Can I take antioxidants during cancer therapy?

Author: Sandra Krstev Barać, Mastr of Nutrition

Antioxidants are responsible for the intense color of fruits and vegetables such as berries, tomatoes and carrots; they are found in dark chocolate, olive oil and green tea; many vitamins and minerals have antioxidant properties, and our bodies also have enzyme systems that act as powerful antioxidants. Antioxidants have important effects on our health: they neutralize unstable and harmful free radicals and protect against oxidative stress. It is believed that a diet rich in antioxidants protects against the development of numerous chronic diseases, including cancer.

However, when it comes to antioxidants in the form of preparations, the story is much more complex. The idea that higher doses of antioxidants present in dietary supplements provide more protection for our cells is not confirmed by the scientific community. Moreover, a number of studies have revealed that supplementing with antioxidants in high doses does more harm than good, which is why caution is advised even in healthy people, and especially in cancer patients.

Antioxidants and cancer – impact on therapy

The use of antioxidants in parallel with oncological therapy is an extremely controversial topic. Numerous doubts on this topic arise from the fact that certain chemotherapeutic agents, as well as radiotherapy, act on cancer cells by generating free radicals. Theoretically, antioxidant preparations could protect healthy cells and tumor cells from the oxidative stress necessary for their destruction and thus reduce the effectiveness of chemo- and radiotherapy.

On the other hand, supporters of antioxidants point out that oxidative stress resulting from oncological therapy is responsible for numerous side effects of therapy, such as hair loss, mucositis, nausea and vomiting. Therefore, the use of antioxidants in combination with therapy could reduce these side effects and improve the quality of life of patients, and according to some authors, improve the outcome of therapy.

In addition, poor antioxidant status is often recorded in malignant patients, partly due to the therapy itself, and partly due to inadequate nutrition. Therefore, some experts believe that the intake of antioxidant preparations can improve the health of people undergoing long-term oncological therapy.

A Word from Science

Despite decades of research efforts to uncover the impact of antioxidant preparations on oncology therapy, we still do not have a consensus on their effectiveness and safety. Vitamins C and E, selenium, beta-carotene and lycopene, melatonin and CoQ10 are just some of the antioxidants that have been tested in the context of oncology therapy, either as stand-alone preparations or in various combinations, but the results have brought us contradictory information.

Thus, a number of randomized clinical trials have shown that the simultaneous use of antioxidants with chemotherapy can protect healthy tissue, reduce treatment-related side effects and improve the outcome of therapy. On the other hand, a good part of the literature has shown that taking antioxidants can also protect tumor cells, reducing the effectiveness of oncology therapy and even increasing the risk of relapse in the long term.

To date, the only consensus that researchers have managed to reach is that people undergoing radiotherapy should not take beta-carotene and vitamin E in parallel, especially if they are smokers, since it has been shown that such a practice can increase the risk of relapse and mortality. It seems that we still have a long way to go before we discover how certain antioxidant preparations work in combination with oncology therapy, and until then, caution and consulting with an expert is the wisest choice.

The use of antioxidants requires an individual approach

The differences in study results can be partly explained by differences between cancer types and therapies, but also by the fact that not all antioxidants work by the same mechanism. In addition, not all cytostatics rely on oxidative stress as a principle of action. Therefore, making a single recommendation (apart from general advice urging patients to be careful) is impossible. Individual consultation with a specialist who will take into account the type of therapy, nutritional and health status, and nutritional status and possibly recommend a preparation when appropriate is the best way.

Finally, there is no evidence to support the thesis that a complete and balanced diet rich in antioxidants should be avoided during therapy. It is believed that the level of antioxidants in food is insufficient to potentially interfere with treatment. However, the same cannot be said with certainty for preparations that provide high doses of antioxidants.

Conclusion

When it comes to malignant diseases and dietary supplements, caution is never enough! The use of antioxidants in conjunction with chemotherapy and radiotherapy, as well as other oncology therapies, requires a critical approach and consultation with an oncologist and nutritionist, as there is still no consensus on their effectiveness and safety.

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