The Dangers of Folic Acid in Multivitamins and Prenatal VitaminsDr. Fuhrman warns:
--------------------------------------------------------------------------------DO NOT take multivitamins
that contain folic acid.
If you are pregnant,
DO NOT take prenatal vitamins
that contain folic acid!
Folic acid supplementation is dangerous – especially for pregnant women
Women who take supplemental folic acid increase their breast cancer risk by 20-30%, according to a study in the American Journal of Clinical Nutrition. Researchers collected data on women's folic acid intake from multivitamins over a 10-year period – they found that the women who took multivitamins containing folic acid were more likely to be diagnosed with breast cancer than those that did not. 1,2
A study published earlier this year found a 163% increased risk of prostate cancer in men taking folic acid supplements.3
A new meta-analysis of folic acid supplementation and colorectal cancer risk found that those who took folic acid for more than three years increased their risk of having a colorectal adenoma by 35%.4 In the U.S., Canada, and most recently Chile, colorectal cancer rates have climbed since the advent of mandatory fortification of flour with folic acid.10-11
Another new study, has found that folic acid supplementation by pregnant women increases the risk of childhood asthma by 26% 5, and yet another study linked folic acid supplementation during pregnancy to increased incidence of respiratory tract infections in infants, especially those resulting in hospitalization.6
This past month in Norway, where there is no fortification of flour with folic acid, researchers conducting a six-year study on the homocysteine-lowering effects of B vitamins in patients with heart disease made an unexpected finding: the patients whose supplement included folic acid had a greater risk of cancer incidence and cancer mortality.7 These patients were 43% more likely to die from cancer.
Most alarming was another study that compared women who took folic acid during their pregnancy to those that did not. Thirty years later those women who followed the typical recommendations to take folic acid were twice as likely to die from breast cancer.8 Shocking info huh!
If folic acid can have these dangerous effects, why is it included in most
multivitamins, prenatal vitamins and fortified grain products?
Folic acid is the synthetic form of folate, a member of the family of B vitamins that is involved with DNA synthesis and DNA methylation, which essentially turns genes on and off. Because of these crucial functions, folate plays important roles in fetal development and nerve tissue health as well as cancer initiation and progression.
The protective effects of folate against neural tube defects (NTDs) have received much attention in the past. Unfortunately, this knowledge and public attention did not result in a campaign by the U.S. government encouraging women to get plenty of natural dietary folate from vegetables – instead, pregnant women are pushed to take folic acid supplements.
Folic acid is chemically different from dietary folate, which results in differences in uptake and processing of these two substances by the cells in the intestinal wall. Some folic acid is chemically modified to be more similar to natural folate, but the intestinal cells are limited in how much folic acid they can modify – excess folic acid often enters the circulation unmodified. Scientists do not yet know the implications of circulating synthetic folic acid. Many Americans, through multivitamin use and consumption of fortified foods, are taking in excessive amounts of folic acid, and thus may have unmodified folic acid circulating in their blood – this could contribute to the cancer-promoting effects.9,10-11
The recommendation that pregnant women take folic acid supplements is especially troubling – these women could safely increase their folate status and prevent neural tube defects (NTDs) by eating green vegetables, but instead they are instructed to take folic acid supplements, which put them at risk for breast cancer later in life. The children are also put at risk –women who take folic acid supplements as a substitute for good nutrition fail to provide their unborn children with the additional nutrients in folate-containing foods. Maternal nutrition is a critical determinant of childhood health – there are inverse associations between maternal vegetable intake and childhood cancers.12-13
Unlike synthetic folic acid, folate obtained from food sources – especially green vegetables – protects against breast and prostate cancer.
Paradoxically, in people who do not take folic acid supplements there is inverse relationship between dietary folate intake and breast and prostate cancer.14,3 Folate is an essential nutrient with vital functions. It is probable that folate levels need to be tightly regulated by the body – that the timing and dose of folate is an important determinant of whether folate has positive or negative effects. Folate's actions on DNA may prevent cancer from initiating, but may also promote the proliferation of tumor cells that may already present.15 Luckily, getting our folate exclusively from food ensures that we do not get too much. It comes naturally packaged in balance with other micronutrients and the body regulates its absorption.9
Rich sources of food folate
As a reference point, the U.S. RDA for folate is 400μg. Below is the approximate folate content for a 100-calorie serving.16
Spinach, raw 843 μg Edamame 225 μg
Endive 835 μg Tomatoes, yellow 200 μg
Romaine lettuce 800 μg Tomatoes, orange 180 μg
Asparagus, cooked 750 μg Chickpeas 150 μg
Mustard greens, raw 700 μg Red peppers, raw 150 μg
Collards, raw 550 μg Papaya 90 μg
Okra, cooked 520 μg Snow/Snap peas, raw 100 μg
Bok choy, raw 500 μg Summer squash 100 μg
Brocolli Rabe, raw 375 μg Tomatoes, red 85 μg
Arugula, raw 340 μg Strawberries 75 μg
Artichokes, cooked 330 μg Oranges 70 μg
Brussels sprouts, cooked 300 μg Beets, cooked 50 μg
Broccoli, cooked 300 μg Blackberries 55 μg
Cauliflower, raw 225 μg Avocado 50 μg
Red leaf lettuce 225 μg Sunflower seeds 40 μg
Celery, raw 225 μg Quinoa, cooked 35 μg
Clearly, we do not need synthetic folic acid supplements to meet our daily folate requirements.
