A clinical trial verifies the effectiveness of a diet based on the glycemic index on risk of cardiovascular disease and diabetes in overweight and obese.
A US randomized controlled trial Sacks and his colleagues, published in the Journal of American Medical Association in 2014, compared the effectiveness of four diets based on the glycemic index and carbohydrate intake on insulin sensitivity, on cholesterol and blood pressure. Make a diet based on the glycemic index is not better than a diet based on the glycemic intake to reduce the risk of cardiovascular disease or insulin resistance in overweight and obese.
The Study Rationale
Carbohydrate consumption in too much and too sweet concern for health professionals and policy makers. For the same amount of pure carbohydrate consumed each food containing carbohydrates causes an elevation different sugar levels in the blood called blood sugar. It is therefore possible to estimate the power of each food hyperglycaemic and compare them. This property is called the glycemic index. Over the glycemic index of a food, the greater insulin secretion is important in the health and vice versa. Insulin is a hormone for the transport and storage of glucose in the blood required by the body. Consuming too much of foods with a high glycemic index may result in a loss of sensitivity to insulin. Insulin resistance results in a blood glucose level remains high. In the long term health problems occur such as diabetes, obesity, hypertension and heart disease. While some nutritionists and some industrial advocate the consumption of low glycemic index foods, specific benefits are uncertain, especially when people already have a healthy diet rich in whole wheat, vegetables and fruits. A study was to answer this question.
Is there an advantage to follow a diet low glycemic index or low carbohydrate intake to reduce the risk of cardiovascular and metabolic disease?
A diet based on low glycemic index or a carbohydrate intake decreased in you it improves insulin sensitivity and the chances of avoiding cardiovascular disease?
The American randomized controlled trial Sacks and his staff of 163 participants older than 30 years without chronic disease. Their body mass index (BMI) greater than or equal to 25, so they were overweight or obese. The study was conducted in parallel in six US cities.
Main measures concerned the insulin sensitivity, systolic blood pressure, cholesterol linked to low density lipoproteins (LDL), cholesterol associated with high density lipoproteins (HDL) and triglyceride levels.
Participants completed a food diary in which they wrote daily food consumed. Eating meals (morning, afternoon and evening) was controlled by the study staff.
The Non-Pharmacological Intervention (NPI) assessed
The duration of the diets tested was approximately 28 weeks. Participants were followed by qualified medical professionals and trained specifically. Caloric intake was adjusted at the start of surgery to maintain the initial body weight.
The participants realized an eight-day test phase during which each of the four regimes of the study was prescribed for two days. Following this test phase, each diet was administered for five weeks, separated by a break of at least two weeks during which participants followed the system of their choice.
– Group 1 enjoyed a hyper-glycemic diet (58% of daily energy) with a high glycemic index, that is to say greater than or equal to 65 on the scale of the glycemic index of up 100.
– Group 2 also benefited from a hyper-glycemic diet with a low glycemic index, ie less than or equal to 45.
– Group 3 enjoyed a hypo-glycemic diet (40% of daily energy) with a low glycemic index, less than or equal to 45.
– Group 4 also enjoyed a hypoglycemic diet with a high glycemic index greater than or equal to 65.
The study shows that a hyper-glycemic diet combined with a low glycemic index reduces insulin sensitivity by 20%, LDL increases of 6% and does not affect HDL, triglyceride levels and blood pressure compared to hyper-glycemic diet that the glycemic index is high. A hypoglycemic diet combined with a low glycemic index does not affect measures except decreased triglyceride levels by 5% compared to a hypoglycemic regime that the glycemic index is high. A hypoglycemic diet with a low glycemic index does not affect sensitivity to insulin, systolic blood pressure, LDL or HDL compared to a high calorie diet with a high glycemic index. However, it lowers triglyceride levels by 23%.
Make a diet based on the glycemic index is not better than a diet based on the glycemic intake to reduce the risk of cardiovascular disease or insulin resistance for overweight and obese.
What it means for Parents of Children Overweight
A diet for 5 weeks based on a low glycemic index compared with a high glycemic index has not been shown to improve the sensitivity to insulin, lipids and blood pressure.
What it means for Healthcare Professionals
A diet consisting of low glycemic index foods does not improve risk factors for cardiovascular disease and diabetes compared a diet with a high glycemic index. It may even reduce the sensitivity to insulin and increase LDL cholesterol.
What it means for Researchers
Paradoxically, hyper-glycemic diet and low glycemic index decreases insulin sensitivity and increases the cholesterol level compared to a hyper-glycemic diet and high glycemic index. These findings run counter to a beneficial use of this type of diet based on the glycemic index.
What it means for Policymakers
A hyper-glycemic diet and low glycemic index decreases insulin sensitivity and increases the cholesterol level compared to a hyper-glycemic diet and high glycemic index. These results do not support the recommendation of diets based on the glycemic index in people who are overweight or obese.
Sacks FM, Carey VJ, Anderson CAM, Miller ER, Copeland T, Charleston J, Harshfield BJ, Laranjo N, McCarron P, Swain J, White K, Yee K, Appel LJ (2014). Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity. The OmniCarb Randomized Clinical Trial. Journal of American Medical Association, 312, 2531-2541.
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To reference this Blog en Sante © article
Ninot G (2015). A diet based on the glycemic index does not reduce the risk of metabolic diseases and cardiovascular. Blog en Sante, A56.
© Copyright 2015 Gregory Ninot. All rights reserved.