Tai Chi for fall prevention and balance improvement in older adults: a systematic review and meta-analysis of randomized controlled trials.

Background and objective: As the population ages, the health of older adults is becoming a public health concern. Falls are a significant threat to their health due to weakened balance. This study aims to investigate the beneficial effects of Tai Chi on fall prevention and balance improvement in older adults. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials related to Tai Chi, falls, and balance ability, searching PubMed, Embase, and Cochrane Library databases from their establishment until December 31, 2022. Two independent reviewers performed the search, screening of results, extraction of relevant data, and assessment of study quality. This study followed the PRISMA guidelines for systematic review and meta-analysis. Results: Totally 24 RCTs were included for meta-analysis, and the results showed that Tai Chi can effectively reduce the risk of falls in older adults (RR: 0.76, 95% CI: 0.71 to 0.82) and decrease the number of falls (MD [95% CI]: -0.26 [-0.39, -0.13]). Tai Chi can also improve the balance ability of older adults, such as the timed up and go test (MD [95% CI]: -0.69 [-1.09, -0.29]) and the functional reach test (MD [95% CI]: 2.69 [1.14, 4.24]), as well as other balance tests such as single-leg balance test, Berg balance scale, and gait speed (p < 0.05). Subgroup analysis showed that Tai Chi is effective for both healthy older adults and those at high risk of falls (p < 0.001), and its effectiveness increases with the duration and frequency of exercise. In addition, the effect of Yang-style Tai Chi is better than that of Sun-style Tai Chi. Conclusion: Tai Chi is an effective exercise for preventing falls and improving balance ability in older adults, whether they are healthy or at high risk of falling. The effectiveness of Tai Chi increases with exercise time and frequency. Yang-style Tai Chi is more effective than Sun-style Tai Chi. Systematic review registration: https://clinicaltrials.gov/, identifier CRD42022354594.

Maternal melatonin supplementation shapes gut microbiota and protects against inflammation in early life.

BACKGROUND: Gut microbiota colonization is critical for immune education and nutrient metabolism. Research shows that melatonin has beneficial effects as a therapy for many diseases via modulating gut dysbiosis. However, it is unclear whether melatonin alters gut microbiota colonization in early life. METHODS: In the experimental group (Mel), mice were intraperitoneally injected with melatonin at 10 mg/kg body weight for embryonic days 14-16 and received drinking water containing 0.4 mg/mL melatonin until 28 days postpartum. In the control group (Ctrl), mice were injected with the same volume of 2.5% ethanol in saline and provided with standard water. Two more groups were created by treating neonatal mice with 20 mg/kg lipopolysaccharide (LPS) to induce inflammation, resulting in the groups Ctrl + LPS and Mel + LPS, respectively. We examined the gut microbiota of the neonatal mice in the Ctrl and Mel group on Days 7, 14, 21, and 28 post-birth. On Day 14, melatonin and short-chain fatty acids (SCFAs) concentrations were measured in the Ctrl and Mel group and the mice were treated with LPS to be evaluated for intestinal injury and inflammatory response 15 h post treatment. According to the result of the SCFAs concentrations, some neonatal mice were intraperitoneally injected with 500 mg/kg sodium butyrate (SB) from Days 11-13, intraperitoneally injected with 20 mg/kg LPS on Day 14, and then euthanized by carbon dioxide inhalation the next morning. Intestinal injury and inflammatory responses were evaluated in the Ctrl + LPS and SB + LPS groups, respectively. RESULTS: By Day 14, it was evident that maternal melatonin supplementation significantly increased the relative abundance of Firmicutes in the ileal [61.03 (35.35 - 76.18) % vs. 98.02 (86.61 - 99.01) %, P = 0.003] and colonic [73.88 (69.77 - 85.99) % vs. 96.16 (94.57 - 96.34) %, P = 0.04] microbiota, the concentration of melatonin (0.79 ± 0.49 ng/ml vs. 6.11 ± 3.48 ng/ml, P = 0.008) in the gut lumen, and the fecal butyric acid (12.91 ± 5.74 µg/g vs. 23.58 ± 10.71 µg/g, P = 0.026) concentration of neonatal mice. Melatonin supplementation, and sodium butyrate treatment markedly alleviated intestinal injury and decreased inflammatory factors in neonatal mice. CONCLUSION: This study suggests that maternal melatonin supplementation can shape the gut microbiota and metabolism of offspring under normal physiological conditions and protect them against LPS-induced inflammation in early life.