Antioxidant Intake and Antitumor Therapy: Toward Nutritional Recommendations for Optimal Results

Abstract

The role of the induction of oxidative stress as the mechanism of action of many antitumor drugs is acquiring an increasing interest. In such cases, the antitumor therapy success may be conditioned by the antioxidants present in our own body, which can be synthesized de novo (endogenous) or incorporated through the diet and nutritional supplements (exogenous). In this paper, we have reviewed different aspects of antioxidants, including their classification, natural sources, importance in diet, consumption of nutritional supplements, and the impact of antioxidants on health. Moreover, we have focused especially on the study of the interaction between antioxidants and antitumor therapy, considering both radiotherapy and chemotherapy. In this regard, we found that the convenience of administration of antioxidants during cancer treatment still remains a very controversial issue. In general terms, antioxidants could promote or suppress the effectiveness of antitumor treatment and even protect healthy tissues against damage induced by oxidative stress. The effects may depend on many factors discussed in the paper. These factors should be taken into consideration in order to achieve precise nutritional recommendations for patients. The evidence at the moment suggests that the supplementation or restriction of exogenous antioxidants during cancer treatment, as appropriate, could contribute to improving its efficiency.

Effect of the polyphenol composition BP‑C3 on haematological and intestinal indicators of 5‑fluorouracil toxicity in mice

“…Oxidative stress is one of the mechanisms of action of various anti-tumour substances; therefore, the effectiveness of chemotherapy may be modulated by substances with antioxidant properties. Some of the most common exogenous antioxidants are polyphenolic compounds, which protect us from developing cardiovascular diseases, diabetes, cancer and infectious diseases (27). Antioxidants may protect normal tissue without affecting the effectiveness of anti-tumour chemotherapeutic drugs (28,29).…”

Dietary Supplements Commonly Used by Cancer Survivors: Are There Any Benefits?

“…The production of reactive oxygen species (ROS) has been proposed to play a dual role in health, as ROS facilitate cell signaling and communication but can also adversely cause cell damage and alterations in gene expression promoting an oxidative environment 97 . In normal physiologic homeostasis, balance is achieved by countering ROS production with a variety of endogenous antioxidant defenses.…”

“…In normal physiologic homeostasis, balance is achieved by countering ROS production with a variety of endogenous antioxidant defenses. However, excessive ROS synthesis can lead to alterations in redox balance, which in turn may stimulate tumorigenesis through cell signaling pathways that increase cellular proliferation, inhibit apoptosis, and facilitate cancer cell metabolic adaptation 97 . In an effort to decrease the risk for developing a number of chronic diseases, consumers, including cancer patients, are drawn to using antioxidant dietary supplements to combat the oxidative stress associated with developing such diseases.…”

“…Additionally, radiotherapy produces ROS, which causes cellular damage to healthy cells while destroying cancer cells 96 , 98 . Therefore, controversy exists whether augmentation of endogenous antioxidant defenses (which are often depleted in cancer patients) with antioxidant supplementation can provide benefits (eg, alleviating ROS damage) and reduce common side effects associated with chemotherapy and radiation therapies 97 . Theoretically, it is thought that antioxidants may be advantageous by preventing DNA damage and oxidation while increasing cellular repair, blocking cell proliferation as well as cell transduction and signaling with increased apoptosis 99 .…”

Targeting reactive oxygen species in development and progression of pancreatic cancer

“…Natural antioxidants like vitamins C and E, and curcumin have been implicated in the prevention and development of multiple types of cancers [109,110]. However, the manner in which some of the epidemiological studies evaluating the correlation between antioxidants and cancer development were conducted is not without limitations [111].…”