Dear Dr. Blonz: Our reading group was discussing milk, and one of the long-standing members argued that milk, especially homogenized milk, is a bad and even dangerous food for seniors. How can this be? I remember it being called “nature’s most perfect food.” I was hoping you could explain if things have changed, and whether milk is a food to avoid. — L.I., San Jose, California

Dear L.I.: One valid reason to avoid milk and milk products would be if you had been tested and found to be allergic to milk protein. Another motivation might be lactose intolerance: a dislike of side effects experienced due to an inability to digest the lactose carbohydrate that milk typically contains. Common lactose intolerance produces intestinal gas or other digestive upset. Some don’t experience symptoms unless milk is consumed on an empty stomach, or if more than a certain volume is involved. Many with lactose intolerance have no problems with yogurt and cheese.

Concerns about homogenization often come from a paper that suggested that an enzyme naturally present in milk (xanthine oxidase) might contribute to the risk of inflammation and several chronic ailments. It was nothing more than a hypothesis, but it was adopted by what became an “anti-milk” crowd. The human body produces its own xanthine oxidase, and it is associated with inflammation, but there is no solid evidence that consuming it in milk has negative health effects. It’s helpful to remember that proteins — and enzymes are proteins — are disassembled during digestion, before absorption.

There is now a growing variety of nondairy milk, and new twists on the dairy version. Lactose-free milk products represent an option for those with the intolerance issue, and some milk products are now offered that contain a slightly different protein. The protein in milk is beta casein, and cows can produce two versions: A1 and A2. Most cows’ milk contains a mix, but there are now milk and dairy products from cows that only make A2. The argument is that negative health effects and discomfort from milk might be related to the A1 protein specifically, not lactose. This is an emerging theory, and the evidence is far from solid. Those who have a milk protein allergy, of course, should avoid either kind.

Assuming you are not eating vegan, and absent an allergy or intolerance to one or more of its components, there are few health reasons to avoid milk. I wouldn’t call milk “nature’s most perfect food,” and it’s certainly not “essential,” but it does have much to offer nutritionally. There are many spreading twists on the “milk is bad” message, but the negative allegations, thus far, have failed to stand up to the light of science. For more on milk, check out b.link/milk27.

Ed Blonz, Ph.D., is a nutrition scientist and an assistant clinical professor at the University of California, San Francisco. He is the author of the digital book “The Wellness Supermarket Buying Guide” (2012), which is also available as a free digital resource at blonz.com/guide. 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.