DEAR DR. BLONZ: Does the freezing of milk harm any of its nutrients? How about lactose-free milk? Military families have been freezing milk for years, but I have never found out if it is a good thing to do. -- M.M., Janesville, Wis.
DEAR M.M.: Freezing is a safe and acceptable way to store milk and the changes in nutritional value would be negligible. This would be the case for any type of milk, including a lactose-free product. In some cases, there will be a few minor changes in the way the milk appears and tastes. Freezing can cause a breakdown of homogenization, the process that distributes the milk fat evenly. This will not be an issue with nonfat milks, but there can be an occasional drop of fat seen floating around in low-fat, reduced-fat or whole milk. The best way to remedy this is to shake the container before drinking.
Depending on the speed at which the milk is frozen, there can be slight changes in taste and color. In addition, a small amount of sediment may develop. These changes are negligible and do not reflect any change in the wholesomeness of the milk. A good rule of thumb is the faster the freeze, the smaller the damage. You can foster a quicker freeze by placing the container next to the freezer wall or on a metal shelf.
Remember, also, that because milk is a rich source of nutrients, it provides an ideal food for bacteria and other microorganisms. Pasteurization helps destroy most of the bacteria that are present at bottling, but not all. Freezing does not destroy microorganisms, it just suspends or slows their growth. The quality of the defrosted milk will be no better than that of the milk at the time it was frozen. It is always best to put the milk in well-sealed containers.
DEAR DR. BLONZ: I am a 70-year-old woman and have been told by my doctor that my body does not absorb vitamin B-12 because I do not have the intrinsic factor needed for absorption. He said that I need to get a monthly B-12 shot. Recently, I have come across an advertisement for a sublingual B-12 supplement. How effective is taking B-12 this way, and could I be able to discontinue my monthly shots? -- G.S., Nashville, Tenn.
DEAR G.S.: There is some research evidence that sublingual (under the tongue) drops of vitamin B-12 can be effective. Nasal sprays can also work. These are not as efficient routes as injections, so it may not be as effective in every case of vitamin B-12 deficiency. Another factor to consider is that about one percent of vitamin B-12 is absorbed in individuals, like you, who do not have the intrinsic factor. This means that taking a higher oral dose might satisfy your requirement. I would encourage you to discuss all this with your health professional and follow what would be best for your particular situation. There are two papers you might mention that cover this issue: one in the Aug. 28, 1999 issue of the journal Lancet, and the other in the December 2003 issue of the British Journal of Clinical Pharmacology.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.