Researchers at the Framingham Offspring Study report that the federal government's requirement that bread and other grain food products be supplemented with the vitamin folate. This government policy, which was implemented in 1998 to reduce the number of infants born with spina bifada and other neural tube defects, has resulted in substantial improvements in the blood levels of folate of Americans and may have implications for reducing risk of heart attacks and strokes.
In the study population, flour supplementation with the B vitamin folate increased the blood levels of folate and reduced blood levels of homocysteine, a natural byproduct of the body's metabolism of food. Several previous studies have linked high blood levels of homocysteine with increased risk for heart attack and stroke.
In the body, folate and other B vitamins break down homocysteine. Therefore, high blood levels of folate, found naturally in green leafy vegetables, citrus fruits and beans, are associated with low levels of homocysteine.
Robert H. Eckel, M.D., chairman of the American Heart Association's Nutrition Committee and professor of medicine and physiology at the University of Colorado Health Sciences Center in Denver, says the Framingham researchers "took advantage of a rare opportunity" to examine the relationship between population-wide folate fortification and folate's association with homocysteine concentrations in the blood.
"This study is important because it provides us with important information about the impact of consuming a specific amount of folate and folate's impact on homocysteine levels in the blood," says Eckel. "Most of the information that we have about folate and homocysteine is based on population-based studies wherein people self-report on their diet and other life-style factors. Population-based studies, like the Framingham Offspring study, allow us to see a trend, but it is unusual to have an explanation for trends as quickly and dramatically demonstrated as for the effect of folate supplementation in this study."
However, whether fortifying grains with folate will result in fewer people with heart disease and stroke remains to be seen primarily because the role of high blood levels of homocysteine in cardiovascular disease has not yet been determined. High homocysteine levels may be a risk factor or a manifestation of another known or unknown risk factor for cardiovascular disease.
In the Framingham study, blood samples from 756 men and women (the control group) that were taken before folate fortification was begun nationally in 1996 were analyzed to determine pre-fortification levels of folate and homocysteine. The findings from this analysis subsequently were compared to blood samples taken from 350 people (the study group) after flour fortification had been instituted. Individuals in the study group had a 117 percent increase in folate levels, and the percentage of individuals with low levels of folate dropped by 92 percent in the study group, compared to the control group.
A subgroup of study participants (102) took additional B-vitamins in the form of vitamin pills. However, the researchers concluded that the difference in homocysteine and folate levels between this small subgroup and the study participants were not significant.
"Our best advice is to continue to eat a diet rich in fruits, vegetables, low-fat dairy products, and whole grains, many of which are fortified with folate," says Eckel.
In January 1998, all U.S. enriched flour, rice, pasta, cornmeal and other grain products were fortified, for the first time, with 140 milligrams of folic acid per 100 grams of grain, in accordance with a new Food and Drug Administration's regulation.