What is the clinical evidence from this study?

Study design: Observational. Population: Coronary artery disease (CAD) (n=313). Intervention: Low-carbohydrate or low-fat diet vs. Regular diet (40% carbohydrates, 40% fat, 20% protein). Primary outcome: Change in 10-year cardiovascular mortality risk (CRBS score) during 3-4 weeks of inpatient CR (p=0.8651).

What does this research mean for the field?

Low-carbohydrate and low-fat diets do not provide additional reduction in 10-year cardiovascular mortality risk compared to a regular diet during inpatient cardiac rehabilitation for patients with coronary artery disease. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

October 23, 2025Frontiers in Nutrition1 citationsOpen Access

Biomarker-based risk assessment of dietary intervention in patients with coronary artery disease during cardiac rehabilitation—a quasi-experimental study

MKMona KotewitschWitten/Herdecke University HSHubert ScharnaglGeneral / Preventive / Lipids DKDennis KöstlerWitten/Herdecke University

Key Result

During 3-4 weeks of inpatient cardiac rehabilitation, low-carbohydrate and low-fat diets did not provide additional reduction in 10-year cardiovascular mortality risk compared to a regular diet.

Study Design

Type

Observational (n=313)

Blinding

Open-label

Randomization

Non-randomized

Multicenter

Structured PICO

Does a low-carbohydrate or low-fat diet improve cardiovascular risk scores, body composition, or MACCE compared to a regular diet in patients with coronary artery disease undergoing cardiac rehabilitation?

Population

313 patients with coronary artery disease undergoing inpatient cardiac rehabilitation, followed for a mean of 470 days.

Intervention

Low-carbohydrate diet (≤25% carbohydrates, 45% fats, 30% proteins) or low-fat diet (55% carbohydrates, ≤30% fats, 15% proteins) provided as full board meals during 3-4 weeks of inpatient cardiac rehabilitation.

Comparator

Regular standard diet (~40% carbohydrates, 40% fat, 20% protein) provided as full board meals during 3-4 weeks of inpatient cardiac rehabilitation.

Outcome

10-year cardiovascular mortality risk estimated by the cardiac rehabilitation biomarker score (CRBS), body composition changes, and major adverse cardiovascular and cerebrovascular events (MACCE) at a mean follow-up of 470 ± 293 days.surrogate

In patients with CAD undergoing cardiac rehabilitation, low-carb and low-fat diets yielded similar reductions in 10-year cardiovascular mortality risk and MACCE compared to a regular diet, though they provided greater short-term reductions in body and visceral fat.

Main Result

Absolute Event Rate: -4.2% vs -3.5%

p-value: p=0.8651

Limitations

Non-randomized design with assisted patient self-selection into dietary arms, introducing potential selection bias
Short controlled intervention phase of 3 to 4 weeks
Post-discharge dietary adherence was not systematically assessed
Study was underpowered to detect smaller but potentially clinically meaningful differences in MACCE incidence

Abstract

Background and aims Cardiac rehabilitation (CR) is integral to secondary prevention in coronary artery disease (CAD), incorporating exercise, medical optimization, and dietary interventions. While low-carbohydrate (low-carb) and low-fat diets may improve metabolic health, their comparative impact on cardiovascular risk in CR remains unclear. This study assessed the effects of low-carb and low-fat diets on cardiovascular risk, body composition, and major adverse cardiovascular and cerebrovascular events (MACCE) in CAD patients undergoing inpatient CR. Methods In this quasi-experimental study, 313 CAD patients (56 ± 7 years, 20% women) participated in CR, adopting a low-carb ( n = 58), low-fat ( n = 136), or regular diet ( n = 119, control). Dietary assignment was non-randomized and based on assisted patient self-selection. A biomarker-based score to estimate the 10-year cardiovascular mortality risk, bioelectrical impedance analysis, and laboratory parameters (HbA1c, lipids, inflammation markers) were assessed at baseline, discharge, and 6-month follow-up. Kaplan–Meier analysis was used to compare MACCE recorded for a mean of 470 ± 293 days. Results During 3–4 weeks of CR, the 10-year cardiovascular mortality risk decreased by a mean of 3.7 ± 9.6%, with no difference between dietary groups ( p = 0.8651). HbA1c improved in the low-carb group during CR compared to the low-fat and regular diet (−4.0 ± 6.6%), but the effect was not significant after adjustments for baseline HbA1c, diabetes prevalence, and medication ( p = 0.168). Reductions in BMI, body fat, and visceral fat were recorded in the low-carb and low-fat group, compared to the control group ( p ≤ 0.0001). Total cholesterol, LDL, and triglyceride levels also decreased in all groups during CR without significant differences ( p ≥ 0.3957). MACCE incidence did not differ between the groups ( p = 0.2). Conclusion No additional immediate benefit in risk reduction during CR for low-carb or low-fat dietary interventions was detected. However, the low-fat and low-carb diet resulted in significantly greater reductions in BMI, body fat and visceral fat, with a tendency towards more stable effects over 6 months in the low-fat group. While glycemic control was improved in the low-carb group during inpatient CR, long-term adherence appeared challenging, particularly for diabetic patients as HbA1c levels re-increased during 6 months follow-up. Since no difference in MACCE was seen, the dietary interventions may be considered equally safe for CAD patients.

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