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1.
Nutr Metab Cardiovasc Dis ; 34(2): 485-496, 2024 02.
Article in English | MEDLINE | ID: mdl-38172006

ABSTRACT

BACKGROUND AND AIMS: Type 2 diabetes (T2DM) is a major cause of morbidity and mortality globally. Carnosine, a naturally occurring dipeptide, has anti-inflammatory, antioxidant, and anti-glycating effects, with preliminary evidence suggesting it may improve important chronic disease risk factors in adults with cardiometabolic conditions. METHODS AND RESULTS: In this randomised controlled trial, 43 adults (30%F) living with prediabetes or T2DM consumed carnosine (2 g) or a matching placebo daily for 14 weeks to evaluate its effect on glucose metabolism assessed via a 2-h 75 g oral glucose tolerance test. Secondary outcomes included body composition analysis by dual energy x-ray absorptiometry (DEXA), calf muscle density by pQCT, and anthropometry. Carnosine supplementation decreased blood glucose at 90 min (-1.31 mmol/L; p = 0.02) and 120 min (-1.60 mmol/L, p = 0.02) and total glucose area under the curve (-3.30 mmol/L; p = 0.04) following an oral glucose tolerance test. There were no additional changes in secondary outcomes. The carnosine group results remained significant before and after adjustment for age, sex, and change in weight (all>0.05), and in further sensitivity analyses accounting for missing data. There were no significant changes in insulin levels. CONCLUSION: This study provides preliminary support for larger trials evaluating carnosine as a potential treatment for prediabetes and the initial stages of T2DM. Likely mechanisms may include changes to hepatic glucose output explaining the observed reduction in blood glucose without changes in insulin secretion following carnosine supplementation.


Subject(s)
Carnosine , Diabetes Mellitus, Type 2 , Prediabetic State , Adult , Humans , Blood Glucose , Carnosine/therapeutic use , Diabetes Mellitus, Type 2/diagnosis , Diabetes Mellitus, Type 2/drug therapy , Dietary Supplements , Glucose , Prediabetic State/diagnosis , Prediabetic State/drug therapy
2.
Eur J Nutr ; 62(2): 951-964, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36333495

ABSTRACT

PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m2) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.5 ± 14.7 nmol/L; treatment: 43.4 ± 18.4 nmol/L; P < 0.001) and reduced stair climb times (placebo: 0.3 ± 1.0 s; treatment: - 0.2 ± 1.0 s; P = 0.046). From 12 to 24 weeks, vitamin D supplementation combined with exercise decreased waist circumference (placebo: 1.3 ± 7.3 cm; treatment: - 3.0 ± 6.1 cm; P = 0.02) and waist-to-hip ratio (placebo: 0.01 ± 0.05; treatment: - 0.03 ± 0.05; P = 0.01) relative to placebo. Vitamin D supplementation, with or without exercise, had no effect on other physical function, body composition or metabolic health outcomes. CONCLUSION: Vitamin D supplementation had no effect on most physical function, body composition or metabolic health parameters when taken alone, or during exercise, in overweight or obese older adults with vitamin D deficiency. Vitamin D-related improvements in stair climb times and waist circumference suggest that future trials should explore the effects of vitamin D on muscle power, and its effects on body composition when combined with exercise, in populations with moderate or severe vitamin D deficiency.


Subject(s)
Overweight , Vitamin D Deficiency , Humans , Aged , Middle Aged , Pilot Projects , Dietary Supplements , Obesity , Vitamin D , Vitamins , Cholecalciferol , Body Composition , Double-Blind Method
3.
J Cachexia Sarcopenia Muscle ; 13(3): 1642-1652, 2022 06.
Article in English | MEDLINE | ID: mdl-35261183

