Can you believe that we have been blaming the wrong fat for heart disease problems? For the past 60 years, we have labeled saturated fat as the nasty culprit responsible for heart attacks - the solid fat in meats, whole milk, cream, and butter. The basis for that theory started in the early 1950's with the landmark Korean Soldiers Study. This study examined autopsies performed on soldiers killed in action in the Korean War. Researchers were shocked to see 18 and 19-year-old males with significant coronary artery blockages not ordinarily seen on subjects that young. Upon microscopic examination, researchers noted the vessels were occluded with mostly saturated fat in which the fat “plaques” contained a good deal of cholesterol. This case study led us to the modern era of frantically trying to control our cholesterol.
However, many colleagues and I have found, there was not a simple, 1:1 correlation between the amount of cholesterol consumed and the amount of cholesterol produced. Some patients, have a genetic predisposition to just naturally produce a lot of cholesterol, which is called familial hypercholesterolemia. Doctors must treat patients with medication to help lower the cholesterol count. Yet,we as doctors, have told our patients for decades to eat a low-fat, low-cholesterol diet to protect against atherosclerosis (those fatty, cholesterol-filled plaques in your arteries). We have told you to cut down on meats. And for Heaven’s sake, eat margarine, never butter! Skim milk, or nonfat milk—never whole milk! These were the guidelines of the American Heart Association, and cardiologists like myself handed out the pamphlets. This conclusion was based on tons of research, including the venerable Framingham Heart Study—which is probably one of the oldest continuing studies on heart health in existence. It started in 1948, and traces the health of people going back three generations.
What if everything we thought we knew about saturated fat was wrong? Two shocking studies suggest that may be true.
While I’m not suggesting the Framingham Study was a frame-up, or anything like that, every so often, investigators are brave enough to challenge such established ideas as “saturated fats clog arteries” and test those assumptions anew. The PURE study, authored by Dr. Salim Yusuf, of McMaster University, followed 135,000 people from 18 different countries over a 7-year period. showed that high fat intake—whether total fat or saturated fat—was associated with a reduced risk of mortality.
Wait—high fat intake is GOOD for you? That reminds me of this scene: https://www.youtube.com/watch?v=dFJopF6WJNw
But, high carbohydrate intake was associated with an increased risk of mortality. Another part of the study also found that eating 3-4 servings/day of fruits, vegetables, and legumes reduced mortality risk, with benefits increased if they were raw rather than cooked.
If you look at the numbers, they tell the story. Here are the investigators’ results:
Hazard Ratio for Total Mortality (Highest Quintile vs Lowest Quintile)
1.00 = Reference
|HR (95% CI)
|P for trend
For those of you who are intimidated by this chart, please don’t be. “HR,” or hazard ratio, just means the mortality rate of that group, compared to the control group, expressed as a ratio, with 1.00 being the same as the control group, or normal. Therefore, this data shows that the group eating more carbohydrates had a 1.28 times greater mortality rate than the control group, while the saturated fat group was only 86% as likely as the control group (-0.22 differential) to die.
Notably, the AHA is furious about this study, because their new advisory, released only just 4 months ago, recommends cutting saturating fat in favor of polyunsaturated fat and carbs.
Replacing saturated fat with monounsaturated and polyunsaturated fats is what we cardiologists used to tell our patients as a matter of course. First, without getting into too much detail for now (I’ll save that for another time), monounsaturated fats are fats with only one “unsaturation,” and an unsaturation just means a double bond in the fat molecule (as opposed to a single bond or a triple bond). Polyunsaturated fats have multiple double bonds. The arrangement of the atoms in space on the double bond also affects its physical and chemical properties: That is what we are talking about when we talk about “trans fats.”
Natural vegetable oils, which have a mixture of different monounsaturated and polyunsaturated fatty acids, have their double bonds in the normal “cis” configuration, meaning the carbon atoms are on the same sides as each other. These double bonds are more vulnerable to auto-oxidation, so that is why sometimes natural oils go rancid quickly, but partially hydrogenated oils do not. Also, when you partially hydrogenate oils by adding hydrogen across those double bonds, you change them to single bonds (making them “saturated,”) and changing the melting point of the oil, and the more solid a fat you get. This is how margarine is made. So, a completely hydrogenated fat is solid at room temperature. But most of the time on labels, you will see “partially hydrogenated soybean oil,” which means the mixture is lower in trans fatty acids. Fast-food companies and big packaged food manufacturer like trans fats because they have a longer shelf life. Unfortunately, when you consume them, you have a shorter self-life. This is because trans fats raise your LDL (bad cholesterol) and lower your HDL (good cholesterol)
The reaction by the AHA is predictable: Anyone who would contradict the well-rehearsed dictum of “saturated fat is the enemy” must, in their minds, therefore be the enemy. Think about it: The AHA has invested so much in that belief system, admitting that it just might be wrong could hurt them. As President Reagan once said, “Facts are stupid things—stubborn things, I should say.” He was saying that facts are stubborn because they stick—kind of like arterial plaque. So, I think we, and the AHA, must give a good listen.
But in the meantime, I would say enjoying that little pat of real, farm-fresh butter is OK. (And when it comes to margarine, stay away!)
I will be writing a lot more on the sugar and fat controversy—including an inflammatory new documentary some of my patients have told me about called What the Health—soon. Till next time, remember, moderation is probably the best prescription.
Dr. B The Heart Doc