There is always a fair amount of controversy surrounding cholesterol. It’s in the news, in our diets, and in our bodies. Let’s start with some background.
Cholesterol is a molecule that is in the “sterol” family. This family of chemicals are the building blocks for many important body compounds, including the sex hormones (testosterone and estrogen), stress hormones (cortisol and cortisone), bile acids that are used in digestion, vitamin D, and other vital component of your cells’ membranes. Your liver makes as much cholesterol as your body requires, and estimates how much to make based on your dietary intake of saturated fats (among other cues). As you can see, cholesterol is truly a vital need for normal body function and physiology.
However, problems arise when the liver makes too much cholesterol. Cholesterol is also one of the components of athersclerosis. These are the plaques and deposits that develop in the arteries throughout the body and can form in the arteries that feed the heart, brain, and limbs. If the plaques become too large or thick, they lead to chest pain (“angina”) and heart attacks, stroke, and poor circulation. In the United States, about 8 out of 10 people die from diseases related to athersclerosis! There other factors that influence your risk for athersclerosis, so don’t think cholesterol is the only culprit. Smoking is a huge risk, but that is for another time.
So Doc, now we know it’s bad, what can we do about it? How do we lower our blood cholesterol level? One way to influence your cholesterol level is by limiting the amount of saturated fat you eat. Saturated fats, put simply, are those that are solid at room temperature. Examples include butter or margarine, lard, and many animal fats. Contrast these with unsaturated fats which are liquid at room temperature (olive oil, canola oil, and most plant fats). First and foremost, no matter what “diet” you eat, you should strive to keep the saturated fats to a minimum. Too many saturated fats will cause your blood cholesterol to rise, putting you at greater risk for athersclerosis.
But what about the cholesterol in my food? Interestingly enough, you probably don’t absorb a lot of the cholesterol you eat. Your body is very efficient at absorbing the fat in your diet. It does this by using the bile acids made by the liver and stored in the gallbladder. Remember, these bile acids are made of cholesterol. The fats you eat combine with the bile acids in the small intestine and are absorbed into the body. Any excess bile acids that are still in the small intestine after the fats are absorbed are recycled and absorbed as well. Since the bile acids are made of cholesterol (and are chemically very similar to cholesterol), the cholesterol that you have eaten in your diet has to compete with the bile acids in order for it to be absorbed as well. As it turns out, very little, if any, of the cholesterol you eat actually makes it into your system. However, notice that of the fats (saturated or unsaturated) are very efficiently absorbed into your system to be used as fuel or stored for a latter time.
So what’s the “skinny”? It is the saturated fats in your diet that are most important to minimized, not the dietary cholesterol. Often cholesterol and saturated fats are found together in foods, but not always. For instance, lobster is very high in cholesterol and protein, but not high in saturated fats. Eating lobster is really quite healthy and “heart smart”, at least until you dip it in the butter!
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