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Sleep quality plays an important role in the modulation of several aging markers. This influence could be explained by aging-induced hormonal changes. Indeed, poor sleep quality has been associated with the development of several endocrine-related health complications. This study examined the relationship of both subjective and objective sleep quantity and quality, with basal levels of selected plasma anabolic and catabolic hormones in sedentary middle-aged adults. A total of 74 volunteers (52.7% women; aged 53.7 ± 5.1) were recruited for this study. Subjective sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI; higher scores indicate worse sleep quality), and objective sleep quality parameters (total sleep time [TST], wake after sleep onset [WASO], and sleep efficiency [SE]) were measured using a wrist-worn accelerometer. Basal levels of plasma dehydroepiandrosterone sulphate (DHEAS), total testosterone, sex hormone binding globulin (SHBG), somatotropin, and cortisol levels, were determined. Free testosterone was calculated from the total testosterone and SHBG levels. No associations of global PSQI score, TST, WASO, and SE with DHEAS, free testosterone, and somatotropin plasma levels were found, neither in men nor in women (all p ≥ 0.05). Global PSQI score was inversely related to cortisol plasma levels in women ( p = 0.043). WASO was positively associated with cortisol plasma levels, while SE was negatively associated with cortisol plasma levels in women (all p ≤ 0.027). Sleep quality is not related to levels of plasma anabolic hormones, but to levels of catabolic hormones, in sedentary middle-aged adults. Therefore, these results suggest that potential changes in aging biomarkers associated with sleep disturbances, could be mediated by age-related changes in the catabolic endocrine system.

The association of physical activity and fitness with sleep still remains unclear since there is a lack of studies in this field of research using objective measurements of these variables. This study aimed to investigate the association of objectively-measured sedentariness, physical activity levels, and physical fitness with sleep quantity and quality in sedentary middle-aged adults. A total of 74 volunteers (52.7% women; aged 53.7 ± 5.1) were recruited for the present study. Cardiorespiratory fitness was measured through a maximal treadmill test, and muscular strength by extension and flexion peak torque, and by the hand grip test. Physical activity and objective sleep parameters were determined through accelerometry, and subjective sleep by the Pittsburgh Sleep Quality Index (PSQI). Reduced levels of sedentariness, greater VO 2max , and greater muscular strength were positively related to improved objective sleep quantity and quality (all P ≤ 0.05). Furthermore, higher levels of overall physical activity, VO 2max , and muscular strength were related to better subjective sleep quantity and quality (all P ≤ 0.05). Reduced sedentariness and increased physical activity and fitness may be a potential prevention and/or treatment pathway to reduce sleep disturbances and, in general, to improve patients physical and psychological health for a successful aging process.

