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Diverging metabolic effects of 2 energy-restricted diets differing in nutrient quality: a 12-week randomized controlled trial in subjects with abdominal obesity.
Schutte, S, Esser, D, Siebelink, E, Michielsen, CJR, Daanje, M, Matualatupauw, JC, Boshuizen, HC, Mensink, M, Afman, LA
The American journal of clinical nutrition. 2022;116(1):132-150
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Energy restriction (ER) diets are considered an effective strategy for managing obesity and preventing or reducing the risk of associated comorbidities. However, there are very few previous studies comparing the quality of energy restriction diets and their effect on maximising the health benefits. Therefore, this 12-week, parallel-designed, randomised controlled trial compared the effects of a 25% high-quality ER diet with a 25% low-quality ER diet and a habitual diet on cardiometabolic risk factors of 110 participants with abdominal obesity. Both ER diets were nutritionally balanced. The high-quality ER diet had added Monounsaturated fatty acids (MUFAs), Omega-3 Polyunsaturated fatty acids (n-3 PUFAs), fibre, and plant protein and had less fructose in it. The low-quality ER diet contained Saturated fatty acids (SFAs) and monosaccharides such as fructose. At the end of the 12-week trial, participants on the 25% high-quality diet showed more promising results in weight loss, reduction in cholesterol and triglycerides, and adipose tissue gene expression of energy metabolism pathways compared to the 25% low-quality ER diet. Insulin-sensitive participants with abdominal obesity on a 25% high-quality diet lost more weight compared to the rest of the participants. Further robust studies are required to evaluate the findings due to the limitations of this study. However, healthcare professionals can use the results of this study to understand the beneficial effects of an ER diet when it is enriched with specific nutrients.
Abstract
BACKGROUND Despite the established relation between energy restriction (ER) and metabolic health, the most beneficial nutrient composition of a weight-loss diet is still a subject of debate. OBJECTIVES The aim of the study was to examine the additional effects of nutrient quality on top of ER. METHODS A parallel-designed, 12-week 25% ER dietary intervention study was conducted (clinicaltrials.gov: NCT02194504). Participants aged 40-70 years with abdominal obesity were randomized over 3 groups: a 25% ER high-nutrient-quality diet (n = 40); a 25% ER low-nutrient-quality diet (n = 40); or a habitual diet (n = 30). Both ER diets were nutritionally adequate, and the high-nutrient-quality ER diet was enriched in MUFAs, n-3 PUFAs, fiber, and plant protein and reduced in fructose. Before and after the intervention, intrahepatic lipids, body fat distribution, fasting and postprandial responses to a mixed-meal shake challenge test of cardiometabolic risk factors, lipoproteins, vascular measurements, and adipose tissue transcriptome were assessed. RESULTS The high-nutrient-quality ER diet (-8.4 ± 3.2) induced 2.1 kg more weight loss (P = 0.007) than the low-nutrient-quality ER diet (-6.3 ± 3.9), reduced fasting serum total cholesterol (P = 0.014) and plasma triglycerides (P < 0.001), promoted an antiatherogenic lipoprotein profile, and induced a more pronounced decrease in adipose tissue gene expression of energy metabolism pathways than the low-quality ER diet. Explorative analyses showed that the difference in weight loss between the two ER diets was specifically present in insulin-sensitive subjects (HOMA-IR ≤ 2.5), in whom the high-nutrient-quality diet induced 3.9 kg more weight loss than the low-nutrient-quality diet. CONCLUSIONS A high-nutrient-quality 25% ER diet is more beneficial for cardiometabolic health than a low-nutrient-quality 25% ER diet. Overweight, insulin-sensitive subjects may benefit more from a high- than a low-nutrient-quality ER diet with respect to weight loss, due to potential attenuation of glucose-induced lipid synthesis in adipose tissue.
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Vitamin D supplementation for the prevention of type 2 diabetes in overweight adults: study protocol for a randomized controlled trial.
de Courten, B, Mousa, A, Naderpoor, N, Teede, H, de Courten, MP, Scragg, R
Trials. 2015;16:335
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With the rising rates of vitamin D deficiency, identifying cost-effective, preventative strategies are imperative. Vitamin D plays a well-known role in bone mineralisation, however its protective role against chronic diseases is not very well understood. The aim of this trial is to investigate whether vitamin D supplementation will increase insulin sensitivity and secretion, as well as to determine whether vitamin D deficiency underlies the inflammatory properties associated with obesity. 50 overweight adults between 18 and 60 years old were recruited and assigned to receive either 4,000 IU vitamin D daily or identical placebo capsules for 16 weeks. This study elucidates the potential role vitamin D supplementation could have on preventing diabetes and its associated co-morbidities. It also provides comprehensive insight into the potential mechanisms of action. The authors conclude that this trial can corroborate existing knowledge while expanding the understanding on the role of vitamin D in the inflammatory response and subsequent development of disease.
