LEP and obesity due to melanocortin 4 receptor deficiency: Aeberli et al. found in Swedish children that dietary intake of antioxidant vitamins (vitamin E and vitamin C and β-carotene) was significantly associated with leptin levels (p < 0.05), suggesting that low concentrations of antioxidant vitamins may alter the genetic expression of leptin, leading to the development of leptin resistance and increasing the risk of obesity (21, 22).