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By Sari Harrar

Do Vitamins Really Help People with Neurologic Conditions?

Seventy-five percent of American adults take vitamins or minerals, contributing to a $40 billion-a-year industry, according to the US Food and Drug Administration, which does not regulate it.

Spoons full of vitamins

But do supplements help people with neurologic conditions? So far, the evidence is mixed.

A 2018 review in JAMA Neurology that looked at 24 vitamins, minerals, and other popular supplements used by people with multiple sclerosis (MS) found that some compounds, like vitamins A and B6 and green tea extract, could have toxic effects, while others could interact with medications or interfere with lab test results in people with MS.

Only one vitamin demonstrated a potential benefit for some people, according to the review. "Our evidence shows that in patients with MS whose vitamin D levels are low, inadequate vitamin D could be harmful and vitamin D supplementation may decrease MRI lesions," says lead author Anne Cross, MD, FAAN, professor of neurology at Washington University School of Medicine in St. Louis.

But a 2018 review published by Cochrane, a nonprofit health research group in England, came to a different conclusion. Vitamin D had no apparent effect on disease progression, worsening disability, or MRI lesions for people with MS. The review, which analyzed 12 randomized controlled studies involving 933 people with MS, concluded that more evidence was needed. Since then, two large studies have been published showing the possible benefit described by Dr. Cross.

Study results are weak for other neurologic conditions, including Parkinson's disease. "We don't have evidence that most supplements are helpful for Parkinson's," says Rodolfo Savica, MD, PhD, associate professor of neurology at Mayo Clinic in Rochester, MN. "When I'm not sure something will work, I'd rather my patients not use it."

To find out if any vitamins are worth taking, we looked at the research and talked to experts about four common conditions. In every case, experts say patients should discuss supplements with their doctors before taking any.

MS and Vitamin D

Low blood levels of vitamin D have been associated with a higher risk of developing MS and with relapses, worsening disability, and brain lesions in people with the disorder, according to Dr. Cross. Several studies have found a lower, but not statistically significant, risk for new, active, or enlarged MS-related brain lesions in people taking vitamin D supplements compared with those not taking D. These studies include a notable 2012 University of California San Francisco study published in Annals of Neurology that tracked 469 people with MS for five years.

But most studies have not found reduced risk of relapse or slowing of MS progression, including two large vitamin D trials whose results were published in 2019, says Dr. Cross. The French CHOLINE study reported in the journal Neurology: Neuroimmunology & Neuroinflammation that among 181 study participants with relapsing-remitting MS and low vitamin D levels, no overall difference was observed in relapse rates between those who took vitamin D and those who took a placebo for 96 weeks. But a smaller group that took D consistently did show improvements in relapses and progression compared with a placebo. And a multi-center European study, published in Neurology in October 2019, of 229 people with relapsing-remitting MS found that those who took high-dose vitamin D3 for 48 weeks had 32 percent fewer new lesions than those taking a placebo. But the number who were relapse-free at the end of the study was the same. In both studies, participants received vitamin D or a placebo as well as disease-modifying therapy.

"We see some evidence that supplementing with D may be helpful for reducing brain-lesion activity measured by MRI, though clinical benefits have not been seen," Dr. Cross says. "Combining that with the fact that many patients with MS may have low levels of vitamin D, which may put them at risk for osteoporosis, I check blood levels in my new patients. If their levels are low, I recommend supplements."

What to know: Physicians may prescribe supplemental vitamin D3 to patients with low blood levels; doses vary depending on baseline levels. Dr. Cross checks calcium levels every six months during routine blood testing. "Vitamin D can raise blood calcium levels, which could cause kidney and liver problems," she says.

What to skip: Dr. Cross cites her 2018 review that found no positive evidence for vitamins A, B2, B3, B5, B6, B7, B9, B12, C, E, and K as well as caffeine, carnitine, coenzyme Q10 (CoQ10), creatine, curcumin, ginkgo biloba, green tea extract, lipoic acid, polyunsaturated fatty acids, probiotics, and resveratrol.

Parkinson's Disease and B6, B12, Folate

Levodopa, the gold standard treatment for Parkinson's disease, may deplete reserves of B6, B12, and folate, says Dr. Savica. "This could increase the risk for nerve damage that causes numbness and tingling in feet and hands, as well as walking problems."

In a 2019 Journal of Movement Disorders study that tracked 1,741 people with Parkinson's disease for three years, those who took a multivitamin plus a B12 supplement had a slightly lower risk for developing sensory symptoms such as numbness, tingling, aching, and pain than those who didn't take these supplements. B12 supplements had no effect on other symptoms like freezing while walking, falls, instability, or cognitive problems that were rated on the Unified Parkinson's Disease Rating Scale prior to the study and again after three years. The researchers note that the results were "secondary"; the study's primary aim was to test creatine supplements as an add-on therapy in early Parkinson's disease. When creatine proved ineffective, the study was halted. The multivitamin and B12 results were seen in a small group of people and should be considered preliminary. Experts agree further study to confirm the finding is warranted.

