For decades, dietary fat, and saturated fat in particular, was positioned as the primary dietary driver of cardiovascular disease. The evidence base for this position has been substantially revised over the past 20 years. The relationship between dietary fat, blood cholesterol, and cardiovascular risk is considerably more nuanced than the simplified messaging would suggest.
The Cholesterol Particle Problem
Total cholesterol and LDL cholesterol are imperfect cardiovascular risk markers. More predictive are LDL particle number, LDL particle size, the ratio of LDL to HDL, and triglyceride levels. Saturated fat consumption raises LDL cholesterol, but predominantly by raising large, buoyant LDL particles, which have a weaker association with cardiovascular events than small, dense LDL particles. Refined carbohydrates and sugar, in contrast, raise triglycerides and small dense LDL while lowering HDL.
The Distinction That Matters
- Trans fats: clearly harmful, raise LDL, lower HDL, and are associated with increased cardiovascular events
- Saturated fats from whole food sources such as meat, eggs, and dairy: modest and context-dependent effects on cardiovascular risk when replacing refined carbohydrates rather than polyunsaturated fats
- Monounsaturated fats from olive oil and avocado: consistently associated with improved cardiovascular risk markers
- Omega-3 polyunsaturated fats from oily fish: anti-inflammatory, protective against cardiovascular events
The Dietary Pattern Approach
Focusing on individual macronutrients is less clinically useful than focusing on overall dietary patterns. The Mediterranean dietary pattern, characterised by olive oil, fish, vegetables, legumes, and moderate whole grains, has the strongest evidence base for cardiovascular protection. It is not a low-fat diet. It is a diet built around food quality and pattern rather than macronutrient restriction.