Time-restricted eating reveals a "younger" immune system and reshapes the intestinal microbiome in human.

Time-restricted eating (TRE) has been shown to extent lifespans in drosophila and mouse models by affecting metabolic and anti-inflammatory activities. However, the effect of TRE on the human immune system, especially on immunosenescence, intestinal microbiome, and metabolism remains unclear. We conducted a 30-day 16:8 TRE single-arm clinical trial with 49 participants. Participants consumed daily meals from 9 a.m. to 5 p.m., provided by a nutrition canteen with a balanced, calorie-appropriate nutrition, which is designed by clinical nutritionists (ChiCTR2200058137). We monitored weight changes and weight-related parameters and focused on changes in the frequency of CD4⁺ senescent T cells, immune repertoire from peripheral blood, as well as serum metabolites and gut microbiota. We found that up to 95.9 % of subjects experienced sustained weight loss after TRE. The frequency of circulating senescent CD4⁺ T cells was decreased, while the frequency of Th1, Treg, Tfh-like, and B cells was increased. Regarding the immune repertoire, the proportions of T cell receptor alpha and beta chains were increased, whereas B cell receptor kappa and lambda chains were reduced. In addition, a reduced class switch recombination from immunoglobulin M (IgM) to immunoglobulin A (IgA) was observed. TRE upregulated the levels of anti-inflammatory and anti-aging serum metabolites named sphingosine-1-phosphate and prostaglandin-1. Additionally, several anti-inflammatory bacteria and probiotics were increased, such as Akkermansia and Rikenellaceae, and the composition of the gut microbiota tended to be "younger". Overall, TRE showed multiple anti-aging effects, which may help humans maintain a healthy lifestyle to stay "young". Clinical Trial Registration URL: https://www.chictr.org.cn/showproj.html?proj=159876.