Background: Unhealthy lifestyle and aging negatively impact sexuality; consequently, the prevalence of sexual problems increases sharply in middle-aged adults, but the determinants of low sexual desire and sexual dysfunction are not fully elucidated., Aims: To investigate the association of cardiometabolic profile, free testosterone plasma levels, body composition, physical fitness, and S-Klotho plasma levels with sexual desire and sexual function in middle-aged sedentary adults., Methods: Seventy-four (39 women) sedentary middle-aged adults (45-65 years old) were recruited for the present cross-sectional study., Outcomes: The blood samples were collected in the morning (12 h of fasting) to determine cardiometabolic biomarkers and free testosterone and S-Klotho plasma levels. The cardiometabolic risk score was calculated based on the International Diabetes Federation's clinical criteria, quantitative insulin sensitivity check index, and homeostatic model assessment of insulin resistance index. A dual-energy X-ray absorptiometry scanner was used to determine the lean mass index (LMI) and the fat mass index. Maximal oxygen uptake was determined by a maximum treadmill test using indirect calorimetry. Muscular strength was measured with knee extensor isokinetic dynamometry (60° s -1 ). Sexual desire was assessed with the Sexual Desire Inventory 2. Sexual function was assessed with the Massachusetts General Hospital-Sexual Functioning Questionnaire., Results: After age adjustment, free testosterone plasma levels were associated with solitary sexual desire in women (R 2  = 0.193, β = 0.342, P = .044). The LMI was associated with solitary sexual desire in men (R 2  = 0.258, β = 0.445, P = .024) and sexual function in women (R 2  = 0.470, β = -0.607, P < .001). S-Klotho plasma levels were associated with solitary sexual desire and sexual function in men (R 2  = 0.412, β = 0.817, P = .001; R 2  = 0.193, β = -0.659, P = .021, respectively) and with dyadic sexual desire and sexual function in women (R 2  = 0.270, β = 0.508, P = .020; R 2  = 0.467, β = -0.676, P < .001, respectively)., Clinical Implications: S-Klotho plasma levels may represent a potential new biomarker for sexual desire and sexual function. Lean body mass development may benefit sexual desire and sexual function., Strengths and Limitations: Strengths include the analysis of novel and diverse biomarkers of health for sexual desire and sexual function. Limitations include the cross-sectional design and a relatively small sample size; thus, results should be interpreted cautiously and in the study population context., Conclusion: S-Klotho plasma levels were strongly associated with dyadic sexual desire, solitary sexual desire, and sexual function in sedentary middle-aged adults. The LMI was also positively associated with solitary sexual desire and sexual function in men and women, respectively. Dote-Montero M, De-la-O A, Castillo MJ, et al. Predictors of Sexual Desire and Sexual Function in Sedentary Middle-Aged Adults: The Role of Lean Mass Index and S-Klotho Plasma Levels. The FIT-AGEING Study. J Sex Med 2020;17:665-677., (Copyright © 2020 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.)

S-klotho, the shed form of α-klotho, is thought to be an ageing suppressor with functions related to the physiology of energy metabolism. However, it remains unknown whether ageing biomarkers such as S-klotho and/or chronological ageing are associated in any way with basal metabolic rate (BMR) and fuel oxidation in basal conditions and during exercise. The present work investigates the association of BMR and fuel oxidation in basal conditions and during exercise, with plasma S-klotho in middle-aged, sedentary adults. BMR was measured by indirect calorimetry in 74 such subjects (53% women; age 53.7±5.1 years) following standard procedures, and their fuel oxidation estimated via stoichiometric equations. The maximal fat oxidation during exercise (MFO) and the intensity of exercise that elicits MFO (Fat max ) were determined using a walking graded exercise test. No relationship was seen between BMR and plasma S-klotho (P>0.1), although both basal fat oxidation and MFO showed positive associations with this protein (both P<0.001); these relationships persisted after controlling for age, sex and fat mass. However, no significant associations were seen between BMR, basal fat oxidation or MFO and chronological age (all P>0.1). The present findings suggest that basal fat oxidation and MFO are strongly associated with plasma S-klotho in middle-aged sedentary adults. These results support the idea that metabolic flexibility is a powerful predictor of biological ageing.

