By Bahram Dideban, MD
Vegetarian diets tend to be lower in saturated fat and cholesterol, and have higher levels of dietary fibre, magnesium, potassium, vitamins C and E, folate, and antioxidants like carotenoids, flavonoids, and other phytochemicals. They are also associated with a number of health advantages. For example, vegetarians tend to be leaner individuals and have a lower BMI, which is associated with lower rates of type 2 diabetes mellitus, hypertension, and heart disease.
The American Dietetic Association, in 2009, produced a set of guidelines that highlighted its opinion and position on vegetarian diets. While it’s evident that a purely vegetarian diet can be as good, if not better, than a typical omnivore diet, it’s important to keep in mind some nutritional considerations that will optimize your plan. Of course, as with any supplementation, make sure you consult your physician before beginning any regimen.
The key word here is lysine. Lysine is really the only protein that may be deficient or lacking from the diet of some vegetarians. The reason for this is cereals, which sometimes compose a very large portion of a vegetarian diet, tend to be very low in lysine. Also, lysine is one of nine “essential” amino acids, meaning that it has to be obtained through the diet whereas the other 11 amino acids can be synthesized in the body. Out of all the plant-based protein sources, soy and bean-based ones are the most complete. So, if you’re getting the majority of your protein from other sources, you could add a lysine supplement into the mix for more completion.
There’s another small caveat. Some protein sources — for example, wheat — are digested much slower by the body than other protein sources are. For this reason, vegans and vegetarians who eat only slow-digesting proteins may have a more “sluggish” utilization of the amino acids they eat, meaning it may take them much longer to recover from a hard workout, for example. This might make very little difference to most vegetarians. For those who measure and weigh out their protein intake daily, through the use of protein shakes and supplements, it’s key to remember that they might need slightly higher amounts to meet their daily requirements. Some sources say you should increase your daily intake by about 10 per cent.
Omega-3 Fatty Acids
Vegetarians and vegans tend to have much lower levels of omega-3 fatty acids, the beneficial compounds that play very important roles in cardiovascular health. This is especially true of diets that don’t include sources of fish, eggs, or large amounts of algae (seaweed, for example). There are two main types of omega-3 fatty acids essential to human health: DHA and EPA, both made in the body from another compound called ALA (alpha-lipoic acid).
DHA-fortified soy milk, nutritional supplements, and other edibles are now available, which make it possible to consume higher levels naturally. If you still have your doubts, DHA supplements made from algae are also readily available and should top the supplement list of any vegetarian or vegan athlete. EPA is a bit harder to come by, but it’s available through retrograde conversion from DHA supplements. Another option is to simply supplement with ALA, although you could make certain that your diet contains sufficient amounts by eating plenty of flaxseed and soy.
This is one area where vegans and vegetarians need to be vigilant. The issue with iron is that animals, including humans, use iron in their red blood cells to carry oxygen. This means iron from animal food sources is readily available for humans to use in their own red blood cells. This is not true of plant-based iron where all of the iron is in its elemental, non-heme form. For this reason it’s also very volatile in our digestive tract. Certain foods, like items high in calcium as well as coffee and tea, can block the absorption of the iron from many different plant sources.
On the other hand, certain food preparation techniques like soaking and sprouting beans, grains, and seeds can enhance the absorption of iron when eaten together with iron-containing plants. Also, fruits and other organic-acid and vitamin C-containing foods can enhance iron absorption.
But, despite most efforts to increase iron absorption, the iron requirements of vegetarians is still almost twice as high as meat-eaters. There is one silver lining though: studies show that the physiology of vegans and vegetarians may eventually get used to living with lower iron intakes and actually become efficient at absorbing and utilizing iron. This is evident in blood tests that show the levels of iron stores in vegetarians are actually equal to that of their carnivorous counterparts.
Calcium balance is a very interesting area when it comes to the various diets. This is one area where some vegetarians actually have an advantage over meat-eaters. A diet high in meat, fish, and dairy products cause an acidic load in the kidneys. While this acidic load is not at all dangerous on its own, our body safeguards against this acid using calcium mainly from our diet and bones. For this reason, carnivorous diets can lead to high calcium losses in the urine whereas vegetarian diets can protect against this loss. But, things are not always so simple.
Calcium is mostly available from animal sources; as a result, lacto-ovo vegetarians (those who still consume some milk and eggs) tend to get similar levels of calcium in their diets as meat-eaters do. Vegans and complete vegetarians, however, tend to suffer in the calcium department. In fact, some studies show that vegans can have as much as a 30-per cent higher risk of fractures due to weaker bones and lower calcium levels than lacto-ovo vegetarians.
So while the diet of some vegetarians can protect against the loss of calcium from the bones, it’s inherently low in calcium to begin with. This is why most vegetarians would benefit from a daily calcium supplement. If you would also like to supplement your diet with natural calcium sources, low-oxalate greens like bok choy, broccoli, Chinese cabbage, collard greens, and kale can be excellent sources of dietary calcium. There are also plenty of products that are calcium-fortified that can help boost a vegetarian’s daily intake of calcium (think milk and juice products).
Another micronutrient that greatly suffers in the diet of vegans and vegetarians is vitamin B12. This is because non-fortified plant foods contain little to no vitamin B12, and even fermented soy products don’t contain enough vitamin B12 to contribute to a healthy vegan or vegetarian diet, despite what some people believe. Not only that, but vegetarian diets are especially rich in folic acid, another B vitamin, which can mask the signs of vitamin B12 deficiency in blood tests.
Vitamin B12 is used by the body mostly in pathways that are involved in the red blood cells and nerves, so a B12 deficiency can lead to anemia, with the resulting fatigue and sluggishness, as well as serious neurological deficits. In most cases, a vitamin B12 supplement is absolutely essential and should be in the top three supplements every vegetarian adds to his or her diet, in my opinion.
Vitamin D levels in humans are highly variable, even in omnivorous individuals. The main reason being that in addition to dietary sources, the majority of vitamin D is produced in the body through exposure to sunlight. Also, because of our recently sedentary, indoor lifestyles and sunscreen use, most of us have trouble producing enough vitamin D in the first place, no matter what our diets are like. Whether or not you are a vegetarian, if you’re not eating enough vitamin D-fortified foods like milk, or getting enough sunshine, you may benefit from supplementation (often sold as vitamin D3).
Like iron, zinc is a trace metal that’s important in normal human physiology and, just like iron, its levels are mostly affected by its dietary absorption. This means your zinc levels, whether you’re vegetarian or not, are dependent on what you eat. The crutch is that vegetarians tend to eat much higher levels of zinc-lowering foods in their diets than omnivores do. Unrefined grains and legumes are rich in phytates, chemicals which interfere with the absorption of zinc (and iron) and can contribute to zinc deficiency.
There is, however, a silver lining. Just as some foods inhibit the absorption of zinc, other foods enhance its absorption, and those foods happen to be the most delicious! Organic acids, like those found in fruits, cheeses, nuts, and some soy products, tend to not only be high in zinc but also help absorb more of it from your diet.
But remember, zinc deficiency is not easily apparent in humans. Some men may experience certain levels of sexual dysfunction, but on the whole zinc deficiency is hard to detect. In other words, do your research and if you feel your diet may be low in zinc or high in phytates, take a zinc supplement every day. Check with your doctor first, however, as many vegetarians in the Western world get more than enough.