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Irisin Serum Levels in Metabolic Syndrome Patients Treated with Three Different Diets: A Post-Hoc Analysis from a Randomized Controlled Clinical Trial.
Osella, AR, Colaianni, G, Correale, M, Pesole, PL, Bruno, I, Buongiorno, C, Deflorio, V, Leone, CM, Colucci, SC, Grano, M, et al
Nutrients. 2018;(7)
Abstract
BACKGROUND Irisin, a hormone-like myokine, regulates energy homeostasis and mediates the benefits of physical activity on health. METHODS To estimate the effect of different diets on irisin concentrations in subjects with the Metabolic Syndrome (MetS). METHODS Subjects with MetS were derived from a population survey; 163 subjects were enrolled and randomized to a: Low Glycaemic Index (LGID), Mediterranean (MD) or Low Glycaemic Index Mediterranean (LGIMD) Diet, and the groups were compared, also with 80 controls without MetS. Sociodemographic, medical and nutritional data were collected and fasting blood samples drawn. Subjects underwent LUS and bioimpedentiometry. Generalized Estimating Equations were performed. RESULTS At baseline, lower irisin concentrations were observed in MetS subjects. Mean irisin levels increased in all diet groups but only the LGID group reached statistical significance, as well as showing an interaction between LGID and time at the sixth month examination (4.57, 95% CI −1.27, 7.87). There was a positive effect of Vegetable Proteins (0.03, 95% CI −0.01,0.06) and Saturated Fatty Acids (0.04, 95% CI 0.01, 0.07) on irisin concentrations. In the LGIMD, a positive effect on Fat-Free Mass (0.38, 95% CI 0.19, 0.57) and a negative effect on the Body Mass Index (−0.75, 95% CI −1.30, −0.19) were observed. CONCLUSIONS There seems to be a link between diet and muscle physiology. We showed that patients following a LGID had higher levels of irisin, a promising biomarker of muscle activity.
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Intramyocellular lipid content is lower with a low-fat diet than with high-fat diets, but that may not be relevant for health.
St-Onge, MP, Newcomer, BR, Buchthal, S, Aban, I, Allison, DB, Bosarge, A, Gower, B
The American journal of clinical nutrition. 2007;(5):1316-22
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Abstract
BACKGROUND Fat deposition in muscle has been found to be related to metabolic risk. OBJECTIVE This study compared soleus intramyocellular lipid (IMCL) concentrations after consumption of weight-maintaining, controlled diets differing in total fat and fat type. DESIGN This study consisted of 3 phases of 25 d each in a crossover, controlled feeding design. The low-fat (LF) diet provided 30.8% and 5.2% of energy from fat and polyunsaturated fat (PUFA), respectively. Two higher-fat diets were tested: the high-fat (HF) diet provided 37.9% and 5.8% of energy from fat and PUFA, respectively, and the high-PUFA (HPUFA) diet provided 36.3% and 9.7% of energy from fat and PUFA, respectively. Twenty-four men and women [age range: 19-65 y; body mass index (in kg/m(2)): 20-35] whose LDL and glucose concentrations were between 130 and 180 mg/dL and <126 mg/dL, respectively, completed all study phases. RESULTS IMCL content was 1.88 times as high after the HF diet (P = 0.005) and 1.71 times as high after the HPUFA diet (P = 0.002) as after the LF diet. There was no significant correlation between percentage fat mass or waist circumference and IMCL content. With pooled data from all diets, there was no significant correlation between IMCL content and insulin or glucose concentration. There was no significant difference in IMCL content in subjects with or without the metabolic syndrome or in subjects with LDL particle pattern A or B. CONCLUSIONS Our results suggest that IMCL content is not modulated by dietary fat type but by total fat intake and that reducing fat intake effectively lowers IMCL. However, the metabolic implications of having lower IMCL concentrations are not clear.