Free Radicals Weaken Immune System In Aging: Antioxidants shown to reverse the damage 07/18/12

It is widely known that our immune system becomes weaker and less efficient as we age. This results in greater risk of more virulent infections, which can be life-threatening (e.g. pneumonia in older persons) and greater risk of cancer development.  A weakened immune system is partly responsible for the dramatic rise in the incidence of many of cancers in people over 50 years of age.


There are a number of reasons for a decline in immune function as we age. The thymus gland shrinks and becomes less functional as we age.  The thymus gland is required to modulate the activity of T-lymphocytes, which are important immune cells that help prevent and fight infection, and help prevent cancer development (1,2).

The decline in melatonin as we age also weakens the immune system. T-helper cells (CD4 cells) have melatonin receptors. When stimulated by melatonin, T-helper cells are better able to recruit many other immune cells into the fight against pathogens (viruses, bacteria, etc) and emerging cancer cells and tumors. Thus, less melatonin results in less recruitment of important immune cells responsible for protecting us against infection and cancer development

Some studies show that lower melatonin levels are linked to increased risk of prostate and breast cancer. Dr Lissoni has shown us that melatonin supplementation is a good adjunctive supplement in the management of certain breast and prostate cancer patients, as well. (3,4,5,6,7).


Free Radicals Are Also Weaken the Immune System

We also have proof that the accumulation of free radical damage over our lifetime damages and weakens immune cells known as dendritic cells. Dendritic are the first responders to the presence of foreign agents in the body, whether they are viruses, bacteria or an emerging cluster of cancer cells. Dendritic cells gobble up the invaders or cancer cells, and then present them to T-helper cells (in the lymphatic system). The T-helper cells respond by recruiting many other immune cells (cytotoxic T-cells, macrophages, B-lympocytes, plasma cells, natural killer cells) to become mobilized to kill off the invader or destroy the cancer cell colony. Thus, free radical-damaged dendritic cells spell trouble for us as we get older, with respect to reduced ability to fight infections and cancer development.

But there is some good news – studies have shown that antioxidant supplements can reverse the damage to dendritic cells and improve their immune modulating functions (8).  Studies on humans have shown that antioxidant supplements strengthen the immune system of older and elderly subjects (9). In a ground breaking 2012 mouse model study, published in Cell Reports (E Cannizzo et al), researchers showed that free radical damage to dendritic cells in older mice can be reversed with the administration of antioxidants (9). This study provides further evidence that antioxidant supplements, taken at meaningful doses, are an important aspect of preserving immune function as we age.  This has important implications for cancer prevention and the prevention of serious infections as we age.





1. A. Goldstein et al. “Thymosin and the Immunopathology of Aging.” Federation Proc., 33, 2053-56, 1974.

2. J. Goss & M. Flye. “The Thymus Regulator of Cellular Immunity.” Austin: R.G. Landes Co. 1993

3. Van Someren EJ, Riemersma RF, Swaab DF. Functional plasticity of the circadian timing system in old age: light exposure. Prog Brain Res 2002; 138: 205231

4. Skene DJ, Swaab DF. Melatonin rhythmicity: effect of age and Alzheimer’s disease. Exp Gerontol 2003; 38: 199206






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