NEW YORK (Reuters Health) - In another blow to the notion that B vitamins ward off heart problems, a new clinical trial finds that folic acid supplements may not slow plaque buildup in healthy older adults' arteries.
In recent years, a number of studies have been set up to test whether B vitamins can help protect older adults from heart problems and strokes.
The hope was based on the fact that B vitamins, particularly folic acid, curb levels of a blood protein called homocysteine. High levels of homocysteine have been linked to an increased risk of clogged arteries, heart attack and stroke.
But clinical trials of people with established atherosclerosis -- a narrowing and hardening of the arteries that can lead to heart attacks and strokes -- have failed to find a benefit of B vitamin supplements (see Reuters Health story of April 23, 2010).
This latest study, reported in the American Journal of Clinical Nutrition, looked at whether folic acid might stave off atherosclerosis in older adults who had high homocysteine levels but were apparently free of cardiovascular disease.
It didn't. Over 3 years, daily folic acid cut study participants' homocysteine levels by an average of 26 percent, but it showed no effect on the thickness of the inner wall of the carotid artery, or on the "stiffness" of the arteries -- which are both considered markers of atherosclerosis.
The findings "suggest that folic acid is not effective in slowing down early stages of cardiovascular disease, as measured by accepted markers of atherosclerosis," said senior researcher Dr. Petra Verhoef, who was with Wageningen University in the Netherlands at the time of the study.
More and more, Verhoef told Reuters Health in an email, researchers are thinking that homocysteine, itself, does not directly contribute to heart disease and stroke.
Instead, it may be more of a bystander, reflecting some sort of metabolic problem that is the actual contributor to cardiovascular ills -- though that, Verhoef said, is still being studied.
For their study, Verhoef and her colleagues randomly assigned 819 adults between the ages of 50 and 70 to take either folic acid or placebo pills every day for 3 years. Those on folic acid took 800 micrograms per day -- double what is generally recommended for adults.
In the end, the researchers found no difference between the two groups when it came to the rate of thickening in the carotid artery wall -- measured non-invasively with ultrasound. Nor was there any difference in arterial stiffness, which was also measured non-invasively.
The bottom line for older adults, according to Verhoef, is that they should try to get adequate folic acid by eating a balanced diet. Folate, the natural form of folic acid, is found in foods like leafy greens like spinach, dried beans and peas, asparagus and broccoli.
In addition, a number of foods are fortified with folic acid; in the U.S., manufacturers are required to add folic acid to enriched flours, breads, cereals, pasta, corn meal and other grain products.
Adults are generally advised to get 400 micrograms of folate/folic acid per day.
"All age groups, including older adults, should make sure they meet the dietary reference intake level of folic acid," Verhoef said.
If they can't do that through food, she added, older adults might consider taking a multivitamin with folic acid.
But they should not use the vitamin as a way to prevent heart disease, Verhoef said.
Instead, she recommended following a generally healthy diet low in salt and saturated fat, getting regular exercise and maintaining a healthy weight.
SOURCE: http://bit.ly/eDKjXs American Journal of Clinical Nutrition, online March 23, 2011.
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