Two posts ago, we made the rounds of the commonly measured blood lipids (total cholesterol, LDL, HDL, triglycerides) and how they associate with cardiac risk. It's important to keep in mind that many things associate with cardiac risk, not just blood lipids. For example, men with low serum vitamin D are at a 2.4-fold greater risk of heart attack than men with higher D levels. That alone is roughly equivalent to the predictive power of the blood lipids you get measured at the doctor's office. Coronary calcium scans (a measure of blood vessel...
Selasa, 28 Juli 2009
Sabtu, 25 Juli 2009
MRFIT Mortality
The Multiple Risk Factor Intervention trial was a very large controlled diet trial conducted in the 1980s. It involved an initial phase in which investigators screened over 350,000 men age 35-57 for cardiovascular risk factors including total blood cholesterol. 12,866 participants with major cardiovascular risk factors were selected for the diet intervention trial, while the rest were followed for six years. I discussed the intervention trial...
Kamis, 23 Juli 2009
The Diet-Heart Hypothesis: A Little Perspective
Now that we've seen that the first half of the diet-heart hypothesis-- that dietary saturated fat and cholesterol elevate serum cholesterol and low-density lipoprotein (LDL)-- is false, let's take a look at the second half. This is the idea that elevated serum cholesterol causes cardiovascular disease, also called the "lipid hypothesis". Heart Attack Mortality vs. Total MortalityWe've been sternly warned that high serum cholesterol leads to heart...
Senin, 20 Juli 2009
The Diet-Heart Hypothesis: Stuck at the Starting Gate
The diet-heart hypothesis is the idea that (1) dietary saturated fat, and in some versions, dietary cholesterol, raise blood cholesterol in humans and (2) therefore contribute to the risk of heart attack. I'm not going to spend a lot of time on the theory in relation to dietary cholesterol because the evidence that typical dietary amounts cause heart disease in humans is weak. As far as I can tell, most diet-health researchers don't subscribe to...
Selasa, 14 Juli 2009
Diet Modification Trials: Notes on Study Design
The other day, my internet meanderings brought me back to a review of fat modification trials conducted by the Cochrane collaboration. This is a not-for-profit group known for its rigorous meta-analyses. They selected 27 studies that reduced saturated fat or total fat (in some cases along with increased PUFA), and fit several inclusion criteria. The results: There was no significant effect on total mortality (rate ratio 0.98, 95% CI 0.86 to 1.12), a trend towards protection form cardiovascular mortality (rate ratio 0.91, 95% CI 0.77 to 1.07),...
Kamis, 09 Juli 2009
The Finnish Mental Hospital Trial
This diet trial was conducted between 1959 and 1971 in two psychiatric hospitals near Helsinki, Finland. One hospital served typical fare, including full-fat milk and butter, while the other served "filled milk", margarine and polyunsaturated vegetable oils. Filled milk has had its fat removed and replaced by an emulsion of vegetable oil. As a result, the diet of the patients in the latter hospital was low in saturated fat and cholesterol, and high in polyunsaturated fat compared to the former hospital. At the end of six years, the hospitals...
Senin, 06 Juli 2009
Unrefined vs. Refined Carbohydrates and Dental Cavities
There's a definite association between the consumption of refined carbohydrates and dental cavities. Dr. Weston Price pointed this out in a number of transitioning societies in his epic work Nutrition and Physical Degeneration. Many other anthropologists and dentists have observed the same thing.I believe, based on a large body of anthropological and medical data, that it's not just an association-- sugar and flour cause cavities. But why? Is...
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