Medical myths: Vegetarian and vegan diets


Following a plant-based diet is becoming increasingly popular. While this is widely regarded as a healthful choice, many myths abound. In this edition of Medical Myths, we dig into the details.

Until fairly recently, vegetarianism was generally considered a fringe lifestyle choice in the United States, and veganism even more so. Anything on the fringes of society tends to inadvertently encourage myths and misconceptions.

Also, deciding to avoid animal products sparks rage in some people. This anger manifests for a range of reasons, which are beyond the scope of this article. Suffice it to say that if a sizable group of the population is against something, conditions are ripe for myths and half-truths.

1. Plant-based diets are always healthful

In recent decades, an increasing number of studies have demonstrated links between red meat consumption and poorer health outcomes. For instance, processed and red meat intake is associated with colon cancer, obesity, heart disease, and diabetes.

This might suggest that a diet without meat is better for the body. But, just as not all meat is red, not all vegetarian or vegan diets are healthful.

To use an extreme example, if an individual only ate potato chips, they would be vegan, but certainly not brimming with vitality, energy, and health.

As with any other diet, it depends entirely on what an individual consumes.

Additionally, lean white meat and fish are not associated with the same health issues as processed and red meats.

And certain meat substitute products can be high in salt.

2. Vegetarianism guarantees weight loss

Sadly, no. As the section above makes clear, not all vegetarian and vegan diets are equally healthful. It is incredibly easy to consume thousands of calories each day without any of them being associated with animals.

The key to weight loss is a healthful diet and regular exercise, and neither requires the avoidance of animal products.

It is still worth noting, though, the evidence that following a plant-based diet is associated with weight loss. For instance, a review published in Translational Psychiatry

explains:

“We found robust evidence for short- to moderate-term beneficial effects of plant-based diets versus conventional diets on weight status, energy metabolism, and systemic inflammation.”

This finding held true for healthy participants, people with obesity, and individuals with type 2 diabetes.

To give another example, another review, published in BMJ Open Diabetes Research and Care, looked at the impact of plant-based diets on people with diabetes. Among other benefits, the authors found that these diets were associated with a “significant improvement” in weight.

3. Vegetarians and vegans cannot get enough protein

This is perhaps the most common of all the myths that we cover today. But it is still a myth. In the world of food, protein abounds.

For people who eat them, dairy products and eggs are high in protein. Vegans also have an array of options, including seitan, tofu, lentils, chickpeas, many types of bean, spelt, spirulina, quinoa, oats, wild rice, seeds, and nuts.

Even some vegetables contain protein, including spinach, asparagus, broccoli, artichokes, potatoes, peas, brussels sprouts, and sweet potatoes.

4. You can’t build muscle without meat

This myth follows on from the protein myth above. In short, the most important nutrient for building muscle is protein, which can easily be found in abundance beyond the animal kingdom.

5. Dairy is essential for strong bones

Dairy is not essential for strong bones, but calcium is. In fact, calcium is important for a number of bodily functions, including maintaining blood pressure, muscle contraction, transmitting signals along nerves, and blood clotting.

Vegans, therefore, need to ensure that they take in enough calcium from plant-based sources. 

As with protein, there are plenty of places to pick up calcium, including soy-based foods, beans, lentils, peas, spinach, turnips, figs, flax, chia, sesame seeds, seaweed, and some nuts — almonds, in particular.

6. You cannot get B12 from a vegetarian diet

This is a myth. While vegans often take B12 supplements to ensure that they have adequate levels, vegetarians have a wealth of other options.

Vegetarians can derive B12 from eggs and milk products, including cheese.

Meanwhile, a range of vegan-friendly foods are fortified with B12, including some cereals, tofu, nondairy milks, and spreads.

B12: An interesting aside

Cows need B12, too, and they rely on gut bacteria to produce it.

To produce B12, gut bacteria need cobalt, which a cow normally derives from grazing. However, many cows destined to become meat only spend the beginning of their lives in pasture before being brought inside where they are fed on grain.

Because of this unnatural diet, their gut bacteria are starved of cobalt and cannot produce B12.

But the cow still needs B12 to thrive, so farmers must provide them with either cobalt or B12 supplements.

So even a staunch, dyed-in-the-wool red meat fanatic is likely to derive their B12 from supplements — but in their case, it’s via a cow.

7. Soy increases the risk of breast cancer

As it stands, there is no convincing evidence that eating soy-based foods increases the risk of breast cancer in humans.

