The 1977 Dietary Guidelines for the United States, aiming to get a handle on the increase in heart disease deaths in this country, for the first time recommended Americans limit their intake of fat, saturated fat, and dietary cholesterol. Americans set out to follow these recommendations, and as a nation, we successfully decreased our intake of all three. Unfortunately, the prevalence of cardiovascular disease and diabetes have only increased since then. What went wrong? To understand, we need first to review the most current science on cholesterol and triglycerides, the lipids found in our blood.
Many of us have heard about “good” cholesterol (HDL) and “bad” cholesterol (LDL). We may even be aware that the ratio of these two components is even more important than our total cholesterol level. Why? The concern with blood cholesterol is when it contributes to atherosclerosis–the hardening and narrowing of the arteries due to build of cholesterol plaque inside them.
HDL, or High-Density Lipoprotein, is good because it acts like a trash collector, picking up free floating cholesterol in the blood stream. The more trash collectors, the cleaner the streets. So we want HDL levels high, because it lowers atherosclerosis plaque buildup. Low-fat diets, like those recommended in the 1977 Dietary Guidelines, actually lower HDL levels. Exercise and a diet with a moderate intake of healthy fats (like those recommended in our program) raise HDL levels.
LDL, or Low-Density Lipoprotein, has been traditionally considered “bad.” Recent research however, has illuminated the fact that there are four different types of LDL, all with varying impacts on disease: Large (Fluffy) LDL, Medium, Small, and Very Small LDL. It turns out the Large LDL is benign; it neither helps nor hinders. The smaller, denser forms of LDL, however, are linked to a three-fold increased risk of heart disease. It is important to note that at this time, the blood tests available to the public do not distinguish between the different types of LDL. However, research has linked different dietary patterns with different types of LDL: we know that intake of saturated fat stimulates Large LDL (which is benign, remember), while intake of high glycemic carbohydrates is implicated in the creation of the smaller LDL. This is just one more reason we focus on education around glycemic load in our nutrition counseling at Healthy Steps.
What about dietary cholesterol intake and blood cholesterol levels? There is no evidence the former impacts the latter. In fact, the 2015 Dietary Guidelines acknowledged this lack of evidence and removed the recommendation to limit dietary intake of cholesterol.
Triglycerides don’t get quite as much press as cholesterol, but they are just as important to understand. Triglycerides are fats in the blood stream; they contribute to atherosclerosis, and elevate heart disease risk. They are also a sign of insulin resistance and elevated risk of diabetes. Excess consumption of high glycemic carbohydrates, trans fats, calories or alcohol, as well as being sedentary, all increase blood triglyceride levels.
Reviewing the most recent findings on cholesterol, triglycerides, and the lifestyle choices that impact them, we see where the 1977 guidelines went wrong. Americans, in their vigor to follow the new recommendations, replaced fat calories with refined carbohydrates (remember the bottom of the food pyramid?) and sugar (all those low-fat products we were buying had to be made palatable somehow). We actually increased our total calorie intake as well, likely because fat provides long-term satiety, and as we cut back, we got hungrier. At Healthy Steps we specialize in helping individuals get back to eating real, whole foods, with the right balance of protein, healthy fats, and low glycemic carbohydrates so you can lower your risk of disease as you lose weight.