New B Vitamin Recommendations
From the publishers of the New England Journal of Medicine
As part
of the newly updated Recommended Dietary Allowances (RDAs) for the B vitamins, the RDA for
folate has increased to 400 micrograms (mcg) for all adults, up from 180 mcg for women and
200 mcg for men.
The recommendations also address the frequently
confused terms "folate" and "folic acid." The two are often used
interchangeably, but they're not the same thing: Folate comes from plants, while folic
acid is the man-made form used in vitamin pills and to fortify grains. Moreover, folic
acid is about twice as potent as folate, so you need to consume only 200 mcg of folic acid
to get the equivalent of 400 mcg of folate.
This difference is particularly important when
considering the new RDA for women who could become pregnant: 400 mcg of folic acid to
prevent birth defects that can happen even before a woman knows she's pregnant. This is in
addition to whatever folate a woman gets through diet. The folic acid can come from
vitamin supplements or any grains (such as breads, rice, or cereals), which are now
fortified with at least 140 mcg of folic acid per 3-ounce serving.
Conversely, people over 50 years old need to worry
about getting too much folic acid. They should be sure to get no more than 1,000 mcg per
day (the new upper intake level), because they're at greater risk of having a vitamin B12
deficiency, which can be masked by high amounts of folic acid. The new RDA specifies that
people over 50 should consume the synthetic form of B12 (from vitamin supplements or
fortified foods) because their bodies tend not to absorb the natural form. All adults need
at least 2.4 mcg of B12 a day.
The new RDA for folate does not take into account
recent studies suggesting that folate can prevent heart disease. A study in the April 9 New
England Journal of Medicine adds to the heart disease research, suggesting that people
who already have heart disease should get 400 mcg of folic acid per daytwice the new
RDA. In the study, people with heart disease who ate cereal with about 400 mcg of folic
acid per 1-ounce serving had an 11 percent decrease in homocysteine, an amino acid linked
with increased risk of heart disease. But those who ate typical breakfast cereal (with
about 100 mcg of folic acid per ounce) had no significant drop in homocysteine.