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Friday, June 27, 2014

My Plant-Based Meals 6-25-14


Some people commented on the fact that I get my B12 from fortified foods and supplements, and have suggested that the assumed lack of B12 in my plant based diet implies that I should be eating animals.  I have previously written about the various fallacies used to suggest that humans should or need to eat animals to obtain B12.

The idea that humans should and can reliably achieve B12 sufficiency by eating animals or their products faces one important problem: Tufts University researchers have reported that up to 40% of meat-eaters have low serum B12 levels.[1]

Katherine Tucker, a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, conducted the research that found that among offspring of residents of Framingham, only consumption of B12 supplements and fortified foods predicted B12 sufficiency, whereas meat and fish intake did not.[2]  The USDA reported on this research:
"Oddly, the researchers found no association between plasma B12 levels and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet. “It’s not because people aren’t eating enough meat,” Tucker said. “The vitamin isn’t getting absorbed.” [1]
Moreover, "Many people over age 50 lose the ability to absorb vitamin B12 from foods." [3]

The Food and Nutrition Board of the National Academy of Science recommends that all people aged more than 50 years eat foods fortified with B12 or take a B12 supplement. 
"Because 10% to 30% of older people do not absorb food-bound vitamin B12 efficiently, those over 50 years should meet the RDA by eating foods fortified with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 mcg per day has been used to maintain vitamin B12 levels in older people."[4]
To reiterate, this applies to everyone, not only people eating plant based diets.  I belong to this age group.

Makes one wonder why so many people don't efficiently absorb B12 from animal products, doesn't it? Does this provide evidence that we aren't biologically adapted to extracting B12 from animal flesh.?

Some people have made comments about the Vitamin D2 I ingest from D2-fortified soy and hemp milks.  Vitamin D2 occurs naturally in some foods (e.g. mushrooms).

"Some mushrooms provide vitamin D2 in variable amounts [13,14]. Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available." [5

I have so far seen no evidence that the doses of D2 obtained from drinking one to two cups of fortified plant-based milk daily (about 200-400 IU) have any harmful effect.  Vieth reports that subjects given vitamin D2 doses as high as 100,000 IU daily over the course of 4 days did not find any significant change in serum calcium levels.[6]  That dose is 500 times more D2 than contained in one cup of these beverages.  Although D2 does not raise serum 25(OH)D levels as efficiently as D3 and on this basis is not the optimal form for supplementation or fortification [7], I presently rely on sunlight, not oral supplements or fortified foods, to obtain vitamin D3. 

Notes

1.  http://www.ars.usda.gov/is/pr/2000/000802.htm
2. Tucker K, et al. Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring Study.  Am J Clin Nutr 2000; 71:514–22.  http://ajcn.nutrition.org/content/71/2/514.full.pdf
3. http://www.nlm.nih.gov/medlineplus/ency/article/002403.htm
4. www.nlm.nih.gov/medlineplus/druginfo/natural/926.html
5. http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
6.  Vieth R.  Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety.  AJCN 1999 May;69(5): 842-856. http://ajcn.nutrition.org/content/69/5/842.full
7. Houghton LA, Vieth R.The case against ergocalciferol (vitamin D2) as a vitamin supplement. AJCN 2006 Oct; 84(4): 694-97.  http://ajcn.nutrition.org/content/84/4/694.full

1 comment:

Charles Grashow said...

Your Omega 6/3 ratio for this day is 18:1 - optimal S/B no higher than 4 or 5:1.

What say you.