Studies have revealed that low blood concentrations of vitamins such as folic acid and high levels of homocysteine are linked to a high risk of heart disease. This study investigated whether consumption of supplemental folic acid could lead to a decrease in the pathology of heart disease. This was measured using a technique which looks at the inner wall thickness of the carotid arteries in the chest and neck. It is known that this thickness increases in a condition called atherosclerosis that predisposes a person to developing heart disease. The results show that in spite of a three-year supplementation with folic acid tablets, the study subjects showed no change in their carotid wall thickness and risk of heart disease.
Studies have shown that low blood concentrations of the B group vitamins, especially folic acid, correlate with increasing blood concentrations of homocysteine, a modified amino acid. Studies have also shown that additional supplementary or dietary intake of folic acid correlates with a decrease in blood homocysteine level. High homocysteine level is linked to a raised risk of heart disease and blood vessel changes, which might affect the brain as well as the heart. The consequential thickening and stiffening of the blood vessel walls cause them to damage easily. In the brain, it may increase the risk of stroke and in the heart it may increase the risk of heart attacks. Studies have explored whether supplementation with folic acid tablets reduces homocysteine levels and also the risk of heart disease. However, results have been inconclusive. Vessel wall thickness and stiffness has never been checked as a measure of efficacy. This study attempted to identify the link.
* This study involved a total of 819 men and women, aged between 50 and 70 years. All the participating women were post-menopausal.
* All the participants had an initial blood concentration of homocysteine below or equal to 13 micromoles per litre.
* All were given either a dummy pill or an 800 microgram folic acid pill regularly for three consecutive years. The participant did not know whether he or she was taking folic acid or the dummy pill.
* At the beginning and the end of the study, the carotid blood vessel wall thickness was measured and the rate of change was assessed.
* At the end of the three-year study period, those on folic acid showed a rise of blood folic acid level by 577 percent.
* Similarly, those on folic acid showed blood homocysteine levels lowered by 26 percent, as compared to those on the dummy therapy.
* Assessment of the carotid artery wall thickness showed an average of 1.9 micrometer change per year in the folic acid group and 1.3 micrometer change per year in the dummy group. This difference was not considered significant enough to recommend folic acid therapy.
* Folic acid supplementation did not decrease the blood vessel wall stiffness. This stiffness is a marker for atherosclerosis and heart disease.
The authors admit that raising blood folic acid and lowering blood homocysteine is not linked positively to reduction of heart disease risk in this study. A possible explanation of this may be that blood vessel wall thickness may not be an appropriate measure for gauging risk of heart disease. Larger studies with more number of participants are necessary to prove the effects of folic acid supplementation in reducing heart disease risk.
This is the first study that reports the effects of folic acid supplementation on the carotid artery wall thickness. Although the study showed that there is no significant benefit offered by supplementation of folic acid for three consecutive years, the level of homocysteine is significantly lowered. The results also reveal that there is no effect either on the disease progression on atherosclerosis or on decreasing the blood vessel stiffness. The progression of the disease studied here was on people who did not have heart disease at the beginning of the study. The authors conclude that the findings are similar to those in earlier studies, conducted on people with heart disease.
For More Information:
Effect of Three Years of Folic Acid Supplementation on Arterial Stiffness and Thickening in Older Adults
Publication Journal: American Journal of Clinical Nutrition, March 2011
By Jane Durga; Michiel L Bots
From the Wageningen University, Wageningen, Netherlands and University Medical Center, Utrecht, Netherlands
*FYI Living Lab Reports Are Summaries of the Original Research.