Dr. Fuhrman's Multivitamins do not contain folic acid
Because folate is abundant in the nutritarian diet, and synthetic folic acid is so potentially dangerous, folic acid is not included in Dr. Fuhrman's Gentle Care or Gentle Prenatal multivitamin supplements.
Dr. Fuhrman does not recommend prenatal vitamins generally available on the market because of the potentially harmful ingredients that they contain, such as folic acid. Sensitive to the needs of women who are pregnant or of childbearing age, Dr. Fuhrman designed his own prenatal.
Dr. Fuhrman's special recommendations for pregnant women:
- Gentle Prenatal (delivers the iron and extra vitamin D needed by pregnant women)
- DHA Purity
- A nutrient dense diet, rich in green vegetables (and folate)
1. Stolzenberg-Solomon RZ et al. Folate intake, alcohol use, and postmenopausal breast cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Am J Clin Nutr. 2006 Apr;83(4):895-904.
2. Kim YI. Does a high folate intake increase the risk of breast cancer? Nut Rev; 2006; 64(10PT1) 468-75.
3. Figueiredo JC et al. Folic acid and risk of prostate cancer: results from a randomized clinical trial. J Natl Cancer Inst. 2009 Mar 18;101(6):432-5. Epub 2009 Mar 10.
4. Fife, J et al. Folic Acid Supplementation and Colorectal Cancer Risk; A Meta-analysis. Colorectal Dis. 2009 Oct 27. [Epub ahead of print]
5. Whitrow MJ. Effect of Supplemental Folic Acid in Pregnancy on Childhood Asthma: A Prospective Birth Cohort Study. Am J Epidemiol. 2009 Oct 30. [Epub ahead of print]
6. Haberg SE, London SJ, Stigum H, Nafstad P, Nystad W. Folic acid supplements in pregnancy and early childhood respiratory health. Arch Dis Child. 2009 Mar;94(3):180-4. Epub 2008 Dec 3.
7. Ebbing M et al. Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12. JAMA. 2009;302(19):2119-2126.
8. Charles D et al. Taking folate in pregnancy and risk of maternal breast cancer. BMJ 2004;329:1375–6
9. Harvard School of Public Health; The Nutrition Source: Keep the Multi, Skip the Heavily Fortified Foodshttp://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/folicacid/
Date accessed: 8/29/08.
10. Hirsch S et al. Colon cancer in Chile before and after the start of the flour fortification program with folic acid. Eur J Gastroenterol Hepatol. 2009 Apr;21(4):436-9.
12. Kwan ML et al. Maternal diet and risk of childhood acute lymphoblastic leukemia. Public Health Rep. 2009 Jul-Aug;124(4):503-14.
Tower RL et al. The epidemiology of childhood leukemia with a focus on birth weight and diet. Crit Rev Clin Lab Sci. 2007;44(3):203-42.
Petridou E et al. Maternal diet and acute lymphoblastic leukemia in young children.Cancer Epidemiol Biomarkers Prev. 2005 Aug;14(8):1935-9.
Jensen CD et al. Maternal dietary risk factors in childhood acute lymphoblastic leukemia (United States).Cancer Causes Control. 2004 Aug;15(6):559-70.
13. Huncharek M et al. A meta-analysis of maternal cured meat consumption during pregnancy and the risk of childhood brain tumors. Neuroepidemiology. 2004 Jan-Apr;23(1-2):78-84.
Pogoda JM et al. An international case-control study of maternal diet during pregnancy and childhood brain tumor risk: a histology-specific analysis by food group. Ann Epidemiol. 2009 Mar;19(3):148-60.
14. Sellers TA et al. Dietary folate intake, alcohol, and risk of breast cancer in a prospective study of postmenopausal women. Epidemiology. 2001 Jul;12(4):420-8.
15. Kim YI. Folic acid fortification and supplementation--good for some but not so good for others. Nutr Rev. 2007 Nov;65(11):504-11.
17. Bjelakovic G, Nikolava D, Gluud LL, et al. Antioxidant supplements for prevention of mortality in healthy participants and patient with various diseases. Cochrane Database Syst Rev 2008;16(2):CD00776.
18. Mayne ST. Beta-carotene, carotenoids, and disease prevention in humans. FASEB. 1996;10(7):690-701.
19. Goodman GE. Prevention of lung cancer. Current Opinion in Oncology 1998;10(2):122-126.
20. Kolata G. Studies Find Beta Carotene, Taken by Millions, Can't Forestall Cancer or Heart Disease. New York Times, Jan 19, 1996.