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- More from Ed Blonz
Q. I have read that skim milk is bad for you because after they remove the fat to make it skim, they then add back dried milk powder as protein fortification. It has the additional benefit of increasing the body in this otherwise thin liquid. The problem is that skim-milk powder contains oxidized cholesterol, which is bad. This argument seems a bit contrived, but I am curious what your take on it is.
J.B., Washington, D.C.
A. Oxidized cholesterol is not something you want in your body. To answer your question, though, we will need to back up a bit.
First, cholesterol serves many functions in the body and is needed to help the brain work properly. It keeps our skin water-tight and provides the basic building block for sex hormones and other essential substances. The negative image of cholesterol comes from studies that associate elevated blood levels with heart disease and stroke.
There is an important distinction between cholesterol we take in as a part of our diet and that carried by the LDL and HDL lipoproteins in our blood. Less than half the cholesterol we eat gets absorbed. A balanced diet and a healthful lifestyle have always been the keys. Cutting down on dietary cholesterol won't have a great effect if your diet lacks the healthy greens, grains, fresh fruits and vegetables, nuts and seeds. It is the components in these foods that give the body the tools it needs to handle the dietary fats and cholesterol we consume.
One of the things that can go "wrong" with cholesterol is that it is susceptible to oxidation, and, once oxidized, it can contribute to different types of damage associated with chronic disease. Our body has defenses to prevent oxidation in the body, but eating sources of cholesterol that are already oxidized bypasses these defenses. It would be a greater risk for those who don't have a healthful diet, and also for those who are already on the road toward chronic disease. These are the reasons why I have no problem with fresh eggs but do not encourage eating dried eggs, and why it is better to grate fresh cheese than purchase commercially grated cheese that's been sitting around for a while. Both these are higher-fat products with higher levels of cholesterol.
Turning back to milk, we should appreciate that it's mostly water, but, similar to human milk, it does contain some cholesterol. Skim (nonfat) milk contains less cholesterol than 2 percent milk, which, in turn, contains less than whole. The cholesterol in dried nonfat milk can become oxidized, but there is not much there to be at risk. When you "protein fortify" skim or 2 percent, the total cholesterol stays the same. Checking the U.S. Department of Agriculture database at tinyurl.com/36uag, we find that a cup of nonprotein-fortified skim milk contains 8.25 grams of protein and 5 milligrams of cholesterol. A cup of protein-fortified skim contains 9.74 grams of protein, but the same 5 milligrams of cholesterol. A cup of 2 percent milk will contain 20 milligrams of cholesterol whether it is the regular or protein-fortified version. There may be small differences with other milk types, but overall, the concern about oxidized cholesterol from protein-fortified milk is a nonissue.
• Ed Blonz, Ph.D., is a nutrition scientist and the author. Write him at "On Nutrition," Ed Blonz, c/o Newspaper Enterprise Association, 200 Madison Ave., New York, NY 10016 or email@example.com. Due to the volume of mail, personal replies cannot be provided.