Cardiovascular diseases, including heart attacks and strokes, are the leading causes of death worldwide, accounting for 32% of deaths. 

While there is clear, convincing evidence of the positive effect of a carbohydrate-restricted diet (CRD) on type 2 diabetes and obesity, the effect on cardiovascular disease has been a subject of much debate.

A recent paper by researchers at Texas A&M University should settle the issue once and for all.

The authors analysed 174 randomised clinical trials (RCTs) published between 1992 and 2025 that met strict criteria and included results from 11,481 participants across 27 countries.

The results showed that, compared with higher carbohydrate diets, CRDs significantly reduced both systolic and diastolic blood pressure, triglycerides, LDL–HDL ratio, TG-HDL ratio, VLDL, and ApoB-ApoA1 ratio, and other endothelial and inflammatory markers such as CRP and TNF-α. Increases were observed in total cholesterol, LDL cholesterol, HDL cholesterol and ApoA1. All measures of body composition (body weight, BMI, etc) were lowered. The overall cardiovascular risk was decreased.

The study authors divided the CRDs into three groups: a ketogenic diet (KD) with <10% of calories from carbohydrates, a low-carb diet (LCD) with 10-26% of calories from carbohydrates, and a moderate-carb diet (MCD) with 26-45% of calories from carbohydrates. All three groups demonstrated significant cardiovascular benefits, including reduced TG and increased HDL cholesterol, as well as reductions in body weight and BMI.

They also compared different carbohydrate replacements—fat, protein, and a combination of the two —and found that the combination exerted the broadest cardiovascular benefits.

In the discussion section of the paper, the authors addressed the critical question, given the mixed lipid results, of whether CRDs are ultimately beneficial for cardiovascular health. They concluded that their meta-analysis further evaluated stronger predictors of cardiovascular disease risk—lipid ratios (LDL–HDL, TG-HDL, and ApoB-ApoA1). Their findings demonstrated favourable effects on all these lipid ratios.

Additionally, CRDs reduced inflammation and endothelial dysfunction markers (CRP, IL-6, and E-selectin).

Overall, as in previous studies, CRDs were associated with a significant reduction in CVD risk.

I particularly note the triglyceride-HDL (Trig-HDL) ratio, as it has been shown to be a strong indicator of insulin resistance. This ratio improved across all three groups, indicating a reduction in insulin resistance.

All in all, these results show a very positive effect of a reduced carbohydrate diet on cardiovascular health.