A vitamin supplement may interfere with chemotherapy but the real vitamin from food will not?

An article I reviewed today advises cancer patients to stop using vitamin and mineral supplements when they have breast cancer. Their rationale is that it might cause cancer to recur.


https://www.healthline.com/health-news/breast-cancer-patients-advised-not-to-use-supplements-during-treatment is a link to a Healthline article. Experts theorize that since chemotherapy damages cancer cells, vitamin and mineral supplements might try to repair the damage done by chemotherapy drugs and renders chemotherapy less viable.

There are many articles telling the world that unless there are placebo-controlled randomized clinical studies, theories are worthless. Has anyone done a study of breast cancer patients with and without nutritional supplements that positively, without question, statistically prove that chemotherapy drug treatment is inhibited by supplements? I think not. Otherwise, it would be mentioned as proof-positive that their theories are valid.

The article mentions an observational study of over one thousand early breast cancer patients that were followed for several years. The conclusion was that patients taking certain vitamins and nutrients were likely to have a recurrence. If they took another set of vitamins, their risk was much higher. The study was published in the Journal of Clinical Oncology (https://ascopubs.org/doi/10.1200/jco.19.01203)

This was a clinical study of a small group, but the variable of nutritional supplements was done by questionnaire. The patients were not monitored for daily usage, brand names, and more. A regression analysis was applied to test and lifestyle choices to determine the results.

The article did not mention anything about what causes cancer. Chemotherapy is a band-aid to fix a problem, not the solution to the problem. Whatever lifestyle the cancer patient had before getting cancer most likely contributed to cancer. I would surmise that a cancer patient returning to her former lifestyle probably prompted the recurrence of cancer.

Cancer Causes

https://www.cancer.org/cancer/cancer-causes.html lists a few causes of cancer – smoking, radiation, diet, infections, etc. Basically, lifestyle choices. Genetics plays a part – usually between five and ten percent (https://www.cancer.gov/about-cancer/causes-prevention/genetics). In my best-selling book, The Joy of Ageless Health (https://amzn.to/327LNIo), I describe several lifestyle choices that can and probably do cause cancer – stress, toxins, radiation, infection, inflammation, diet, and even expectation.

I read articles that poo-poo vitamins as a waste of money. The manufactured vitamins provide no real help and end up in the toilet. https://www.hopkinsmedicine.org/health/wellness-and-prevention/is-there-really-any-benefit-to-multivitamins is one article about the value (or lack of value) of multivitamins and improved health. Do vitamin and mineral supplements cause cancer? I think not.

If the medical community has such a low view of vitamin and mineral supplementation, why are they giving credence to them now? Is it a way to explain why cancers recur or chemotherapy is not effective? I do not know. It just seems strange to blame something without the same level of a clinical study that that industry demands FDA approval.

Maybe it is because the FDA does not approve vitamins and mineral supplements and will come down hard on any manufacturer that provides a health claim for such products. https://www.fda.gov/food/buy-store-serve-safe-food/what-you-need-know-about-dietary-supplements.

Supplements and Natural Foods

One part I have trouble fully comprehending is that it is OK for the cancer patient to eat food with vitamins, but not take vitamins. If anything, the vitamins coming from food are more powerful than a manufactured vitamin.

The speculation is that antioxidants from vitamins and minerals might interfere with the effectiveness of chemotherapy drugs. Again, do placebo-controlled, randomized clinical studies to prove this.

The American Institute for Cancer Research (https://www.aicr.org/) posted this recently – “After a cancer diagnosis, many people look to dietary supplements for a health boost. However, a recent study adds to the concern about using supplements during treatment, finding that breast cancer patients who take certain supplements both before and during chemotherapy may be at increased risk of recurrence and earlier death.” https://www.aicr.org/news/vitamin-supplements-may-affect-breast-cancer-recurrence-aicr/

This cancer research group bases its recommendation on the study cited previously (https://ascopubs.org/doi/10.1200/jco.19.01203). I fail to see how or why they put so much trust in this single small study that was not placebo-controlled. Again, my opinion. I am sure their scientists have data that is not available to me.

Countering Viewpoints

Memorial Care Cancer Institute at Orange Coast Medical Center in Fountain Valley, California published an opinion that there are not enough high-quality studies to make firm conclusions regarding manufactured vitamin and mineral supplements during chemotherapy treatments for women with breast cancer. Additionally, there was clarification that all cancers, not just breast cancer, should be included, as well as radiation therapy.

When a person begins walking down the medical road to cancer treatment, he or she may see several physicians along the way. The general practitioner at the beginning, the surgeon, the oncologist, the radiologist, other specialists depending on cancer. Each may have a different opinion regarding the treatment for the cancer patient.


It was strong and clear to me that food supplementation is OK, but other nutritional supplements are not. When I do not eat a balanced meal, I am deficient in certain nutrients. Taking a multivitamin or multi-mineral does not guarantee full spectrum coverage of the nutrients I need.

I do not eat the right kinds of foods to provide me with vitamin K2. I know I need it. I supplement with vitamin K2 and ensure that I am getting both menaquinones (MK4 & MK7). If I were relying on eating during chemotherapy, I would still not eat the foods rich in vitamin K2. I would still be deficient. This deficiency can extend across a dozen or more vitamins and minerals.

I understand that some vitamins and minerals may not provide even the basic levels of nutrition. However, I do not understand how even those non-functioning supplements interfere with chemotherapy treatments when I can eat foods with the same real vitamins and minerals and not interfere with the effectiveness of chemotherapy drugs.

Doctors, in general, are not trained in nutrition – food or manufactured supplements. They read articles as I do, but they are not down and dirty into the day-to-day nitty-gritty of nutrition. I had a minor knock-down-drag-out discussion with my wife’s oncologist when he suggested that all she needed was to supplement with calcium and vitamin D.

I told him that unless she also had magnesium and vitamin K2, the calcium was worthless and would end up in the toilet. He did not understand the chemical pathway to get calcium from a pill or food to the bone and what happens when part of that pathway is missing.

It was two visits later before we returned to a civil level of discussion. Since I was his direct contact with his patient, my wife, and she would demand that he speak to me and answer my questions, it became a stalemate and we agreed to disagree.

We learn things every day. I believe in constant learning. That is why I research health headlines today to determine what is happening today that is of value to my readers.

Live Longer & Enjoy Life! – Red O’Laughlin – RedOLaughlin.com



2 Responses

  1. Cancer treatment often involves powerful therapies such as chemotherapy, radiation, and targeted medications. These treatments are meticulously designed to target cancer cells and minimize potential harm. Some nutritional supplements, however, may interact with these treatments or interfere with their effectiveness. Certain supplements can have unintended effects, such as promoting cell growth or interfering with the metabolism of chemotherapy drugs

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