While vitamin and supplement use has become trendier than ever, research shows nutrients in capsule or powdered form are still no match for a healthy diet—and may even cause more harm than good for people with cancer.
“You’ve got cancer” is a dreaded phase. But thanks to medical advancements, facing cancer can also include a wealth of treatment options and a positive, long-term prognosis.
According to the American Cancer Society, studies show that, in addition to medical intervention, people who eat more vegetables and fruits may be at lower risk for some types of cancer. And because some cancer survivors may be at risk for second cancers that are new and different cancers, they should eat a diet consisting of antioxidant-rich foods, including fruits and vegetables. Additionally, research by the American Institute of Cancer Research has found that in laboratory studies, many of the minerals, vitamins and phytochemicals in fruits, vegetables, grains and legumes demonstrate anti-cancer effects.
But what about vitamins and other mineral supplements? It depends on whom you ask, but experts agree that patients need to work with their physicians individually to determine what is appropriate.
Vitamin and supplement use has become more popular than ever, says Dr. Arielle Levitan, an internal medicine physician at NorthShore Medical Group and co-author of the book “The Vitamin Solution: Two Doctors Clear the Confusion About Vitamins and Your Health.”
“On one hand, this is because of increasing awareness about health and wellness. But on the other hand, it is also reflective of people following influencers of all sorts, many of whom are not valid sources for medical information,” Levitan says.
Vitamins and mineral supplements can be useful tools for cancer patients. “Addressing your individual nutritional needs can not only help support your overall health and ability to recover from taxing treatments, but taking the right vitamins can also help you improve your health going forward after treatment and to help restore energy, address hair regrowth, neuropathy symptoms, and help with bone health and overall immunity,” Levitan says. “We have valid medical data to support the use of certain supplements—in differing doses depending on the individual’s needs.”
That said, other studies suggest taking some vitamins via supplements may increase rates of cancer—including vitamin A and excessive doses of vitamin E and folic acid. The University of Colorado Cancer Center investigator Tim Byers, M.D., MPH, conducted 12 research trials involving more than 300,000 people, showing that over-the-counter supplements may actually increase cancer risk if taken in excess of the recommended daily amount. One research trial exploring the effects of beta carotene supplements showed that taking more than the recommended dosage increased the risk for developing both lung cancer and heart disease by 20 percent. Another study conducted by Dr. Byers and his team found that folic acid, which was thought to help reduce the number of polyps in a colon, actually increased the number. And another trial showed men who took vitamin E had an elevated risk for prostate cancer.
Exceeding the toxic levels of individual nutrients and interactions with chemotherapy or radiation therapy treatments are additional concerns to consider regarding vitamins and supplements. For example, as registered dietitian nutritionist, Rebecca Guterman, MS, RD, CDN explains, while getting antioxidants in your diet from eating blueberries or citrus fruits is beneficial, taking a mega dose (1000 mg) of vitamin C is not recommended as vitamin C supplements have been shown to reduce the effectiveness of certain chemotherapy drugs. “The active components in other vitamins and supplements could increase or lessen the effects of other medications,” Guterman says.
Brandy-Joe Milliron, Ph.D., associate professor of nutrition sciences at Drexel University, has been researching nutrition-related beliefs and behaviors, as well as healthy eating for people with cancer.
“The evidence to date confirms the importance for people to avoid vitamin and mineral supplement use when they are going through cancer treatment,” Milliron says. “For cancer prevention, and to prevent cancer recurrence in survivors, we encourage people to meet dietary and nutrient recommendations through consuming foods, and not through supplement use.”
“The synergistic benefits of consuming a diet containing a variety of plant and unprocessed foods has been studied to be the most beneficial.”Rebecca Guterman, MS, RD, CDN
Dietary vitamin and mineral supplement use in the United States has grown comparatively to the public’s awareness of the relationship between food, nutrition and cancer survivorship. “This may be to ensure that they’re meeting nutrient recommendations due to poor intake, or to maximize their intake of certain nutrients that are thought to play a role in cancer prevention and cancer-free survivorship,” Milliron says.
In a recent study published in the Journal of Nutrition, researchers examined dietary supplement use among adult cancer survivors in the United States participating in the National Health and Nutrition Examination Survey. More than 70 percent of cancer survivors used dietary supplements compared to 51.2 percent of people without cancer. This included multivitamin and multimineral supplements, individual vitamin and mineral supplements, as well as other types of supplements.
“Many cancer survivors reported taking these supplements in amounts that exceed the tolerable upper intake level and nearly half of the cancer survivor respondents used dietary supplements on their own, without consulting with health care providers, including a registered dietitian nutritionist,” Milliron says. “Despite this increase in dietary supplement interest and usage, the evidence-based recommendations from organizations such as the American Cancer Society, American Institute of Cancer Research and the National Cancer Institute has remained consistent—during cancer treatment, people should not take vitamin and mineral supplements, unless under the guidance of their oncology dietitian.”
According to the American Institute for Cancer Research, “supplements do not offer cancer protections or provide benefits to survivors who are worried about recurrence.”
“Despite the cure-all claims made by many supplement manufacturers, research shows that consuming nutrients through supplements does not lead to the same benefits as eating nutrients through foods,” Milliron says.
Guterman points to studies that show getting a wide variety of phytonutrients is very important when it comes to a cancer patient’s diet. Also known as antioxidants, phytonutrients consist of a variety of compounds produced by plants and are found in fruits, vegetables, grains, beans and other plants. By consuming different types of fruits and vegetables, individuals can provide their bodies with many different beneficial compounds, including phytonutrients.
“However, the body does not process and absorb these vitamins, minerals and antioxidants the same way when taken in a capsule or powdered form,” Guterman says. “The synergistic benefits of consuming a diet containing a variety of plant and unprocessed foods has been studied to be the most beneficial.”
If you are concerned that you are vitamin deficient or not meeting the recommended daily intake of vitamins and minerals, check with your physician. Milliron recommends that instead of reaching for the supplements, try something new. What are you missing? Sometimes trying a new recipe or new food is just the shift a person needs. Or simply add more fruit to your diet. Many fruits are high in vitamins and lower in calories. They don’t require cooking and can more easily be added to your diet if time is a constraint.
“A small changes approach can help you maintain new behaviors because you won’t feel overwhelmed and these small changes add up over time,” Milliron says. “If you have completed treatment, it’s still critically important to discuss dietary supplement use with your treatment team.”