Abstract
BACKGROUND Despite Australia's sunny climate, low vitamin D levels are increasingly prevalent. Sun exposure is limited by long working hours, an increase in time spent indoors, and sun protection practices, and there is limited dietary vitamin D fortification. While the importance of vitamin D for bone mineralization is well known, its role as a protective agent against chronic diseases, such as type 2 diabetes and cardiovascular disease, is less understood. Observational and limited intervention studies suggest that vitamin D might improve insulin sensitivity and secretion, mainly via its anti-inflammatory properties, thereby decreasing the risk of development and progression of type 2 diabetes. The primary aim of this trial is to investigate whether improved plasma concentrations of 25-hydroxyvitamin D (25(OH)D), obtained through vitamin D supplementation, will increase insulin sensitivity and insulin secretion. A secondary aim is to determine whether these relationships are mediated by a reduction in underlying subclinical inflammation associated with obesity. METHODS/DESIGN Fifty overweight but otherwise healthy nondiabetic adults between 18 and 60 years old, with low vitamin D levels (25(OH)D < 50 nmol/l), will be randomly assigned to intervention or placebo. At baseline, participants will undergo a medical review and anthropometric measurements, including dual X-ray absorptiometry, an intravenous glucose tolerance test, muscle and fat biopsies, a hyperinsulinemic euglycemic clamp, and questionnaires assessing diet, physical activity, sun exposure, back and knee pain, and depression. The intervention group will receive a first dose of 100,000 IU followed by 4,000 IU vitamin D (cholecalciferol) daily, while the placebo group will receive apparently identical capsules, both for a period of 16 weeks. All measurements will be repeated at follow-up, with the primary outcome measure expressed as a change from baseline in insulin sensitivity and secretion for the intervention group compared with the placebo group. Secondary outcome measures will compare changes in anthropometry, cardiovascular risk factors, and inflammatory markers. DISCUSSION The trial will provide much needed clinical evidence on the impact of vitamin D supplementation on insulin resistance and secretion and its underlying mechanisms, which are relevant for the prevention and management of type 2 diabetes. TRIAL REGISTRATION Clinicaltrials.gov ID: NCT02112721 .
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Dairy proteins, dairy lipids, and postprandial lipemia in persons with abdominal obesity (DairyHealth): a 12-wk, randomized, parallel-controlled, double-blinded, diet intervention study.
Bohl, M, Bjørnshave, A, Rasmussen, KV, Schioldan, AG, Amer, B, Larsen, MK, Dalsgaard, TK, Holst, JJ, Herrmann, A, O'Neill, S, et al
The American journal of clinical nutrition. 2015;101(4):870-8
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The health effects of dairy products on cardiovascular disease (CVD), diabetes, obesity and total mortality may depend on their varying composition. This study aims to examine the long-term effects of milk proteins (whey and casein) and milk with a high or low content of medium-chain saturated fatty acids (MC-SFAs) on postprandial lipid metabolism. In this randomised, parallel-controlled, double-blinded, 12-week intervention study, 63 abdominally obese individuals were randomised to one of four diets, containing different compositions of whey, casein and MC-SFAs. Results showed that whey compared to casein significantly decreased postprandial apoB-48, independently of the fatty acid composition. Fasting and postprandial triacylglycerol and FFA responses were independent of protein or fatty acids composition. Authors conclude that 12-week supplementation with whey protein reduces postprandial apoB-48 compared to casein, indicating a beneficial effect on CVD risk.
Abstract
BACKGROUND Abdominal obesity and exaggerated postprandial lipemia are independent risk factors for cardiovascular disease (CVD) and mortality, and both are affected by dietary behavior. OBJECTIVE We investigated whether dietary supplementation with whey protein and medium-chain saturated fatty acids (MC-SFAs) improved postprandial lipid metabolism in humans with abdominal obesity. DESIGN We conducted a 12-wk, randomized, double-blinded, diet intervention study. Sixty-three adults were randomly allocated to one of 4 diets in a 2 × 2 factorial design. Participants consumed 60 g milk protein (whey or casein) and 63 g milk fat (with high or low MC-SFA content) daily. Before and after the intervention, a high-fat meal test was performed. We measured changes from baseline in fasting and postprandial triacylglycerol, apolipoprotein B-48 (apoB-48; reflecting chylomicrons of intestinal origin), free fatty acids (FFAs), insulin, glucose, glucagon, glucagon-like peptide 1 (GLP-1), and gastric inhibitory polypeptide (GIP). Furthermore, changes in the expression of adipose tissue genes involved in lipid metabolism were investigated. Two-factor ANOVA was used to examine the difference between protein types and fatty acid compositions, as well as any interaction between the two. RESULTS Fifty-two participants completed the study. We found that the postprandial apoB-48 response decreased significantly after whey compared with casein (P = 0.025) independently of fatty acid composition. Furthermore, supplementation with casein resulted in a significant increase in the postprandial GLP-1 response compared with whey (P = 0.003). We found no difference in postprandial triacylglycerol, FFA, insulin, glucose, glucagon, or GIP related to protein type or MC-SFA content. We observed no interaction between milk protein and milk fat on postprandial lipemia. CONCLUSION We found that a whey protein supplement decreased the postprandial chylomicron response compared with casein in persons with abdominal obesity, thereby indicating a beneficial impact on CVD risk. This trial was registered at clinicaltrials.gov as NCT01472666.