What are dietary supplements?

Dietary supplements range from basic vitamins & minerals to protein powders, fish oil capsules, and botanicals. Most of us are familiar with common supplements like vitamins & minerals such as vitamin C or calcium. However, the overall category is much larger and includes products in a variety of different forms.

According to the U.S. Food and Drug Administration (FDA), there are about 30,000 different dietary supplements on the market today. An average of 1,000 new supplement products are introduced every year. Dietary supplements are manufactured products extracted from food or created synthetically. They are best used to fill dietary gaps or in some cases to maintain or improve health.

THE BOTTOM LINE: It is important for you to know that many supplements are not effective and sometimes have misleading or false marketing claims. Also, they could contain incorrect dosages and/or contaminants which could be unsafe and potentially harmful.

Can supplements prevent or cure cancer?

No, research does not currently support this claim. What does science support? There is increasing evidence that a mostly whole food, plant-based diet will provide your body with all the nutrients and diet components to guard against a variety of diseases, including cancer. When we eat a mostly whole food, plant-based diet, we consume a tremendous amount of nutrients as well as compounds that are contained within a package that no dietary supplement can replace. Supplements often fall short of offering the most bioavailable form and quantity of phytochemicals, food is a superior source. Supplement dosages may also be higher than what your body can safely process.

Relative to supplements, what advice would an Oncology Dietitian offer?

Focusing on FOOD FIRST, it’s your best strategy! Supplements may be required but let your healthcare team help you determine that. With FOOD FIRST, and subscribing to a mostly plant-based diet, you get a more balanced nutrient intake and lower calorie load, more healthful dietary fiber, and biologically active components like phytochemicals. Many of these food components cannot be extracted without some type of processing or additives which often impacts their quality and effectiveness. Also, nutrition is a “team sport” so to speak, there are a variety of positive synergistic effects that occur when consuming many nutrients at the same time. This phenomenon doesn’t occur when taking supplements as there are many different nutrient components and combinations working together to bring about healthy metabolism.

Could supplements be unsafe or harmful?

Yes, this is a distinct possibility, for a several reasons:

  • LOOSE REGULATIONS — Many supplements are developed under strict guidelines and tested to make sure they contain what they claim but, many are not. The U.S. Food and Drug Administration heavily regulates pharmaceuticals but only loosely regulates dietary supplements. As such, supplements may not contain what the label claims or contain additives or impurities that are not listed on the label.
  • SELF-PRESCRIBED — Dietary supplements are usually self-prescribed without any review from a qualified healthcare practitioner for safety, adverse effects, or drug-drug or drug-supplement interactions.
  • INTERACTIONS WITH CANCER TREATMENT — Some dietary supplement components, that act as antioxidants, may interfere with the way chemotherapy or radiation targets cancer cells. This can sometimes lead to a reduced response during chemotherapy. Other unwanted interactions are possible too.
  • ADVERSE REACTIONS – Adverse effects could be problematic too. Some supplements, for instance, can sensitize the skin to radiation therapy.

Should people undergoing treatment for cancer avoid supplements?

Not necessarily, as some supplements might help increase essential nutrients in cancer patients or reduce discomfort caused by treatment. The American Cancer Society sums it up best, “Most people can use dietary supplements safely, within certain dosage guidelines, but taking dietary supplements can be risky, especially for people who are getting cancer treatment.”

Before taking any supplements be sure and do your homework in order to make an informed decision and always be sure to confirm your intentions with your medical team. It’s critical that you pick the right supplement, if any, and determine proper dosages. Your doctor or one of the CNC Oncology Dietitians can assist you in achieving a balance between your diet, required nutrients, and any supplements you might require.

When are supplements helpful?

Supplements might play a role in correcting a nutrient deficiency or helping with side effects but only with the guidance of a trained healthcare practitioner. In most situations, a registered dietitian can complete a thorough diet review to identify any nutrient gaps.

How do I determine if a supplement is effective and high quality?

There are many good sources of information on supplement effectiveness and quality. The Cancer Nutrition Care (CNC) FREE Supplement Review is a good place to start. This review will provide you with an excellent knowledge base along with the CNC Supplement ToolBox, which contains a wealth of relevant information. It’s important to be cautious when searching the internet for supplement information as many sources may appear to be legitimate but are not. Many companies make claims that are not suitably supported by research or backed by other evidence.
CNC Oncology Dietitians can help you better understand the efficacy, safety, and quality of dietary supplements that might be relevant for you. Please consider scheduling a Q&A Session or Screening Consultation as a next step.

This blog was written and produced by
The Cancer Nutrition Care Editorial Board

Lori Bumbaco, MS, RDN, CSO, LDN
Co-Founder, Cancer Nutrition Care

Angela Hummel, MS, RDN, CSO
Consulting Oncology Dietitian

Jeanne Gee, RD, CSO, CDCES
Oncology Dietitian, Cancer Nutrition Care

Executive Editor & Producer
Bob Simek
Founder & President, Cancer Nutrition Care