March 13, 2006 -- Fortifying flour and other enriched-grain products might help cut stroke death, researchers report in Circulation.
In the U.S. and Canada, stroke deaths declined at a faster rate after mandatory folic acid (also known as folate) fortification. But in England and Wales, which don't require folic acid fortification, the decline in stroke deaths didn't speed up.
The results support -- but don't prove -- the idea that folic acid fortification cuts stroke deaths, Yang and colleagues write. Stroke is the No. 3 cause of death for U.S. adults.
The U.S. ordered folic acid fortification in 1996 to help prevent neural tube birth defects. Canada followed two years later.
Stroke deaths were already dropping in both countries, but the rate of improvement sped up in the years following folic acid fortification, Yang's team reports.
For instance, U.S. stroke deaths fell by about 0.3% per year from 1990 to 1997. From 1998 to 2002, U.S. stroke deaths dropped nearly 3% annually. The figures add up to nearly 13,000 fewer stroke deaths per year for people in the U.S. aged 40 and older.
In Canada, stroke deaths dropped 1% per year from 1990 to 1997 and 5.4% yearly from 1998 to 2002, the study shows. In England and Wales, the rate of decline in stroke deaths didn't change much during that time, according to Yang and colleagues.
Does Folic Acid Get the Credit?
Elevated blood concentrations of homocysteine appear to be a stroke risk factor, the researchers note. They found that after folic acid fortification, people in the U.S. had more folic acid and less homocysteine in their blood.
"The increase in folate concentration in the population is inversely associated with homocysteine level, so if you have high folic acid concentration, you have lower homocysteine concentration," Yang says in a news release.
Stroke is still a "major health burden" in the U.S., Canada, and many other countries, Yang's team writes. "Many factors" have probably helped cut down on stroke deaths, the researchers add.
"Additional studies are urgently needed to either prove or disprove what we observed," Yang says in the news release. His study only tracked stroke deaths, not stroke-related disability.