Low glycaemic index diets and blood lipids: a systematic review and meta-analysis of randomised controlled trials.

Low glycaemic index (GI) diets are beneficial in the management of hyperglycemia. Cardiovascular diseases are the major cause of mortality in diabetes therefore it is important to understand the effects of GI on blood lipids. The aim was to systematically review randomised controlled trials (RCTs) of low GI diets on blood lipids. We searched OVID Medline, Embase and Cochrane library to March 2012. Random effects meta-analyses were performed on twenty-eight RCTs comparing low- with high GI diets over at least 4 weeks (1272 participants; studies ranged from 6 to 155 participants); one was powered on blood lipids, 3 had adequate allocation concealment. Low GI diets significantly reduced total (-0.13 mmol/l, 95%CI -0.22 to -0.04, P = 0.004, 27 trials, 1441 participants, I(2) = 0%) and LDL-cholesterol (-0.16 mmol/l, 95%CI -0.24 to -0.08, P < 0.0001, 23 trials, 1281 participants, I(2) = 0%) compared with high GI diets and independently of weight loss. Subgroup analyses suggest that reductions in LDL-C are greatest in studies of shortest duration and greatest magnitude of GI reduction. Furthermore, lipid improvements appear greatest and most reliable when the low GI intervention is accompanied by an increase in dietary fibre. Sensitivity analyses, removing studies without adequate allocation concealment, lost statistical significance but retained suggested mean falls of ~0.10 mmol/l in both. There were no effects on HDL-cholesterol (MD -0.03 mmol/l, 95%CI -0.06 to 0.00, I(2) = 0%), or triglycerides (MD 0.01 mmol/l, 95%CI -0.06 to 0.08, I(2) = 0%). This meta-analysis provides consistent evidence that low GI diets reduce total and LDL-cholesterol and have no effect on HDL-cholesterol or triglycerides.

Goff LM ，Cowland DE ，Hooper L ，Frost GS ... -  《-》

Effects of low-fat diet on serum lipids in premenopausal and postmenopausal women: a meta-analysis of randomized controlled trials.

Wu L ，Ma D ，Walton-Moss B ，He Z ... -  《-》

Low-glycaemic index diets in the management of blood lipids: a systematic review and meta-analysis.

Fleming P ，Godwin M 《-》

Dietary fibre for the primary prevention of cardiovascular disease.

Hartley L ，May MD ，Loveman E ，Colquitt JL ，Rees K ... -  《Cochrane Database of Systematic Reviews》

Comparison of effects of long-term low-fat vs high-fat diets on blood lipid levels in overweight or obese patients: a systematic review and meta-analysis.

Dietary fat plays an important role in the primary prevention of cardiovascular disease, but long-term (≥12 months) effects of different percentages of fat in the diet on blood lipid levels remain to be established. Our systematic review and meta-analysis focused on randomized controlled trials assessing the long-term effects of low-fat diets compared with diets with high amounts of fat on blood lipid levels. Relevant randomized controlled trials were identified searching MEDLINE, EMBASE, and the Cochrane Trial Register until March 2013. Thirty-two studies were included in the meta-analysis. Decreases in total cholesterol (weighted mean difference -4.55 mg/dL [-0.12 mmol/L], 95% CI -8.03 to -1.07; P=0.01) and low-density lipoprotein (LDL) cholesterol (weighted mean difference -3.11 mg/dL [-0.08 mmol/L], 95% CI -4.51 to -1.71; P<0.0001) were significantly more pronounced following low-fat diets, whereas rise in high-density lipoprotein (HDL) cholesterol (weighted mean difference 2.35 mg/dL [0.06 mmol/L], 95% CI 1.29 to 3.42; P<0.0001) and reduction in triglyceride levels (weighted mean difference -8.38 mg/dL [-0.095 mmol/L], 95% CI -13.50 to -3.25; P=0.001) were more distinct in the high-fat diet groups. Including only hypocaloric diets, the effects of low-fat vs high-fat diets on total cholesterol and LDL cholesterol levels were abolished. Meta-regression revealed that lower total cholesterol level was associated with lower intakes of saturated fat and higher intakes of polyunsaturated fat, and increases in HDL cholesterol levels were related to higher amounts of total fat largely derived from monounsaturated fat (of either plant or animal origin) in high-fat diets (composition of which was ~17% of total energy content in the form of monounsaturated fatty acids, ~8% of total energy content in the form of polyunsaturated fatty acids), whereas increases in triglyceride levels were associated with higher intakes of carbohydrates. In addition, lower LDL cholesterol level was marginally associated with lower saturated fat intake. The results of our meta-analysis do not allow for an unequivocal recommendation of either low-fat or high-fat diets in the primary prevention of cardiovascular disease.

Schwingshackl L ，Hoffmann G 《Journal of the Academy of Nutrition and Dietetics》