Since the national agency in charge of our health awareness says its National Folic Acid Week, I’d like to take a few minutes to tell you why you should not take extra folic acid. The folates are water soluble B vitamins known collectively as ‘B9’. The word folate comes from the Latin ‘folium’, because the natural forms were first found in leafy green vegetables. It is the folate form that is most efficiently used by the body for several key functions, including arterial circulation, nerve function and in producing rapidly dividing cells like the bone marrow in blood formation or the fetus in pregnancy. Pregnancy doubles the need for folate, and neural tube defects in early pregnancy are used as the poster child for why pregnant Americans should take folic acid.
I’ll bet you are getting the drift that folate does not necessarily equal folic acid. In fact, folic acid didn’t exist commercially until it was first synthesized in 1943. Folic acid can be turned into the naturally active form of B9, called methyltetrahydrofolate, by a process called methylation which is done mostly in the liver and small bowel. Unfortunately, many Americans have a reduced efficiency of the enzyme that does this job, and the excess folic acid they take goes on to be dumped into the body with several potential downsides. I’d like to share three reasons why you should avoid excess folic acid, and use the healthy folate version instead:
1) Excess folic acid can increase your cancer risk, particularly colon, prostate, and lung cancers. 1,2,3,4 Those with more interest in this can find a good review of folic acid and cancer risk in this 2006 article from Cancer Epidemiology.
Excess folic acid can also suppress your natural killer cells, an important immune system defense against cancer. See my article on this site discussing the importance of these NK cells.
2) Excess folic acid can mask detection of vitamin B12 deficiency and lead to a deterioration of central nervous system function, especially in the elderly. Many aging adults don’t take in or absorb B12 well enough already, and excess folic acid can make the clinical symptoms harder to assess. 4
3) Excess folic acid competes with folate for key cellular binding sites, and is counterproductive if you can’t adequately methylate B vitamins. If you don’t methylate well, you need to 1) take the methylated versions instead (called L-methylfolate), especially if you are pregnant or contemplating pregnancy, and 2) actively scrub folic acid out of your diet and avoid taking any extra in your supplements.
Folate Action Items for your consideration:
–Always look for the folate vs folic acid versions of Vitamin B9. Avoid prepackaged foods where commercial processing reduces folate, and then ‘adds back’ folic acid, such as white flour, rice, breakfast cereals, nutrition bars, multivitamins and many beverages. Focus instead on whole foods, especially those that are naturally high in folate, such as citrus fruits and juices, avocados, dark green leafy vegetables like Brussels sprouts, spinach and dark green lettuces, sprouted grains and also in liver.
–You can find out if you are one of the 30% or more of Americans who can’t methylate their B vitamins well enough. Most labs can do the blood testing for the MTHFR gene set that codes for this biochemical reaction that turns B6, B9 and B12 vitamins into their biologically active forms. If you have one or more mutations in this set, you may also have an elevation in your homocysteine blood test. Elevated homocysteine can be a powerful agent promoting aging of the brain and your arterial blood vessels, so it’s best to keep it at a low level. Have your homocysteine level checked, and if it is over a level of 10, you may benefit from testing of the MTHFR gene set. If you have mutations there, you will probably need a higher support dose of the methylated forms of your B vitamins. If you have family members with known vascular (stroke or heart attack) or a serious brain aging (Alzheimer’s or Parkinsons) disorder, or have a family member with newborn neural tube defects, I would get at least a homocysteine level as a screening measure, and possibly the MTHFR gene test as well.
-If you take methylfolate, a typical amount per day is 800 mcg, but more may be required if you lack methylating capacity (see above).
1 Folate status: effects on pathways of colorectal carcinogenesis. Choi SW, Mason JB. J Nutr. 2002 Aug;132(8 Suppl):2413S-2418S. https://www.ncbi.nlm.nih.gov/pubmed/12163703
2 Cancer incidence and mortality after treatment with folic acid and vitamin B12. Ebbing M, Bønaa KH, et.al. JAMA. 2009 Nov 18;302(19):2119-26. doi: 10.1001/jama.2009.1622. https://www.ncbi.nlm.nih.gov/pubmed/19920236
3 Folic acid and risk of prostate cancer: results from a randomized clinical trial. Figueiredo JC, Grau MV,J Natl, et. al. Cancer Inst. 2009 Mar 18;101(6):432-5. doi: 10.1093/jnci/djp019. Epub 2009 Mar 10. https://www.ncbi.nlm.nih.gov/pubmed/19276452
4 Folic acid for the prevention of colorectal adenomas: a randomized clinical trial. Cole BF, Baron JA, et. al. JAMA. 2007 Jun 6;297(21):2351-9. https://www.ncbi.nlm.nih.gov/pubmed/17551129
5 Folate and vitamin B-12 status in relation to anemia, macrocytosis, and cognitive impairment in older Americans in the age of folic acid fortification. Morris MS, Jacques PF, et. al. Am J Clin Nutr. 2007 Jan;85(1):193-200.