First, I'll start with what so many people seem to have hang-ups about--the possible nutrient deficiencies of a vegan diet:
- Omega-3 Fatty Acids--important for cardiovascular health and brain and eye function, these are most bio-available (in the forms DHA and EPA) from salmon and trout and algae sources. They are also found in a less bio-available, but nevertheless useful, forms (ALA) in walnuts and flaxseeds. These fats are "all the rage" these days though, so are now (you guessed it) also fortified in everything from granola bars to beverages. We have been eating a large number of walnuts; our almond milk is also fortified. The risk for not getting enough? Increased risk of Cardiovascular Disease, which has actually been shown to have decreased incidences in the vegan population, so I'm not that worried.
- Vitamin-D status depends on both sun exposure and intake of vitamin D-fortified foods (not just for vegans, but for the entire population). It being June, us both being relatively fair-skinned, and (again) with an at-least adequately fortified food system, I'm again not too worried.
- Calcium--"a diet rich in fruits and vegetables that is typical of a vegan diet has a positive effect on the calcium economy and markers of bone metabolism in men and women."* So basically, we just have to make sure we get enough...not too tough.
- Iron--the risk for iron-deficiency anemia is no different in the vegan population than the omnivore population. This is likely due to the large amount of vitamin C consumed by most vegans, which increases the absorption of the iron that they do get from plant sources.
- Vitamin B-12--Vegans have a higher prevalence of this deficiency since it can only be found in animal sources and fortified foods (hooray for almond milk!) Risk factors include difficulty with concentration...I'm sorry, what was I saying?
- Cardiovascular Disease--"In general, vegetarians typically enjoy a lower risk of cardiovascular disease (CVD), obesity, type 2 diabetes, and some cancers." So why not just eliminate meat? "Compared with other vegetarians, vegans are thinner, have lower total and LDL cholesterol, and modestly lower blood pressure...Vegans also have a higher consumption of whole grains, soy, and nuts all of which provide significant cardioprotective effects."
- Cancer--With obesity as a risk factor for cancer, the lower BMI in vegetarians and vegans is one important protective factor. The other protective factors are more directly diet-related; high intake of fruits and vegetables in a vegan diet is negatively associated with cancer risk and there is an obvious lack of red and processed meat, which are both implicated in increased risk of colorectal cancer.
- Weight--I already stated that vegans on average have a lower BMI than both lactoovo-vegetarians (those who eat no meat but do eat dairy and eggs) and omnivores. In addition to looking better in a swimsuit, this has numerous implications on a decreased likelihood of obesity-related chronic disease later in life.
*Most information from this post came from a particularly clear summary, found in the article--Craig, W. (2009). Health Effects of Vegan Diets. The American Journal of Clinical Nutrition, 89(5), 1627S.