Objectives: To determine the association between physical activity and physical fitness levels (i.e. cardiorespiratory fitness and muscular strength) and the shed form of the α-Klotho gene (S-Klotho plasma levels) in middle-aged sedentary adults., Study Design and Main Outcome Measures: A total of 74 middle-aged sedentary adults (52.7% women; 53.7 ± 5.1 years old) were enrolled in the FIT-AGEING study. Physical activity and sedentary time were assessed with a wrist-worn accelerometer. Maximal oxygen uptake (VO 2 max) was determined by a maximum treadmill test using indirect calorimetry. Lower- and upper-body muscular strength were assessed by an isokinetic strength test and by the hand grip strength test, respectively. The S-Klotho plasma levels were measured in the EDTA plasma using a solid-phase sandwich enzyme-linked immunosorbent assay., Results: Based on the principal-component analysis, overall physical activity, moderate and vigorous physical activity levels, and sedentary time (as outcomes included in the 'sedentary time and physical activity' category) explained a total of 17.5% of the cumulative variance in S-Klotho plasma levels, while extension peak torque, hand grip strength, and maximal oxygen uptake (as outcomes included in the 'physical fitness' category) explained a total of 15.5% of the cumulative variance in S-Klotho plasma levels. Based on the loading of variables in these 2 categories, the percentage of the cumulative variance in S-Klotho plasma level explained was 28.9%s; this reached 33.0% of cumulative variance when sex was included in the model., Conclusions: In summary, our results indicate that physical activity and physical fitness levels are associated with S-Klotho plasma levels in middle-aged sedentary adults. Therefore, the S-Klotho protein could be a key factor in the relationship between physical activity and physical fitness and health improvements during the ageing process., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction: The ageing process can be influenced by different dietary patterns and dietary factors., Aim: To analyse the association of dietary factors, which include the Mediterranean diet adherence, the compliance with the "Sociedad Española de Nutrición Comunitaria" food portion recommendations, and the intake of different food groups, with the secreted form of the α-Klotho gene (S-Klotho as an anti-ageing marker) in middle-aged sedentary adults., Methods: A total of 74 (39 women) middle-aged sedentary adults participated in the study. Dietary factors were assessed with a food frequency questionnaire and the PREDIMED questionnaire. The S-Klotho plasma levels were measured using a soluble α-Klotho ELISA assay kit., Results: We observed: (i) a negative association between the adherence to the Mediterranean diet and the S-Klotho plasma levels (β = -53.219; R 2  = 0.078; P = 0.020), (ii) a higher intake of wine (>7 glasses/week), was associated with lower S-Klotho plasma levels (P = 0.039), and (iii) a positive association between nuts portion intake and the S-Klotho plasma levels (β = 26.087; R 2  = 0.070; P = 0.029). All the associations disappeared after controlling for lean mass index (LMI) (all P > 0.05)., Conclusion: Our study suggests that, although dietary factors could be related to S-Klotho plasma levels in middle-aged sedentary adults, LMI is the main determinant in this regard., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: Alcohol consumption is related to several diseases and injuries that accelerate the ageing process and increase the mortality and morbidity risk. The soluble form of the α-Klotho gene (called S-Klotho) is widely considered as a powerful anti-ageing biomarker., Aim: The aim of the present study was to analyze the association between alcohol consumption and S-Klotho plasma levels in sedentary middle-aged adults., Methods: 74 (39 women) middle-aged sedentary adults (40-65 years old) participated in the present study. Alcohol consumption was assessed with a food frequency questionnaire previously validated and with three non-consecutive 24-hours recall. The S-Klotho plasma levels were measured by ELISA using a soluble α-Klotho ELISA assay kit., Results: Total alcoholic drinks consumption was negatively associated with S-Klotho plasma levels (β=-17.031; R 2  = 0.096, P = 0.013). Furthermore, we observed that higher consumption of total alcoholic drinks is associated with lower S-Klotho plasma levels in middle-aged sedentary adults controlling for BMI (β=-16.372; R 2  = 0.201, P = 0.011), LMI (β=-31.854; R 2  = 0.305, P = 0.010) and for FMI β=-13.337; R 2  = 0.075, P = 0.049)., Conclusion: In conclusion, our study shows that total alcoholic drinks consumption is negatively associated with the S-Klotho plasma levels in middle-aged sedentary adults., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Ageing is associated with sleep pattern changes and body composition changes, which are related to several diseases. Purpose: This study aimed to analyse the association between sleep quality and an extensive set of body composition parameters (waist-hip ratio, body mass index, bone mineral content, bone mineral density, lean mass, lean mass index, fat mass, fat mass percentage, fat mass index, visceral adipose tissue) and sleep quality in sedentary middle-aged adults. We also aimed to evaluate whether the possible associations accord between subjective and objective measurements of sleep quality. Methods: 74 (39 women) middle-aged sedentary adults (40⁻65 years old) participated in the present study. The sleep quality was assessed using the Pittsburgh sleep quality index (PSQI) scale and accelerometers. A PSQI global score more than 5 indicates poor sleep quality. Weight, height, waist and hip circumferences were measured, and body mass index and waist-hip ratio were also calculated. Body composition was assessed with a dual-energy X-ray absorptiometry scanner. Results: The PSQI global score was negatively associated with bone mineral content, bone mineral density, lean mass, lean mass index and positively associated with fat mass percentage. No association was found between accelerometer parameters and body composition variables. Conclusion: We showed that a subjective poor sleep quality was negatively associated with bone mineral content (BMC), bone mineral density (BMD), lean mass and lean mass index (LMI) whereas was positively associated with fat mass percentage in middle-aged adults. We also observed that these associations did not accord with objective sleep quality measurements.

