Background: Previous studies had revealed that Body Mass Index (BMI) positively affected Bone Mineral Density (BMD). However, an excessively high BMI was detrimental to health, especially for the elderly. Moreover, it was elusive how much BMI was most beneficial for BMD in older adults to maintain.Objective: To investigate whether there was a BMI saturation effect value that existed to maintain optimal BMD.Methods: A cross-sectional study was conducted using the datasets of the National Health and Nutrition Examination Survey (NHANES) 2005–2006, 2007–2008, 2009–2010, 2013–2014, and 2017–2018. After adjusting for covariates, an analysis of the association between BMI and BMD in different femoral regions (Total femur, Femoral neck, Trochanter, Intertrochanter, and Ward's triangle) and lumbar spine regions (Total spine, L1, L2, L3, and L4) in the whole population was performed using the multivariate linear regression models, smoothing curve fitting, and saturation effects analysis models. Then, subgroup analyses were performed according to gender, age, and race.Results: A total of 10,910 participants (5,654 males and 5,256 females) over 50 years were enrolled in this population-based study. Multivariate linear regression analyses in the population older than 50 years showed that BMI was positively associated with femoral BMD and lumbar spine BMD (P < 0.001, respectively). Smoothing curve fitting showed that the relationship between BMI and BMD was not simply linear and that a saturation value existed. The saturation effect analysis showed that the BMI saturation value was 26.13 (kg/m2) in the total femur, 26.82 (kg/m2) in the total spine, and showed site-specificity in L1 (31.90 kg/m2) and L2 (30.89 kg/m2). The saturation values were consistent with the whole participants in males, while there was high variability in the females. BMI saturation values remained present in subgroup analyses by age and race, showing specificity in some age (60–70 years old) groups and in some races.Conclusions: Our study showed a saturation value association between BMI and BMD for people over 50 years old. Keeping the BMI in the slightly overweight value (around 26 kg/m2) might reduce other adverse effects while obtaining optimal BMD.

Objective To investigate the association between different body fat distribution and different sites of BMD in male and female populations. Methods Use the National Health and Nutrition Examination Survey (NHANES) datasets to select participants. The weighted linear regression model investigated the difference in body fat and Bone Mineral Density (BMD) in different gender. Multivariate adjusted smoothing curve-fitting and multiple linear regression models were used to explore whether an association existed between body fat distribution and BMD. Last, a subgroup analysis was performed according to age and gender group. Results Overall, 2881 participants were included in this study. Compared to males, female participants had lower BMD (P < 0.05) and higher Gynoid fat mass (P < 0.00001), while there was no difference between Android fat mass (P = 0.91). Android fat mass was positively associated with Total femur BMD (Males, β = 0.044, 95% CI = 0.037, 0.051, P < 0.00001; Females, β = 0.044, 95% CI = 0.039, 0.049, P < 0.00001), Femoral neck BMD (Males, β = 0.034, 95% CI = 0.027, 0.041, P < 0.00001; Females, β = 0.032, 95% CI = 0.027, 0.037, P < 0.00001), and Total spine BMD (Males, β = 0.036, 95% CI = 0.029, 0.044, P < 0.00001; Females, β = 0.025, 95% CI = 0.019, 0.031, P < 0.00001). The Gynoid fat mass, subgroup analysis of age and ethnicity reached similar results. Conclusion Body fat in different regions was positively associated with BMD in different sites, and this association persisted in subgroup analyses across age and race in different gender.

Probiotics were used for liver transplantation (LT) patients to reduce postoperative infection, but clinical trials examining the combined use of prebiotics and probiotics are limited. This meta‐analysis aimed to compare the safety and efficacy of combined use of prebiotics and probiotics in patients undergoing LT. PubMed, Cochrane, and Embase databases were reviewed for the combined use of prebiotics and probiotics in patients undergoing LT. The weighted mean difference (WMD), risk ratio (RR), and 95% CI were calculated. A total of 6 related studies comprising 345 patients were included. Most prebiotics and probiotics were given for 7.14 days. The overall infection rate (RR = 0.29; 95% CI, 0.14.0.60; P value for heterogeneity [PH] = .066; test for heterogeneity [I2] = 51.7%) and the incidence of urinary tract infection (RR = 0.14; 95% CI, 0.04–0.47, PH = .724; I2 = 0%) were lower in the probiotics group when compared with those in the control group. Furthermore, probiotics significantly reduced the hospital length of stay (WMD = −1.37; 95% CI, −1.92 to 0.82; PH = .506; I2 = 0%) and the duration of antimicrobial therapy (WMD = −4.31; 95% CI, −5.41 to 3.22; PH = .019; I2 = 69.8%) in patients undergoing LT. These findings suggested that the combined use of prebiotics and probiotics (Lactobacillus and Bifidobacterium) was effective in lowering the incidence of bacterial infections and shortening the hospital length of stay and duration of antibiotic therapy in patients undergoing LT, when compared with conventional nutrition.