Abstract
BackgroundLow-carbohydrate diets are associated with cardiovascular risk factors; however, the results of different studies are inconsistent.PurposeThe aim of this meta-analysis was to assess the relationship between low-carbohydrate diets and cardiovascular risk factors.MethodFour electronic databases (PubMed, Embase, Medline, and the Cochrane Library) were searched from their inception to November 2018. We collected data from 12 randomized trials on low-carbohydrate diets including total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, and blood pressure levels, as well as weight as the endpoints. The average difference (MD) was used as the index to measure the effect of a low-carbohydrate diet on cardiovascular risk factors with a fixed-effects model or random-effects model. The analysis was further stratified by factors that might affect the results of the intervention.ResultsFrom 1292 studies identified in the initial search results, 12 randomized studies were included in the final analysis, which showed that a low-carbohydrate diet was associated with a decrease in triglyceride levels of -0.15mmol/l (95% confidence interval -0.23 to -0.07). Low-carbohydrate diet interventions lasting less than 6 months were associated with a decrease of -0.23mmol/l (95% confidence interval -0.32 to -0.15), while those lasting 12–23 months were associated with a decrease of -0.17mmol/l (95% confidence interval -0.32 to -0.01). The change in the body weight in the observation groups was -1.58kg (95% confidence interval -1.58 to -0.75); with for less than 6 months of intervention,this change was -1.14 kg (95% confidence interval -1.65 to -0.63),and with for 6–11 months of intervention, this change was -1.73kg (95% confidence interval -2.7 to -0.76). The change in the systolic blood pressure of the observation group was -1.41mmHg (95% confidence interval—2.26 to -0.56); the change in diastolic blood pressure was -1.71mmHg (95% confidence interval—2.36 to -1.06); the change in plasma HDL-C levels was 0.1mmHg (95% confidence interval 0.08 to 0.12); and the change in serum total cholesterol was 0.13mmol/l (95% confidence interval 0.08 to 0.19). The plasma LDL-C level increased by 0.11mmol/l (95% confidence interval 0.02 to 0.19), and the fasting blood glucose level changed 0.03mmol/l (95% confidence interval -0.05 to 0.12),which was not significant.ConclusionsThis meta-analysis confirms that low-carbohydrate diets have a beneficial effect on cardiovascular risk factors but that the long-term effects on cardiovascular risk factors require further research.
Highlights
The plasma low-density lipoprotein cholesterol (LDL-C) level increased by 0.11mmol/l (95% confidence interval 0.02 to 0.19), and the fasting blood glucose level changed 0.03mmol/l (95% confidence interval -0.05 to 0.12),which was not significant
This meta-analysis confirms that low-carbohydrate diets have a beneficial effect on cardiovascular risk factors but that the long-term effects on cardiovascular risk factors require further research
According to statistics from the World Health Organization, 17 million people die of cardiovascular disease every year [1], and 80% of cardiovascular disease deaths occur in developing countries [2]
Summary
According to statistics from the World Health Organization, 17 million people die of cardiovascular disease every year [1], and 80% of cardiovascular disease deaths occur in developing countries [2]. Diets with high levels of carbohydrates, especially refined or high glycemic index carbohydrates, appear to be associated with hypertension, coronary heart disease, obesity, type 2 diabetes, metabolic syndrome and increased risk of mortality.[6,7,8]. The public has become increasingly aware of this problem and its impact on global health. This problem is speculated to be caused by excessive energy intake, low energy consumption, or both. Studies have shown that low-carbohydrate diets are effective for losing weight, improving cardiovascular risk factors and preventing or treating diabetes [11,12,13]. Low-carbohydrate diets are associated with cardiovascular risk factors; the results of different studies are inconsistent. Editor: Wisit Cheungpasitporn, University of Mississippi Medical Center, UNITED STATES
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