Our aim in this study was to examine the association between breastfeeding duration and cardiorespiratory fitness, isometric strength, and explosive strength during adolescence. A total of 2567 adolescents (1426 girls) from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) cross-sectional study aged 12.5-17.5 y were included. Information about duration of any and exclusive breastfeeding was obtained retrospectively by means of a parental questionnaire. The 20-m shuttle run, handgrip strength, and standing long jump tests were used to assess physical fitness. Significant differences among the categories of breastfeeding duration were tested using ANCOVA after adjusting for a set of potential confounders: gestational and current age, birth weight, sexual maturation, fat mass, fat-free mass, maternal education, parental weight status, country, smoking behavior, and days of vigorous physical activity. Longer breastfeeding (either any or exclusive) was associated with a higher performance in the standing long jump test in both boys and girls (P < 0.001), regardless of fat mass, fat-free mass, and the rest of potential confounders. In adolescents who were breastfed for 3-5 mo or ≥6 mo, the risk of having a standing long jump performance below the 5th percentile was reduced by half compared with those who were never breastfed [odds ratio (OR) = 0.54, 95% CI = 0.30-0.96, P < 0.05; and OR = 0.40, 95% CI = 0.22-0.74, P < 0.01, respectively). These findings suggest a role of breastfeeding in determining lower body explosive strength during adolescence.

Background: Hyperhomocysteinemia is an accepted risk factor for cardiovascular disease, and possibly also for cognitive impairment and dementia. It has also been proposed as a marker for the status of the B vitamins, which participate in the metabolism of homocysteine. Therefore, especially in the elderly, it is important to know the prevalence of high homocysteine (tHcy) levels and the influence that B vitamins have on them., Material and Methods: 218 elderly of both sexes, aged 60-105, living in an elderly home in Granada (Spain), were screened for serum folate, red blood cell (RBC) folate, serum cobalamin (B12) (Abbott, IMx), holotranscobalamin II (Holo-TC II) (HoloTC RIA, Axis-Shield), methylmalonic acid (MMA) (MS-GC), total pyridoxine (B6) (HPLC), and total homocysteine (tHcy) (Abbott, IMx)., Results: Hyperhomocysteinemia (tHcy >12 pmol/L) was detected in 80.7%. Serum folate deficiency was severe (< or =4 ng/mL) in 19.3% and moderate (4-7 ng/mL) in 43.1%. In 14.2% of the elderly RBC folate was < or =175 ng/mL, and in 61.0% it was between 175-400 ng/mL. Vitamin B12, measured in serum (< or =200 pg/mL), was deficient in 15.8%, but if measured as Holo-TC II (< or =45 pmol/L), deficiency ranged up to 39.1%. MMA was high (> or =300 nmol/L) in 45.6%. Vitamin B6 (< 20 nmol/L) was low only in one person. In order to identify the factors that could predict tHcy levels, a multiple regression analysis was performed. Best results corresponded to the combination of log serum folate and log Holo-TC II, which gave values of R > 0.5. If analyzed independently, the highest correlation was with log serum folate (r = -0.290), followed by RBC folate (r = -0.263), Holo-TC II (r = -0.228), log B12 (r = -0.175), and log B6 (r = -0.078)., Conclusion: There is a high prevalence of vitamin B deficiency and hyperhomocysteinemia in the studied population. Our data confirm the influence of these vitamins, especially folate, on tHcy levels, but hyperhomocysteinemia cannot be used as the only diagnostic criterion to detect subclinical vitamin deficiency in elderly people, especially to detect vitamin B12 deficiency.

