Should we aim to limit our intake of saturated fat, regardless of what our overall diet is like? The World Health Organization (WHO) seems to be taking this position.
In draft recommendations published in May of 2018, the WHO proposed that cutting saturated fat intake to less than 10% of daily calories might greatly reduce the risk of cardiovascular disease, the leading cause of death from non-infectious disease. This works out to about 22 grams of saturated fat per day for someone consuming 2,000 calories daily.
Recently, an international team of researchers - including noted lipidologist Ronald Krauss, MD - published their response explaining why a focus on reducing saturated fat consumption could have unintended health consequences on a global scale:
The British Medical Journal: WHO draft guidelines on dietary saturated and trans fatty acids: time for a new approach?In their paper, the experts make several points supporting their position that saturated fat restriction may be counterproductive:
- Foods containing saturated fats are very diverse: Even when saturated fats come from the same original food source - for example, dairy from cows - processing and the addition of other ingredients (like sugar and flour in baked goods) can change the way these fats are metabolized. We don't eat nutrients in isolation; we eat foods, which contain a complex blend of nutrients. Saturated fats in full-fat plain yogurt will have different fates in the body than saturated fats in a chocolate milkshake.
- Unconvincing evidence that reducing saturated fat decreases heart disease risk: Most systematic reviews of clinical trials - considered the strongest, most reliable type of evidence - have failed to show that replacing saturated fats like butter with unsaturated vegetable oils decreases the risk of heart attack or dying of heart disease, regardless of any changes in cholesterol levels.
- Reliance on LDL cholesterol values to determine risk: It's true that in some studies, LDL cholesterol levels have been found to decrease when saturated fat intake is reduced. However, although various saturated fatty acids affect LDL differently based on chain length and other factors, nearly all saturated fats raise HDL cholesterol as much or more than they raise LDL cholesterol. Additionally, large LDL particles are considered less likely to contribute to heart disease than small particles, and higher saturated fat intake has been linked to larger LDL particle size.
- Many nutritious foods are high in saturated fat: Avoiding or restricting nutrient-dense foods like fatty meats, cheese, and full-fat dairy could potentially lead people to choose low-fat foods higher in refined carbohydrates instead. Will this be beneficial for reducing heart disease risk? Again, overall diet composition is key. A recent large meta-analysis of clinical trials found that low-carb diets unrestricted in saturated fat lowered triglycerides and raised HDL cholesterol levels more than low-fat diets did, thereby decreasing risk.
Directives to limit saturated fat intake to an arbitrary level while failing to take overall diet into account are misguided. We at Diet Doctor applaud these researchers and wholeheartedly agree with their concluding appeal to the WHO:
"We strongly recommend a more food-based translation of how to achieve a healthy diet and reconsideration of the draft guidelines on reduction in total saturated fatty acids."
