Vitamin B9 is methyl folate, a nutrient readily found in many foods, most abundantly in leafy greens. Folic acid is a man made chemical not found in any food found in nature.
While mankind has recognized the value of food for health since the beginning of recorded history as documented in Traditional Chinese Medicine as well as Ayurvedic Medicine it was not until less than 100 years ago that scientists decided to investigate what it was in food that resulted in the health benefits. Initially these were called ‘extrinsic’ factors and later they were classified as vitamins and minerals.
Folate was first discovered by Lucy Wills (1931) as a factor of yeast discovered to correct macrocystic anemia in pregnancy when extracted as a compound called ‘Marmite’ which was later identified as folate and isolated from spinach leaf (folium = leaf (latin)) and then synthesized in 1943 as folic acid (pteroylglutamic acid). By 1947 it was recognized that while macrocystic anemia was cured with Marmite it was not cured by folic acid but was often precipitated or relapsed with folic acid. Further investigation showed that B12 (cobalamin) was another extrinsic factor in Marmite and both were necessary. It should be noted that cobalamin also has a synthetic form called cyanocobalamin which should not be confused with or substituted for the natural form of methyl cobalamin. The natural forms found in Marmite as well as in food are methyl folate and methyl cobalamin. Observation that folic acid enhanced tumor growth led to the discovery of folate antagonists (eg aminopterine and methotrexate) which were needed to fully oxidize (methylate) folic acid to active folate. Folic acid is never found in nature, only the active folate, and some people have differing degrees of difficulty converting folic acid to folate. One study have found accumulation of folic acid in the brains of people who died of Alzheimer’s disease and a new study has found a correlation between high levels of folic acid in mothers with autism in their children so while cause and effect have not been established there is reason for concern. With impaired methylation folic acid has also been found to trigger inflammation, impair the immune system, raise cancer risk and trigger thyroid disease or with thyroid disease impair healing.
This is similar to the story of Ascorbic acid, commonly referred to as vitamin C. Albert Szent-Gyorgyi, who won the Nobel prize in 1936 for the discovery of vitamin C and its effects on human health (preventing/curing scurvy and improved blood circulation) wrote in his 1939 book ‘Oxidation’ that he recommended ascorbic acid to a colleague for hemorrhagic diatheses (infection) but since no crystalline ascorbic acid was available in sufficient quantity he provided a paprika preparation that was high in ascorbic acid and the man was cured. Later when they tried to produce the same therapeutic effect with pure ascorbic acid there was no response, suggesting that the therapeutic effect was due to some other substance or substances in the plant extract. While ascorbic acid is found in nature it does not produce a therapeutic effect in isolation, but acts in conjunction with other phytochemicals (a vitamin C complex.) and for optimum health benefits it is always best to take the whole plant that is the source of the phytonutrients.
As it relates to folic acid, it is always better to take the plant sources of vitamin B9 (folate and folinic acid in particular) rather than the fully oxidized, never-before-found-in-nature, form called folic acid. While your body may be able to convert it to a useful form, if your diet is lacking in folate it may well also be lacking in the cofactors needed to convert folic acid to a useful form as well. In 2010 researchers reported that human beings have an extremely slow and variable activity of the liver enzyme dihydrofolate reductase needed for this conversion and the unmetabolized folic acid is far from harmless. Seniors with detectable levels of unmetabolized folic acid were found to have lower cognitive test scores.
If your body can rapidly and effectively metabolize folic acid (something that can be tested for) you can consume all the folic acid your hearts desire (although your hearts really don’t desire it), but if your metabolism of folic acid is slow (a weakness that increases with age) make sure your supplements contain B9 in the form of folate rather than folic acid, or better still get your supplements in the form of green leafy vegetables.
The FDA recently tried to prevent supplement makers from including folate in supplements arguing that only folic acid had been ‘approved’ as a supplement, but when presented with the facts they backed off deciding to allow folate in supplements. This was particularly significant since the FDA is not usually inclined to change it’s position based on facts of science presented to it, but usually tend to lean toward expensive double blind placebo controlled studies which often have bias built into them.