An associate professor of medicine at Harvard Medical School - author of more than 100 scientific papers on nutrition and health.
Q: Saturated fat has been dietary public health enemy number one for decades. Why do you think telling people to avoid it is bad advice? A: The recommendation to cut back on saturated fat was based on concerns that it raises the risk of heart disease. But we’ve learned that its effects are more complex than we first thought.
We’ve known since the 1960s that saturated fat raises LDL cholesterol, the “bad” cholesterol. But LDL is just one biomarker for risk. We now know that there are other cholesterol-containing particles, called HDL, that are related to a lower risk of heart disease. We also know that high levels of triglycerides in the blood, along with other factors, predict heart disease risk. Saturated fat does raise LDL cholesterol. But compared to carbohydrates, it also raises HDL cholesterol and lowers triglycerides. If we looked just at LDL, we would predict that saturated fat raises heart disease risk. If we looked at the effect of saturated fat on HDL and triglycerides, we would suppose that saturated fat lowers that risk. If we looked at the combination, we would predict that saturated fat is relatively neutral for heart disease risk compared to carbohydrates.
Q:So is saturated fat good or bad? A: To answer that, we need to study how eating saturated fat relates to actual diseases, not simply to biomarkers such as blood cholesterol that only suggest the possibility of artery damage. Three groups of researchers have recently weighed data from all available large long-term studies that have tracked saturated-fat intake and heart attacks or strokes. All three found no association between saturated fat and heart attacks or strokes. People who consumed the highest levels of saturated fat had about the same rates of heart disease as people who consumed the least.