To Your Health

A. The uncomfortable feeling, "like insects crawling inside my legs," and the nearly uncontrollable urge to move the legs in an effort to relieve that feeling, was described in medical literature in the 1600s. In the 1940s Karl A. Ekbom first used the term "Restless Legs Syndrome" to describe the condition. Because moving the legs relieves the discomfort, people with RLS like to keep their legs in motion to minimize the discomfort and as a result have difficulty falling asleep and staying asleep. Left untreated, the condition leads to exhaustion and daytime fatigue. RLS is a complex disorder that appears to have several causes and probably involves various interacting neurotransmitter systems. Surveys indicate that 10-15% of the population suffers from RLS.

Because RLS often occurs in pregnancy, iron deficiency has long been suspected to be involved. Some have argued against this since less than half the people with RLS are found to be iron-deficient. The resolution of the question came recently with the finding that the brain can be iron-deficient, even though there is an excess of iron in the rest of the body. An article in the Journal of Neurology, Neurosurgery, and Psychiatry for July of 2005 (p. 1009-1010) described a "regional" iron deficiency in the brains of some RLS patients. Even though they suffered from hemochromatosis – the metabolic disorder in which toxic amounts of iron accumulates in the body – brain-iron levels were low. The low level of iron in the brain apparently hinders its ability to control nerve activity in the legs, resulting in RLS.

The association of RLS with pregnancy also suggested that folic-acid deficiency could be involved. It was also noted that certain anti-seizure medications that are known to induce folic-acid deficiency could worsen RLS. At present this connection remains only a theory. A small number of RLS patients have used high-dose folic-acid supplements (5000-10,000 micrograms per day, compared to the usual supplement of 400 micrograms per day) with heartening results. Other studies have combined folic-acid supplements with other nutrients, most often iron supplements, so the effect of folic-acid supplements alone has not been adequately investigated.

In most cases, the cause of RLS is unknown. Often there is a family history of RLS, suggesting a genetic component to the disorder. The people with inherited RLS appear to have also inherited an unusually high requirement for folic acid. Folic acid deficiency is probably the most common of all the vitamin deficiencies, and sometimes the deficiency is not due to a poor diet, but to a genetic factor that causes the unusually high folic acid requirement. Although not all people with RLS are deficient in folic acid, those who inherit a high requirement for folic acid all seem to suffer from RLS. Patients with inherited RLS tend to develop the problem about 10 years earlier than usual. With supervision from a nutrition-oriented health professional, these people would likely benefit from very large supplements of folic acid.