We aimed to investigate the effect of three types of exercise interventions on memory (i.e., immediate memory (IM), long‐term memory (LTM), and recognition). We also investigated whether exercise‐induced changes in circulating S‐Klotho and 1,25‐dihydroxivitamin D (1,25(OH)2D) levels were related to those observed in memory in healthy middle‐aged sedentary adults. A 12‐week randomized controlled trial was performed with a parallel‐group design. Seventy‐four participants (45–65 years old: 53% women) were randomly assigned to (1) no exercise (control) group, (2) concurrent training based on the international physical activity recommendations (PAR) group, (3) high‐intensity interval training (HIIT) group, or (4) HIIT plus whole‐body electromyostimulation (HIIT‐EMS) group. Memory outcomes were assessed using the Wechsler Memory Scale‐third edition. S‐Klotho plasma levels were determined according to a solid‐phase sandwich enzyme‐linked immunosorbent assay kit while 1,25(OH)2D plasma levels were measured using a DiaSorin‐Liaison immunochemiluminometric analyzer. IM‐Verbal Paired Associates (IM‐VPA) and IM‐Logical Memory (IM‐LM) were improved in both the HIIT and HIIT‐EMS groups compared with the control group (all p ≤ 0.045). Exercise‐induced changes in S‐Klotho plasma levels were positively associated with those observed in IM, LTM, and recognition (all p ≤ 0.007), whereas exercise‐induced changes in 1,25(OH)2D plasma levels were directly related to changes in IM and LTM (all p ≤ 0.048). In conclusion, a 12‐week HIIT intervention with or without WB‐EMS seems to be the most effective exercise program to improve IM. The significant and positive associations between exercise‐induced changes in S‐Klotho and 1,25(OH)2D levels with those observed in memory outcomes suggest that these factors may be potentially related to exercise‐induced improvements of memory in middle‐aged adults. [ABSTRACT FROM AUTHOR]

α-Klotho protein is a powerful predictor of the aging process and lifespan. Although lowered circulating soluble α-Klotho levels have been observed in aged non-healthy individuals, no specific reference values across a wide range of ages and sex using an enzyme-linked immunosorbent assay (ELISA) are available for larger cohorts of healthy individuals. The present analytical cross-sectional study was aimed to establish the reference values of soluble α-Klotho serum levels in healthy adults by age and sex groups. A total of 346 (59% women) healthy individuals aged from 18 to 85 years were recruited. Subjects were divided by sex and age as: (i) young (18–34.9 years), (ii) middle-aged (35–54.9 years), and (iii) senior (55–85 years) individuals. The soluble α-Klotho levels were measured in serum using ELISA. Senior adults were the age-group that presented the lowest soluble α-Klotho serum levels (p < 0.01), with age showing a negative association with soluble α-Klotho serum levels (p < 0.001). No differences between sexes were observed. Therefore, soluble α-Klotho levels were especially decreased—regardless of sex—in our cohort of healthy individuals because of the physiological decline derived from the aging process. We recommend routine assessments of soluble α-Klotho levels using ELISA as a simple and cheap detectable marker of aging that improves quality of life in the elderly. [ABSTRACT FROM AUTHOR]

The steady rise in life expectancy occurred across all developed countries during the last century. This demographic trend is, however, not accompanied by the same healthspan extension. This is since aging is the main risk factor for all age‐associated pathological conditions. Therefore, slowing the rate of aging is suggested to be more efficient in preventing or delaying age‐related diseases than treat them one by one, which is the common approach in a current pharmacological disease‐oriented paradigm. To date, a variety of medications designed to treat particular pathological conditions have been shown to exhibit pro‐longevity effects in different experimental models. Among them, there are many commonly used prescription and over‐the‐counter pharmaceuticals such as metformin, rapamycin, aspirin, statins, melatonin, vitamin antioxidants, etc. All of them are being increasingly investigated in preclinical and clinical trials with the aim of determine whether they have potential for extension of human healthspan. The results from these trials are frequently inconclusive and fall short of initial expectations, suggesting that innovative research ideas and additional translational steps are required to overcome obstacles for implementation of such approaches in clinical practice. In this review, recent advances and challenges in the field of repurposing widely used conventional pharmaceuticals to target the aging process are summarized and discussed. [ABSTRACT FROM AUTHOR]

