Over the past several years I have read literature suggesting that our prevailing understanding of nutrition is entirely off base. Here is a bit of my current understanding, pertaining specifically to the misconceptions about carbohydrates, saturated fats, and cholesterol:
How cholesterol and HDL lead to heart disease
When arteries become damaged or inflamed, low-density lipoprotein (LDL) carries cholesterol to the site of the abnormality to aid the healing process, which is a natural and necessary function of the human body. Then, high-density lipoprotein (HDL) carries the cholesterol from the site of the abnormality to the liver where it is recycled. However, when LDL becomes damaged through oxidation via free radicals in the blood, it can enter the artery walls via the damaged site. The body responds to this by creating macrophages which are sent to absorb the oxidized LDL and cholesterol in the artery walls. These macrophages become large, cholesterol enriched cells (foam cells) which become embedded in the vessel wall. As these foam cells accumulate the vessel expands and encapsulates them in a fibrous capsule; this is the formation of plaque.
The problem with our understanding: the case for saturated fats and cholesterol and against carbohydrates
The prevailing nutritional mores (I call them mores because they are far from good science) revolve around the notion that diets high in saturated fats and cholesterol lead to an increase in LDL, which leads to a higher proportion of oxidized LDL in the blood, and thus propagates plaque formation and leads to heart morbidity and mortality. **This is the only reason why we consider saturated fats to be unhealthy** However, while diets high in saturated fat have been shown to increase total LDL, the specific type of LDL increased (large LDL) is largely benign. Rather, it is the other types of LDL (medium, small, and very small) which, when oxidized, tend to enter the vessel walls. Recent research has shown that diets high in high-glycemic-index-carbohydrates and low in saturated fats will increase the smaller LDL while decreasing HDL, thus significantly contributing to heart disease. Furthermore, the correlations observed between heart disease and elevated cholesterol have been shown to be linked to common-causal variables, such as smoking, elevated blood sugar, and stress (which cause both increased artery inflammation/damage and increased cholesterol). Basically, fats and cholesterol do not lead to heart and vascular disease, but carbohydrates can.
How to achieve good health
Although I have been faced with significant evidence which suggests that my basic understanding of nutrition is basically nonsense, it is hard for me to shake the notion that I should avoid saturated fats and cholesterol. However, good health is a product of avoiding those things which cause bad health, and in the context of this discussion, that means avoiding plaque formation. Therefore, one should seek out those foods and activities which minimize the causes of plaque formation, and avoid those foods and activities which cause plaque formation.
- Avoid Stress
- Don't Smoke
- Avoid Spikes in Blood Sugar (through the consumption of low-glycemic-index foods)
- Reduce Oxidation (little is known about how to actually accomplish this)
I would suggest that everyone seek out for themselves the current research about nutrition and health. Don't be satisfied with some article on nutrition, follow the research! A major issue with the current state of science, which was addressed in another thread, is that it is rampant with politics, agendas, and bias. This results in selective science, which ignores research findings which contradict preconceptions in favor of anything (regardless of method) which supports them; this means it might be harder to find the supporting research than to find some article parroting government protocol. Even the most innocuous of institutions, The American Heart Association, participates in the dissemination of misinformation. Our notions about what is healthy for us are a product of these corruptions, and it is up to each of us to think for ourselves and be free of this tyranny of misinformation.