Plastic cartons of organic skimmed milk, left, and whole milk. (Simon Dawson/Bloomberg)

The Oct. 7 front-page article “A thinning case that fat causes heart ills” selectively described the evidence and argued that dietary recommendations to replace whole milk with low-fat milk and cut down on saturated fat were unsubstantiated. The assertion that saturated fat increases only large low-density lipoprotein (LDL cholesterol) and thus does not cause heart disease is contradicted by evidence that medium/large LDL independently predicts coronary heart disease, but associations between small, dense LDL and coronary heart disease are weakened after adjustment for triglycerides.

The article indicated that recent analyses show no relationship between saturated fat and coronary heart disease but did not highlight that the comparison macronutrient is typically refined carbohydrates. Recent research by the Harvard T.H. Chan School of Public Health confirmed high-saturated-fat diets are as unhealthy as high-refined-carbohydrate diets but shows that replacing saturated fats with unsaturated fats or healthy carbohydrates such as whole grains decreases coronary heart disease risk. Previously, we found whole milk is associated with increased coronary heart disease risk; reduced-fat milk is not.

The quality of fats and carbohydrates with which we replace saturated fat is critically important. There is little evidence to support the assertion that whole milk is more healthful than reduced-fat milk.

Frank B. Hu, Boston

The writer is a member of the 2015 Dietary Guidelines Advisory Committee and a professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health.