The healthcare community was recommending eating everything low-fat and steering clear of dietary sources of cholesterol for fear of raising blood cholesterol levels, particularly the “bad” cholesterol (low-density lipoprotein or LDL). Even foods like peanut butter, which never contained cholesterol in the first place, were labeled as cholesterol-free. It’s as though the more we could label as “free” the more we felt free to eat. So for decades foods such as cod liver oil and egg yolks were demonized without clear evidence they contributed to risk of disease. They certainly weren’t “free” so of course, we were terrified of them. But at what cost?
What we know now is that there is no direct correlation between the amount of cholesterol you eat and the amount in your blood. The liver makes about ¾ of your body’s cholesterol, and only about 30% of the population might see dietary cholesterol increasing concentration of blood cholesterol. But contrary to what some might still be led to believe, dietary cholesterol increases the “good” cholesterol (high-density lipoprotein or HDL) and may, in fact, promote health – not destruct it!
It plays a positive role in many physiological processes:
HDL is often referred to as the “good” type of cholesterol as it helps keep cholesterol away from arteries and from building up as arterial plaque, which is a factor in the development of heart disease.
LDL has been deemed “bad” cholesterol because historically it has been suggested to contribute to plaque buildup, making the arteries less flexible and narrower which is the basis for atherosclerosis. The idea that fats are bad stems from the notion that foods containing fat and cholesterol will lead to heart disease. What we now know is that it’s not fat or cholesterol themselves that are an issue, but the problem lies in the breakdown of UNSTABLE fats, particularly the oxidation of polyunsaturated fatty acids (PUFA’s) found in vegetable oils (like corn, canola, cottonseed, soy, safflower, sunflower) that we have been told for decades are healthier for us than animal fats but are actually prone to oxidation.
In 2013, Dr. Fred Kummerow published a paper reviewing over 60 years of research on dietary factors – especially oxidized cholesterol – that contribute to heart disease. The premise is that when fats degrade, a free radical chain reaction ensues, leading to cell damage. In the late Dr. Kummerow’s view and the opinion of an increasing number of experts, the primary cause of heart disease is oxidized cholesterol and fats. The point is that scientists have known for a while now that the cholesterol that dangerously builds up in artery walls is oxidized LDL and that is what contributes to atherosclerosis.
While decades of studies suggest that PUFA’s will increase how fast LDL is removed from the blood, what we weren’t taught is that PUFA’s do so by attaching to LDL particles which makes that LDL more unstable and vulnerable to oxidation. So although PUFA’s may cause cholesterol to go down, there may be a hidden price in terms of risk for heart disease due to oxidation.
In addition to consuming excess PUFA’s, other contributors to the build-up of oxidized cholesterol in the bloodstream include consuming partially hydrogenated oils or trans fats, eating processed foods such as commercially fried chicken, French fries, margarine, and commercial baked goods, as well as cigarette smoking.
Although preventing oxidized damage through diet, supplements, and lifestyle rather than responding to lab tests is more my cup of tea, it is important to remember that lab tests can help identify if there are deeper issues going on which might also affect LDL receptor function.