Modulating the immune response by oral zinc supplementation: a single approach for multiple diseases.

Zinc is required for multiple cellular tasks, and especially the immune system depends on a sufficient availability of this essential trace element. During the last decades, many studies attempted to affect the outcome of various diseases by zinc supplementation. These efforts either aimed at supporting immunity by zinc administration or at correcting a loss of zinc secondary to the disease to restore the zinc-dependent functions of the immune system. This review aims to summarize the respective findings and to discuss possible molecular mechanisms by which zinc could influence viral, bacterial, and parasitic infections, autoimmune diseases, and the response to vaccination. Zinc supplementation in diseases such as diarrhea, chronic hepatitis C, shigellosis, leprosy, tuberculosis, pneumonia, acute lower respiratory infection, and leishmaniasis seems beneficial. In contrast, the results for the common cold and malaria are still not conclusive, and zinc was ineffective in most vaccination and rheumatoid arthritis studies. For AIDS and type 1 diabetes, zinc supplementation may even be a risk factor for increased mortality or deterioration of the glucose metabolism, respectively. In these cases, zinc supplementation should be used with care and limited to clearly zinc-deficient individuals.

Zinc and infection: a review.

Dietary zinc deficiency is widespread in developing countries and is often aggravated by intercurrent acute and chronic infections. Recent studies have demonstrated that zinc supplementation can significantly reduce the morbidity and mortality of apparently well-nourished children and shorten the time to recovery from acute infectious diseases. This review summarises current knowledge of the role of zinc in childhood diarrhoea, acute respiratory infections and malaria, and its potential role in diseases associated with impaired cellular immunity, namely tuberculosis, lepromatous leprosy and leishmaniasis, and explores avenues for future research.

Oral zinc therapy in recurrent erythema nodosum leprosum: a clinical study.

Effect of oral zinc as an immunomodulator was studied clinically in patients with recurrent ENL over a period of one year. In this study, 40 leprosy patients with chronic ENL, requiring more than 30-40 mg of prednisolone/day for the control of their reactions, were given oral zinc sulphate for a period of four months, and, marked improvement in the frequency, duration and severity of reactions was observed after zinc therapy. Also evident was marked reduction in the steroid requirement after oral zinc therapy. It appears that zinc may be a good substitute for the present day anti-reaction treatment which is not free from disadvantages. Further investigations to know the precise action of zinc on immune-system may help to understand the role of zinc therapy and its optimum duration.

Serum zinc/copper ratio in subtypes of leprosy and effect of oral zinc therapy on reactional states.

Serum zinc and copper levels and zinc/copper ratios were studied in 86 healthy controls, 45 cases of borderline tuberculoid (BT), 31 cases of borderline lepromatous (BL), 117 cases of lepromatous (LL) leprosy patients, 16 cases with severe erythema nodosum leprosum (ENL) reaction, and 16 cases with ENL reaction receiving oral zinc therapy. A significant reduction in serum zinc levels was noticed in all types of leprosy, the maximum decrease being seen in cases with ENL reaction. Conversely, the copper levels were significantly increased from BT to LL cases with ENL reaction in a progressive manner. A very good negative correlation (r = -0.998) was noticed between mean serum zinc and copper levels from healthy controls to active LL cases with ENL reaction. After oral zinc therapy, the serum zinc levels were significantly increased in all of the 16 LL patients with ENL reaction. In contrast, the copper levels were not decreased, indicating that oral zinc therapy can restore normal zinc levels in leprosy patients but is unable to reduce the increased copper levels.

Oral zinc as an adjunct to dapsone in lepromatous leprosy.

Oral zinc was tried in 15 cases of multibacillary leprosy as an immunostimulant in addition to conventional antileprosy drugs. Results were compared with those in ten similar cases treated with dapsone alone. Cases treated with zinc showed faster clinical improvement, regrowth of eyebrows, rapid fall in the bacterial index (BI) and in the bacterial index in the granuloma (BIG), early and greater influx in lymphocytes in the granuloma, and neovascularization. Upgrading occurred in 6 out of 15 patients taking zinc, but in only 1 out of 10 patients in the control group. Five out of six patients who showed upgrading in the treated group became lepromin positive. Only one patient (BL) showed lepromin conversion in the control group.

Oral zinc in recurrent Erythema Nodosum Leprosum reaction.

Oral zinc sulfate was tried in Eight cases of recurrent Erythema Nodosum Leprosum. To control ENL, they required high dosage of clofazimine and steroids for prolonged periods. After instituting oral zinc, the dose of clofazimine could be reduced to 100 mg twice a week and steroids could be withdrawn completely. Four out of five patients who were not tolerating dapsone earlier, started tolerating dapsone. Incidence and severity of subsequent ENL was also reduced.