Vegetarian diets are increasing in popularity, at least partly due to the purported health benefits. Studies show that compared to the typical Western omnivorous diet, vegetarians have lower rates of heart disease, cancer, and obesity. Of course, the typical western diet is nothing to strive for, being high in ultraprocessed foods, artificial additives, and excessive sugar.
So, it’s not surprising that vegetarians are healthier since they tend to eat more vegetables, beans, and whole grains, which translates into consumption of significantly more fiber, antioxidants, and key nutrients such as magnesium and vitamin C.
However, certain nutrients are lacking in a healthy vegetarian diet, which may harm health and compromise athletic performance. This article will discuss three of the dangers of a vegetarian diet and provide strategies for avoiding them.
#1: Greater Risk of Mental Disorders
A well-designed 2012 study from Germany found that vegetarians had an increased risk of depressive and mental disorders. This study follows other studies showing similar negative effects of plant-based eating on mental health.
The German study used a matching protocol where vegetarians were paired with individuals who were similar in terms of age, sex, and education who ate meat. Compared to the matched controls, risk of having a mental disorder was two times higher in vegetarians.
When the data was looked at from another direction, it was found that the subjects in the study with depression, anxiety, and eating disorders consumed less meat than people without a mental disorder. For example, strict vegetarians had a 15 percent greater rate of mental disorder than non-vegetarians.
Two things were particularly interesting about this study. First, vegetarians tend to perform better on other measures of health (lower cancer and heart disease risk) and generally have healthier lifestyle habits (less smoking, more exercise) than meat eaters.
Second, the study found that the mental disorder isn’t caused by the vegetarian diet. Rather, having a mental disorder increases the probability of choosing a vegetarian diet. This is somewhat surprising since there are nutritional pitfalls to the typical vegetarian diet that could put an individual at risk for compromised cognitive function and lower mood.
For example, vegetarian diets are deficient in EPA and DHA fish oil, which are consistently associated with improved mood and a better psychological profile as well as better cognition. This was evident in this study: Fish consumption was most clearly negatively associated with anxiety disorders—that is individuals with higher fish consumption had the lowest risk of anxiety.
Other nutrients lacking in the vegetarian diet that impact brain function are vitamin B12, creatine, zinc, and vitamin D.
Researchers were unsure why people with mental disorders chose a vegetarian diet but put forth a few theories:
- Individuals with a history of a mental disorder may exhibit more health-oriented behavior in order to positively influence the course of their disease.
- The experience of a mental disorder may sensitize individuals to the suffering of other living beings, including animals.
Bottom Line: More research is needed to explore the relationship between plant-based eating and mental issues, so there’s no need to ditch your vegetarian diet yet. Protect yourself by ensuring you get enough EPA and DHA (a plant-based source made from microalgae is now available), vitamin B12, vitamin D, creatine, and zinc.
#2: Negative Body Composition Changes With Strength Training
A 1999 study compared the effect of 12 weeks of resistance training in older men who ate a lacto-ovo-vegetarian diet with an omnivorous diet and found that the vegetarian diet group didn’t experience the same beneficial changes in body fat and muscle mass as the meat eaters.
The men on the vegetarian diet actually gained a tiny bit of body fat and lost muscle mass (0.8 kg), which is a very surprising outcome in response to resistance training. Body fat percentage increased by 1 percent. In contrast, the omnivores decreased body fat by 1.3 kg and gained 1.7 kg of muscle for a 5 percent decrease in body fat, which is what would be expected from this type of workout program.
Interestingly, changes in maximal strength were similar in both groups, with no negative effect of the vegetarian diet. The lack of difference in strength gains likely reflects the novice status of the trainees whose initial increase in strength is due to adaptations to the nervous system rather than to muscle growth.
It’s unclear why the vegetarian group had poor body composition results from the program but a few possible reasons are as follows:
- A difference in total protein intake and calories between the groups. Food was not provided and the subjects had to provide their own food. The vegetarians ended up eating less protein than the omnivores (71 grams versus 91 grams a day), and they decreased their energy intake over the course of the study by 120 calories whereas the meat eaters increased calories by 140 daily.
- Lack of leucine, which is the primary amino acid that stimulates protein synthesis. Vegetarian protein sources are low in leucine than carnivorous diets.
Bottom Line: More research is needed about the nuances of vegetarian diets on body composition changes but it’s safe to recommend the following if your goal its to optimize body composition from training:
- Due to the lower quality of plant-based protein, vegetarians should bump up daily protein goal and spread it out over the course of the day.
- Shoot for at least 25 grams of protein at each meal to trigger protein synthesis.
- Consider using whey or pea protein if you’re having trouble reaching protein goals. Whey is a dairy-based protein that has been shown to have many health benefits and produce superior improvements in body composition and performance with training. Pea protein also performs well and is a vegan protein source.
#3: Reduced Athletic Performance
Chances are, even if you’re not a competitive athlete, you take your workouts seriously. Your want to get everything you can out of the precious hours you spend in the gym. Nutrition is key to this equation and it just so happens that there are certain “performance” nutrients that are only available in animal foods. If you are a vegetarian or eat a low-meat diet, you may be missing out on reaching your true athletic potential.
The most researched is creatine—a compound that is only present in meat and fish and serves as an energy reserve for short-term, intense exercise. Studies show that in order to equalize the playing field with meat eaters, vegetarians need to supplement with creatine. Doing so can increase training volume and work capacity by as much as 15 percent, which translates into greater improvements in body composition.
Creatine supplementation can also benefit brain function. In two studies, creatine supplementation benefited cognition in vegetarians compared to omnivores so that vegetarians improved working memory and intelligence.
Carnosine is a second performance-enhancing nutrient that improves lactate buffering in order to slow the increase in acidity that makes your muscles burn. Carnosine is completely absent from the vegetarian diet. The only source for vegetarians is through uracil degradation from phospholipids—a pathway with very poor rate of production. Therefore, vegetarians may benefit from supplementing with beta-alanine—the precursor to carnosine.
Carnitine is another compound that plays a critical role in energy production, transporting fatty acids into cells to be burned for energy. Interestingly, even meat eaters who are not deficient in carnitine can improve exercise performance and muscle function with carnitine supplementation. One study found that when trained triathletes took 2 grams of carnitine twice a day for 24 weeks, they increased cycling performance by 11 percent compared to a placebo.
The athletes also increased work output by 35 percent and burned more fat for fuel, while sparing glycogen. Lactate and RPE levels were significantly lower than the placebo group, indicating that carnitine supplementation reduced fatigue and allowed the athletes better training tolerance.
Bottom Line: It’s a no-brainer for every serious vegetarian athlete to supplement with creatine, carnitine, and beta alanine to achieve your athletic potential and equalize the playing field with your meat-eating peers.