Frequently Asked Questions

Folic Acid and Its Link to Other Health Outcomes

Hypertension, or abnormally high blood pressure, increases the risk for having a stroke. A recent large study of adults in China with hypertension found that taking 800 micrograms of folic acid each day reduced the occurrence of stroke by 21%. An accompanying editorial in the journal that published this study stated that this reduction in stroke would likely apply to all adults ^{36, 37}.
More recently, a study looking at the results of 30 randomized control trials, involving more than 80,000 people, suggested a 10% lower risk of stroke and a 4% lower risk of overall cardiovascular (heart and blood vessel) disease among those taking folic acid supplements ³⁸.

In many countries in the world, arsenic in the water results in chronic (that is, constant) exposure of people to arsenic. A randomized control trial in Bangladesh found that taking 400 micrograms per day of folic acid for 12 weeks reduced total blood arsenic levels by 13.6%. The authors stated that taking folic acid to lower blood arsenic levels may help reduce the risk of illnesses that can result from arsenic poisoning ³⁹.

Anyone being treated for cancer should discuss with his or her physician whether to take supplements that contain folic acid. Supplements (including those containing folic acid) can interfere with some drugs used to treat cancer. The physician should be told about any supplements the patient is taking.
In 2007, a randomized control trial study was published that looked at whether people who previously had a colorectal adenoma could prevent future colorectal adenomas by taking folic acid supplements of 1,000 micrograms per day; the researchers found that people taking the folic acid supplements had an increased risk of developing three or more additional adenomas after six years of follow-up ⁴⁰. However, many large individual studies and the results of many additional studies combined together into a single analysis (i.e., a meta-analysis) do not find a relationship between folic acid supplementation and developing additional colorectal adenomas ^41-44.
The Centers for Disease Control and Prevention continually monitors the latest research on the effects of folic acid on colorectal cancer.

A recent analysis used data from randomized control trials, which included information on 50,000 individuals. This analysis showed that for people taking folic acid, there was neither an increase nor a decrease over time in the number of new cases of cancer of the large intestine, prostate, lung, breast, or any other specific site ⁴⁵.

Low blood folate concentrations can cause anemia among both men and women. There are different types of anemia, which have a variety of causes. The type of anemia that can be caused by very low blood folate concentrations is called megaloblastic anemia ²⁷.