This aim was to examine differences on lumbar lordosis and thoracic kyphosis in standing position by gender, age and weight status in healthy subjects using a noninvasive method. A total of 297 women (36.6 ± 7.3 years) and 362 men (39.8 ± 7.5 years) participated in this study. Participants were categorized according to the international BMI (kg/m2) cut-off points. Age was stratified by ten years increments starting from 20 y. Men showed smaller lumbar lordosis (17.3 ± 9.3) and larger thoracic kyphosis (42.8 ± 8.8°) than women (29.6 ± 11.3 and 40.4 ± 9.5° respectively; both p < .001 ). Older groups presented smaller lumbar lordosis and larger thoracic kyphosis values compared with the 20-29 y group (20.9 ± 10.4,20.8 ±11.2 and 23.6 ± 12.6° for ≥50, 40-49 and 30-39 y, respectively vs. 26.7 ± 12.2° for 20-29 y in lumbar lordosis and 42.6 ± 9.8, 42.61 ± 8.7 and 41.8 ± 8.9° for ≥50, 40-49 and 30-39 y, respectively vs. 37.5 ± 10.9° for 20-29 y in thoracic kyphosis; both p < .05). Finally, overweight and obese groups showed smaller lumbar lordosis (19.4 ± 11.1 and 20.9 ± 11.8° respectively) and larger thoracic kyphosis values (42.7 ± 8.9 and 42.8 ± 9.4° respectively) compared with nonoverweight participants (25.1 ± 12.4 and 40.6 ± 9.2° for lumbar lordosis and thoracic kyphosis respectively; all p < .05). However, when gender, age and weight status were take into account all together only gender seems to influence the lumbar lordosis curvature. The results of this study suggest that gender could be the only determinant factor of lumbar lordosis in healthy people. [ABSTRACT FROM AUTHOR]

Aim The present cross-sectional study aimed at assessing muscle strength of hands, the dominant arm and legs in Spanish institutionalized elderly people according to sex, age and cognitive status. Methods A total of 153 elderly subjects (102 females, 51 males, mean age 83.6 ± 6.8 years) living in the region of Madrid were measured for handgrip strength (kg) with a Takei TKK 5101 digital dynamometer (range 5-100 kg, precision 0.1 kg), and arm and leg endurance strength (repetitions) according to the Rikli and Jones tests. Cognitive status was determined with the Mini- Mental State Examination ( MMSE). Results The values for men and women were, respectively: 23.5 ± 7.3 kg and 11.6 ± 4.6 kg (right handgrip), 22.0 ± 7.8 kg and 10.7 ± 4.8 kg (left handgrip), 13 ± 5 and 10 ± 5 repetitions (arm strength), 8 ± 5 and 5 ± 4 repetitions (legs strength), and 21 ± 6 and 17 ± 7 ( MMSE score). All parameters were significantly higher for men ( P ≤ 0.01), but strength decline with age was less pronounced in women. In all MMSE groups, lower strength was associated with lower cognitive status. Conclusions Strength values were lower in older subjects in both sexes; this difference was higher in men than in women. Higher strength values were associated with better cognitive status, which was the most influencing variable, even more than sex and age. Geriatr Gerontol Int 2013; 13: 1026-1034. [ABSTRACT FROM AUTHOR]

