Researchers enrolled fifty PHN patients for at least 3 months and fifty healthy controls. Nine circulating nutrients including ionized Ca, Zn, retinol, folic acid, vitamin B12, vitamin C, alpha-tocopherol, gamma-tocopherol and lycopene associated with both immunity and the modulation of neuropathic pain, were selected and their concentrations in plasma/serum were measured. Concentrations of ionized Ca, Zn, vitamin C and vitamin B12 were significantly lower in PHN patients than in controls after excluding those patients receiving supplements since the outbreak of herpes zoster (HZ). The prevalence of either mild/marginal or severe deficiencies for any of the nine selected circulating nutrients in PHN patients (92%) was much higher than that in controls (46%) (P < 0.001). Lower concentrations of vitamin C ( ? 45.0 mmol/l), ionised Ca (? 1.05 mmol/l) and Zn (? 0.91 g/l) were found to increase independently the risk of PHN using binary variable (dichotomy) analyses with both PHN patients and controls in a multivariate logistic regression analysis. No significant correlations existed between the risks of PHN and the concentrations of retinol, folic acid, vitamin B12, lycopene or alpha:gamma-tocopherol ratios. These results suggest that lower concentrations of circulating nutrients, in particular vitamin C, ionised Ca or Zn, may be risk factors for PHN. Additional research is warranted.
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