Dietary supplements: weighing the health risks and benefits


From daily vitamins to bodybuilding products, it is important to realize that supplements are not regulated the same way as medicines by the Food and Drug Administration (FDA). So consider the health benefits — and risks — before taking a dietary supplement.

What are dietary supplements?

Dietary supplements are manufactured to provide the body with nutritional support. They include:

  • Vitamins
  • Minerals
  • Herbals
  • Botanicals
  • Amino acids
  • Enzymes

Supplements come in several forms: pills, liquids, powders or bars. They may replace the essential nutrients you are missing in your diet, but they are not a substitute for a healthy diet.

Effectiveness of nutritional supplements

“Personally, I’ll occasionally take a multivitamin,” says Jacob Gold, MD, an internal medicine physician at UCLA Health. “I take a vitamin D supplement every day. That’s probably the one supplement I might encourage my patients to take because it’s good for bone health and the associated risks are quite low.”

Dr. Gold generally considers standard doses of these supplements to be safe:

  • Calcium for bone health
  • Vitamin D for bone health
  • Folic acid for pregnant women or women trying to become pregnant to help prevent birth defects
  • B12 for vegetarians who may lack this nutritional component of meat
  • B vitamins for alcoholics

Dr. Gold warns that the FDA does not determine or certify the safety and effectiveness of over-the-counter supplements. “Many supplements, even multivitamins, haven’t been studied in a scientific way,” says Dr. Gold. “Since we don’t know exactly what they do or what risks they carry, we need to be careful in using them.”

Risks of dietary supplements

“Anything that has an intended effect also has a side effect,” says Dr. Gold. “The truth is, if a supplement does something you want it to do, it will probably also do something you don’t want it to do.”

Dr. Gold suggests that supplements that have a positive outcome are generally turned into a regulated medicine. As a result, they are better studied, dosing is better understood and risks are clearly identified. For that reason, he looks to use medicines, rather than over-the-counter supplements, to help his patients achieve a health goal.

“People will sometimes use red rice yeast to help control cholesterol. And, truthfully, it has the same chemical that’s in statin medications,” says Dr. Gold. “But when I prescribe a statin, I know how many milligrams I’m giving you and I know it’s a well-studied medicine. I don’t actually know what’s in the red rice yeast you bought from a vitamin store. That’s because there’s no regulatory body checking supplement samples to know what’s in there.”

Dr. Gold has seen firsthand the harmful effects of bodybuilding supplements. Many of these have creatine, an amino acid that may build muscle, but can also damage the kidneys. He’s also found many of these supplements have high levels of caffeine, which can cause muscle breakdown, hyperactivity and agitation.

Tell your doctor what vitamins you’re taking

The biggest concern, Dr. Gold says, is that people often don’t share what supplements they’re taking with their health care provider.

“Taking supplements is generally OK. You’re not likely to run into too many problems, though the benefit may not be clear,” says Dr. Gold. “But if you don’t tell your provider what you’re taking, they could prescribe a medication that interacts with the supplement. This has the potential to be very dangerous, even fatal.”

Dr. Gold cites these examples:

  • Ginkgo biloba can thin your blood, so it is problematic when used with a blood thinner.
  • John’s wort can build up in the liver and cause interactions with other drugs, such as antidepressants.
  • Ephedra is a stimulant that can cause high blood pressure.
  • Ginseng can cause bleeding in patients who are taking blood thinners.
  • Kava kava can cause liver damage with overuse; some patients have even needed a liver transplant.
  • Black cohosh used for menopausal symptoms may cause liver failure.

“Many of these side effects are rare, but they can happen,” says Dr. Gold. “The number one rule with supplements is to tell your doctor what you’re taking. We want to protect you from unintended interactions between medications and over-the-counter supplements.”

UCLA Health provides patient care focused on the prevention, diagnosis and treatment of health concerns. You can request an appointment online or by calling 800-825-2631.