There is no one right way to eat for everyone.
We are all different and what works for one person may not work for the next.
I personally advocate consumption of both animals and plants and I think there is plenty of evidence that this is a reasonable way to eat.
However, I often get comments from vegans who think that people should eliminate all animal foods.
I’m tired of having to constantly defend my position regarding animal foods, so I decided to summarize what I think are some potential problems with vegan diets.
Here are 5 reasons why I think vegan diets may be bad idea from a nutrition perspective.
1. Vegans Are Deficient in Some Nutrients
Humans are omnivores. We function best eating both animals and plants.
There are some nutrients that can only be gotten from plants (like Vitamin C) and others that can only be gotten from animals.
Vitamin B12 is a water soluble vitamin that is involved in the function of every cell in the body.
It is particularly important in the formation of blood and the function of the brain.
Because B12 is critical for life and isn’t found in any amount in plants (except some types of algae), it is by far the most important nutrient that vegans must be concerned with.
In fact, B12 deficiency is very common in vegans, one study showing that 92% of vegans are deficient in this critical nutrient (1).
But B12 is just the tip of the iceberg, there are other lesser known nutrients that are only found in animal foods and are critical for optimal function of the body.
Here are a few examples:
- Animal protein contains all the essential amino acids in the right ratios. It is important for muscle mass and bone health, to name a few. Vegans don’t get any animal protein, which can have negative effects on body composition (2, 3, 4, 5).
- Creatine helps form an energy reservoir in cells. Studies show that vegetarians are deficient in creatine, which has harmful effects on muscle and brain function (6, 7, 8).
- Carnosine is protective against various degenerative processes in the body and may protect against aging. It is found only in animal foods (9, 10, 11).
- Docosahexaenoic Acid (DHA) is the most active form of Omega-3 fatty acids in the body and primarily found in animal foods. The plant form of Omega-3s, ALA, is inefficiently converted to DHA in the body (12, 13, 14).
Two other nutrients that have been demonized by vegan proponents are saturated fat and cholesterol.
Cholesterol is a crucial molecule in the body and is part of every cell membrane. It is also used to make steroid hormones like testosterone. Studies show that saturated fat intake correlates with increased testosterone levels (15).
Bottom Line: Vegans are deficient in many important nutrients, including Vitamin B12 and Creatine. Studies show that vegans have much lower testosterone levels than their meat-eating counterparts.
2. There Are No Studies Showing That They’re Better Than Other Healthy Diets
Despite what vegan proponents often claim, there are no controlled trials showing that these diets are any better than other diets.
They often claim that low-carb, high-fat diets (the opposite of vegan diets) are dangerous and that the evidence clearly shows vegan diets to be superior.
This has actually been studied in a high quality randomized controlled trial (the gold standard of science).
This study clearly shows that the Atkins diet causes greater improvements in pretty much all health markers, although not all of them were statistically significant:
- The Atkins group lost more weight, 10.4 lbs, while the Ornish group lost only 5.6 lbs.
- The Atkins group had greater decreases in blood pressure.
- The Atkins group had greater increases in HDL (the “good”) cholesterol.
- The Atkins group had greater decreases in Triglycerides. They went down by 29.3 mg/dL on Atkins, only 14.9 mg/dL on Ornish.
- Then the Atkins dieters were about twice as likely to make it to the end of the study, indicating that the Atkins diet was easier to follow.
Put simply, the Atkins diet had several important advantages while the Ornish diet performed poorly for all health markers measured.
The problem with these studies is that they are so-called observational studies. These types of studies can only demonstrate correlation, not causation.
The vegetarians are probably healthier because they are more health conscious overall, eat more vegetables, are less likely to smoke, more likely to exercise, etc. It has nothing to do with avoiding animal foods.
In another study of 10,000 individuals, where both the vegetarians and non-vegetarians were health conscious, there was no difference in mortality between groups (23).
One controlled trial showed that a vegan diet was more effective against diabetes than the official diet recommended by the American Diabetes Association (24).
A vegan diet may be better than the typical low-fat diet recommended by the mainstream nutrition organizations, but pretty much any diet fits that description.
Bottom Line: Despite all the propaganda, there isn’t any evidence that vegan diets are any better than other diets. Most of the studies are observational in nature.
3. Proponents of Vegan Diets Often Make False Claims
Some vegan proponents aren’t very honest when they try to convince others of the virtues of the vegan diet.
