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Can Folic Acid Prevent High Blood Pressure?

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Updated June 18, 2014

What is Folic Acid?

Folic acid is a water soluble form of vitamin B9. It is the synthetic form of folate, a nutrient found in certain foods, and is used in vitamin supplements. However, for general use, the two terms can be used interchangeably. Folic acid is an important nutrient that the body uses to generate, replicate, and repair cells, including DNA. Deficiencies in folic acid are particularly problematic during pregnancy, when the body must quickly produce lots of new cells. Red blood cell production is also very sensitive to folic acid levels, and low levels of this nutrient can lead to certain types of anemia. It is believed that folic acid and its derivatives also play an important role in repairing DNA damage that could otherwise lead to cancer.

Can Folic Acid Prevent High Blood Pressure?

Several large studies have examined the role of folic acid in the prevention of high blood pressure and found that it provides some benefit in reducing risk of the condition. While the exact role is unclear, it may help maintain the flexibility of arteries and other blood vessels or help blood pressure receptors make more accurate blood pressure adjustments. The most widely discussed study on folic acid and blood pressure is the Nurses' Health Study II, which was published in 2005 by researchers from Harvard Medical School. This study found that women who consumed at least 1000 micrograms of folate per day were about 25 percent less likely to develop high blood pressure than women who consumed less than 200 micrograms per day. Earlier studies have looked at lower doses of folic acid and found that doses beyond 800 micrograms per day do not appear to provide any additional benefit.

One limitation of the data on folic acid is that the strongest research was conducted exclusively in women. Some studies have examined potential benefits in men, but almost all relate in some way to the effects of folate on the amino acid homocysteine. It was once thought homocysteine played a central role in the development of high blood pressure and other cardiovascular problems, but newer research has called certain details of this role into question. Research is currently underway to help answer these questions, but until the data is analyzed, no clear recommendations can be made.

Also be aware that while folate may have preventative value for high blood pressure, the most recent American Heart Association Guidelines state that it is not effective for the prevention or treatment of heart disease.

Should I Take Folic Acid Supplements?

In 1998, the U.S. government began a wide-scale program asking manufacturers to fortify bread, cereal, and other foods with folate as they were being produced. Estimations show that most Americans are currently consuming very close to the recommended daily allowance (RDA) of 400 micrograms of folic acid per day. However, the RDA is less than half the dose shown to be effective for healthy, non-pregnant adults in the Nurses' Health Study. For this reason, it is worthwhile to consider taking a folic acid supplement (400 to 500 micrograms per day.) As with any supplement, you should ask your doctor before starting. Folate supplements may not be recommended for those with certain conditions.

Because folic acid is water soluble, it is very difficult to consume dangerous amounts. That means that whatever your body doesn't use is filtered by the kidneys and excreted into the urine. Though excess folic acid consumption isn't likely to cause serious harm, it can cause side effects. Too much folic acid can cause headaches, stomach upset, diarrhea, and other discomfort.

Good Dietary Sources of Folic Acid

Many prepared cereals, canned goods, and breads are fortified with the nutrient. Green leafy vegetables and legumes (beans) are the best natural sources of folic acid. Some wise choices:

  • Lentils: 1 Cup, boiled = 386 micrograms
  • Chickpeas: 1 Cup, boiled = 282 micrograms
  • Spinach: 1 Cup, raw = 210 micrograms
  • Cauliflower: 1 Cup = 180 micrograms
  • Lettuce: 1 Cup = 156 micrograms
While folic acid is an important part of a healthy high blood pressure diet, it is only one component. Healthy eating is one of the most important steps towards the prevention of high blood pressure, and overall balance is the key.

Sources:

  1. Eichholzer, M, Tonz, O, Zimmermann, R. Folic acid: A Public Health Challenge. Lancet 2006; 367:1352.
  2. Jacques, PF, Selhub, J, Bostom, AG, et al. The Effect of Folic Acid Fortification on Plasma Folate and Total Homocysteine Concentrations. New England Journal of Medicine 1999; 340:1449.
  3. Bechir, M, et al. Folic Acid Improves Baroreceptor Sensitivity in Hypertension. Journal of Cardiovascular Pharmacology 2005; 45:44-8.
  4. Forman, JP, Rimm, EB, Stampfer, MJ, Curhan, GC. Folate Intake and the Risk of Incident Hypertension Among US Women. JAMA 2005; 293:320.
  5. United States Department of Agriculture. USDA National Nutrient Database for Standard Reference. Release 18, 2002-2006.

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