How but in custom and ceremony

Are Innocence and Beauty Born?

—William Butler Yeats


Folate and Folic Acid

Saturday, December 15, 2012

The terms folate and folic acid are used interchangeably, even in medical literature or on the labels of vitamin supplements; but the two forms should be distinguished. The first is a naturally-occurring synergistic chemical complex found in food, and the second is a synthetic vitamin analogue derived from petroleum. The two are chemically and structurally distinct, with different absorption pathways in the body. It is no wonder, then, that many of the protective effects of folate are not observed with folic acid.

What’s in a Name?—The terms folate and folic acid are frequently confused, but there are more technical terms to distinguish between the two forms. The natural form of the vitamin is called pteroylglutamate; the synthetic form is pteroylglutamic acid (PGA). I’ll continue here to use the more familiar terms, but please remain aware that they are used interchangeably elsewhere, as their equivalence is most often assumed.

Still, it is easy to see why folic acid is such a popular supplement. It is a very stable chemical, easy to standardize, and inexpensive. Food folate, however, is very unstable. Three days after harvesting fresh greens, up to 70 percent of its folate content has disappeared. Folate is also destroyed by protracted cooking and other processing.

Proponents of folic acid argue that it is superior to food folate because more readily assimilated in the body. Folic acid is indeed rapidly absorbed through the gastrointestinal tract, but the liver can daily convert
only 400 mcg of folic acid into dietary folate equivalent (DFE)—less for those with a certain genetic limitation. (An estimated 40-50 percent of the population has a MTHFR mutation that reduces their ability to convert folic acid into the useable form. MTHFR is the liver enzyme methylenetetrahydrofolate reductase.) Un-metabolized folic acid circulating in the body then competes with folate for transport. It has also been shown to decrease the activity of killer T cells; this is believed to be the link between folic acid supplementation and increased cancer risk. So the very readiness with which folic acid is absorbed can actually be quite problematic, and is nothing to recommend it.

Proponents of folic acid argue that it is a more productive source of DFE. A single microgram of folic acid provides up to two micrograms of DFE. Studies show that after 266 mcg of folic acid, the body’s ability to convert it begins to diminish; the numbers plateau at 400 mcg of folic acid. Long-term supplementation may further diminish the effectiveness of folic acid by exhausting the liver enzymes needed for conversion.

Those with advanced symptoms of folate deficiency will experience some benefit with supplementation of folic acid; however, supplementation with folic acid is not optimal, particularly for the long-term correction of an inadequate diet. Certainly, there are clear health risks to indiscriminate supplementation of folic acid, as with the mandatory ‘enrichment’ of refined grain products. Avoid eating enriched products, eat plenty of fresh folate-rich foods, and choose one of the several supplements with natural food folate.


October 14, 2011      Originally published as “Folate vs. Folic Acid” on the blog Cabbages and Kings.

December 15, 2012    Revised for publication as “Folate and Folic Acid” on the blog Linnet on the Leaf.

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