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Vegan For Life
by Jack Norris, RD &
Ginny Messina, MPH, RD
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"I was Vegan for A While, But..."

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Let's start with the good news: Vegans have a much lower risk of type-2 diabetes than do meat-eaters – in fact, it's not even close. Research has also shown that vegans have a slightly lower risk of cancer by virtue of our diets.

Unfortunately, this isn't the end of the story. While many people thrive on a vegan diet, others have a hard time. When someone is committed to reducing animal suffering, there are often solutions to these dilemmas, and finding answers has been a major focus of my nutrition writing. While bringing attention to these issues might not initially attract as many people as claiming that a vegan diet is a health panacea, getting people to stay vegan long-term is the more important task because every vegan who fails to thrive provides reasons for many people not to try veganism.

Macronutrients: The Bigger Picture

Something as simple as not eating enough calories might be a problem for an uninformed person who decides to eat vegan for a few days. They might only be aware of low-calorie vegan foods (e.g., salads, vegetables, fruits), and eating only these foods for a day might leave them feeling hungry and weak.

Of course, many advocacy groups are actively trying to educate people about the wide variety of satisfying vegan foods. In promoting the diet, each person could help prepare potential vegans for the real possibility that they won't feel good if they don't choose some calorie-dense foods.

In addition to calories, a lack of protein in the diet for a few days could lead to someone feeling less than optimal and wanting to eat animal products. While severe protein deficiency is certainly nothing to worry about on a vegan diet, if someone doesn't know what high-protein vegan foods to choose, they could go from eating large amounts of protein (on an animal-based diet) to much smaller, less satisfying amounts on a vegan diet. Legumes (beans, peanuts, peas, lentils, soy), seitan, and quinoa are the best sources of protein for vegans. Include a few servings of these foods each day – maybe even each meal.

While a low-fat diet might improve someone's health in the short term, it might not be ideal over longer periods. If you are avoiding all added fats and you start to crave animal products, it might be time to add some fat back into your diet. People tend to think of animal products, and especially meat, as "protein," but they are actually about 50% fat in many cases.

It's theoretically possible that some vegans' cholesterol levels might get too low on a low-fat, low-calorie, and/or low-saturated fat diet, leading to a low production of steroid hormones. In this case, adding plant saturated fat, such as coconut oil, to the diet, could improve their health. There is not much research into how low cholesterol levels must go, on average, to inhibit steroid hormone production and it may be very rare for this to happen. Two studies have shown vegans to have sex hormones on par with meat-eaters (1, 2), but one report showed vegan women to have lower levels of estrogen (3). A few anecdotal reports provide some evidence that low cholesterol problems might be an issue for some vegans (see Bonzai Aprodite's story of regaining her health as a vegan, Facing Failing Health As A Vegan).

While the science is still in the early stages, it appears that some people genetically do not do well basing their diet on carbohydrates (see Dieting by DNA? Popular diets work best by genotype, research shows). For those people, the eco-Atkins type diet, high in plant proteins such as soy meats, legumes, and seitan, might be a better choice than a higher carbohydrate, low-fat diet.

Finally, if you find yourself craving animal products, it could be because you have a strong preference for the taste of glutamate, also known as umami. You can read more about foods high in umami in Ginny Messina, MPH, RD's article, Is Umami a Secret Ingredient of Vegan Activism?

Micronutrient Deficiencies

Vitamin B12 in plant-based diets has long been a source of controversy and myths, so much so that a large portion of this site is dedicated to discussing B12. Although it rarely happens quickly, these myths have led to many vegans getting B12 deficiency. If you do not get a reliable source of vitamin B12, the chances are high that you will, at some point, find your health failing.

The need for calcium on vegan diets has also been surrounded by misleading ideas. Many vegan advocates have suggested that animal protein, including milk, is the main cause of osteoporosis in Western countries. Following this line of logic, it would make sense that vegans do not need to worry about osteoporosis since they are not eating animal protein. The research actually shows that vegans, like non-vegans, should try to meet the calcium recommendations for the greater population (more info). Vegans are at a disadvantage in this area because our diets tend to contain much less calcium than your typical animal-based diet, so we must make an effort to ensure good sources of calcium on a daily basis.

More often than not, vegans who come to me with severe fatigue are suffering from vitamin D deficiency. This is not just a vegan problem, many people develop vitamin D deficiency in this era of sun avoidance. But vegans are at a slight disadvantage, on average, because we get less vitamin D in our diets. Make sure that you have a reliable source of vitamin D.

Although it appears to be a small percentage, some women develop iron-deficiency anemia after becoming vegetarian. If you think you are at risk, see the article on Iron for tips on increasing iron absorption from plants.

Iodine is a nutrient that most vegans rarely think about but a 2011 study showed that vegans do not get enough. Especially if you eat soy, you should make sure you are getting some iodine.

DHA is an omega-3 fatty acid that is important for cognition. A short time on a vegan diet is not likely to cause any sort of deficiency, but long-term vegans should take a supplement.

Finally, some vegans might not get enough vitamin A and zinc, depending on their dietary choices. Vitamin A is easy to get through orange vegetables, though eating them daily is critical to this strategy. Zinc is trickier and some vegans just opt for a modest supplement of 50-100% of the RDA.

For more information on all of these nutrients, please see the Daily Recommendations for people on plant-based diets.


References

1. Thomas HV, Davey GK, Key TJ. Oestradiol and sex hormone-binding globulin in premenopausal and post-menopausal meat-eaters, vegetarians and vegans. Br J Cancer. 1999 Jul;80(9):1470-5. | link

2. Key TJ, Roe L, Thorogood M, Moore JW, Clark GM, Wang DY. Testosterone, sex hormone-binding globulin, calculated free testosterone, and oestradiol in male vegans and omnivores. Br J Nutr. 1990 Jul;64(1):111-9. | link

3. Goldin BR, Gorbach SL. Effect of diet on the plasma levels, metabolism, and excretion of estrogens. Am J Clin Nutr. 1988 Sep;48(3 Suppl):787-90. Review. | link