For these and other reasons the Food and Nutrition
Board in 1998 recommended a new RDA for folate of 400 mg/day for
both men and women. They reaffirmed the recommendation that at-risk
women take an additional 400 mg pill daily. They also determined
that an intake of 320 mg/day was about what the average adult required
and that 1000 mg/day was the tolerable upper limit of intake, the
toxic threshold. Based on previous bioavailability studies they
determined that synthetic folic acid was 70% more digestible and
absorbable than the natural folate. This has important implications
when trying to calculate actual intakes of the vitamin from a varied
Also in 1998, food fortification with folic acid became required
by the FDA for a variety of grains, flour, and baked goods. The
goal was to increase the average American's intake by about 100
mg/day (or the equivalent of 170 mg of natural folate). Several
studies since have demonstrated the success of this policy in raising
American blood folate levels and decreasing blood homocysteine levels.
The final cloud shape we will discuss is a report last year in which
a group of FDA scientists tried to carefully combine all of this
information into a new analysis of how much folate Americans are
now getting in their diets. The answer was a shocking increase to
about 700 mg/day, a 3-fold rise. But no one popped champagne corks
and declared the folate war over and won. Why not? Only a small,
and unspecified, amount of this "increase" was the additional
amount from fortification. The rest was from the 70% better bioavailability
of the synthetic folic acid that was already in the diet (from fortified
foods like breakfast cereals and from vitamin pills) but were not
previously counted in the total. Besides, there are two downers
in the news. Only about 30% of women were heeding the auspicious
advice of the Feds and taking their folic acid pills daily. The
rest were getting less than half the recommended amount.
The other downer was like a fluffy cloud teddy bear turning into
a dark grizzly bear thunderstorm: toxicity. If a woman consumes
the usual 250 mg/day of natural folate and then adds 400 mg of synthetic
folic acid, now adjusted for bioavailability, she is consuming the
equivalent of 930 mg/day, dangerously close to the tolerable upper
limit of safety. Here is where the thunderstorm breaks and we all
run for cover. What is a woman to do? If she does not take the vitamin
pill she risks her baby and if she does then she is apparently risking
herself and maybe the baby too.
The threat of NTD is small (about 1 in 1000 live births) but real
and serious. All the studies show consistent beneficial effects
of folate in preventing NTD; even over the levels that we are now
suppose to consider toxic. However, this toxicity level should not
be interpreted in the usual manner. It is more like saying, "Don't
bother to consume more than this amount. It probably doesn't help
that much more and it might complicate things."
I believe there is a real live vegetarian alternative to this dilemma.
We need to return to the foliage from which folate first came. A
recent study by a Dutch group determined that a diet rich in citrus
fruit, citrus juice and green vegetables (spinach, green peas, broccoli,
Brussels sprouts, and green beans) could give a daily intake of
560 mg. This did not include the approximately 170 mg/day in fortification
now present in all our diets and the other great plant-based sources
in legumes like chickpeas, lentils, split peas, kidney bean, etc.
Think about this. Doesn't this really define a healthy piece of
a great vegan diet, legumes, greens, and fruit? Nobody is asking
you to actually calculate your folate intake everyday but a healthy
varied diet that includes plenty of these foods, leaving the whole
"5-a-day" thing in the dust, should have no trouble. For
the woman who wants to make sure her bases are covered, maybe a
folic acid pill every other day would be safe and efficacious.
The clouds clear and we have a reasonable solution: a variety of
legumes, greens, and citrus, and for that special woman, maybe a
pill every couple of days. And remember, the folate is in the foliage.
Comments? Please post them on the New
Century Nutrition Discussion board.
Marty Root has a PhD in Nutrition from Cornell
University, and works as a Senior Research Scientist at BioSignia,
Inc. in Chapel Hill, NC. His work involves making statistical
models that predict the onset of chronic diseases such as heart
disease and the cancers. A frequent contributor to VegSource.com,
Dr Root is married and has three children.