Study participants, aged between 50 and 70 years, were given an 800-mcg folic-acid supplement every day for three years. This resulted in a far slower decline in their hearing than those who were given a placebo, or sugar pill, instead.
As well as in supplements, folate can also be found in green leafy vegetables, chickpeas and lentils. Grain products sold in America and Canada have been fortified with folic acid, the synthetic, bioavailable form of folate, since 1998.
Researchers believe that folate deficiency during the early stages of pregnancy can cause neural-tube defects (NTD) such as spina bifida and anencephaly in the baby (Ann Intern Med, 2007; 146: 1-9).