Abstracted by Greg Arnold, DC, CSCS, June 8, 2012, from “Effect of folic acid supplementation on the progression of carotid intima-media thickness: A meta-analysis of randomized controlled trials” in the June 2012 issue of Atherosclerosis. Posted June 11, 2012. r/ar
Atherosclerosis involves deposits of fatty substances in the inner lining of arteries called the “intima media” (1). This leads to the creation of plaques that can become large enough to significantly reduce blood flow (2). Atherosclerosis can progress to cardiovascular disease, which is the second and third biggest killer of Americans, in the form of heart disease and stroke, in the United States (3) and cost our healthcare system $316.4 billion (4) and $53.9 billion (5), respectively, in 2010.
Now a new study (6) suggests that folic acid may help maintain the health of the intima media and help maintain overall blood vessel health in ill patients. In the study, researchers reviewed 10 studies consisting of 2,052 patients between the ages of 40.2 to 73.2 years supplementing with folic acid. The doses ranged from 0.80 to 15.0 milligrams per day for periods ranging from 3 to 42 months.
While the researchers found folic acid to “significantly reduces the progression of intima media thickness”, the benefits occurred mostly in ill patients (kidney disease or cardiovascular disease) but “not in subjects who were generally healthy.” Of the three studies judged to be of the highest quality, a 2009 study (7) showed 5 milligrams of folic acid per day for 3.1 years to produce “a statistically significant lower average rate of carotid artery intima media thickness progression, compared with placebo” but only in patients who initially had blood levels of an inflammatory protein called homocysteine > 9.1 micromoles/Liter.
The second study, also done in 2009, and in kidney transplant patients (8), 5 mg per day for 6 months reduced carotid intima-media thickness from 0.73 to 0.71 millimeters after 6 months, while those in the control group saw an increase in thickness from 0.81 to 0.85 millimeters. Finally, the third study from 2007 (9) saw 2.5 mg of folic acid per day for 3 years to reduce artery thickness (from 0.83 to 0.72 millimeters), but only in those with a certain genetic mutation that increases their risk for heart disease (10).
For the researchers, “Our findings indicate that folic acid supplementation may be effective in reducing the progression of carotid-intima media thickness, particularly in subjects with [chronic kidney disease] or high [cardiovascular disease] risk.”
- Polak JF. Carotid-wall intima-media thickness and cardiovascular events. N Engl J Med 2011 Jul 21;365(3):213-21.
- “Heart and Stroke Facts” from the American Heart Association website.
- “Heart Disease and Stroke Statistics – 2005” from the American Heart Association website.
- 0918119HDSStats2005Update.pdf”Heart Disease Fact Sheet” – http://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_heart_disease.htm
- “Stroke Fact Sheet” – http://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_stroke.htm
- Qin X. Effect of folic acid supplementation on the progression of carotid intima-media thickness: A meta-analysis of randomized controlled trials. Atherosclerosis 2012;222(2):307-13.
- Hodis HN, Mack WJ, Dustin L, et al. High-dose B vitamin supplementation and progression of subclinical atherosclerosis: a randomized controlled trial. Stroke 2009;40:730–6.
- Nafar M, Khatami F, Kardavani B, et al. Role of folic acid in atherosclerosis after kidney transplant: a double-blind, randomized, placebo-controlled clinical trial. Exp Clin Transplant 2009;7:33–9.
- Fernandez-Miranda C, Yebra M, Aranda JL, et al. Effect of folic acid treatment on carotid intima-media thickness of patients with coronary disease. Int J Cardiol 2007;118:345–9.
- Bagley PJ. A common mutation in the methylenetetrahydrofolate reductase gene is associated with an accumulation of formylated tetrahydrofolates in red blood cells. Proc Natl Acad Sci U S A. 1998 October 27; 95(22): 13217–13220.