In August 2019, KFC trialed Beyond Meat vegan chicken nuggets at an Atlanta location and sold out in five hours, selling the equivalent amount as it normally does of regular popcorn chicken in one week. As of October 2019,  24 chains have adopted “meat 2.0”, or plant-based meats from Beyond Meat or Impossible Foods. Now, more than ever, is the time of the plant-based diet.

However, the excitement around veganism has been met with substantial backlash, both towards the vegan diet as well as vegans themselves. The term “soy boy” , which has gained substantial currency in certain online circles, might epitomize this. It is used to characterize vegan men in particular as weak, sanctimonious, and contemptible.

She’s back! After authoring the second most popular post on this site last year on the ketogenic diet, Ari Kenney enlightens us on vegan diets from both nutritional and sociological perspectives. Ari’s guest posts are longer and more technical than others on this site, but I am pleased to offer her perspective on this topic. We would love to start a dialog with your comments.

In this article, we’re going to try to cut through both the hype and the ridicule. We’re going to first consider what the scientific literature has to say about the health effects of veganism, both positive and negative, before considering why this diet is so divisive.

The Good

Adhering to a vegan diet has been linked with a wide variety of potential health benefits. A study comparing 2,000 vegans with 65,000 omnivores found that vegans consumed more mono- and poly-unsaturated fatty acids versus saturated and trans fats, as well as more complex and unrefined sugars. In addition, vegans had lower intake of saturated fatty acids, vitamins B12 and D, calcium, zinc and protein, and higher intake of fiber, magnesium, iron, folic acid, vitamin B1, C and E in vegan compared to the omnivore dieters.

A meta-analysis of multiple vegan cohorts found that in most countries vegans consumed fewer calories, total fat, saturated fat and protein compared to controls that ate an omnivorous diet. In addition, vegans had a lower body mass index, LDL-cholesterol, blood glucose, triglycerides and blood pressure compared to healthy controls.

These different nutritional intakes have been shown to have a positive effect in reducing the risk of chronic disease. Compared to standard lacto-ovo-vegetarian diets, vegan diets appear to offer additional protection from obesity, hypertension, type-2 diabetes, and cardiovascular mortality.

One review examined the effects of different eating patterns in three large cohorts, comparing non-vegetarian diets to vegan and lacto-ovo-vegetarian diets (plant-based diets including eggs and milk).  They found that for all cardiometabolic-related outcomes including ischemic heart disease and cardiovascular disease, vegans had substantially lower risk than lacto-ovo-vegetarians, which both had lower risk than non-vegetarians. Another study found that vegans had substantially lower total cholesterol and LDL cholesterol, predicting a 24% lower incidence of ischemic heart disease in lifelong vegetarians and 57% lower in lifelong vegans than in meat eaters.

A follow-up with 34% of the original cohort 11 years later in 2013 determined that vegetarians and vegans had the lowest mortality ischemic heart disease—a 32% lower risk in total and a 28% lower risk when removing the confounding factor of body mass index (BMI). However, a follow-up with a different cohort found a directional but not statistically significant increase in the risk for total stroke. Their lack of statistical significance was likely due to the small number of cases in vegans. While the long-term impacts of the vegan diet on heart health are still not confirmed due to lack of randomized controlled studies, there are documented short term benefits—one study found that just 7 days of a vegan diet resulted in significant beneficial changes in risk factors for cardiovascular disease such as weight, blood pressure, blood sugar, and blood lipids.

Vegan diets also appear to be particularly effective at improving markers of blood sugar control and may lower one’s risk of developing type 2 diabetes. A study found that semi-vegetarians, vegetarians, and vegans had a stepwise lower risk of diabetes than non-vegetarians when controlling for age, gender, education, income, physical activity, smoking and alcohol use, and BMI. A randomized, controlled 74 week clinical trial found that, while both facilitated long-term weight reduction, a low-fat vegan diet was more effective for control of glycemia and plasma lipid concentrations than a conventional diabetes diet.

