According to combined analyses of previously published studies, folate does not appear to influence the risk of developing breast cancer. These results were published in the Journal of the National Cancer Institute.
Breast cancer is diagnosed in over 200,000 women annually in the United States alone. Because it is so prevalent, researchers continue to evaluate ways to prevent breast cancer and to identify patients who may be at a high risk of developing the disease.
Folate is a water-soluble B-vitamin that occurs naturally in foods such as spinach. Its synthetic form-folic acid-is found in dietary supplements and fortified foods.
Though some studies have suggested that higher dietary folate intake may decrease the risk of breast cancer, results have been inconsistent.
To summarize the available evidence about the relationship between dietary folate and breast cancer, researchers conducted a combined analysis of previously published studies. In addition to evaluating dietary folate, researchers evaluated a gene involved in folate metabolism. Individuals with different variants of this gene may be exposed to different levels of folate.
The studies included in the analysis were all observational studies. In an observational study, the researchers do not assign study participants to a particular treatment group. Rather, the researchers simply observe what happens to study subjects with particular characteristics or behaviors. While well-conducted observational studies can provide very useful information, they tend to be less definitive than randomized clinical trials.
• Analysis of nine cohort studies (the type of observational study least prone to bias) found no link between folate intake and breast cancer risk.
• Individuals with different variants of the MTHFR gene (a gene involved in folate metabolism) had similar risks of breast cancer.
The researchers conclude that they found “no consistent or reliable evidence to support a role of dietary folate in breast cancer prevention.”
Reference: Meta-analyses of Observational and Genetic Association Studies of Folate Intakes or Levels and Breast Cancer Risk. Journal of the National Cancer Institute. 2006;98:1607-22.
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