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Vitamin Scoop: Before you shell out money for vitamins or supplements, consider these answers to commonly asked questions.

Kritz, Fran

doi: 10.1097/01.NNN.0000515868.55449.92
Departments: The Waiting Room

Ask Your Doctor: Before you shell out money for vitamins or supplements, discuss these questions with your neurologist.

Many patients with neurologic conditions ask their doctors about vitamins and supplements. Some may have read studies that claim supplements can be helpful. Products such as ginseng, Ginkgo biloba, omega-3, and coconut oil have been variously overhyped to promote brain health, despite a lack of scientific evidence. Other patients wonder if they could take a vitamin instead of a prescription drug, hoping that it will be more effective or have fewer side effects. Here are questions doctors often hear, and answers from leading physicians.

1. Do I need to check with my neurologist before buying supplements or vitamins? Always tell all your doctors about any vitamins and supplements you take or plan to take, says Joseph F. Quinn, MD, FAAN, associate professor of neurology at Oregon Health & Science University in Portland. Your physician may be able to advise you about which ones are appropriate and whether they will interact with your current medication.

2. Can some vitamins prevent or treat neurologic disorders? Little evidence suggests that vitamins or supplements can prevent or treat neurologic conditions, says Ralph L. Sacco, MD, MS, FAHA, FAAN, professor of neurology at the University of Miami Miller School of Medicine in Florida. For some people, certain B vitamins, including B6, B12, and folate, as well as vitamin D, might be beneficial, but only if a deficiency is confirmed by a blood test, he says. A vitamin D deficiency, for example, is associated with increased risk for multiple sclerosis (MS) and may be associated with increased disease activity, says Patricia K. Coyle, MD, FAAN, director of the Multiple Sclerosis Comprehensive Care Center at Stony Brook University in New York. A study published in the November 30, 2016, issue of Neurology found that babies born with low levels of vitamin D may be more likely to develop MS later in life than babies with higher levels.

3. Can vitamins or supplements do harm? Vitamins and supplements can have side effects and may interact negatively with drugs, says Dr. Coyle. “Excess B and C vitamins are excreted in the urine, but vitamin D can accumulate in the body,” she says. In very rare cases, excess vitamin D can result in too much calcium in the blood, which can cause weakness and lead to kidney stones and can even be life-threatening, according to research published by the Mayo Clinic.Drug interactions are also a concern. For example, St. John's wort, a supplement sometimes used for depression, can interact with some antidepressants and create an excess of the brain chemical serotonin, which can lead to serious side effects, including diarrhea, agitation, tremor, and even death.It is also important to know that many vitamins and herbal supplements—including fish oil, garlic, Ginkgo biloba, ginseng, vitamin E, and St. John's wort—can cause bleeding, so they should be stopped prior to surgery.

4. Are supplements and vitamins regulated? Yes, but not in the same way as prescription drugs, says Lyndsay Meyer, a spokesperson for the US Food and Drug Administration (FDA). Drug companies must conduct clinical trials to prove that prescription drugs are safe and effective. Up until 1994, when new FDA regulations went into effect, vitamin and supplement companies could put health claims on product labels without substantiating the claims. Since then, companies can only make a health claim if they cite their own or someone else's study. They must also include a disclaimer that the claims have not been substantiated by the FDA. The FDA checks samples from stores and will take a product off the market if it finds a safety problem through its own checks or after reviewing reports of safety issues or adverse events from consumers or health care providers.

5. What does a USP seal mean? Certain organizations, including US Pharmacopeia (USP), http://ConsumerLab.com, and NSF International, grant supplements the right to carry their seal. It doesn't indicate a therapeutic value or that the supplement has been tested by the FDA, but it is a sign that the product contains the ingredients advertised on its label and doesn't have contaminants such as bacteria, arsenic, or lead.

6. Should I discuss the vitamins and supplements I take with my doctor or neurologist at every visit? Absolutely, says Dr. Coyle. That allows your doctor to update your records. If you have access to your medication list through a patient portal, you should update your information, including if you are taking any new vitamins or supplements or discontinuing any. If you forget to discuss vitamins at the next visit, that information will be in your files and your doctor can access it before making any prescription drug changes, says Dr. Coyle. You should also talk to your doctor about whether to stop taking a supplement instead of simply discontinuing it on your own, adds Dr. Quinn.

7. Should I tell my pharmacist about supplements I take? Definitely, says Dr. Coyle. Pharmacists are often knowledgeable about interactions, she says, so it's a good idea to seek their advice to reinforce what you've heard from your doctor.

8. Can some vitamins and supplements help relieve symptoms associated with neurologic conditions? Yes, so it's worth asking your doctor which ones might be helpful, says Dr. Sacco. For example, he says, the supplement coenzyme Q10 (CoQ10) might help relieve muscle pain associated with cholesterol-lowering statin drugs, which are often prescribed to prevent a stroke. Some studies have shown a benefit while others have not, according to patient resources published by the Mayo Clinic. And certain vitamins and supplements, including riboflavin and feverfew, may help reduce the severity or even incidence of migraine headaches.

For more about vitamins and migraine, go to http://bit.ly/NN-VitaminsforMigraine.

© 2017 American Academy of Neurology