Research suggests that a large proportion of the Western population is deficient, or at least insufficient, in the mineral zinc. The likely reason for the low intakes in zinc are major changes to the diet over the last century, coupled with the over farming of soils that has resulted in low mineral yields in staple crops such as cereals. The reproductive functions of zinc in males is well researched and correlations between low zinc status and infertility are established. In addition, zinc plays an important role as a co-factor in many enzymes involved in pathways involving inflammation and antioxidant function, such as superoxide dismutase and delta-6-desaturase. Therefore deficiency may be expected to increase systemic inflammation and oxidative stress. The elderly are particularly susceptible to mineral deficiencies because of reductions in absorption and decrease energy intake associated with the aging process.
Researchers1 have investigated the effects of zinc supplementation on inflammatory and oxidative stress markers in elderly patients (age 56 to 83y). The treatment group received 45 mg of zinc gluconate for 6 months, while the control group received a placebo supplement. After 5 months the plasma levels of zinc had increased in the treatment group but not in the control. Concomitant to an increase in plasma zinc, the researchers reported reductions in C-reactive protein (CRP), interleukin 6 (IL-6), macrophage chemo-attractant protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1) and secretary phospholipase A2. These results suggested that inflammation had been reduced, with decreased CRP plasma concentrations being indicative of reduced systemic inflammation. In addition the markers of oxidative stress, malondialdehyde and hydroxyalkenals were lowered in the zinc supplemented group, but not in the placebo group.
Interestingly, when regression analysis was performed on the data, it was found that changes in the plasma zinc levels were inversely associated with inflammatory and oxidative markers after 6 months. This supports previous evidence suggesting that supplementation is beneficial in terms of increasing plasma levels of zinc to normal. However, these results also suggest that this increase in plasma zinc in turn leads to a reduction in inflammation and oxidative stress. It is likely that these elderly subjects were deficient or marginally deficient (insufficient) in zinc, and therefore it might not be expected that zinc supplementation would lead to similar results in zinc sufficient populations. However, a number of studies have highlighted widespread marginal zinc deficiency in Western populations. These same individuals may have elevated levels of inflammatory and oxidative markers which could respond to zinc supplements.
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