Objective:To investigate the effects of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on muscle mass and strength improvement through systematic review and meta-analysis.Methods:Electronic databases, namely Cochrane Library database, MEDLINE, EMBASE, CENTRAL, China National Knowledge Infrastructure, and Wanfang were searched for publications in English and Chinese from database establishment to June 20, 2022. All randomized controlled trials involving any n-3 fatty acid (fish oil capsules, pure fish oil and oral nutritional supplements) interventions for more than 4 weeks among adults aged ≥ 18 years were included in the analysis. The effects of n-3 PUFA on muscle mass and strength were compared with controls using RevMan 5.4. The mean differences (MDs) or standardized mean differences (SMDs) with 95% confidence intervals (CI) were calculated and pooled effects were assessed. The quality of the included studies was evaluated using the Cochrane risk-of-bias tool.Results:27 trials were included, with both healthy adults and patients with various types of cancer, with chronic obstructive pulmonary disease and on hemodialysis due to chronic renal failure. Most trials were judged as "low" to "high" risk of bias. The meta-analysis showed that n-3 PUFA supplementation significantly improved the lean body mass in the group without physical activity intervention compared to the control group, while showing no significant increase in muscle mass or handgrip strength in overall participants. There was no significant difference between intervention and control groups in subgroup analyses based on health/disease condition, intervention duration, route of administration and dosage and risk of bias. However, significant increases in mid-arm muscle circumference (MAMC) and lower body strength (MD = 0.8, 95% CI: 0.26 to 1.34, P = 0.005; SMD = 0.45, 95% CI: 0.21 to 0.69, P = 0.0002) were observed in n-3 PUFA supplement group. Conclusions:This meta-analysis indicates that n-3 PUFA supplementation does not improve muscle mass or handgrip strength in healthy adults as well as patients, but do improve MAMC and lower body strength. The limited sample size and prominent heterogeneity of the included studies impede the extrapolation to clinical practice and warrants individual analysis based on population characteristics. Well-designed large-scale RCTs are required to verify these findings.

Objective:To explore the correlation between dietary fiber intake and intestinal barrier function in patients with irritable bowel syndrome with diarrhea (IBS-D).Methods:IBS-D patients were recruited from May 2019 to October 2019 at the clinic of gastroenterology department in China-Japan Friendship Hospital and healthy controls (HCs) were recruited by advertisement. Clinical manifestations, psychological status and quality of life were assessed using standardized questionnaires. A food frequency questionnaire was used to assess dietary habits in the preceding year. Serum diamine oxidase (DAO) was measured via ELISA.Results:64 IBS-D patients and 35 HCs were enrolled, with no significant difference in sex ratio, age and BMI between the two groups. Second to health concern, food avoidance was the dominant impacting factor for quality of life in IBS-D patients. The intake frequency of dietary fiber was decreased in IBS-D patients, and the intake frequencies of dietary fiber-rich foods were significantly lower in IBS-D patients ( P < 0.01 for tubers, P = 0.002 for vegetables, P = 0.019 for fruits and P = 0.045 for legumes). On the other hand, the intake frequencies of processed meat ( P < 0.01), greasy food ( P = 0.009), barbecued food ( P = 0.002) and animal offal ( P = 0.003) were significantly higher in IBS-D patients compared with HCs, indicating the increased intake frequency of fat. Multivariate logistic regression showed that tubers might reduce the risk of IBS-D ( OR = 0.409,95% CI: 0.232 to 0.722, P = 0.002). The frequency of abdominal pain was positively associated with the intake frequency of greasy food in IBS-D patients. Serum DAO was measured in 37 IBS-D patients and 27 HCs. IBS-D patients had significantly higher serum DAO than HCs ( 77.0 [55.3, 100.6] μg/L vs 42.5 [28.0, 58.2] μg/L, P < 0.01). Among all the participants with serum DAO test results, the level of DAO was negatively associated with the intake frequencies of tubers, vegetables and fruits while positively associated with the intake frequencies of processed meat and barbecued food. Conclusions:Food avoidance was an important impacting factor for quality of life in IBS-D patients. IBS-D patients might have insufficient dietary fiber intake and excessive fat intake. Tubers could possibly reduce the risk of IBS-D. The decreased intake frequency of dietary fiber might have a role in intestinal barrier dysfunction in IBS-D patients.

肠易激综合征（irritable bowel syndrome,IBS）是功能性肠病中最常见的类型,表现为反复发作的腹痛,伴随排便习惯和（或）粪便性状改变。不同国家IBS患病率有差异,一项包括80项研究的Meta分析显示总患病率为11.2% [1] 。中国人群IBS患病率约为6.5%,女性患病率较男性高（8.1%对6.8%）,发病高峰年龄为30~59岁 [2] 。IBS患者虽无器质性