Can Folic Acid Help Cure Heart Attacks?
Heart disease is a growing concern and heart attacks are a leading cause of death of both men and women, with one person suffering a heart attack around every three minutes.
Folic acid (vitamin B9) is required for the formation of new cells through the synthesis of DNA and cell division, which is important because healthy cells depend on the faultless replication of DNA. Its benefits in pregnancy are well documented, but many people are unaware that folic acid may also offer a relatively cheap and simple means of lowering the risk of heart disease.
Folic acid is the most important vitamin for the maintenance of normal homocysteine levels, high levels of which are an important risk indicator of heart disease.
Why Is Homocysteine Important?
The body produces the amino acid homocysteine from foods containing the amino acid methionine, primarily meat based foods. It then converts homocysteine in the blood into glutathione or SAMe (S-adenosyl methionine), and any excess is converted back to methionine.
Scientific interest in folic acid stems from the vitamins critical role in converting homocysteine back to methionine. If this conversion process cannot take place, blood levels of homocysteine rise, which increases free radical oxidation and the damage this causes to cholesterol and artery walls.
Oxidation causes circulating cholesterol to become “sticky” and clump together, leading to a thickening and stiffening of the arteries (atherosclerosis). High homocysteine levels also reduce the level of nitric oxide in the blood, a molecular chemical that is needed to keep the artery walls flexible and prevent atherosclerosis.
For these reasons, high homocysteine levels are closely linked to an increased risk of cardiovascular disease and stroke. Lowering homocysteine levels have been shown to reduce the “stickiness” of blood platelets and the thickening of arterial walls, and increasing folic acid intake appears to lower homocysteine levels by as much as 25%.
Is There Reliable Evidence?
Many clinical trials have examined the association between folic acid, homocysteine levels, and heart attack risk. Here are a few of the most comprehensive studies completed to date:
- A recent meta-analysis involved a total of 2052 patients with at least one cardiovascular risk. The findings, published in the journal Atherosclerosis showed that supplementing with 500mcg of folic acid daily for 18 months reduced homocysteine levels by 25%. Folic acid also reduced hardening of the arteries and the authors noted that the highest degree of protection was found in studies with the largest reduction in homocysteine levels.
- In a separate study, 151 adults with a history of heart disease were given 200, 400, 600, 800, or 1,000 mcg of folic acid or a placebo daily for three months. Researchers measured homocysteine levels at the beginning of the trial, immediately following three months of supplementation, and three months after supplementation was discontinued. At the end of the three month supplementation period, all groups taking folic acid had reduced homocysteine levels. The drop was proportionate to the dose, up to 800mcg. A daily intake of 800mcg reduced homocysteine levels by 23% compared to the placebo group, but at 1000mcg per day, the drop reduces slightly. Researchers also found that 3 months after supplementation ceased, homocysteine levels returned to the same levels as before the trial. They also stated that the 23% drop in homocysteine levels could reduce the incidence of heart disease by 15%.
- A study published in JAMA involved 20,000 participants with high blood pressure but without a history of stroke or heart attack. Findings showed that the combined use of enalapril and folic acid (0.8mg) significantly reduced the risk of heart attack and stroke, compared with enalapril alone.
While the evidence supporting folic acids ability to lower homocysteine levels is fairly conclusive, not all studies have found that reducing homocysteine levels also lowers the risk of heart attacks:
- The Heart Outcomes Prevention Evaluation 2 (HOPE2) trial monitored 5500 participants over 5 years, who were given either a placebo or a combination of folic acid (2.5mg), vitamin B6 (50mg), and vitamin B12 (1mg) daily. Findings showed that while folic acid did reduce homocysteine levels, it did not lower the incidence of heart attack or stroke, compared to the placebo group.
- The Norwegian Vitamin Trial (NORVIT) involved 3700 patients who had recently suffered a heart attack. Again, while a combination of folic acid and vitamin B6 lowered homocysteine levels, it did not lower the risk of recurrent heart attacks or strokes.
Overall, high homocysteine levels are observed in people who suffer a heart attack and folic acid has been shown to effectively reduce homocysteine levels. However, lowering homocysteine levels doesn't necessarily prevent the onset of future heart attacks of strokes. In adults who have already suffered a heart attack, it may be too late for folic acid supplementation to have a significant impact.
What Should My Homocysteine Level Be?
If you have a high risk of heart disease, measuring homocysteine levels is a potentially life-saving test. It requires a simple pinprick sample of blood, which is then measured in micromoles per litre (umol/L), often referred to as units.
There is no official safe homocysteine level as more research is needed. However, current findings indicate that a homocysteine level below 6 units is ideal, as levels above 6.3 have been shown to cause a steep progressive risk of heart attack and Alzheimer's disease.
It is estimated that the average homocysteine level in the UK is around 10.5 units and up to 30% of people with a history of heart disease have levels above 14 units.
How Much Folic Acid Do I Need?
The current recommended daily intake for adults and children over 11 years is 200mcg per day, which many people can achieve through diet alone. Good food sources include dark leafy green vegetables broccoli, nuts, seeds, oranges, and whole wheat bread.
Any woman considering pregnancy should take a daily 400mcg folic acid supplement and continue throughout the first 12 weeks of pregnancy.
The mandatory fortification of wheat flour with folic acid is currently being considered by the UK's Department of Health to further protect against birth defects during pregnancy. 83 countries around the world already have legislation for the mandatory fortification of food with folic acid, including Australia, Canada, and the US, where homocysteine levels have fallen significantly since it was introduced.
For heart health, the amount of folic acid needed depends on your current homocysteine levels. If your homocysteine level is 6 or below, 200mcg of folic acid per day should be sufficient to maintain healthy homocysteine levels. However, clinical trials indicate that higher doses are needed to reduce elevated homocysteine levels, which means that the 200mcg found in most multivitamins is not sufficient to provide maximum protection against heart disease.
If your homocysteine level is slightly elevated, a dose of 400mcg may be required to lower homocysteine, while those with seriously high levels above 9 units may benefit from 800mcg of folic acid per day.
Should I Supplement with Folic Acid?
It's important to remember that high homocysteine levels are not the only risk factor for heart attacks, and so lowering levels will not prevent heart attacks alone. If you have a high risk of heart disease, it is best to adopt a well-rounded approach to lower homocysteine, cholesterol and blood pressure, which includes avoiding fatty meats, limiting lean meats to four portions per week, reducing alcohol consumption, and cutting back on stress.
In addition to this, a daily intake of folic acid supplement can help to keep homocysteine at a safe level, particularly for those with a family history of heart disease, stroke or Alzheimer's disease. It is best to take folic acid in combination with vitamins B6 and B12 so opt for a high strength vitamin B complex multi vitamin each day, with at least 400iu of folic acid.
If you have a history of heart attacks, consult with your GP so that your dosage can be based on your individual needs.
Wald DS, Bishop L, Wald NJ, et al. Randomized trial of folic acid supplementation and serum homocysteine levels. Arch Intern Med 2001;161:695–700.
Wald NJ, Watt HC, Law MR, et al. Homocysteine and ischemic heart disease: results of a prospective study with implications regarding prevention. Arch Intern Med 1998;158:862–7.
Effect of folic acid supplementation on the progression of carotid intima-media thickness: A meta-analysis of randomized controlled trials. DOI: http://dx.doi.org/10.1016/j.atherosclerosis.2011.12.007
Folic acid supplementation and the occurrence of congenital heart defects, orofacial clefts, multiple births, and miscarriage1,2,3. DOI: http://ncbi.nlm.nih.gov/pubmed/11231701