Vitamin a supplementation and serum Th1- and th2-associated cytokine response in women.

AIMS AND BACKGROUND: T helper (Th)1/Th2 immune response has been linked to obesity-related immune disorders. It has been proven that retinoid active derivates improve immunity via regulating Th1/Th2 balance. However, there is not a well-identified report of direct effect of vitamin A on Th1/Th2 balance in obesity. The present study aimed to investigate the possible role of vitamin A on serum Th1/Th2 response in obese women. MATERIALS AND METHODS: A randomized double-blind placebo-controlled trial was conducted on 84 obese (n = 56; body mass index [BMI] 30-39.9 kg/m(2)) and nonobese (n = 28; BMI 18.5-24.9 kg/m(2)) women. Obese women were randomly allocated to receive either vitamin A (retinyl palmitate 25,000 IU/d) or placebo. Nonobese women also received 25,000 IU/d retinyl palmitate. Anthropometric variables were assessed and serum interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-4, and IL-13 were analyzed before and 4 months after intervention. RESULTS: Vitamin A treatment significantly reduced serum concentrations of IL-1β in obese vitamin A-treated subjects (from 3.58 ± 0.36 to 2.45 ± 0.23 pg/ml, p < 0.006). Serum concentrations of IL-4 and IL-13 were also reduced in obese and nonobese vitamin A-treated subjects (p < 0.05). A significant reduction in IL-1β/IL-4 ratio in the obese vitamin A-treated group was also observed (p = 0.03). CONCLUSIONS: Decline in serum concentrations of IL-1β and IL-1β/IL-4 ratio in obese women suggests that vitamin A is capable of regulating the immune system and possibly reducing the risk of autoimmune disease in this group. Further studies are needed to explore the possible underlying mechanisms.