Research is split on the benefits and drawbacks of a diet that includes increased supplemental folic acid (a.k.a. vitamin B-9). On one hand, general studies show that a higher amount of natural folate in your diet is associated with a lower risk of cancer; other research has shown that a high daily dosage of synthetic folic acid might actually speed up the growth and development of existing tumors or precancerous lesions. Furthermore, folate deficiency has been linked to heart attack, stroke, Alzheimer’s, osteoporosis, birth defects, depression and more.
Folate, or folic acid in natural form, is found in leafy greens like spinach and romaine, other veggies like broccoli, asparagus and brussels sprouts, fortified grains like pasta and cereal, and certain fruits like oranges (and orange juice), bananas, raspberries, and cantaloupe. Some nutritionists recommend getting your recommended daily allowance in its natural form to avoid potential side effects associated with the synthetic form.
Generally, increased intake of folate and folic acid is associated with lowered cancer risk. A December 2009 study showed that folic acid supplements did not increase the risk of colon cancer; in fact, participants who started out with the lowest levels of folate in their system showed a 39% reduced risk of colon cancer when given folic acid supplements. Similarly, a different 2009 study found that women with the highest dietary folate intake had a decreased risk of pancreatic cancer compared to women with the lowest level of dietary folate intake. Additionally, some research has shown that increased intake of folic acid is protective against breast cancer, particularly in women who regularly drink alcohol. But for every study comes counter-evidence: in recent unpublished Swedish research, a small subgroup of women with a specific genetic variant actually had increased risk of breast cancer when supplementing folic acid.
Amid this controversy, though, increased folate intake or the addition of folic acid supplements is recommended for women who are pregnant or trying to conceive (to prevent brain and spinal birth defects in the developing fetus), patients diagnosed with anemia related to low folate levels, those with a diet low in fruits and vegetables, or women who drink more than one drink per day (since alcohol destroys folic acid found in the system).
If you are looking to add folic acid to your diet, aim to add it through increased consumption of fruits and vegetables as opposed to synthetic folic acid. (Pregnant women are the exception here, as experts recommend a supplement containing 600mcg just to be safe.) If you’re concerned that your diet falls short, though, a folic acid supplement in the form of a multivitamin works; just be sure it does not contain more than 400 mcg (600 mcg for pregnant women), which is 100% of the recommended daily allowance.