DEAR DR. BLONZ: Is it true that there are important enzymes in raw milk that are destroyed by pasteurization, and that these enzymes are needed to assimilate the calcium from milk? I heard this from a doctor on a taped presentation, and was wondering if whether it's correct. -- E.B., Chicago
DEAR E.B.: This smacks of a bogus spin on a partial truth. First, there are indeed enzymes in raw (unpasteurized) milk; some come from the cow, and others can come from bacteria. These enzymes will be destroyed, in part, by the pasteurization process. The question is whether these enzymes are essential for the assimilation, or absorption, of the milk's calcium.
The answer here is "no." Or, put another way: The enzymes have not been demonstrated, by any competent and reliable evidence, to be essential to the process of calcium absorption.
One cow enzyme is called plasmin, a protein-digesting enzyme that we produce as well. The human body uses its plasmin to help dissolve blood clots. In milk, the bovine plasmin degrades the milk protein. This can play a role in the ripening of cheese, or leads to clumping and the development of "off" flavors and odors in milk that has been around too long.
Pasteurization is not a sterilization process, but it involves the application of heat to destroy potentially harmful microorganisms that can cause spoilage or disease. It knocks out some, but not all, of the enzymes and bacteria that are present. Refrigeration also serves to slow bacterial growth and enzymatic action. All this helps to explain why milk goes bad if it is allowed to sit too long or is stored at the wrong temperature. Storage time can be extended with milk products processed with higher temperatures (ultra-pasteurized) and packaged in aseptic containers.
I'm uncertain why the doctor in your presentation believes that the enzymes in raw milk are needed for us to absorb calcium and other minerals. What you heard on that tape smacks of an unscientific milk attack. If you are interested in debunking it, go to the source -- if you can find it -- and demand proof for those statements. If you find any substance, please make sure to send it my way; I would be interested in the basis used to promote such stuff.
There are a number of individuals who really do not like milk, with some feeling that it is an unhealthful food. I disagree, but it is certainly up to the individual to decide for themselves. Not everyone wants to drink milk, and not everyone needs to. Our freedoms allow us to make our own food choices.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.