They actively use lies and fear mongering to scare people away from fat and animal foods.
People who promote vegan diets should be more honest and not use scare tactics and lies to make people feel guilty about eating animal foods, which are perfectly healthy (if unprocessed and naturally fed).
I’d also like to briefly mention The China Study, which is the holy bible of veganism and apparently proves that vegan diets are the way to go.
This was an observational study performed by a scientist who was in love with his theories. He cherry picked the data from the study to support his conclusions and ignored the data that didn’t fit.
The main findings of the China study have been debunked.
I recommend you look at these two critiques:
- Denise Minger: The China Study – Fact or Fallacy
- Chris Masterjohn: What Dr. Campbell Won’t Tell You About The China Study
Also, a new study from China came out very recently, directly contradicting the findings of the China study.
According to this study, men eating red meat had a lower risk of cardiovascular disease and women eating red meat had a lower risk of cancer (26).
Bottom Line: Vegan proponents often use fear mongering and scare tactics in order to convince people not to eat animal foods. They frequently cite The China Study as evidence, which has been thoroughly debunked.
4. Vegan Diets Work For Many People, But Not Others
If you look at vegan message boards, you will quickly find stories of people who have seen amazing health benefits on a vegan diet.
I’ve got no reason to believe that these people are lying.
But it’s important to keep in mind that this is anecdotal evidence, which isn’t science.
You will find the same kinds of success stories for pretty much any diet.
Then you’ll also find tons of people saying they got terrible results on a vegan diet.
Personally, I think that vegan diets can have health benefits for a lot of people. At least in the short term, before the nutrient deficiencies kick in (which can be partly circumvented by supplementation).
However, I don’t think this has anything to do with avoiding animal foods!
Vegan diets don’t just recommend that people avoid animal foods. They also recommend that people avoid added sugars, refined carbohydrates, processed vegetable oils and trans fats.
Then they suggest that people stop smoking and start exercising. There are so many confounders here that can easily explain all the beneficial effects.
These are extremely unhealthy foods, that’s something the vegans and I agree on. I personally think that avoiding these foods is what is causing the apparent benefits.
I am 100% certain that a plant-based diet that includes at least a little bit of animals (the occasional whole egg or fatty fish, for example) will be much healthier in the long-term than a diet that eliminates animal foods completely.
Bottom Line: Vegan diets also recommend that people shun added sugar, refined carbohydrates, vegetable oils and trans fats. This is probably the reason for any health benefits, not the removal of unprocessed animal foods.
5. There is No Health Reason to Completely Avoid Unprocessed Animal Foods
Humans have been eating meat for hundreds of thousands (or millions) of years.
We evolved this way.
Our bodies are perfectly capable of digesting, absorbing and making full use of the many beneficial nutrients found in animal foods.
It is true that processed meat causes harm and that it’s disgusting the way “conventionally raised” animals are treated these days.
However, animals that are fed natural diets (like grass-fed cows) and given access to the outdoors are completely different.
Even though processed meat causes harm, which is supported by many studies, the same does NOT apply to natural, unprocessed meat.
Saturated fat has also never been proven to lead to heart disease. A study of almost 350 thousand individuals found literally no association between saturated fat consumption and cardiovascular disease (32, 33, 34).
The thing is that animal foods like meat, fish, eggs and dairy products are extremely nutritious.
They are loaded with high quality protein, healthy fats, vitamins, minerals and various lesser known nutrients that have important effects on health.
There are some ethical and environmental reasons not to eat animals. I get it. But there is no scientifically valid health reason to completely eliminate animal foods.
Take Home Message
At the end of the day, the optimal diet for any one person depends on a lot of things.
This includes age, gender, activity levels, current metabolic health, food culture and personal preference.
Vegan diets may be appropriate for some people, not others. Different strokes for different folks.
If you want to eat a vegan diet, then make sure to be prudent about your diet. Take the necessary supplements and read some of the books by the vegan docs, I’m sure they at least know how to safely apply a vegan diet.
If you’re getting results, feeling good and are managing to stick to your healthy lifestyle, then that’s great. If it ain’t broken, don’t fix it.
2015 Update: This article was written in 2013. I have since changed my mind about vegan diets. I do think that they can be healthy when properly planned and based on whole, unprocessed foods.