Katie’s Nutritionist Breaks Down How to Use Supplements — and Whether They Can Prevent Cancer

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Plus, details on the supplements you should avoid when undergoing cancer treatment.

After being diagnosed with breast cancer in the summer of 2022, I was stunned, of course. But then I did what comes naturally to me as a reporter: I tried to find out everything I could. I talked to a host of experts to understand what was going on in my body and make sure I was being proactive about staying healthy.

I’ve always been interested in nutrition, so I have to admit I geeked out when I met with nutritionist Emily Buchholtz, RD, CDN, CSO. She’s the oncology dietitian at NewYork-Presbyterian/Weill Cornell Medical Center, and she’s spent years working with cancer patients to revamp their diets, doling out stellar advice on what to eat more of, which foods to limit (sugar, we’re looking at you), which foods to avoid entirely, and how to use supplements to compensate for nutritional deficiencies.

I wanted to offer you all the chance to capitalize on her knowledge, so I called her up for a chat. Today, we’re bringing you her thoughts on the do’s and don’ts of supplements (in combination with your favorite health-boosting foods, of course): which ones to take, how many, and how to use them to boost energy and fight back against bone loss. Ready for a dose of good-for-you medicine? Read on.

Katie Couric: What do you tell the average person about supplements?

Emily Buchholtz, RD, CDN, CSO: What I’ve learned over time is that most people take more supplements than necessary. Studies show that in order of importance, it’s food first, and supplements second, always. In fact, the American Institute of Cancer Research says that no patient should take a supplement for cancer prevention. But supplements can be beneficial when taken appropriately. 

For example, low vitamin D is a very common problem, and it’s often hard to get enough of it through food, so that’s a supplement I prescribe often. I encourage people to check their vitamin D levels annually and make sure to speak with their medical team or dietitian about the proper dose. Because it’s a fat-soluble vitamin, it is possible to take too much, which is just as harmful as having low levels. Sometimes I see patients who follow a vegan diet, which can be low in vitamin B12, and these patients could benefit from a vitamin B12 supplement. Magnesium can be beneficial for constipation and great for someone who doesn’t want to be on a laxative. Whatever your health goals are, you should always speak with a dietician to figure out your individual supplement regimen. 

I know that vitamin D is really important. What role does vitamin D play in overall health?

Vitamin D helps with bone health, mood, energy, your immune system, gut health… It’s so important for overall well-being. This nutrient is tough to get enough of solely through food, and sunshine impacts the absorption of vitamin D, which means New Yorkers like you and I tend to have lower levels of vitamin D in the winter months. You can determine your vitamin D level with a simple blood test.

So most people can get a blood test to determine their vitamin D level?

Absolutely. I encourage all patients to request a vitamin D test annually, which can be done with your primary care physician. Based on those results, I can easily determine which dose is appropriate, since it varies from person to person.

I know it’s also really important if you’re getting chemotherapy or immunotherapy or radiation to mention supplements to your doctor, to make sure that they aren’t interfering with your treatment.

Absolutely. When it comes to chemotherapy and radiation, there are certain supplements, like vitamin C, that we don’t want patients taking during that time. The reason for that is because vitamin C helps build immunity, and helps to rebuild and regrow cells quickly. But when someone’s undergoing chemotherapy or radiation, we don’t want any cells growing or rebuilding rapidly. We want them to be functioning at a normal and stable rate, so the chemotherapy and radiation can do their jobs properly.

I know that when my mom was on Coumadin, a blood thinner, she couldn’t drink grapefruit juice or eat grapefruit.

Exactly. Some cancer drugs are like that, too: Grapefruit and grapefruit juice interfere with tamoxifen and the chemotherapy drug Taxol.

Let’s talk about aromatase inhibitors: I’m on one to prevent a recurrence of my breast cancer, and I know it can accelerate osteopenia and osteoporosis. So should women like me be taking calcium supplements?

It depends on the circumstance, because all patients on aromatase inhibitors are monitored for osteoporosis. Regardless of being on an aromatase inhibitor, as we get older, our bones can start to deteriorate. So once women hit their 50s, it’s worthwhile to start a calcium supplement to help protect their bones. The standard recommendation for women with osteopenia or osteoporosis is 1,200 milligrams of calcium per day. What I recommend for most women is 600 mg of calcium through food and an additional 600 milligrams of calcium through a supplement.

While we’re on it, should you take calcium citrate or calcium carbonate?

Both of them are absorbable, so both are OK. The thing to know is that calcium carbonate is better absorbed with food, whereas you can have calcium citrate at any time, since it’s absorbed with or without food. Calcium carbonate also happens to be absorbed poorly in patients taking proton pump inhibitors. So I usually tell people to take calcium citrate, because it’s a bit more foolproof.

We talked about aromatase inhibitors impacting your bone density, and I know that joint pain is another side effect. What do you recommend for that?

From a dietary perspective, I recommend an anti-inflammatory diet, as well as stretching and exercise. Most of us sit at a desk all day, so we’re not moving as much as we should. Prioritize stretching, walking more, and taking the stairs whenever it’s feasible. Weight loss can also help take pressure off our joints. Plus, it’s best to limit processed foods, desserts, red meats, and alcohol as much as possible, because they can all increase inflammation.