CHICAGO (Reuters) - Giving B vitamins and folic acid supplements to reduce high levels of a blood protein that is a marker for heart disease did nothing to protect women from heart trouble, according to a study released on Tuesday.
The findings published in the Journal of the American Medical Association raised further doubts about whether addressing an indicator for heart disease — in this case, the amino acid homocysteine — can prevent heart attacks or strokes.
A high level of homocysteine in the bloodstream is believed to damage arteries and has been linked to blood clots, strokes and heart attacks.
Homocysteine is produced naturally by the body but in rare cases in children whose levels are out of control, some are given heavy doses of folic acid and Vitamins B6 and B12 to break it down. Previous research has shown that when one of these vitamins is lacking, homocysteine rises.
It is unclear whether lowering elevated homocysteine levels in the general population will prevent heart problems.
Dr. Christine Albert of Brigham and Women’s Hospital and Harvard Medical School in Boston and colleagues followed patients for a longer period than past studies — more than seven years.
The volunteers, all women, were 42 or older at the start of the study and either considered at risk for heart disease or had already experienced heart problems.
Half the 5,442 participants took 2.5 milligrams of folic acid, 50 milligrams of Vitamin B6, and 1 milligram of vitamin B12 daily, while the rest took a placebo.
No harm came from the vitamins and homocysteine levels fell by nearly one-fifth in that group but there was no appreciable difference in the incidence of heart problems or heart-related deaths compared to the placebo group in the seven years.
In a commentary on the study, Dr. Eva Lonn of McMaster University in Hamilton, Ontario, Canada, wrote that large-scale studies examining homocysteine and the impact on heart disease are under way in Europe.
She said North American women may take in such high levels of B vitamins that adding supplements may not affect their health.
Unlike in the United States and Canada where folic acid has been added by law to white floor and grain products since the late 1990s, European flour is not routinely supplemented. She said people’s homocysteine levels are likely higher and the impact of lowering them may be better seen.
“Until further data become available it is essential to remain firmly grounded on the available evidence and to admit that once again experimental and observational data do not always translate into therapeutic benefits,” Lonn wrote.
She pointed to recent studies that overturned conventional wisdom — such as the study showing that hormone replacement therapy actually worsened the risk of heart disease and a study showing that raising so-called “good” cholesterol did not have immediate and clear heart benefits.
Reporting by Andrew Stern; Editing by Maggie Fox and Bill Trott