The vegan diet may also help with chronic inflammation. A plant based diet has been shown to help with fibromyalgia—patients that were put on a vegan diet showed a significant improvement in symptoms including visual analogue scale of pain, joint stiffness, and quality of sleep, as well as several health questionnaires. Vegan diets have also been shown to reduce symptoms of arthritis such as pain, joint swelling and morning stiffness

While studies overall imply that there are many positive health effects associated with a vegan diet, it is important to keep in mind that most of the studies are observational, which makes it difficult to determine whether the vegan diet directly caused the benefit. More randomized controlled studies are needed before definitive conclusions about vegan health benefits can be made.

In addition to these potential health benefits, the vegan diet has been shown to have a positive impact on weight loss. A shift to vegan food with no caloric restriction caused a significant reduction in body mass index. One study randomly assigned 60 women to either a vegan diet or a US National Cholesterol Education Program diet, which is a low-calorie low-saturated fat diet for 14 weeks. The vegan dieters showed greater weight loss than the NCEP diet at 1 and 2 year checkpoints, and those provided with group support meetings for 1 year after the 14 weeks of dieting showed even more weight loss.

Both the weight loss and other health effects of a vegan diet are likely due to both the increased presence of healthful foods such as fruits, veggies, and legumes as well as the lack of potentially less healthful animal products.

Vegan diets, due to their plant-based nature, have lower energy density. The increased fiber content is helpful for participants to naturally eat fewer calories and reach satiety without having to consciously restrict their food intake, naturally facilitating weight loss. The resulting lower mean BMI observed in vegans is by itself known to reduce risks from heart disease and is a known protector against type 2 diabetes. In addition, the high fiber intake from legumes, grains, veggies, and fruit is known to prevent chronic diseases by slowing down digestion, blunting the blood sugar response, and improving lipid control including reducing LDL cholesterol. Fiber may also induce changes on the microbial level leading to lower long-term weight gain and insulin resistance.

Several studies noted that the gut bacteria of those consuming plant-based diets were different, with lower counts of Bacteroides, Bifidobacterium, E. coli and Enterobacteriaceae than vegetarians and omnivores, although the functional implications are unclear. These changes appear to happen quickly—one study found that the gut microbiome responded within 30 days to a plant-based diet.

Additional studies further hypothesized that health benefits observed in a plant-based diet stem from higher levels of fruits and vegetables providing phytochemicals that might that have been shown to have beneficial effects on CVD, cancer, overweight, body composition, glucose tolerance, digestion and mental health.

A plant-based diet excludes certain components found in meat including saturated fat which have been linked to negative health effects including a higher risk for inflammation that can lead to cardiovascular diseases and insulin resistance. A plant-based diet also often results in a lower consumed quantity of consumed sugar and refined grains linked to weight gain and insulin resistance.

The Bad

Despite the potential health benefits of a vegan diet, a poorly planned or unbalanced vegan diet may lead to nutritional deficiencies that could cause serious health issues. The micronutrients that are most likely to be lacking in a vegan diet are vitamins B-12 and D, calcium, and long-chain n-3 (omega-3) fatty acids, all of which are most easily sourced from animal-based foods. Iron and zinc, two minerals with limited bioavailability in plants, may also be of concern for vegans. Unless vegans regularly consume foods that are fortified with these nutrients, dietary supplements should be consumed.

Vitamin B₁₂ occurs naturally only in animal foods and plays an important role in converting homocysteine into nonharmful compounds. When homocysteine accumulates in the body it can promote the formation of plaques in arteries and which increases the risk for stroke and Alzheimers disease. B₁₂ deficiency may increase CVD risk factors, blood disorders, and a wide range of neurological conditions including potentially irreversible neurological damage. B₁₂ deficiency can also lead to tiredness, weakness, constipation, and depression.  A literature review of vegetarian diets found a range of 0 to 86.5% B₁₂ deficiency for all subgroups, with a concerning 62% among pregnant woman. Higher rates of deficiency were reported among vegans compared with vegetarians and among individuals who had adhered to a vegetarian diet since birth compared with those who had adopted such a diet later in life. There are no plant-based sources of B_12, so it is critical that dieters take supplements or consume fortified foods to ensure adequate intake of this vitamin.

