DEAR DR. BLONZ: A holistic doctor featured at a recent wellness conference stated that pasteurization destroys a critical enzyme in raw milk that is needed to absorb calcium. Is this true? -- M.Q., Phoenix

DEAR M.Q.: There are enzymes in raw milk that are broken down by the process of pasteurization, so that part is correct. However, the real issue is whether these enzymes are critical for the body's absorption of the calcium in milk -- and the answer is no. The calcium in dairy has good bioavailability, and there is no clinical evidence that it is significantly better absorbed when consumed in raw versus pasteurized milk.

There are several enzymes in raw milk -- some are from the cow, and others are in the bacteria naturally present in the cow's digestive system. One milk enzyme produced by the cow is plasmin, a protein-digesting enzyme that degrades milk, causing spoilage. Anyone who has seen the clumps or mistakenly consumed spoiled milk can attest to its unpleasantness.

Pasteurization, while not a sterilization process, involves the application of heat to reduce the level of potentially harmful microorganisms that can cause spoilage or disease. It knocks out some, but not all, of the enzymes and bacteria, which allows the milk to remain wholesome through its projected period of storage and use. Refrigeration slows bacterial growth and enzymatic action, which is why milk goes bad if it's allowed to sit out too long. (There are extended storage periods for milk products processed at higher temperatures [ultrapasteurized] or packaged in aseptic containers. For more information on milk expiration, see b.link/qb4mmax.)

The lecture you mentioned sounds like an unscientific milk attack. Some people have no interest in milk, and others feel it is food only for calves. Dairy provides us a healthful package of essential nutrients, but not everyone wants to drink milk, and not everyone needs to.

DEAR DR. BLONZ: I read an article concerning the benefits of selenium, but it recommends taking yeast as a supplement. I seem to have an intolerance to the yeast in bread and cheese, which causes bad stomach pain. Does this mean I shouldn't take selenium? -- N.S., Tulsa, Oklahoma

DEAR N.S.: The selenium present in our foods depends significantly on the selenium content of the soils or waters in which they're grown. The same can be said for yeast, as the mineral will be present only if the yeast is allowed to grow on a selenium-rich medium. Typical food sources for selenium include seafood, such as tuna, clams, oysters and swordfish, nuts (especially Brazil nuts) and seeds, organ meats, and grains such as oats and wheat. (For more on selenium, see b.link/ebgbcf9.)

Selenium deficiencies are uncommon, but if you are looking for a supplement and are concerned about yeast, be sure to find one that's yeast-free. Finally, check with your health professional concerning the stomach pains you have been experiencing.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I have been using olive oil as much as possible in cooking and salads. Much of the time, and always in baking, I use the "extra light" olive oil from a warehouse store. Recently, I have heard suggestions that the extra light may not have the same healthful fats and other benefits that fruity extra virgin olive oil has. How do the health properties of these two types of olive oil compare? -- O.O., Chicago

DEAR O.O.: The fats in all types of olive oil are comparable, containing approximately 77% monounsaturated, 9% polyunsaturated and 14% saturated fatty acids. The calorie content is also comparable. Extra-virgin olive oil, however, tends to have a greater concentration of healthful phytochemicals and more health attributes than lighter oils.

The phytochemical benefits become apparent when you consider that the olive is the fruit of the olive tree, and the oil is there to nurture the developing seed until it can begin to grow on its own and sprout leaves to gather needed energy from the sun. It would reduce the seed's growth ability if the oil it needed for energy had turned rancid.

Because oils are prone to breakdown, mostly through oxidation, successful plants have evolved to produce protective phytochemical compounds that include different antioxidants. We find some vitamin E and other important antioxidant compounds, known as polyphenols, in the olive. These compounds help maintain the vitality of the olive oil, and many have distinct flavor characteristics that can be detected in premium oils.

If you want the fats provided by the olive and are less interested in its flavorful polyphenols, then the "extra light" version is worth consideration. (For more on olive oils, see b.link/qwngx9ee.)

DEAR DR. BLONZ: I buy raw almonds and roast them at home, baking them in a toaster oven at 250 degrees for about half an hour. I often add spices for unique flavors. After serving them at a party, one of my friends asked whether roasting the almonds causes the oil in the nuts to become saturated fat. I have also heard that heating almonds diminishes their nutritional value, specifically vitamin B. Is this true? Are raw almonds preferable for their nutrition and health value? -- M.C., San Diego

DEAR M.C.: Dry-roasting in a toaster oven is not associated with any meaningful decrease in almonds' nutrient value. The same can be said for oil-roasting, although the oil adds a bit more fat content. Using either method and roasting correctly, the oils in the nuts do not become more saturated.

In terms of nutritional value, any high-heat process can destroy some thiamin (vitamin B1), but the other nutrients, especially the minerals, are relatively unharmed. I consider nuts and seeds to be healthful foods. The choice between raw and roasted almonds, nuts or seeds is simply personal preference. In all cases, be sure to store them properly. (For more information on correct nut storage, see b.link/2xb9aq7.)

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: Please explain the difference between fats, oils, serum lipids, cholesterol and triglycerides. My main question is about a close friend with high blood cholesterol who is now on a statin, which brought down their lipid profile into the normal range: Is there any reason, except for weight gain, why they should not eat high-fat, high-cholesterol foods? -- M.K., Chicago

DEAR M.K.: We can discuss these components and the general impact of diet, but discussions about health issues relating to blood lipids and medications should be with your physician.

"Lipids" is an umbrella term for a group of chemicals, including fats and oils (both made of fatty acids), waxes and steroids. Each type of lipid has a particular chemical structure that distinguishes it from the others. Although the terms "fats" and "oils" tend to be used interchangeably, the difference is that the former are solid, while the latter are liquid at room temperature. All lipids share one characteristic: They cannot dissolve in water, but will dissolve in organic solvents, such as mineral spirits or cleaning fluids. Triglycerides are also lipids; they're the form in which fats and oils are packaged in the body. (For more on dietary fats, see b.link/s2fd25z.)

Cholesterol, a type of steroid, is a waxy, fatlike substance with a complex structure resembling a honeycomb. It is an essential structural element in every body cell. Unlike fats and oils, the body does not use cholesterol for energy; it is a raw material used to make hormones, including estrogen and testosterone.

However, whether due to a genetic predisposition, poor diet and lifestyle or some other factor, cholesterol can become elevated. Taking a cholesterol-lowering drug, such as a statin, provides a means to help correct that element of imbalance in the body. (Read more about statins at b.link/8wsa7ak.) If you're prescribed such medication, by all means, use it.

Medications to control an elevated blood cholesterol level should not be considered a "license to eat" and live in an unhealthful manner. It is not correct to assume that a pharmaceutically lowered cholesterol level fixes the problem -- medication can help, but it does not absolve us of the responsibility to treat our bodies with care.

The takeaway, and the message for your friend, is to consider it a worthy goal to adopt diet and lifestyle changes that might help reduce the need for such medications.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.