WebMD Medical News
Daniel J. DeNoon
Louise Chang, MD
Jan. 2, 2007 - Folic acid -- a B vitamin already added to U.S. flour -- may
slow age-related hearing loss, a Dutch study shows.
Folic acid is also known as folate. Folic-acid deficiency causes birth
defects and seems to contribute to heart disease
The study looked at 728 Dutch men and women aged 50 to 70. Unlike the U.S.,
the Netherlands does not require folic acid supplementation of flour.
Participants in the Dutch study had high blood levels of homocysteine. Folic
acid reduces homocysteine levels, so the Dutch study participants apparently
consumed very little folic acid.
Half the study participants got strong folic acid supplements -- 800
micrograms per day, about twice what one would get in a multivitamin pill. The
other participants got an inactive placebo pill.
After three years, those who got folic acid pills had less low-frequency
hearing loss than did placebo recipients. The difference was slight: 0.7
decibels. The smallest change in sound intensity most people can notice is 1.0
There was no slowing of high-frequency hearing loss. That may be because
high-frequency hearing loss begins earlier in life than age 50.
Researchers Jane Durga, PhD, of Wageningen University, Netherlands, and
colleagues suggest that by fortifying their flour with folic acid, nations
might lessen their citizens' age-related hearing loss.
If a little folic acid from flour is good, would more folic acid be better?
That's not known, suggests Robert A. Dobie, MD, of the University of
California, Davis. Dobie's editorial accompanies the Durga study in the Jan. 2
issue of Annals of Internal Medicine.
"If this [hearing] benefit applies to the entire population (a big 'if')
and continues to accrue each year (another big 'if'), one might expect a
5-decibel reduction in age-related [hearing loss] over a 20-year period,"
Such a shift would cut the percentage of 75-year-old men who need hearing
aids from 33% to 22%.
Dobie notes that much more study is needed to see whether the study results
-- seen in people with low folic-acid intake -- might apply to the
better-nourished U.S. population.
SOURCES: Durga, J. Annals of Internal Medicine, Jan. 2, 2007; vol
146: pp 1-9. Dobie, R.A. Annals of Internal Medicine, Jan. 2, 2007; vol 146: pp
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