Concurrent Ingestion of Alkaline Water and L-Glutamine Enhanced Salivary α-Amylase Activity and Testosterone Concentration in Boxing Athletes.

Athletes often take sport supplements to reduce fatigue and immune disturbances during or after training. This study evaluated the acute effects of concurrent ingestion of alkaline water and L-glutamine on the salivary immunity and hormone responses of boxers after training. Twelve male boxing athletes were recruited in this study. During regular training, the participants were randomly divided into three groups and asked to consume 400 mL of alkaline water (Group A), 0.15 g/kg body weight of L-glutamine with 400 mL of water (Group G), and 0.15 g/kg of L-glutamine with 400 mL of alkaline water (Group A+G) at the same time each day for three consecutive weeks. Before and immediately after the training, saliva, heart rates, and the rate of perceived exertion were investigated. The activity of α-amylase and concentrations of lactoferrin, immunoglobulin A (IgA), testosterone, and cortisol in saliva were measured. The results showed that the ratio of α-amylase activity/total protein (TP) significantly increased after training in Group A+G but not in Group A or G, whereas the ratios of lactoferrin/TP and IgA/TP were unaffected in all three groups. The concentrations of salivary testosterone after training increased significantly in Group A+G but not in Group A or G, whereas the salivary cortisol concentrations were unaltered in all groups. In conclusion, concurrent ingestion of 400 mL of alkaline water and 0.15 g/kg of L-glutamine before training enhanced the salivary α-amylase activity and testosterone concentration of boxers, which would be beneficial for post-exercise recovery.

Is there an optimal vitamin D status for immunity in athletes and military personnel?

Vitamin D is mainly obtained through sunlight ultraviolet-B (UVB) exposure of the skin, with a small amount typically coming from the diet.It is now clear that vitamin D has important roles beyond its well-known effects on calcium and bone homeostasis. Immune cells express the vitamin D receptor, including antigen presenting cells, T cells and B cells, and these cells are all capable of synthesizing the biologically active vitamin D metabolite, 1, 25 hydroxy vitamin D.There has been growing interest in the benefits of supplementing vitamin D as studies report vitamin D insufficiency (circulating 25(OH)D < 50 nmol/L) in more than half of all athletes and military personnel tested during the winter, when skin sunlight UVB is negligible. The overwhelming evidence supports avoiding vitamin D deficiency (25(OH)D< 30 nmol/L)to maintain immunity and prevent upper respiratory illness (URI) in athletes and military personnel.Recent evidence supports an optimal circulating 25(OH)D of 75 nmol/L to prevent URI and enhance innate immunity and mucosal immunity and bring about anti-inflammatory actions through the induction of regulatory T cells and the inhibition of pro-inflammatory cytokine production. We provide practical recommendations for how vitamin D sufficiency can be achieved in most individuals by safe sunlight exposure in the summer and daily 1, 000 IU vitamin D3 supplementation in the winter. Studies are required in athletes and military personnel to determine the impact of these recommendations on immunity and URI; and,to demonstrate the purported benefit of achieving 25(OH)D>75 nmol/L.

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes.

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D3 supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D3 supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D3 group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D3 group was higher than in the placebo group (P = 0.025). Only in the vitamin D3 group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D3 supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.