What to know: If you have Parkinson's disease, ask your doctor if you should be tested for B6, B12, and folate deficiencies. "If you have deficiencies and your doctor rules out other causes, consider taking supplements," says Dr. Savica. He prescribes 25 milligrams of B6, 2 mg of B12, and 2.5 mg of folate. Supplements may help with sensory symptoms such as numbness, tingling, aching, and pain, he says. "But don't take megadoses, especially of vitamin B6," Dr. Savica warns. "They can be toxic."

What to skip: Insufficient evidence exists to recommend CoQ10, creatine, glutathione, turmeric, and vitamin E for Parkinson's disease, says Dr. Savica.

Duchenne Muscular Dystrophy and Creatine

Creatine, a popular supplement among athletes and weightlifters for its ability to enhance muscle performance, has been shown to aid in rebuilding muscle strength for people with Duchenne muscular dystrophy. In a 2013 review of six studies involving 192 people, published by Cochrane, creatine supplements increased muscle strength by an average of 8.5 percent compared with a placebo. Those who took creatine also felt better, according to pooled data. "Nothing has been published since then that alters those conclusions," says the study's co-author Mark Tarnopolsky, MD, PhD, FAAN, professor of neurology and head of neuromuscular and neurometabolic disease at McMaster University in Canada. Creatine also may protect against the side effects of corticosteroids often used in the treatment of Duchenne muscular dystrophy, Dr. Tarnopolsky says. It is less effective for myotonic muscular dystrophy, which causes weakness and shrinking of muscles and is one of the most common forms of muscular dystrophy in adults.

What to know: The recommended daily dose of creatine is 0.1 grams per kilogram (2.2 pounds) of body weight, up to a maximum of five grams of creatine per day, Dr. Tarnopolsky says. "Take it with food," he suggests. "If creatine upsets your stomach, cut the dose in half." Dr. Tarnopolsky recommends using creatine monohydrate supplements. "All the studies were done with this form. There's no credible evidence that any other salts are more tolerable or effective, but they are definitely more expensive."

What to skip: Melatonin, traditional Chinese herbs, green tea extract, curcumin, resveratrol, beet root juice, l-arginine, and taurine are not effective, according to a 2016 Canadian review of popular supplements for Duchenne muscular dystrophy, published in the journal Nutrients.

Migraine and B2, Magnesium, CoQ10

Vitamin B2, also called riboflavin, showed "a consistent positive therapeutic effect in adults" for reducing the frequency of migraines, according to a 2017 review in the Journal of Clinical Pharmacy and Therapeutics. Evidence was mixed for children and teenagers. "B2 appears to work for about half the people who try it," says Stephen D. Silberstein, MD, FAAN, professor of neurology at the Sidney Kimmel Medical College at Thomas Jefferson University and director of the Jefferson Headache Center in Philadelphia. "It is safe, has no side effects, and is affordable."

Several randomized controlled studies have found benefits of magnesium for migraine prevention and pain reduction. But not all headache experts agree. When a dietitian and a neurologist at Mayo Clinic reviewed the evidence in a 2015 article in the journal Cephalalgia, they found it "limited" and said getting magnesium from foods such as almonds, spinach, cashews, peanuts, and shredded wheat was probably better.

Meanwhile, a 2019 review published in Acta Neurologica Scandinavica of five studies involving 346 people concludes that CoQ10 is a "potent therapeutic agent" for migraine.

What to know: Vitamins and supplements aren't curealls and can take as long as three months to be effective, says Teshamae Monteith, MD, FAAN, associate professor of clinical neurology and director of the headache program at the University of Miami Miller School of Medicine in Florida. It's also not clear which is best. "There are no head-to-head studies to determine which may be more effective," Dr. Monteith says. In the meantime, the recommended dose of B2 is 100 mg four times a day. "The body only absorbs about 27 milligrams of B2 from a dose and it only lasts about two hours in the body, so we think it's best to take 100 milligrams at each meal plus at bedtime rather than larger doses less often," Dr. Silberstein says. The recommended dose of magnesium is 600 mg daily. The recommended dose of CoQ10 for migraine prevention is 100 mg three times a day.

What to skip: Vitamin D supplements don't seem to reduce migraine pain or frequency. In addition, it is too early to recommend probiotic strains due to conflicting findings in a limited number of studies, says Dr. Monteith.

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