Zinc is an important antioxidant and anti-inflammatory mineral which plays a key role in immune functions. An adequate level of zinc improves resistance to infections, boosts antibody production, maintains levels of hormones in the thymus (the organ responsible for producing T-cells) and permits vigorous T-cell responses. Zinc deficiency leads to a fall in testosterone levels, which in turn affects the body's ability to maintain and build lean muscle tissue. Zinc competes with copper for absorption, and AZT (zidovudine, Retrovir) may also reduce zinc levels.
A two-and-a-half year study in asymptomatic HIV-positive people showed that significantly lowered levels of zinc in serum (and correspondingly elevated levels of copper) were a strong predictor of progression to AIDS. The study failed to show any relationship between dietary intake of zinc and serum levels, suggesting that supplementation may not slow disease progression.1
However, another smaller study showed that when compared with an untreated HIV-negative group, eleven HIV-positive men who received 1 mg/kg body weight (about 60 to 70 mg a day for the average adult male) of zinc sulphate for ten weeks gained weight and showed a moderate increase in CD4 cell count.2
Italian researchers found that giving 200mg zinc sulphate for 30 days to AZT-treated people reduced the subsequent incidence of opportunistic infections in the study group when compared with a control group of AZT-treated patients. The study followed 35 people with lymphadenopathy but no other symptoms and 22 people who had already been diagnosed with AIDS. The study followed participants for two years and among the group with AIDS noted eleven life-threatening infections in the zinc-treated group compared with 25 in the control group. In the group who only had lymphadenopathy only one zinc-treated individual developed an opportunistic infection compared with 13 in the AZT-only group.3
This study needs to be treated with caution because of the confounding effect of AZT treatment on zinc status. Dr Richard Beach has noted that in a group of patients who began AZT treatment, serum zinc levels continued to decline, whilst a matched group of patients who did not receive AZT showed no change in zinc status. Some studies have shown that low serum zinc is a strong predictor of CD4 cell count decline.
Overdosing with zinc is dangerous: it can impair immune responses and disrupt the metabolism of iron in the body, leading to anaemia. Doses above 200mg per day are not recommended and anaemia and neutropenia have been noted in people receiving doses above 50mg a day. A 1994 study showed that HIV-positive men with the highest level of zinc intake at the outset were most likely to have developed AIDS after seven years of follow up. This suggests that too much zinc can be just as bad as too little zinc in the diet.4
Zinc comes in several forms. People taking a supplement should check what quantity of elemental zinc is contained in the supplement. High zinc intake is especially dangerous in people with candidiasis. If supplementing it is important to ensure an adequate intake of copper and selenium, since these minerals compete for absorption. Intakes of zinc as low as 50mg a day have been shown to interfere with the utilisation of copper and lead to symptoms such as lowered white blood cell count, lack of resistance to bacterial infections and to anaemia.
Good food sources of zinc are whole-grain products, brewers' yeast, wheat bran and germ, seafoods and animal meats.