Calcium and vitamin D are often found together in foods and work together to maintain bone health. In one study vegans had 30% higher fracture rates than meat-eaters. However, when adjusted for calcium intake (comparing vegans whose consumption averaged more than 525 mg calcium per day), vegans no longer showed a higher fracture rate. Inadequate levels of vitamin D have long been known to contribute to bone problems such as rickets, but more recently have also been found to contribute to a range of other conditions, including fibromyalgia, rheumatoid arthritis, multiple sclerosis, depression, cancer, hypertension, and diabetes. To prevent the risk of health problems, vegans must monitor these two nutrients closely.

Omega-3 and omega-6 fatty acids are considered essential because our bodies cannot make them. They play key roles in heart health, brain and eye health, and reducing chronic inflammation. Sustained lack of them in one’s diet could lead to a risk for depression, and the ratio of omega-3 to omega-6 is important. A review found that multiple vegan studies identified an unbalanced ratio of omega-6 to omega-3 fatty acids. It is important that vegans obtain the right ratio of these critical fatty acids by consuming foods such as flaxseeds, or by supplementation.

Iron is used by the body to make hemoglobin and myoglobin, proteins that carry oxygen throughout the body. Lack of iron can cause anemia, a lack of healthy, functional red blood cells. Symptoms of iron deficiency anemia include weakness or lack of energy, problems with memory, and lack of ability to control body temperature and fight off infection. Vegans are more likely to develop iron deficiency because heme iron, available only from animals, is more easily absorbed by the body than non-heme, which comes from plants. Not only are iron amounts lower in plant foods, but that iron isn’t absorbed as well.

Zinc is another nutrient often lacking in vegan diets. It plays a vital role in multiple aspects of metabolism, immune system response, wound healing, and many other bodily functions. Unfortunately, it is not absorbed easily from plant foods. Many plant sources of zinc also contain phytates, which inhibit zinc absorption. For this reason, vegans are often zinc-deficient. To account for the challenges in bioavailability, the recommended requirement of zinc for vegans is 50% higher than the U.S. RDI.

Those who begin a vegan diet are often asked by concerned omnivores whether they are getting enough protein. However, protein is one of the areas where vegans are not shown to be deficient. The average adult needs about 50 grams of protein per day, which is typically not a challenge to obtain if diets contain enough energy (e.g. calories). A meta-analysis with seven randomized controlled trials on physical performance and dietary habits concluded that a vegetarian diet did not adversely influence physical performance compared to an omnivorous diet.

Some vegans enjoy plant-based products that mimic the flavor and texture of real meat. These products may fill a temporary role to replace animal protein while dieters learn to develop meals around other protein sources such as nuts, seeds, beans, and lentils, or a more permanent role as a meat substitute. Sales of these refrigerated plant-based meats grew 37% in 2019, and these products now account for 2% of retail packaged meat sales. This growth has prompted some to question if plant-based meats are “healthy”.

One study audited 137 plant-based meat products in Australia and found that plant-based options were generally lower in calories, total and saturated fat, and higher in carbohydrates, sugars and dietary fiber compared with meat. Only 4% of products were low in sodium and less than a quarter of products (24%) were fortified with vitamin B₁₂, 20% with iron, and 18% with zinc. The wide range of nutrient content in plant-based meats suggests that those looking to supplement their diet with these foods may want to read the nutrition facts to ensure that they are getting what they need for a balanced diet.

Any group that diverges from the norm faces challenges, and that is particularly true for any group that adopts and advocates a restrictive diet. Food is so intimately associated with culture, that anyone who deviates from standard accepted practices is likely to face social consequences.