Background: Soluble Klotho (S-Klotho) is an aging suppressor with a close link with inflammation. However, it is still unknown whether the dietary inflammatory potential is associated with S-Klotho plasma level. We aimed to investigate the association of the Dietary Inflammatory Index (DII) with S-Klotho plasma levels in middle-aged sedentary adults. Methods: 73 middle-aged sedentary adults (40–65 years old) participated in the present study. DII was determined from 28 dietary items obtained by 24 h recalls and food frequency questionnaires. The S-Klotho plasma levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. Results: a weak positive association was observed between DII and S-Klotho plasma levels (β = 52.223, R2 = 0.057, p = 0.043), which disappeared after controlling for body mass index (p = 0.057). Conclusions: A pro-inflammatory dietary pattern measured with the DII was slightly and positively associated with S-Klotho plasma levels in middle-aged sedentary adults. [ABSTRACT FROM AUTHOR]

The main active metabolite of vitamin D, the 1,25-dihydroxyvitamin D (1,25(OH)2D), and the shed form of the α-Klotho gene (S-Klotho) play an important role in aging-related physiological processes and are currently considered powerful antiaging renal biomarkers. We aimed to investigate the relationship between 1,25(OH)2D and S-Klotho plasma levels in middle-aged sedentary healthy adults. We also aimed to study the mediation role of body composition, physical activity levels, dietary parameters, and blood markers in the association between 1,25(OH)2D and S-Klotho plasma levels. A total of 73 middle-aged sedentary adults (53.4% women; 53.7 ± 5.1 years old) were enrolled in this cross-sectional study. The 1,25(OH)2D plasma levels were measured using a DiaSorin Liaison® immunochemiluminometric analyzer. S-Klotho plasma levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. Body composition analysis was performed using dual-energy X-ray absorptiometry scanner. A tendency toward a negative association was observed between 1,25(OH)2D and S-Klotho plasma levels (β = -0.222, R2 = 0.049, p = 0.059). The association was attenuated after controlling for age and sex and become significant after controlling for fat mass index. In addition, the association between 1,25(OH)2D and S-Klotho levels was indirectly influenced by bone mineral density (BMD), with a percentage of mediation of 31.40%. Our study shows that 1,25(OH)2D is negatively associated with S-Klotho plasma levels in middle-aged sedentary adults, which is partially mediated by BMD. Clinicaltrial.gov: ID: NCT03334357. [ABSTRACT FROM AUTHOR]

The α-Klotho gene was identified as a possible "aging-suppressor" agent that extends life span when overexpressed. However, little is known about the association of the body composition with the secreted protein form of the α-Klotho gene (S-Klotho). Therefore, the aim of this study was to analyze the association of body composition, including lean and fat mass as well as bone mineral density (BMD), with S-Klotho plasma levels in middle-aged sedentary adults. A total of 74 (39 women) middle-aged sedentary adults (53.7 ± 5.1 years old; 75.7 ± 14.0 kg; 167.8 ± 9.8 cm) participated in the study. We measured weight and height, and we used dual-energy X-ray absorptiometry to measure fat mass and lean mass. We calculated the body mass index (BMI), fat mass index (FMI), and lean mass index (LMI). The S-Klotho plasma levels were measured in the ethylenediaminetetraacetic acid plasma using a solid-phase sandwich enzyme-linked immunosorbent assay. There was a strong positive association between LMI and S-Klotho plasma levels (β = 74.794, R2 = 0.346, p < 0.001), which persisted after controlling for age and gender as well as after additionally controlling for FMI. Significantly positive associations of BMI and BMD were also found with S-Klotho plasma levels (β = 33.981, R2 = 0.125, p = 0.002 and β = 858.194, R2 = 0.058, p = 0.041, respectively), which disappeared after controlling for LMI (β = 0.183, R2 = 0.611, p = 0.984 and β = -379.426, R2 = 0.617, p = 0.290, respectively). FMI was not significantly associated with S-Klotho plasma levels. Our study shows that LMI is strongly associated with S-Klotho plasma levels and explains the associations of BMI and BMD with S-Klotho plasma levels in middle-aged sedentary adults. [ABSTRACT FROM AUTHOR]