Prevention of allergies by vitamin D

Abstract

Vitamin D is synthesized in the body through exposure to ultraviolet rays and is also obtained from dietary sources. Vitamin D has been shown to be involved in allergic diseases through its immunomodulatory function. It is thought to play a role in suppressing excessive allergic reactions by acting on immune cells such as T cells and dendritic cells, and promoting immune tolerance. Many epidemiological studies have suggested that vitamin D deficiency is a risk factor for food allergies. The CHIBA study confirmed that the blood vitamin D levels of breast-fed infants were low, and the rate of egg white sensitization was high. However, the results of intervention studies using vitamin D conducted in other countries have not yet reached a conclusion regarding its preventive effects. Vitamin D deficiency is a serious problem in Japan, and interventions that take into account the unique lifestyle and nutritional background of the Japanese are necessary. Therefore, we conducted a randomized controlled trial using vitamin D with the aim of preventing food allergies (the Vitamin D mediated Prevention of Allergic march in Chiba (D-PAC) study), and were able to achieve a high preventive effect. In the future, clinical applications that increase the effectiveness of vitamin D supplementation are expected through investigations into the optimal timing and optimal concentration of administration.