San Francisco Adding the vitamin folate to flour, a practice begun in 1996 to prevent birth defects, also appears to have a striking effect against cardiovascular disease, preventing an estimated 48,000 deaths a year from strokes and heart attacks, a government study found.
Many experts hoped from the start that adding folate to food would be good for people's circulatory systems. The vitamin lowers homocysteine, and high levels of this amino acid have long been linked to heart attacks and strokes.
However, the new data, released at a conference Friday, are the first evidence from a large, population-based study to suggest this is actually happening.
The Food and Drug Administration ordered that grain foods be fortified with folate, one of the B vitamins, to help prevent serious birth defects called neural tube defects. Studies have shown the strategy worked, reducing these tragedies by about 20 percent.
However, the latest data suggest that by helping tame two of the world's biggest killers, the benefits of the extra folate "extend to the entire population, including those with limited access to health care," said Quanhe Yang, an epidemiologist at the Centers for Disease Control and Prevention.
Yang reported the findings, based on a review of death records, at a meeting in San Francisco of the American Heart Assn.
Dr. Robert Eckel of the University of Colorado, head of the heart association's nutrition council, called the results "provocative and exciting."
"If it's really true, this could be a far greater benefit for the public" than the original purpose of preventing birth defects, he said.
People now get extra folate from enriched bread, flour, corn meal, rice, pasta and other grain products. Experts already know this has doubled the amount of folate in the average American's bloodstream and reduced people's homocysteine levels by 14 percent.
To learn if this has also translated into fewer deaths, the CDC researchers reviewed nationwide death certificate data to see how deaths from strokes and heart disease changed after folate was added. Deaths from both causes already were declining, so all of the change could not be attributed to folate.
"The critical issue is timing," Yang said. "We expect these changes to be gradual. We observed a sudden change around the time of the fortification."
From 1990 to 2001, there were almost 26 million deaths among Americans over age 40, including 8.2 million from heart disease and 3.2 million from stroke.
Stroke mortality fell the most. It was going down about 1 percent a year before 1997. That accelerated to almost 5 percent annually afterward. The decline was especially steep among black men, falling 7 percent a year after folate.
The researchers took into account other changes in major cardiovascular risk factors, such as smoking, obesity, cholesterol, high blood pressure and obesity. Most of these did not change or got worse and could account for no more than a third of the total decline in recent years.
In all, the researchers estimate that folate in food led to 31,000 fewer deaths from stroke and 17,000 from heart disease each year from 1998 to 2001.
The growing popularity of low-carbohydrate diets means many people are eating less of the folate-fortified foods. However, many of these diets recommend that people also take a daily multivitamin, which contains more folate than bread and other grains.
Eckel said he doubted that most people on low-carb diets stuck with them long enough to significantly reduce their folate levels. Furthermore, they may increase their vitamin B12, which also lowers homocysteine, if they eat more meat.
Homocysteine is an amino acid that results naturally from the breakdown of protein. Experts suspect it somehow weakens artery walls.