The role of antioxidants in the immune function

Antioxidants are essential to the body’s function to cope with the constant burden of highly reactive molecules and free radicals arising from exogenous as well as endogenous sources.

However, while reactive oxygen and nitrogen species (ROS and RNS) can be detrimental to body structures like fatty acids and proteins and impair their functions, they are also part of physiological processes. Most importantly, they are used to kill pathogens during the respiratory burst. Damage to the radical-generating immune cells is prevented by antioxidants that are needed in adequate amounts to enable efficient defence.

Radicals are also involved in the synthesis of eicosanoids, important regulators of immune responses especially of the inflammatory kind. Moreover, ROS and nitric oxide (NO) play a role in cell signal transduction. As inducers of transcription factors like NFkB or AP-1, they regulate the synthesis of proinflammatory cytokines.

An imbalance in the oxidative system, known as oxidative stress, disrupts these processes making a tight control of oxidative balance necessary for optimal immune function. Indeed, many non-communicable diseases linked to oxidative stress are characterised by chronic low-grade inflammation.

Considering the involvement of free radicals in the generation and progression of inflammatory processes, antioxidants can be used in the therapy as modulators of the immune answer. There is good evidence of the beneficial effects of nutritional antioxidants such as vitamins C and E and secondary plant compounds on diseases like rheumatoid arthritis and inflammatory bowel disease.

A good status of antioxidants down-regulating inflammatory processes can also contribute to longevity and better health in later life.

However, due to the complex interactions between single antioxidants and their involvement in various processes, supplementation particularly with high doses requires great care. Especially in healthy persons, a well-balanced diet rich in vegetables, fruits and whole grain cereals is the best source of antioxidants.

About Ibrahim Elmadfa

Professor Ibrahim Elmadfa is the President of the International Union of Nutritional Science (IUNS), and President of the Austrian Nutrition Society.

Professional appointments:
  • 1990 - 2011 Professor for Human Nutrition and director of the Institute of Nutritional Sciences, University of Vienna
  • 1980 – 1990: Professor for Human Nutrition at the University of Giessen, Germany

Scientific advisor to the European Commission and member of Steering Committee on Nutrition, Diet and Healthy Lifestyle of EU commission (DG Sanco).

The Austrian MOH as member of the Codex Alimentarius Austriacus Committee (Dietetic Foods, Novel Foods, Upper Safe Level of nutrients),The WHO as member of Nutrition Guidance Expert Advisory Group (NUGAG) and the International Advisory Council of theGlobal Non-communicable Disease Network (NCDnet ).

Editor-in-Chief, Annals of Nutrition and Metabolism and Forum Nutrition (2000-2011); Author and co-author of over 400 original papers, 24 books. Coordinator and author of the Austrian Nutrition Report 1998, 2003, 2008, 2012 and the European Nutrition and Health Report 2004 and 2009.