin D, mushrooms are the only vegan food in which it occurs naturally; however, most cereals, plant milks, and orange juice are fortified with the micronutrient (Richter et al, 2016). Furthermore, the human body can metabolize enough Vitamin D to suit its needs just from exposure to the sun’s UV rays, no direct consumption required. Just 30 minutes of midday sun exposure for a few days a week is enough to be healthy (Eyvazzadeh, 2020).
Lastly, the most challenging nutrient for vegans to acquire is Vitamin B12. B12 is a component of DNA, and is also necessary for cell reproduction. Even though humans need only about 2.5 micrograms of Vitamin B12 per day (about one ten-thousandth of the weight of a grain of rice), not consuming enough of it has disastrous consequences (National Institutes of Health, 2020). Vitamin B12 deficiency causes depression, memory loss, and anemia, and severe cases can lead to irreversible brain damage and heart failure (The AND, 2015). Furthermore, B12 deficiency can be left undetected with minor symptoms, until it suddenly causes permanent neurological damage. This is why the prevalence of Vitamin B12 intakes below the recommended daily value in vegan diets is so concerning. B12 is synthesized within the intestines of animals, but is not found anywhere in the plant kingdom; no vegan foods have Vitamin B12 unless artificially fortified (Richter et al, 2016). Multiple studies have concluded that most vegetarians and vegans who do not supplement their diets possess frighteningly low concentrations of B12 in their blood (The AND, 2015). While B12-fortified foods include plant milks, nutritional yeast, and some tofu, the AND recommends that all vegetarians and vegans should take B12 supplements (under the advice of a physician), to ensure they are consuming at least 2.5 micrograms a day. The AND also recommends that all pregnant or lactating vegans consult a registered dietitian nutritionist to ensure that they are properly supplementing the vitamin, because it is so crucial to fetal development and growth of infants.
These five nutrients are the ones most commonly associated with vegetarian or vegan nutrient deficiencies. While there is some concern about the proper consumption of other minerals (e.g. iron, zinc, iodine, and selenium), these are readily found from plant-based sources, and most vegans appropriately consume these minerals as a result.
The discussion of these specific nutrients reveals the truth about vegan and vegetarian diets. It is very possible to abstain from animal products while still maintaining the recommended daily amounts of nutrients in the diet and remaining healthy. However, careful planning must be taken to vary one’s sources of certain nutrients (such as protein) to ensure proper consumption of each essential nutritional component. Furthermore, vegans have shown to consistently possess lower levels of specific nutrients than omnivores; therefore, those on a plant-based diet must make sure to eat foods rich in these micro- and macronutrients. In particular, omega-3 fatty acids are found in nuts and seaweed; calcium is present in green, leafy vegetables, soy foods, and certain beans; and Vitamin D can be absorbed from mushrooms and common fortified foods, or simply though 30 minutes a day of sun exposure. Lastly, Vitamin B12 does not occur naturally within vegan food products at all. Therefore, vegans must usually consume a vitamin supplement to ensure adequate intake of B12. Overall, if these specifications are met, there are no significant health detriments associated with a vegan or vegetarian diet. In fact, there is evidence that these diets greatly improve one’s health, by reducing risk of cancers, Metabolic Syndrome, and heart disease (Pilis et al., 2014). Therefore, anyone contemplating the switch to a plant-based diet should not fear nutrient deficiencies or any significant health risks, if they follow the preceding advice. While it is always good practice to consult a doctor when making any diet transitions, vegetarian and vegan diets are completely safe and sustainable, with a bit of research, planning, and creativity.
References
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Article written by Alex Borengasser
Article edited by Devanandh Murugesan
Graphics by Tiya Shah
Group advised by Lakshmi Sriram
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