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Selasa, 16 Agustus 2011

Natural Diet Require Supplements

Diet Require Supplements
Some vegans wrote me after reading earlier versions of Vitamin B12: Are You Getting It?, saying that by implying vegans need to take a supplement, I am portraying the vegan diet as unnatural. One person said, "All the vegans I know are healthy and they neither take vitamin B12 supplements nor eat foods fortified with vitamin B12."

It is true that many vegans do not supplement with B12 and remain apparently healthy for many years. These vegans normally do not know what their homocysteine levels are, which could be contributing to chronic disease. You are taking a chance by assuming you have transcended a need for a typical B12 intake.

As people live longer, homocysteine has more years to cause damage to the body. Because of this, the human need for B12 has increased over time. The longer a vegan does not supplement with B12, the lower their active B12 levels will drop, increasing their homocysteine levels.

In Western society today, it is easy to ensure an adequate B12 intake. Vegans who supplement with B12 can have superior B12 status to non-vegetarians who do not supplement. In fact, the Food and Nutrition Board says that all people (not just vegans) over age 50 should "meet their RDA mainly by consuming foods fortified with B12 or a B12-containing supplement." 

I would encourage vegan advocates to make achieving superior B12 status for all vegans one of our goals. As such, all new vegans should be told to ensure an adequate supply of B12 by the people or organizations who encourage them to change their diet. 

Is the Vegan Diet Natural?
Whether any prehistoric humans were vegan cannot be concluded from the research presented here. I recommend an article that examines the subject of the naturalness of a vegan diet: Comparative Anatomy and Physiology Brought Up to Date: Are Humans Natural Frugivores/Vegetarians, or Omnivores/Faunivores? by Tom Billings. After an extensive review of the research, Billings concludes that humans are not naturally vegetarians or vegans. Despite this, he says: 

I am both pro-vegetarian and pro-[eating raw foods as a large portion of the diet]. Readers should be aware that I am a long-time vegetarian (since 1970), a former long-time (8+ years) fruitarian (also a former vegan),... However, I am definitely not a promoter of, or a "missionary" for, any specific diet. In reality, I am tired of seeing raw and [vegan/vegetarian] diets promoted in negative ways by extremists whose hostile and dishonest behavior is a betrayal of the positive moral principles that are supposedly at the heart of veg*ism.

He continues:
You really don't need the naturalness claim to be a veg*n! That is, moral/spiritual reasons alone are adequate to justify following a veg*n diet (assuming the diet works for you, of course). Further, if the motivation for your diet is moral and/or spiritual, then you will want the basis of your diet to be honest as well as compassionate. In that case, ditching the false myths of naturalness presents no problems; indeed, ditching false myths means that you are ditching a burden.

Readers may also be interested in the article Humans are Omnivores, adapted from a talk by John McArdle, PhD (originally published in the May/June 1991 edition of the Vegetarian Journal).

Whose Diet is Really Natural?
The suffering endured by the majority of animals raised in contemporary animal agriculture far outweighs any desire of mine to eat the same as my prehistoric ancestors. But, even if the animals' suffering were of no consequence, these assumptions are dubious:
  • There is one prehistoric or natural diet.
  • This diet can reasonably be approximated today.
  • This diet is optimal for human health in today's world.
Today's commercial plant foods and meats are different from the foods available in prehistoric times. We eat hybrids of plants and we feed foods to animals that they would not normally eat. We keep them confined so that they do not exercise. The U.S. food supply is routinely fortified with a host of vitamins and minerals (such as vitamin D in milk), and most people who turn to what they consider to be a more natural diet as adults have often benefited from this supplementation.

The Medical Community: Future of Research on Vegans
Some vegans dislike the medical community. By refusing to accept the scientific evidence in favor of the need to supplement with B12, the vegans who dislike the medical community are providing a steady flow of vegans with poor health for the medical community to study. If you do not like the medical community, the best thing you can do is ensure that you do not develop B12 deficiency and will never be used by them to say that a vegan diet is unhealthy. 

I tend not to believe that medicine is one big conspiracy against veganism, and am glad that research has been done on vegans who do not supplement with B12. But enough is enough. I am tired of seeing study after study looking at vegans who do not supplement with B12. It is the vegan community's responsibility to stop this flow of research subjects. When a researcher decides to do a study looking at the various health problems of vegans who do not supplement their diets with B12, it would be best if they simply could not find any.

Encourage New Vegans to Concern Themselves with B12 Supplements
All vegan advocates should be made aware of the symptoms of B12 deficiency (with the realization that elevated homocysteine levels occur long before these symptoms are noticeable). As pointed out earlier (in the section Transcobalamin II under Blood B12 Level: Not a Reliable Measure of B12 Adequacy), adequate transport of B12 to the tissues may considerably slow after B12 intake significantly decreases. Some people who try a vegan diet may already have low B12 levels or hampered absorption mechanisms. Some of these factors could cause a new vegan to feel bad and go back to eating animal products. Therefore, it is prudent for new vegans to follow the Recommendations. This will prevent any potential lapse in adequate B12 delivery to tissues.

Daily or Weekly Supplementation?
Throughout human history, people have ingested B12 on a daily basis, and most often throughout the day. This has given people a steady supply of B12 to their tissues (above that which is reabsorbed through the enterohepatic circulation). While there is no research on whether a vegan is better off taking B12 on a daily vs. weekly basis, I would err on the side of caution and supplement daily.

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