The Ugly

It’s no secret that, on the whole, vegans aren’t a very well-liked group. In fact, three studies have shown that vegans have one of the worst reputations among marginalized groups. According to the authors: “Only drug addicts were evaluated more negatively than vegetarians and vegans.” Negative sentiment was especially felt towards those “motivated by animal rights or environmental concerns”, which different research found to be the vast majority of vegans—the diet is typically chosen for three main reasons: concern for the welfare of animals (90%), personal well-being or health (69%), and environmental factors (47%). Vegetarian or vegan men were viewed slightly more negatively than women, and those with conservative views harbor more negative bias.

Why so much hate for veganism, and why the particular hate for vegans motivated by animal welfare and environmentalism? One theory is that by choosing to undergo a significant and difficult lifestyle change for moral reasons, vegans create a feeling of implicit moral judgement in the non-vegans around them. By choosing to forego a behavior that most people view as morally permissible, vegans represent “a perceived symbolic threat to social and cultural norms.” By choosing to live a different lifestyle, they prompt the rest of us to consider if they are right to do so, which in turn prompts the uncomfortable question, “what if we’re wrong?”

One article compares the vegans experience to the figure of the feminist killjoy, “transgressing scripts of happiness and commensality in a dominant meat and dairy consuming culture.” By going against the social order which doesn’t question, and often celebrates, the consumption of animal products, vegans directly challenge the dominant affective community. These perceptions are of course amplified by the vocal minority of vegan activists who turn the implicit challenge to accepted norms into an explicit one.

Because veganism has such a high potential for inspiring conflict, there is a growing body of resources to help negotiate different diet choices, including a “ “combination cookbook and lifestyle book which takes a unique look at inter-palate partnering, with personal stories and tips for “peaceful co-existence when one partner wants a cheeseburger and the other wants a tempeh slider.”

It’s no wonder that veganism is such a difficult diet to stick with. One study found that in order to remain vegan, people typically require social support from friends and family. Those that return to eating animals may do so due to factors such as personal inconvenience, meat cravings, awkwardness in social settings, or health/nutrition concerns.

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The take away is that while veganism can provide a wide array of health benefits, it’s one of the more difficult diets to do right, both nutritionally and socially. It requires a degree of conscientiousness in the daily choices one makes that won’t be sustainable for many people. The upside is that by approaching veganism with a more flexible attitude, one can get most of the health benefits while avoiding many of the nutritional and social pitfalls. US News rated veganism #17 in Best Diets overall, but they rated flexitarianism  #2 in Best Diets overall. Flexitarianism is exactly what is sounds like. It’s adhering to a mostly plant based diet, but allowing oneself a little bit of wiggle room.

By sticking to plants most of the time but allowing oneself the occasional egg or piece of fish, flexitarians are able to get most of the benefits of a vegan diet without having to worry too much about not getting enough of the nutrients that a pure vegan diet can leave out. Vegans remain a small minority, with a Gallup poll in 2018 finding that 5% of Americans are vegetarian and 3% are vegan. Flexitarians, on the other hand, seem to be on the rise. 83 percent of US consumers are adding plant-based foods to their diets, and Impossible Food shared that almost 90% of their plant-based burger consumers are meat eaters. In fact, the total market for plant-based alternatives to animal-based foods was found to be worth $4.5 Billion in 2019, growing at five times the rate of total food sales. If you’ve been curious about veganism, but aren’t ready to fully commit, there has never been a better time to explore.

Ari Kenney is an Insights Analyst at E&J Gallo Winery. She has a B.S. in Food Science from UC Davis and a M.S. in Food Science with a focus on Sensory Science from the University of Georgia. Her thesis explored the emotions of coffee drinking and her current work seeks to understand the emotional impact that brands have on consumers. In her spare time, she enjoys exploring new restaurants, trying out recipes, and decorating cakes. All of the beautiful photos on display in this post were taken by Ari.

Next week: Healthy meals as viewed by a cook and a dietitian by Linn Steward