Are Dietary Supplements Harmful?

 Interesting research from a few weeks ago. We like to think that dietary supplements can hep us, but sometimes they do the opposite for cancer patients, and can actually hurt us.

The article, titled "Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)," lwas published in the Journal of Clinical Oncology, and looked at the use of dietary supplements by breast cancer patients who were being treated with chemotherapy.

The study looked at 1,134 patients, and found (maybe surprisingly) that using antioxidants before and during chemo increased the chances of the cancer coming back after treatment. These included vitamin A, vitamin C, vitamin E, carotenoids (like beta carotene), and Coenzyme Q10. Patients taking antioxidants during chemo had a 41% higher chance of the cancer coming back than those who didn't take them.

Other supplements besides antioxidants were also problematic. Patients taking Vitamin B12, iron, and omego-3 fatty acids also had a greater risk of recurrence and death.

Patients taking a multivitamin seemed unaffected by it.

So what's the deal? Aren't dietary supplements supposed to be healthy?

Yes. Usually. Full disclosure -- I take a multivitamin, vitamin D, and fish oil every day. I don't plan on stopping.

The issue is that the patients in the study were being treated with chemotherapy. While the study called for more research on why exactly these supplements had the effect they did, it might be easy to guess why, in a really general way. Antioxidants help keep cells healthy. Chemo is meant to kill them. There's kind of a basic mis-match there. If you're a cancer patient who is trying to kill cancer cells, it doesn't make sense to take something that helps prevent damage to them. There's no evidence that a supplement can distinguish between healthy cells and cancerous ones.

To be clear -- that's my own observation, not something from the research.

A few important things to consider here.

First, the researchers say that, while the results are interesting, the number of patients in the study who were taking single supplements was pretty small. So while more may have been taking a multivitamin, the amount of (for example) Vitamin E in that multivitamin was much smaller than it would be in a straight Vitamin E supplement. Not many patients were taking those straight supplements. A larger, more focused study would be helpful.

Second, this study obviously focuses on breast cancer, not Follicular Lymphoma. We can't say for sure that the same results apply to our disease. Though if my general idea of why supplements make for worse chemo outcomes is really true, then maybe so?

Third, the study looks at chemotherapy, not other types of treatment like radiation or immunotherapy. There's no evidence that they would hurt, or that they would help, people taking those treatments.

Here's the real lesson, I think -- we should talk to our doctors about the things were are taking. All of them. Prescription medicines, over-the-counter medicines, supplements, herbs that someone recommends, whatever. Because even the medicines or supplements that we take to help us with one condition might have a negative effect on another. Unless we know the way those things interact with each other, we won't know if they're ultimately helping us or hurting us. The best person to ask about that isn't a friend or a Facebook ad or a well-meaning co-worker. It's your doctor.

Now, back to my own supplements. As I said, I take a multivitamin, Vitamin D, and fish oil every day. I don't take any of them because I think they will prevent or cure my cancer. I've been taking a multivitamin for years, and I continue mostly out of habit. I do believe that if I stopped, I'd be fine, especially since I'm being better about eating vegetables and fruit. I've been taking the fish oil for a while, too, mostly for heart health. I could probably stop taking that, too; it hasn't done anything for my blood pressure, which has gone up in the last few years.

Vitamin D? Hmm. I started taking that a while ago, too, but it also wasn't to prevent or cure cancer. I'd been reading about its benefits for lots of conditions, and its importance to general health, so I started taking it, with the encouragement of my doctor. Like the other supplements, the upside seemed bigger than the downside -- they're relatively inexpensive, they might help, and they probably won't hurt. Since I started, there has been some suggestion that Vitamin D levels might have a positive effect for FL patients. But like everything else related to supplements and cancer, there just isn't enough evidence either way to know for sure.

So here's what I do not want to happen. I do not want any of you writing to me and asking me how much fish oil or Vitamin D I take, or what brand of multivitamins I buy. I won't give you an answer. I won't add to the false hope that a certain vitamin D dose will help you. That's not my place to say.

If you want advice about supplements, ask your doctor, She's the best one to get advice from. She'll know about your other conditions, and how supplements and medications will interact with each othr, and what you might need for your general health. And if anyone else offers you advice about supplements and cancer and says they know for sure that something will help, I suggest you read what they say very carefully, ask for real scientific studies to back up the advice (on actual people in clinical trials, not "in vitro" or in test tubes), and then run it by your doctor.

In the meantime, if I do come across any other research that gives answers about how to make us healthy, you can believe I will pass it along.