ABSTRACT

BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis. A significant decrease in SPPB scores was observed with vitamin D supplementation compared with placebo (MD: -0.23; 95% CI -0.40 to -0.06; I2  = 0%; P = 0.007). Vitamin D supplementation conferred no effect on HGS (MD: -0.07 kg; 95% CI -0.70 to 0.55; I2  = 51%, P = 0.82), TUG (MD: 0.07 s; 95% CI -0.08 to 0.22; I2  = 0%, P = 0.35), ALM (MD: 0.06 kg/m2 ; 95% CI: -0.32 to 0.44; I2  = 73%, P = 0.77), general muscle strength (SMD: -0.01; 95% CI -0.17 to 0.15; I2  = 42%, P = 0.90), or general physical performance (SMD: -0.02; 95% CI -0.23 to 0.18; I2  = 71%, P = 0.83). CONCLUSIONS: Vitamin D supplementation did not improve any sarcopenia indices in community-dwelling older adults and may compromise some aspects of physical performance. Future studies are warranted to investigate the impact of vitamin D supplementation on individual indices of SPPB, including mobility and balance, in older adults.


Subject(s)
Sarcopenia , Aged , Dietary Supplements , Humans , Independent Living , Sarcopenia/drug therapy , Vitamin D/therapeutic use , Vitamins/therapeutic use
4.
J Steroid Biochem Mol Biol ; 186: 169-175, 2019 02.
Article in English | MEDLINE | ID: mdl-30367939

ABSTRACT

This randomised placebo-controlled trial aimed to determine the effect of 16-weeks cholecalciferol supplementation on calcium-phosphate homeostasis and bone mineral density (BMD) in overweight and obese adults. Fifty-four vitamin D-deficient (25OHD<50 nmol/L), overweight and obese adults (mean age 32 ± 8.5 years) were included in the trial. Participants were randomly assigned to receive either a bolus oral dose of 100,000 IU cholecalciferol followed by 4000 IU cholecalciferol/d or a matching placebo for 16 weeks. Before and after the intervention, serum calcium, phosphate, 25-hydroxyvitamin D [25(OH)D], intact parathyroid hormone (iPTH) and C-terminal plasma fibroblast growth factor-23 (cFGF-23) concentrations were measured. Whole-body BMD was assessed using dual-energy X-ray absorptiometry (DXA) and diet and sun exposure were assessed using self-administered questionnaires. There were no significant differences in baseline characteristics between the vitamin D and placebo group. After 16-weeks of vitamin D supplementation, mean changes in 25(OH)D concentration were higher in the vitamin D group (57 nmol/L 95% CI 49, 65) compared with placebo (2 nmol/L 95% CI -4, 8), P < 0.001. Additionally, iPTH concentrations declined in the vitamin D group (-1.19 pmol/L 95% CI -1.9, -0.47) compared with placebo (0.14 pmol/L 95% CI -0.49, 0.77), P = 0.006. There were no significant differences in calcium, phosphate, iPTH and cFGF-23 concentrations and whole-body BMD between vitamin D and placebo at follow-up. Inverse correlations were observed between mean change in serum iPTH and cFGF-23 in the vitamin D group only (r=-0.41, P = 0.029). In individuals with greater vitamin D deficiency at baseline (25(OH)D < 30 nmol/L), there was a significant increase in mean whole-body BMD (0.01 g/cm2, 95% CI 0.001, 0.025) however, the mean change in BMD was not different between vitamin D and placebo groups in this sub-group analysis. We conclude that cholecalciferol supplementation for 16 weeks increases serum 25(OH)D concentrations and reduces iPTH concentrations in overweight and obese, but otherwise healthy adults with vitamin D deficiency, and has no effect on calcium, phosphate and iFGF-23 concentrations and whole-body BMD.


Subject(s)
Calcium/blood , Cholecalciferol/therapeutic use , Overweight/complications , Phosphates/blood , Vitamin D Deficiency/complications , Vitamin D Deficiency/drug therapy , Vitamins/therapeutic use , Adult , Bone Density/drug effects , Fibroblast Growth Factor-23 , Fibroblast Growth Factors/blood , Humans , Obesity/blood , Obesity/complications , Overweight/blood , Parathyroid Hormone/blood , Placebo Effect , Vitamin D/analogs & derivatives , Vitamin D/blood , Vitamin D Deficiency/blood
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