DEAR DOCTOR K:
I’m a healthy woman in my 40s. Should I take extra folic acid to boost my immune system?
Folic acid is, essentially, a vitamin. We all need vitamins. Indeed, the word “vitamin” was coined to refer to a substance that was essential to human life. The natural form of folic acid, folate, occurs in some foods, including vegetables, fruits, and dried beans and peas.
Each of us is a collection of about 13 trillion cells. If our cells get sick, we get sick. If our cells get old, we get old. Folate is essential for the production and maintenance of our cells. That’s especially true during rapid periods of growth, such as pregnancy and infancy. Folate is needed to make DNA and RNA, the genetic material that dictates how our cells function, and it helps prevent mutations to DNA that may lead to diseases, including cancer.
Our immune system cells, which are white blood cells, are always in a rapid period of growth. These cells don’t live very long, so they constantly need to be replaced. Folate deficiency can cause anemia — inadequate production of red blood cells. But it doesn’t weaken the immune system sufficiently to make us more vulnerable to infections, for example.
Over the past 30 years, many studies have found that people with high blood levels of a natural substance called homocysteine are at higher risk for heart disease. One easy way to reduce homocysteine levels is by taking folic acid supplements. Studies have not shown that taking folic acid supplements protects most people from heart disease. The exception is people born with a genetic defect that causes high homocysteine levels. I’m one of them; I take folic acid every day.
For most healthy adults, the Recommended Dietary Allowance (RDA) of folate is 400 micrograms (mcg) a day. Pregnant women should take more: 600 mcg a day. The extra folate helps to reduce the risk of neural tube defects, a serious malformation of the spine, skull or brain in the baby.
Experts advise against getting more than 1,000 mcg per day of folic acid from supplements or fortified foods. You’re unlikely to suffer any ill effects even if you exceed that limit, because your body excretes excess folic acid in the urine. Still, there might be long-term health effects that we don’t yet know about.
On the other hand, there’s no health risk associated with getting plenty of naturally occurring folate from foods. Get as much of your daily requirement as you can from a healthy diet. Good food sources of folate include spinach, asparagus, rice, green peas, broccoli and great northern beans. Many breads, cereals, flours, cornmeal, pastas, rice and other grains are enriched with folic acid.
If you’re not getting enough folate from foods, take a multivitamin that contains 400 mcg of folic acid.