Tuesday, November 14, 2006
And the Verdict Is
Ok, I'm am still unconvinced that Saturated fat is good for you. I am also unconvinced that saturated fat is bad for you. I have read so much about saturated fat that it makes my head hurt. In the beginning I, like many people, believed with out much question that SFA's were bad. I dismissed most people, especially on the Internet, as cranks who said otherwise. It was and is fairly well proven that SFA raise your cholesterol, and that was bad. Right? After all, back in my Nut-Pharm ( thats what we called nutrition and pharmacology in college) classes they told us cholesterol is bad. It was even on the exam. Well, then one of those events that occurs from time to time happened, and all of a sudden I had reason to question the validity of the whole cholesterol connection. What they neglected to tell me was that SFA raises both HDL and LDL, and it is the ratio of these two things, not the total number that was important. Despite all the hoopla, people with "normal" cholesterol get heart attacks too. In fact much to my surprise, about half of all heart attack sufferers have normal cholesterol prior to their first attack. The only real connection to Heart Attacks and cholesterol is after the fact. Once you've had a heart attack, reducing your cholesterol lowers your relative risk (vs absolute risk) of having a second incident. Logical Fallacy is about the best way to sum up the evidence against SFA in the case of causing CHD. But as any good philosopher would tell you, absence of evidence is not evidence of absence. This became a guiding thought for me as I looked into other aspects of SFA metabolism. One of the studies I came across was KANWU. In this study, SFA was shown to decrease sensitivity to insulin, at least in healthy adults with total fat intake of less than 37% of calories. A number of other studies using a baseline diet of 45-55% carbs, have also shown that increasing SFA at the expense of either PUFA or MUFA decreased sensitivity to insulin. Enter the Ketogenic diet. A ketogenic diet can be well defined, were as the term "low carb" is a relative term subject to much interpretation. So when researchers refer to a ketogenic diet the meaning is clear. Under ketogenic metabolism, SFA exerted no nasty effects. No increase in inflammation, no increase in insulin, and pretty much was a solid metabolic citizen. In other news, certain SFA's have been shown to exert positive effects on our GI Tract, and improve hormonal tonus. So, for me the jury is still out. What is missing so far is evidence of the effect of saturated fat on people who eat a high protein, non-ketogenic reduced carb diet. We have a collection of data that shows that SFA and carb don't play nicely together, but no data that I am yet aware of that show the effect of SFA when carbs are reduced and protein is elevated. Maybe I need to get a meter and experiment on myself. It may turn out that SFA is neither good nor bad, or both good and bad depending on the metabolic context. In the mean time as I do not eat a ketogenic diet, I'll limit, but not eliminate, the SFA in my diet. After all, butter makes my veggies taste better.