oa South African Journal of Clinical Nutrition - Some health benefits of low glycaemic index diets - a systematic review
Background. Controversy exists regarding practical use of the glycaemic index (GI), often with reference to the responsibility of health professionals to advise consumers only when scientific evidence supports their recommendations. There are indications that low-GI diets may improve health, but the strength of the evidence is not known.
Objectives. The objective of this systematic review was to determine the strength of scientific evidence encouraging dieticians to incorporate the GI concept when planning diets.
Design. A meta-analysis was performed as part of the systematic review. We searched for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low-GI versus high-GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), total cholesterol (TC) and triacylglycerols (TGs).
Results. Literature searches identified 13 studies that met strict inclusion criteria. Low-GI diets significantly reduced fructosamine by -0.1 mmol/l (confidence interval (CI): -0.20, 0.00, p = 0.05), HbA1c by 0.27% (CI: -0.5, -0.03; p = 0.03), LDLC in type 2 diabetics by -0.24 mmol/l (CI: -0.45, -0.04; p = 0.02) and TC by -0.33 mmol/l (CI: -0.47, -0.18; p < 0.0001) compared with high-GI diets. No effects were observed for HDLC and TGs.
Conclusion. This systematic review presents convincing evidence to recommend the use of the GI as a scientifically based tool when choosing carbohydrate-containing foods to reduce TC and LDLC concentrations and to improve overall metabolic control of diabetes.
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