New Heart Scan Results: Good News (context)

I posted yesterday that a recent heart scan found my arteries about 50% less calcified than a previous scan predicted. Apparently the improvement was due to eating much more animal fat (pork fat and butter).

In 2004, an American Journal of Clinical Nutrition article found something similar: heart disease progressed less in women who ate more saturated fat. “In postmenopausal women with relatively low total fat intake, a greater saturated fat intake is associated with less progression of coronary atherosclerosis,” the authors wrote. Here’s how they saw this finding:

The inverse association between saturated fat intake and atherosclerotic progression was unexpected. However, this finding should perhaps be less surprising. Ecologic and animal experimental studies showed positive relations between saturated fat intake and CHD risk (8). However, cohort studies and clinical trials in humans have been far less consistent (9 —12). Furthermore, most studies of dietary fat and CHD risk have been performed in men (15, 16). The relations in women—particularly postmenopausal women—are much less well-established, and evidence from dietary intervention trials suggests that diets low in saturated fat may have different effects on CHD risk factors in women (15, 17—22).

In their study, women with the highest intake of saturated fat did not get worse during the study period, whereas women with lower intakes did get worse.

An editorial about this study described some of the evidence that supports the “article of faith” that “saturated fat . . . accelerates coronary artery disease”:

One of the earliest and most convincing studies of the better efficacy of unsaturated than of saturated fat in reducing cholesterol and heart disease is the Finnish Mental Hospital Study conducted in the 12 y between 1959 and 1971. In this study, the usual high-saturated-fat institutional diet was compared with an equally high-fat diet in which the saturated fat in dairy products was replaced with soybean oil and soft margarine and polyunsaturated fats were used in cooking. Each diet was provided for 6 y and then the alternate diet was provided for the next 6 y. After a comparison of the effects of the 2 diets in both men and women, the incidence of coronary artery disease was lower by 50% and 65% after the consumption of polyunsaturated fat in the 2 hospitals.

My results make the results of that earlier study exceedingly puzzling. I found a large change in one direction; the Finnish study found a large effect in the opposite direction. Given the huge effect (50% or 65% reduction) observed in the Finnish study, it is hard to understand why “cohort studies and clinical trials in humans have been far less consistent”.