From: https://www.westonaprice.org/health-topics/childrens-health/dietary-recommendations-for-children-a-recipe-for-future-heart-disease/#gsc.tab=0

Heart Disease

There are two types of cholesterol. The High Density Lipid (HDL) is said to be good, while the Low Density Lipid (LDL) cholesterol is said to be bad. Actually the LDL cholesterol plays many important roles and it is not bad—nor are high levels of LDL a marker for proneness to heart disease. Normally our genes produce a form of LDL that is described as “fluffy and light.” When the LDL produced is “small and dense,” this is a cause for concern because this form of LDL cholesterol is not normal, and is associated with increased proneness to heart disease.

What happens when children are put on lower fat diets? When researchers prominently associated with the American Heart Association fed children lower fat diets and measured some of the markers they consider important predictors of heart disease, they learned that these lower fat diets were causing the very problems they wanted to prevent. The children whose genes would normally have been producing the desirable light and fluffy form of LDL started to make the dangerous small and dense form of LDL (Dreon, MD et al, American Journal of Clinical Nutrition 2000 71:1611-1616). Thus the US dietary recommendations are likely to be causing heart disease, not preventing it.