This misunderstanding might stem from earlier studies in rodents. Scientists showed that when these animals received large amounts of soy compounds called isoflavones, they were more likely to develop breast cancer. However, humans process soy differently from rodents.

A study published in February 2020 searched for associations between soy, dairy intake, and breast cancer risk. The scientists had followed 52,795 cancer-free women in the U.S. for an average of 7.9 years.

They found no clear association between soy intake and breast cancer, but they did identify a link between dairy milk and breast cancer.

However, the full picture is, perhaps, slightly more complex. Some women use soy-based supplements as a natural alternative to hormone therapy during menopause. One large study investigated whether these supplements might be associated with breast cancer risk.

The researchers found “no association between past use of soy supplements and breast cancer.” But, they also found that taking soy supplements, for some women, might increase the risk of breast cancer, particularly for those with a family history.

Overall, as the American Cancer Society explain:

“The evidence does not point to any dangers from eating soy in people, and the health benefits appear to outweigh any potential risk. In fact, there is growing evidence that eating traditional soy foods may lower the risk of breast cancer, especially among Asian women.”

8. Pregnant people need meat and dairy

During pregnancy, it is important to take in all the nutrients that a growing baby needs. But, as we have seen along the way, plant-based foods can provide the vast majority of them.

Someone who is vegetarian or vegan may need to do a little extra planning to be sure that have enough nutrients, especially at the beginning of pregnancy. 

As we mentioned above, it is important to ensure an adequate intake of vitamin B12, through supplements or fortified foods, and this is especially true during pregnancy and breastfeeding. The American Dietetic Association recommend vitamin B12 supplementation throughout pregnancy and breastfeeding for people with vegan or vegetarian diets.

As the authors of a review of research about plant-based diets during pregnancy explain, “The available evidence shows that well-planned vegetarian and vegan diets may be considered safe during pregnancy and lactation, but they require a strong awareness for a balanced intake of key nutrients.”

Excited cheerful young couple cooking healthy salad while sitting at the kitchen

DIABETES

Diabetes is a disease in which your blood glucose, or blood sugar, levels are too high. Glucose comes from the foods you eat. Insulin is a hormone that helps the glucose get into your cells to give them energy. With type 1 diabetes, your body does not make insulin. With type 2 diabetes, the more common type, your body does not make or use insulin well. Without enough insulin, the glucose stays in your blood. You can also have prediabetes. This means that your blood sugar is higher than normal but not high enough to be called diabetes. Having prediabetes puts you at a higher risk of getting type 2 diabetes.

Over time, having too much glucose in your blood can cause serious problems. It can damage your eyes, kidneys, and nerves. Diabetes can also cause heart disease, stroke and even the need to remove a limb. Pregnant women can also get diabetes, called gestational diabetes.

Blood tests can show if you have diabetes. One type of test, the A1C, can also check on how you are managing your diabetes. Exercise, weight control and sticking to your meal plan can help control your diabetes. You should also monitor your blood glucose level and take medicine if prescribed.

How can I prevent or delay getting type 2 diabetes?

If you are at risk for diabetes, you may be able to prevent or delay getting it. Most of the things that you need to do involve having a healthier lifestyle. So if you make these changes, you will get other health benefits as well. You may lower your risk of other diseases, and you will probably feel better and have more energy. The changes are:

  • Losing weight and keeping it off. Weight control is an important part of diabetes prevention. You may be able to prevent or delay diabetes by losing 5 to 10% of your current weight. For example, if you weigh 200 pounds, your goal would be to lose between 10 to 20 pounds. And once you lose the weight, it is important that you don’t gain it back.
  • Following a healthy eating plan. It is important to reduce the amount of calories you eat and drink each day, so you can lose weight and keep it off. To do that, your diet should include smaller portions and less fat and sugar. You should also eat a variety of foods from each food group, including plenty of whole grains, fruits, and vegetables. It’s also a good idea to limit red meat, and avoid processed meats.
  • Get regular exercise. Exercise has many health benefits, including helping you to lose weight and lower your blood sugar levels. These both lower your risk of type 2 diabetes. Try to get at least 30 minutes of physical activity 5 days a week. If you have not been active, talk with your health care professional to figure out which types of exercise are best for you. You can start slowly and work up to your goal.
  • Don’t smoke. Smoking can contribute to insulin resistance, which can lead to type 2 diabetes. If you already smoke, try to quit.
  • Talk to your health care provider to see whether there is anything else you can do to delay or to prevent type 2 diabetes. If you are at high risk, your provider may suggest that you take one of a few types of diabetes medicines.