Background: Inflammation is one of the most misunderstood aspects of human
health. People have been encouraged to eat foods that have a high antioxidant capacity, and in
vitro tests for total antioxidant capacity emerged. They were based on measuring the destruction
of oxidized test compounds in direct reactions with the antioxidants in foods. Many dietary
supplements arrived in the market. They contained purified antioxidants, such as resveratrol
and EGCG that were and still are widely assumed by many to be quite healthy at any
Methods: The literature on inflammation and the Nrf2/ARE antioxidant system was searched
systematically. Articles from prestigious, peer-reviewed journals were obtained and read. The
information obtained from them was used to write this review article.
Results: Over 150 articles and books were read. The information obtained from them showed
that very few dietary antioxidants exert their effects by reacting directly with Reactive Oxygen
and Nitrogen Species (RONS). Instead, most of the effective antioxidants activate the endogenous
Nrf2/ARE antioxidant system. This helps prevent smoldering inflammation and the
diseases that it can cause. However, when overactivated or activated constitutively, the
Nrf2/ARE antioxidant system can cause some of these diseases, including many types of
multidrug resistant cancer, autoimmune, neurodegenerative and cardiovascular diseases.
Conclusion: Even though green tea, as well as many fruits, vegetables and spices are quite
healthy, dietary supplements that deliver much higher doses of antioxidants may not be. People
who are diagnosed with cancer and plan to start chemotherapy and/or radiotherapy should
probably avoid such supplements. This is because multidrug resistant tumors can hijack and
overactivate the Nrf2/ARE antioxidant system.