Low-Fat vs Low-Carb Diet Battle for Dangerously High Triglycerides

Multifactorial chylomicronemia (MCM) is an underappreciated but serious lipid disorder affecting roughly 1 in 600 adults. Driven by reduced lipoprotein lipase activity, it causes extreme fasting triglyceride elevations — sometimes exceeding 2,000 mg/dL — which carry a 10–20% risk of acute pancreatitis. As obesity, metabolic syndrome, and type 2 diabetes continue to rise globally, MCM prevalence is expected to grow alongside them, making optimal dietary management an urgent clinical question.

The challenge is that nutritional guidance for MCM patients sits in a confusing middle ground. For the general public with elevated triglycerides, guidelines like those from the American Heart Association emphasize reducing simple carbohydrates. But for the closely related condition of familial chylomicronemia syndrome (FCS), treatment centers on strict fat restriction. MCM involves both increased VLDL production by the liver and impaired clearance of both VLDL and chylomicrons, making it biologically distinct from either scenario and leaving the optimal diet unclear.

This completed clinical trial, sponsored by the Institut de Recherches Cliniques de Montreal, was designed to resolve that ambiguity. Researchers directly compared a low-fat diet to a low-carbohydrate diet in patients diagnosed with MCM. The primary endpoint was fasting serum triglyceride concentration. Secondary endpoints were extensive and clinically rich, covering LDL, HDL, total cholesterol, glucose, insulin, HOMA-IR, apoB, hs-CRP, PCSK9, free fatty acids, blood pressure, waist circumference, and lipoprotein subfractions. The trial also assessed postprandial responses to standardized test meals and collected patient feedback on compliance and tolerability.

The results of this head-to-head comparison could directly inform dietary prescriptions for a patient population that faces both pancreatitis risk and elevated cardiovascular disease risk. Understanding whether fat or carbohydrate restriction more effectively lowers triglycerides — and improves the broader metabolic profile — would give clinicians a clearer, evidence-based framework.

This summary is based on the registered protocol abstract only, as full trial results are not yet publicly available. The phase designation is not applicable, and the intervention was dietary rather than pharmacological.