They can offer tempting claims, but when it comes to dietary supplements, do these products do more harm than good?

We’re clearing up some of the biggest dietary supplement myths with facts, especially for those who may be in treatment.

Dietary Supplements Defined

The Food and Drug Administration broadly defines dietary supplements as products intended to add nutritional value to your diet. They can be:

• Vitamins

• Herbs

• Botanicals (such as ginger, garlic, etc.)

• Minerals

• Concentrates or extracts

• Amino acids

Given the lack of regulation around these products, it’s no surprise there are many questions surrounding dietary supplements.

Taking a dietary supplement may help support your treatment plan, or it could do more harm than good. It’s important to always discuss dietary changes and supplements with your care team to prevent problems and safeguard your health.

Myth 1: Supplements Won’t Interfere With Treatments

Despite "natural" claims on labels, pairing dietary supplements with other medications and cancer treatments can create dangerous and possibly life-threatening effects.

Drug interactions and interference are real concerns, no matter how safe a supplement may seem.

Supplements can:

• Render chemotherapy and radiation therapy ineffective

• Reduce your body’s ability to absorb, distribute and metabolize medications

• Block the production of free radicals that destroy cancer cells

Myth 2: Supplements are Regulated and Safe

Supplement manufacturers don’t have to conduct thorough clinical studies to show the FDA that the drugs are safe and work as they claim. Unlike prescribed medications, the FDA does not review dietary supplements for safety and effectiveness.

The FDA will step in only if there’s a known problem with a dietary supplement and proof the product causes a significant danger to those taking it.

Myth 3: The More You Take, the Better

When it comes to herbs and supplements, mega-dosing, the term for taking more than the recommended amount of a medication or supplement, can be extremely dangerous. Too much of a supplement can cause adverse effects, such as treatment failure or chemotherapy overdose.

Taking too much of a vitamin or mineral can inhibit the absorption of other nutrients your body needs. In other cases, your body can’t rid itself of the excess fat-soluble vitamins and nutrients build up in your system if you’re taking large doses.

Some supplements may become necessary during treatment. Your doctor will make the recommendation and let you know what you should be eating, and if necessary, which supplements are needed to address deficiencies.

Myth 4: "Natural" Supplements Are Safe to Take

Because the FDA doesn’t strictly regulate dietary supplements and doesn’t define "natural," it can be difficult to verify whether all the ingredients do, in fact, come from nature.

Studies by the U.S. Government Accountability Office revealed that 93 percent of supplements tested contained trace amounts of contaminants such as lead, arsenic, mercury, cadmium and pesticides.

"A common, false belief is that ‘if it’s natural, it must be safe,’" said Dr. Barrie Cassileth, chief of the Integrative Medicine Service at the Memorial Sloan-Kettering Cancer Center. "But herbs and other dietary supplements are biologically active compounds, and they frequently have negative interactions with prescription pharmaceuticals."

Because manufacturers don’t have to prove the accuracy of their ingredients list, there’s no way to be 100 percent sure what substances are in a supplement.

Myth 5: Dietary Supplements Can Help Prevent Illness

More than a dozen major studies have found supplements do not prevent illness and do not help people live longer.

Dietary supplements are meant to fill the gaps, not replace food-based nutrition. The preferred method for getting vitamins and minerals is through different types of nutritious foods.

Talk to Your Doctor

If you’re looking for natural options, commonly referred to as alternative, integrative and complementary therapies, let your care team know. Together, you can discuss your options and how certain supplements may affect your treatment.