Navigating hidden risks: Safeguarding patients from unchecked supplement use

Primary care providers are always thinking about how best to support the health, safety and well-being of our patients. But what happens when there is an underlying danger that we don’t normally think about or perhaps don’t even know about?

There is a serious dilemma that often escapes our notice: our patients, particularly cancer patients, are purchasing and consuming an unprecedented quantity of dietary supplements, estimated at almost $60 billion annually in the United States. Yet a large percentage of consumers remain unaware or misinformed about the adverse effects that can arise from taking some of these supplements.

Various studies estimate that up to 80% of Americans take supplements, but only about 25% of them do so because medical tests have demonstrated that they need them, such as a lack of a sufficient level or intake of vitamins, minerals, hormones or other nutrients. Patients with cancer in particular take a large variety of supplements before, during and after their treatment. And what is particularly alarming is that less than half of these vulnerable patients talk to their health care provider before taking supplements.

I have practiced primary care for 30 years and ran what is now called the National Center for Complementary and Integrative Health at the NIH. Based on my experience, I believe that we are failing our patients and even putting them at risk if we do not help guide them through the complicated and confusing process of deciding whether and how to use supplements.

About half of Americans who take dietary supplements mistakenly believe that the FDA has approved them as safe and effective. As many of us know, the FDA has no authority to approve dietary supplements and does little to regulate them — except in the rare cases in which FDA has belatedly removed them from the market after they were demonstrated to be unsafe.

Supplements, of course, can be part of a successful whole-person integrative health plan that uses a holistic approach, including a healthy diet, exercise, rest, social support and other healing practices. We also know that the best way to get nutrients is healthy eating, but as our patients age or suffer certain chronic conditions, supplements can be an important addition — if carefully used.

I serve on the National Cancer Institute’s Advisory Board PDQ — Physician’s Data Query — which tracks the use of numerous complementary and alternative treatments, many of them common supplements used by patients with cancer. The PDQ’s summaries provide comprehensive, evidence-based, up-to-date content prepared by cancer experts and include fully referenced links to published literature about specific interventions. Similar resources are put out by Memorial Sloan Kettering Cancer Center and the American Cancer Society.

But this valuable information can be hard to access when physicians are already crunched for time, or the sources are spread among disparate places online.

Patients with cancer need extra attention in these areas from their primary care providers. They often use supplements to deal with fatigue, sleep problems, low energy and the side effects of chemotherapy such as nausea, vomiting and neuropathy. But they rarely discuss supplements directly with their oncologists because they do not interact with these specialists as frequently, and they may be reluctant or even afraid to broach the subject. Oncologists focus on killing the cancer and often do not think to incorporate discussions of self-care such as the use of supplements, nutrition, exercise or other wellness practices into their treatment plans. And oncologists, too, often have little knowledge about supplements.

It is our responsibility as PCPs to bridge that gap, particularly for our patients with cancer. These patients are taking a bewildering variety of dietary supplements in tablets, capsules, gummies, liquids, teas and powders. They are taking ginger, ginseng, zinc, St. John’s wort, vitamin E and beta-carotene, among others. Adding to the challenge, one component may go by several different names, so the patient unknowingly may be putting themselves in danger of overdosing. One patient I had was taking vitamin E in five different pills and had no idea what his total dose was.

Some supplements can contain unknown dangers. In one case, the herbal supplement PC-SPES, used by many patients with prostate cancer, was taken off the market after being found to contain the drugs diethylstilbestrol, warfarin, indomethacin and alprazolam—none of which were listed on the label. Up to 20% of herbal products purchased over the counter have heavy metals in them, especially when imported from India and China.

Seemingly harmless supplements can put people at risk if improperly managed. For example, ginger and garlic can work as blood thinners; ginseng can cause fast heartbeat; and zinc can aggravate copper deficiency. During cancer treatment, St. John’s wort can reduce the effectiveness of chemotherapy and cause skin problems; vitamin E increases the chances of recurrence for some cancers; and beta-carotene can increase the risk of lung cancer in smokers.

Social media has compounded the problem by bombarding patients with unproven claims and making it easier than ever to order supplements from anywhere in the world at the touch of a button. This convenience can put our patients at risk by purchasing them from unregulated facilities whose products may be mislabeled or tainted.

For all our patients, and especially our patients with cancer, we know that we need more than pills and procedures to provide the best, most comprehensive care. We must make the extra effort to go beyond just monitoring the basics. Whole-person care, I believe, is the gold standard for giving our patients an optimal chance at living a good life with or after cancer.

Admittedly, many of us learned little or nothing about supplements in medical school. But we need to learn about the most common ones and to add to our medical checklist questions about supplements use. It may seem obvious, but we do our best job when we ask and advise on whole-person care, including supplement use. And our patients will appreciate us taking the time to ask and discuss with them.

References:

• National Cancer Institute. PDQ cancer information summaries: Integrative, alternative, and complementary therapies. https://www.cancer.gov/publications/pdq/information-summaries/cam. Accessed March 13, 2024.
• Memorial Sloan Kettering Cancer Center. About herbs, botanicals & other products. https://www.cancer.gov/publications/pdq/information-summaries/cam. Accessed March 13, 2024.
• Jonas WB, McManamon A. Healing and Cancer. Rodin Books. Forthcoming 2024.