Supplements: Do They Help, or Hurt?

PJ Hamel Health Guide
  • A typical healthy person might unthinkingly pop a daily multivitamin as a matter of course. But cancer survivors often react to their diagnosis by searching out every vitamin, mineral, or herb that might possibly “help” fight cancer – or temper the side effects of treatment. Can supplements really improve your chance of surviving cancer? Or might they actually be hurting you?

    I was diagnosed with stage 2 breast cancer 11 years ago. After three surgeries, chemo, and radiation, I was a pretty much a physical mess.

    Aside from lymphedema, fatigue, and abdominal weakness (as a result of a TRAM flap reconstruction), I was also experiencing up to 20 hot flashes a day. So I asked my oncologist what, if anything, might help.

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    He pulled out his yellow notepad, and wrote a list of possible hot-flash treatments. I wondered what drugs he was suggesting. I’d heard certain antidepressants had been effective in cooling down hot flashes…

    When he handed me the list, I was taken aback. Black cohosh was at the top of his list, followed closely by St John’s wort, with vitamin E next in line.

    Black cohosh and St. John’s wort – aren’t they plants? And vitamin E – I thought vitamins simply ensured good health; I didn’t know they could “cure” specific conditions.

    As it turned out, none of those recommendations had any effect on my hot flashes, which gradually – over the course of many years – abated on their own.

    But they made me think – can herbs and vitamins and minerals really affect the course of cancer, and its aftermath?

    Many researchers over the past several decades have had the same question. And their answer is, “We don’t really know.”

    Supplements. It’s a confusing world out there.

    While numerous lab and animal studies will show a certain vitamin or mineral or plant component seems to suppress the formation of cancer cells, when the experiment leaves the lab and is conducted with human subjects, the hoped-for results just aren’t there.

    Back in the early 1990s, researchers noticed that eating beta-carotene-rich foods seemed to lessen the risk of lung cancer in smokers. But when smokers were given high amounts of beta-carotene as part of a cancer prevention study, their risk of lung cancer actually increased.

    Today, despite myriad plant- and supplement-based “miracle” cures for cancer available at unscrupulous online sites, there’s simply no scientific proof that supplements have any effect on cancer – good, or bad.

    One thing doctors do agree on, though – certain supplements can interfere with certain types of cancer treatments, and should be avoided.

    If you’re taking Adriamycin (doxorubicin) – a.k.a. “Red Devil – as part of chemotherapy, avoid taking black cohosh and vitamin C, both of which may increase the drug’s toxicity, and reduce its effectiveness. Black cohosh may also increase the toxicity of another common chemo drug, Taxotere (docetaxel).

    Methotrexate, another chemo drug, becomes less effective in the presence of vitamin C; so avoid vitamin C supplements if you’re on a protocol including methotrexate.

  • If your long-term hormone therapy to reduce recurrence risk is tamoxifen, avoid green tea, black cohosh, and St. John’s wort; these may variously increase your risk of side effects, increase drug toxicity, and decrease effectiveness.

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    If you’re taking a bisphosphonate to combat bone loss due to long-term hormone therapy, avoid iron supplements, which make it hard for your system to absorb that Fosamax tablet or Boniva pill.

    So, what about your daily multivitamin? Should you forego that, too?

    According to the American Cancer Society, a daily multivitamin shouldn’t hurt your long-term cancer prognosis. And it might help your health in other ways. But the ACS recommends patients not load up on any particular vitamin or mineral; as is often the case with anything you ingest, more isn’t better.

    One thing researchers, nutritionists, and doctors all seem to agree on is this: the best way to get the vitamins and minerals we all need is through food – not pills.  

    A healthy diet, exercise, and weight control – not herbal medicines and supplements – are the best bets in your quest to remain cancer-free.


    Beil, L. (2011, Fall). Supplements during cancer: help or hype? Cure, 10(3), 39-44.

Published On: August 14, 2012