Diet & Fitness

Several controlled studies have shown that long-term anticonvulsant treatment decreases blood levels of biotin. In children, a deficiency of biotin can lead to withdrawn behavior and a delay in mental development. Adults with low biotin levels might experience a loss of appetite, feelings of discomfort or uneasiness, mental depression, or hallucinations. To avoid side effects, individuals taking anticonvulsants should supplement with biotin either alone or as part of a multivitamin.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency. Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life. Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

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In various studies of children treated with valproic acid for epilepsy compared with control groups, serum zinc levels remained normal or decreased, serum copper levels remained normal or decreased, and red blood cell zinc levels were decreased. The importance of these changes and how frequently they occur remain unclear.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels. Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine. However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation. Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A. Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

Anemia is an uncommon side effect experienced by people taking anticonvulsant drugs. Though many researches believe that low blood levels of folic acid are involved, the effects might be caused by a vitamin B12 deficiency. Deficiencies of folic acid and vitamin B12 can lead to nerve and mental problems. One study revealed that individuals on long-term anticonvulsant therapy, despite having no laboratory signs of anemia, had dramatically lower levels of vitamin B12 in their cerebrospinal fluid (the fluid that bathes the brain) when compared with people who were not taking seizure medications. Improvement in mental status and nerve function was observed in a majority of symptomatic individuals after taking 30 mcg of vitamin B12 daily for a few days. Another study found that long-term anticonvulsant therapy had no effect on blood levels of vitamin B12. The results of these two studies indicate that people taking anticonvulsant drugs might experience side effects of vitamin B12 deficiency, and that the deficiency is not easily detected by the usual blood tests. Therefore, individuals taking anticonvulsant drugs for several months or years might prevent nerve and mental problems by supplementing with vitamin B12.

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity, which might lead to softening of bones (osteomalacia). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication. In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months. Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months. Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease. Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.

Two studies showed that individuals taking phenytoin and phenobarbital had lower blood vitamin E levels than those who received no treatment for seizures. Though the consequences of lower blood levels of vitamin E are unknown, people taking multiple anticonvulsant drugs might supplement with 100 to 200 IU of vitamin E daily to help prevent a deficiency.

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity, which might lead to softening of bones (osteomalacia). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication. In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months. Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months. Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease. Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.