Most of us are aware that heart disease is the leading cause of death among U.S. men and women. It is also indisputable that abnormal blood cholesterol level is one of the eight major risk factors for heart disease. While approximately 100 million Americans have abnormal blood cholesterol levels, many of them are not aware of the presence of this ticking time bomb. Current guidelines recommend that everyone undergo baseline blood cholesterol testing at age 20; sooner if a strong family history of heart disease is present.
Before we continue our discussion, it’s very important to note that cholesterol in and of itself is not a bad thing. In fact, cholesterol is a key to our existence. The outer covering of our cells is known as the cell membrane, which is made partly from cholesterol. The sex hormones testosterone, estrogen, and progesterone are made from the cholesterol molecule, as is vitamin D. A key point that people need to understand is that cholesterol only causes problems if the levels in the blood are abnormal.
Most individuals with abnormal blood cholesterol levels have high levels of LDL (the bad cholesterol), while others have low levels of HDL (the good cholesterol). There are also some individuals who have high LDL and low HDL; I would call this a ‘double whammy’. There are many factors that determine our blood cholesterol level. Besides genetics, one of the most important factors is diet. The Dietary Guidelines for Americans (DGA) are published every 5 years, and are developed by a prestigious group of nutrition scientists from the U.S. Department of Agriculture and the Department of Health and Human Services. Since the first DGA was published in 1980, we have been advised to limit our intake of dietary cholesterol (e.g. egg yolks, liver) in order to lower our LDL cholesterol level. More specifically, the Dietary Guidelines have historically advised us to limit our dietary cholesterol intake to no more than 300 mg daily. For years, food manufacturers touted their sometimes not-so-healthy products as ‘cholesterol free.’ While the recommendation to limit dietary cholesterol sounds perfectly logical, it turns out that the issue is more complicated than it seems. In fact, the 2015-2020 Dietary Guidelines for Americans state that dietary cholesterol is no longer a nutrient of concern! While this statement came as a surprise to most of the U.S. public, it was actually long overdue. We have known for more than two decades that for the overwhelming majority of the population, dietary cholesterol has virtually no impact on blood cholesterol levels. In fact, many other countries dropped dietary cholesterol recommendations years ago.
What is still an important determinant of blood cholesterol level is dietary saturated fat and trans fat intake. Unfortunately, much of the public is still a little fuzzy on the concept that dietary cholesterol and dietary saturated fat are two entirely different things. For example, while egg yolks are relatively high in cholesterol, they are low in saturated fat. On the other hand, whole milk is relatively low in cholesterol, but is high in saturated fat. The 2015-2020 DGA still include recommendations for limiting saturated and trans fats in the diet. So, to conclude:
Of note, the most recent DGA also recommend an increase in fruit, vegetable, whole grain, legume, reduced-fat dairy, and fatty fish consumption. At the same time, consumption of sodium and added sugars should be reduced.
ReferenceU.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at http://health.gov/dietaryguidelines/2015/guidelines/.