Folic acid fortification/supplementation and breast, prostate and colorectal cancers
In the past decade an accumulating body of scientific evidence now makes it absolutely clear that the FDA’s mandatory folic acid fortification program represents one of the worst blunders in the history of U.S. public health. An alarming number of human clinical trials, animal experiments and epidemiological studies show that excess folate via folic acid fortification has resulted in population wide increases in the risk for breast, prostate and colorectal cancers.7-11, 15-17, 20, 23, 24, 26, 27-29
Let’s start off with prostate cancer. A recent (2010) meta analysis (compilation of many population studies) carried out at Bristol University in the UK demonstrated that high levels of blood folate were associated with increased prostate cancer risk.9 Even more convincing evidence comes from a clinical trial by Dr. Figueiredo and colleagues at the University of Southern California.11 In this experiment 643 men were randomly assigned to either a folic acid supplementation group or a placebo (dummy pill) group. After nearly 11 years, the percentage of men developing prostate cancer in the folic acid treatment group was 9.7 %, whereas only 3.3 % of the men in the placebo group were diagnosed with prostate cancer. Higher blood concentrations of folate from folic acid supplementation also cause a faster progression of this sometimes fatal disease. Although scientists aren’t completely sure how excess folate and folic acid promote cancer, animal experiments indicate that these compounds induce a cancer causing reaction called hypermethylation in the DNA of cancer cells.24, 29, 30
A disturbing number of recent epidemiological (population) studies have suggested that high folate intake, largely from folic acid in supplements and fortified foods may increase breast cancer risk. In a study of 70,656 postmenopausal women who were followed from 1992 until 2005, dietary folate intake (from both folic acid and folate) was positively associated with breast cancer risk.26
I’d like to make it clear once again that folate and folic acid are not one-in-the-same compounds. Folate is the natural, healthful B vitamin that is found in leafy green veggies, organ meats and some nuts. Folic acid is an artificial chemical that can be converted to folate in the liver. Because folic acid builds up and forms pools of this manmade chemical in our bodies at doses as low as 200 mcg (half the DRI), it is known to disrupt normal folate metabolism. To summarize, dietary folate from natural food sources does not produce harmful health effects, whereas folic acid does.
To continue with our discussion of folic acid and breast cancer risk, a recent animal experiment by Dr. Ly and co-workers at the University of Toronto demonstrated that folic acid supplementation led to an increased risk of mammary cancer in rats.29 It is notable that the equivalent (~800 mcg) dietary levels of folic acid necessary to produce breast cancer in the rats could easily be achieved in humans by eating fortified foods and taking folic acid supplements.
The situation with colorectal cancers and folic acid supplementation/fortification is nearly identical to which I have described for breast and prostate cancer. Animal, tissue, epidemiological and human dietary trials all reveal that folic acid increases the risk for colorectal cancers. The most powerful type of research design in human supplementation experiments is called a “double blind, placebo controlled randomized trial.” With these types of experiments, scientists can be relatively sure that a certain treatment causes a certain outcome. In just such a study of 1,021 men and women carried out over a 10 year period, I quote the authors of this study, “Folic acid was associated with higher risks of having 3 or more adenomas [cancers] and of noncolorectal cancers.”7 A similar double blind, placebo controlled randomized trial from Norway came up with similar conclusions, “Treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes, and all-cause mortality in patients with ischemic heart disease in Norway, where there is no folic acid fortification of foods.”10 The folic acid fortification/cancer story certainly makes Paracelsus’s word’s ring true, “dose makes the poison.” Indeed, many European nations, including the U.K. have taken a more cautious approach and have decided not to fortify their food supply with folic acid.
References
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