Lowering Blood Protein Won't Help Kidney Patients

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Because of the association between homocysteine and vascular disease, Jamison's group hoped that if they could lower homocysteine levels, they could also reduce mortality and the rates of heart attack, stroke and amputations.

They enrolled more than 2,000 veterans at 36 Veterans Administration medical centers across the country. All had advanced chronic kidney disease or end-stage renal failure.

Half of the participants were given a placebo, and the other half were instructed to take a daily capsule that contained 40 milligrams (mg) folic acid, 100 mg vitamin B6 and 2 mg of vitamin B12.

The study lasted five years, and the average follow-up time was 3.2 years.

The vitamin therapy was successful in lowering homocysteine levels. Homocysteine went down almost 26 percent in the treatment group, but less than 2 percent in the placebo group.

However, those lowered levels did not translate into saved lives. In total, 448 people from the vitamin group and 436 people in the placebo group died during the study -- statistically nearly equal. Additionally, the researchers found no statistically significant differences in the rates of heart attack, stroke and amputation.

While this study wasn't designed to determine why lowering homocysteine levels was ineffective in preventing deaths and disease, Jamison said there are several possibilities. "One is that homocysteine is a marker of vascular disease, rather than a cause of it. Another is that the vascular burden in these patients may be too great. It may be that we started too late to make a difference in these patients."

Dr. Robert Provenzano, chief of nephrology at St. John Hospital and Medical Center in Detroit, said he believes this study "puts to rest the idea that homocysteine causes vascular damage. It looks like it's nothing more than a marker for inflammation."

"In my field, this is very important. We've been trying to bring homocysteine down in our patients, hoping it would have a positive impact," said Provenzano. "But, the decrease in homocysteine was quite profound in this study. If there were any benefit, we would have seen it."

If you have kidney disease and are concerned about your kidney health, both Jamison and Provenzano recommended quitting smoking, lowering your cholesterol and blood pressure, staying at a healthy weight and maintaining good blood sugar control if you have diabetes.

More information

To learn more about preventing kidney disease, visit the National Kidney Disease Education Program.