The Effect of Low-carbohydrate Diets on Cardiovascular Risk Factors: Meta-Analysis
Date Issued
2007
Date
2007
Author(s)
Hsueh, Yu-Pei
DOI
zh-TW
Abstract
Background
Attention on low-carbohydrate diets is increasing with the popularity of weight loss. However, trials showed contradictory results on benefits and risks of these diets to achieve weight loss and modify cardiovascular risk factors. The objective of this meta-analysis was to determine the effect of low-carbohydrate diets on weight, serum lipids, fasting glucose, and blood pressure. In addition, meta-regression was applied to characterize the components of low-carbohydrate diets that affect changes in cardiovascular risk factors.
Methods
PUBMED engine was used for searching literatures about low-carbohydrate diets published between January 1, 1998 and December 31, 2006. We selected articles which recruited control groups and presented diet contents and at least one of the cardiovascular risk factors. After characteristics of study, diet variables, and outcome were independently abstracted by two researchers, meta-analysis, meta-regression, and trend surface analysis were done.
Results
21 studies which included in meta-analysis showed low-carbohydrate diets group lose more 1.6kg (95%CI, 0.4~2.8kg) of weight than the control group. Triglycerides (weighted difference in changes, -0.25mmol/L; 95%CI, -0.32 to -0.18mmol/L) and high-density lipoprotein cholesterol (weighted difference in increment, +0.1mmol/L; 95%CI, +0.06 to +0.15mmol/L) levels changed more favorably in individuals assigned to low-carbohydrate diets, but total cholesterol (weighted difference in changes, 0.12mmol/L; 95%CI, 0.05 to 0.41mmol/L) and low-density lipoprotein cholesterol (weighted difference in changes, 0.28mmol/L; 95%CI, 0.14 to 0.42mmol/L) values changed more favorably in individuals assigned to control group. The results of meta-regression indicated that no single macronutrient by itself contributed to the outcomes. Contrarily it is the macronutrient combination of “low-carbohydrate, moderate protein, and high-fat” that betters weight, high-density lipoprotein cholesterol and triglycerides, according to trend surface analysis. Intakes of “high-carbohydrate and low-fat” tend to reduce total cholesterol and low-density lipoprotein cholesterol.
Conclusion
Compared with ”low-fat and energy-deficit” diets, combination of “low-carbohydrate, moderate protein, and high-fat” showed effects on losing weight, reducing triglycerides, increasing high-density lipoprotein cholesterol, as well as raising low-density lipoprotein cholesterol level. Future studies with experimental designs might be needed to investigate the best ratios of different fatty acid contents in the “low-carbohydrate, moderate protein, and high-fat” diets in order to achieve a favorable cardiovascular profile.
Subjects
低碳水化合物飲食
心血管危險因子
整合分析
The Effect of Low-carbohydrate Diets
Cardiovascular Risk Factors
Meta-Analysis
Type
thesis
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