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Studies debate role of homocysteine in heart disease
'It's time for the matter to be resolved'
October 27, 1997
Web posted at: 8:30 p.m. EST (0130 GMT)WASHINGTON (CNN) -- Most people know that smoking, high blood pressure and diabetes can increase their chances of getting heart disease.
But whether high levels of homocysteine -- an amino acid produced when the body breaks down meat and dairy products -- is a risk factor is still not clear. Research reported in two medical journals this week reach different conclusions.
A glass of milk, a steak or a cheese omelet raise homocysteine levels at least temporarily, researchers have found. They also have discovered that people who don't have enough vitamin B-12 or folic acid in their diet tend to have high concentrations of homocysteine -- as do some people with genetic defects.
A study by scientists at the Allegheny University of Health Sciences in Pittsburgh, reported in the journal Arteriosclerosis, Thrombosis and Vascular Biology, suggests that homocysteine may clog heart arteries by making cells grow in thickness and accumulate collagen.
Collagen is found in the plaque that clogs arteries. The researchers found that collagen increased after they added homocysteine to lab dishes of artery cells from a rabbit.
The scientists also found that adding a form of vitamin B-12 to the mixture inhibited the process, lending credence to studies suggesting that vitamin B-12 or folic acid, another B vitamin, may lower homocysteine.
'It's time for the matter to be resolved'
Another study by a team of doctors in Hong Kong confirmed the role of homocysteine in middle-aged adults with hardening of the arteries. The study, reported in the journal Circulation, concluded that increased homocysteine was a risk factor.
But another study challenges that premise.
That study, also published in Arteriosclerosis, Thrombosis and Vascular Biology, found no difference in homocysteine levels between men who suffered heart attacks and men who had not.
Dr. David Wilcken of the Prince Henry Hospital in Sydney, Australia, addresses the contradictory nature of the findings in an editorial in Circulation.
Noting that it's been 20 years since homocysteine was first proposed as a possible risk factor for heart disease, he writes, "Surely the time has come for the matter to be resolved."
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Related sites:
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- Allegheny University of the Health Sciences
- "Arteriosclerosis, Thrombosis and Vascular Biology" journal
- "Circulation" journal
- American Heart Association
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