Veganism: Encyclopedia II - Veganism - Vegan nutrition

Veganism - Vegan nutrition

Nutrition authorities say that a properly planned vegan diet presents no significant nutritional problems. Supplementation is highly recommended, though to a lesser extent this applies to non-vegans, too. Drs. Fletcher and Fairfield concluded, in JAMA (Journal of the American Medical Association) in June 2002, that "[i]t appears prudent for all adults to take vitamin supplements." The British government's annual survey of nutritional content of food, McCance and Widdowson's 'The Composition of Foods,' notes that the 2002 nutritional profile of foods is seriously lacking in trace elements compared with their 1931 profiles; indeed, a steady decline over the past 60 years has been noted. There are several nutrients vegans should pay attention to. These include Vitamin B12, iron and iodine: deficiencies in these are more likely following a vegan diet, and deficiencies of these have potentially serious consequences, including anemia, pernicious anemia, cretinism and hyperthyroidism. Interestingly, B12 deficiency can be a problem for others, too; aging, for example, can lead to an inability to absorb B12 from food, and supplementation is recommended for those over fifty-five years of age.

Protein

Frances Moore Lappé's 1971 besteller Diet for a Small Planet popularized the myth that the protein in plant foods was "incomplete" and that vegetarians had to "combine" different plant foods by eating both of them (e.g., beans and grains) in order to get a "complete" protein. A decade later in The McDougall Plan (1983) Dr. John McDougall showed that this idea is incorrect and that common plant foods actually contain complete proteins. In The McDougall Program (1990) he wrote, "Fortunately scientific studies have plainly debunked this complicated nonsense. Nature designed and synthesized our foods complete with all the essential nutrients for human life long before they reach the dinner table. All the essential and nonessential amino acids are represented in single unrefined starches such as rice, corn, wheat, and potatoes in amounts in excess of every individual's needs, even if they are endurance athletes or weight lifters." McDougall's claims are easily verified by comparing the individual amino acids supplied by foods to the World Health Organization standard for protein intake.

Iodine

Residents of the UK may find themselves iodine-deficient if they rely on local produce, since in the UK iodine is usually obtained via dairy products rather than iodized salt that is more common elsewhere. The Vegan Society says, "Iodine is typically undesirably low (about 50 micrograms/day compared to a recommended level of about 150 micrograms per day) in UK vegan diets unless supplements, iodine rich seaweeds or foods containing such seaweeds are consumed. The low iodine levels in many plant foods reflects the low iodine levels in the UK soil, due in part to the recent ice-age." This demonstrates that location may also be a factor in what deficiencies may be present in any given diet.

Vitamin B12

Vitamin B12, a bacterial product, cannot be reliably found in plant foods, and so vegans are recommended to eat foods with B12 added (such as fortified soy milk, fortified margarines, or many commercial breakfast cereals), certain brands of nutritional yeast, or take dietary supplements (a good multivitamin will likely include B12 in sufficient quantities). Tempeh, miso, and a few other fermented foods can sometimes contain B12 as well, though they cannot be considered reliable sources. Older people, vegan and non-vegan alike, may find they experience difficulties in absorbing B12 from their food, and pernicious anaemia, caused by a B12 deficiency, is not unknown amongst omnivores.

Iron

Iron is present in many typically vegan foodstuffs. These include grains, nuts and green leaves, although the iron in these sources is in a less easily absorbed, non-heme form. Nevertheless, the Society quotes research to show that iron deficiency is no more prevalent in vegans than in the general population. This research did not account for the fact that many vegans take nutritional supplements that are not found in food alone, whereas other research that excludes this subset of people does indeed show a marked iron deficiency among a majority of those studied.

It is important to note that iron deficiency is one of the most common nutritional deficiencies in the general population, and many nutritionists and dieticians recommend a daily multivitamin because of this. Vitamin C is necessary to the absorption of iron, and, indeed, can double or triple the amount of iron absorbed when taken with food (i.e. a glass of orange juice with a spinach salad). Vegans typically have high levels of vitamin C in their diets, which may account for the rarity of anaemia amongst them.

Calcium

Calcium may also be a concern if the vegan is not eating a variety of foods, especially leafy green vegetables (such as spinach, kale, collard greens, cabbage, etc.), almonds, oats, soy products (soy milk, tofu, etc.), sesame seeds, most beans, and dried fruits, most of which should be included in any diet, vegan or not. The USDA's study on calcium andosteoporosis in women began with the premise that animal proteins create sulphur in the body, which leaches out calcium from the bones. The results, though, were more complex: the vegan subjects lost bone density at the same rate as their vegetarian and non-vegetarian peers; when put on a weight-bearing exercise regimen, the vegan subjects built bone density at a significantly higher rate than the other subjects. The researchers remark, "If you have less bone formation, the result is the same as if you had an increase in bone resorption. So, even though bone resorption was the same in both groups of volunteers, the lower amount of bone formation in the omnivore women could lead to a decrease in their bone density."

DHA

One nutrient that is sometimes overlooked when analyzing the vegan diet is docosahexaenoic acid (DHA). For non-vegetarians, good sources for this omega-3 fatty acid include edible marine fish and shellfish and eggs. This healthy fat can also be found in Algae and vegan DHA dietry supplement capsules are now available. This fatty acid is very important for brain function, eye function, and for the cellular transport of valuable nutrients. "ALA" can be converted by the body into DHA. ALA is found in soybeans, walnuts, flaxseed, pumpkin seeds, and canola oil: many vegans include these specific foods in their diets. To obtain the same benefit, it has been estiamted that 10x the amount of ALA as DHA must be consumed. [24]

Omega-3 fatty acids must be included in any diet: this is specially true for younger children and the elderly because growing and ageing brains need more of these nutritious fats. There are multiple sources of omega-3 fatty acids available to vegans: flaxseed oil (sometimes called edible linseed in the UK) and hemp oil, nuts (especially walnuts), and certain green, leafy vegetables all provide omega-3s as well.

Omega 3 interacts with another dietary fatty acid: Omega 6. it is believed that the health benefits of Omega 3 consumption are obtained only when the Omega 3: Omega 6 ratio is increased. Oils which should therefore be avoided due to their high Omega 6 content are: sunflower, safflower, and corn oil. Olive oil is an an example of an omega-neutral oil as its fat is monounsaturated and does not contain much omega 3 or omega 6 and may be consumed without affecting the 3:6 ratio.

Adapted from the Wikipedia article "Vegan nutrition", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki