W ASHINGTON , DC - Doctors have known for decades about a rare metabolic disorder that increases blood levels an amino acid called homocysteine, which causes mental retardation in children severely affected and early cardiovascular problems in others. Recently, however, scientists began looking for subtle effects, and they get a lot of them. Even the moderately elevated homocysteine levels are associated with heart attacks, strokes, problems during pregnancy, and impaired cognition in middle and old age.
homocysteine occurs naturally when another amino acid, methionine, is decomposed. Normally, it is quickly returned to methionine or converted to cysteine - reactions requiring the presence of folic acid, vitamin B6 or vitamin B12. If these channels fail, however, blood homocysteine levels begin to rise.
Dozens of observational studies have shown an association between moderately increased homocysteine levels and the incidence of cardiovascular disease, noted epidemiologist Petra Verhoef the Wageningen Centre for Food Sciences in the Netherlands out there, who spoke February 18 at the meeting of the American Association for the advancement of science ( science is now editor). But until now, she said, no rigorous clinical study clinched the argument that the protein actually causes such diseases. Several major trials on this subject have begun recently, Verhoef said, and results are expected over the next two years. However, all seven speakers of the session on homocysteine agreed that there is already enough evidence to recommend immediately reduce homocysteine levels.
Many Americans, in fact, already do not know it. Grain products in the US are now "fortified" with folic acid to reduce the incidence of neural tube defects in the developing fetus. Besides, says Meir Stampfer of the Harvard School of Public Health, many people pop pills multiple vitamins, most correct all but the most severe homocysteine abnormalities. The good news, said Stampfer, is that Americans reduce their chances of having a heart attack or stroke that way. The bad news is that, like almost everyone benefits, it will be increasingly difficult to launch a clinical trial that proves the point.
0 Komentar