The use of supplements is a common practice among cancer patients. According to the latest Supplemental Business Report put out by Nutrition Business Journal, multivitamins are projected to bring in sales of $7.5 billion in 2020, with growth spiking to 17.1% over just 3.7% in 2019. This spike is in part due to the current pandemic of COVID-19 and the population’s concern with our body’s ability to fight infection and to boost immunity overall. This year is on target to be the highest growth year for the industry since 1997 with a 12.1% increase for 2020.

Over half of American adults take dietary supplements with hopes to increase energy, live longer, improve their overall health, and prevent and treat disease. With the growing interest in supplement use, it is important to examine the literature to see if current studies align with what minimally-regulated supplement companies report and what the general public believes to be true.

A Scarcely Regulated Industry

The supplement industry has benefitted from minimal regulations thanks to the Dietary Supplement Health and Education Act (DSHEA) in 1994. This law is a double-edged sword: on the one hand, it promotes broad access of supplements to consumers, which allows consumers to make their own choices about what they use. On the other hand, there is little FDA oversight on the effectiveness and safety of supplement use.

Manufacturers don’t have to prove the effectiveness of their products before they go to market. The only way for a product to be removed from the marketplace is if there are reported severe adverse reactions, such as death.

That being said, only a few products have been removed from the market. With inconsistencies in clinical trials and scientific literature, it is difficult to balance the cost of supplements with the lack of data to support its use in an otherwise healthy population.  

Because supplements are poorly regulated, several agencies provide an avenue for third-party testing. These companies test supplement products for consistency and accuracy with what is reported on the label. Two of these third-party companies are USP (US Pharmacopeia) and NSF (National Sanitation Foundation). Another subscription-only organization, Consumer Labs, also verifies content. Alternatively, your registered dietitian can guide you to high-quality products.

Supplement Use During Cancer Treatment

Cancer patients frequently use supplements as a way to manage side effects, boost their immune system, or relieve pain.

One of the most contested areas of supplementation is the use of antioxidants — like vitamins C, E, and A, as well as selenium and Co-Q10 — during chemotherapy and radiation. Laboratory tests suggest that antioxidants may enhance conventional therapies by protecting normal cells from being damaged. For this very reason, many oncologists believe that they may actually interfere with treatment by protecting cancer cells as well. However, human studies have not provided a definitive answer.

It is not recommended to supplement with herbs while receiving treatment unless there is a clear indication of a micronutrient deficiency that needs correction, and it is recommended by your registered dietitian and oncologist.

If you are currently being treated for cancer and are taking supplements, provide your oncologist and registered dietitian a detailed list of all the supplements and herbs you are taking and include the brand and dosage of each one. It may be helpful to provide a list to each health care worker on your team. It is very important to be as transparent as possible with your medical team, so they understand what you are doing outside of the care you are receiving for your diagnosis.

It is important to understand both the potential benefits and harms that may come with supplements. There is conflicting evidence of the effectiveness of supplementation in a healthy population. There is also evidence that shows populations with noted nutritional deficiencies may benefit from supplements. Supplements should be considered on a case by case basis and only be recommended after close analysis of a person’s disease state, current medications, and overall nutritional status.

Focus on Nutrients from Food

Supplement use is and will continue to be a controversial topic. But many experts (including Cook for Your Life dietitians) encourage people to get as many of their nutrients from whole foods as possible. If that is within your reach, then supplements may not be necessary.

For the general healthy population, supplements are not justified and therefore should be avoided. If a person is consuming a wide variety of fruits and vegetables, whole grains, legumes, and lean protein sources, then taking supplements such as a multivitamin could be excessive or ineffectual. Many of the supplements on the market meet or exceed the recommended daily upper limits of a vitamin or mineral, which, when combined with a diet high in fortified foods and fruits and vegetables, can potentially lead to harmful effects.

With little research into the efficacy and potency of the various supplements on the market, it is impossible to predict the outcomes of exceeding the upper limits of micronutrients over an extended period. For the general population who eat a diet high in fruits and vegetables, whole grains, legumes, and lean sources of protein, there is currently no overwhelming evidence that suggests supplementation with a multivitamin or other singular vitamin or mineral would prove to have beneficial effects on overall health and longevity. 

Looking for recipe inspiration to add more cancer-protective foods into your meals? We’ve got all the recipes you need!

Kate Ueland, MS, RD, specializes in oncology nutrition, primarily working with breast, ovarian, renal, and melanoma cancer patients throughout all stages of the cancer journey at Seattle Cancer Care Alliance (SCCA) in Seattle, WA. As Cook for Your Life’s nutrition advisor and editor, Kate ensures all culinary content adheres to the Academy of Nutrition and Dietetics and follows science-based guidelines.