Ask Dr. Gourmet

What's the difference between a milk allergy and lactose intolerance?

My partner has said for years he thinks he's lactose intolerant. He can fairly easily digest skinny milk (i.e. only 0.10 grams of fat per 100ml), as well as goat's cheese. He finds the biggest culprits for upsetting his stomach are yoghurt made with cow's milk (both regular and low-fat) and cow's milk cheeses.

Not sure if this is actually lactose intolerance or a milk allergy. I'm hoping you might be able to explain the difference?

Dr. Gourmet Says...

Lactose intolerance occurs because the body does not have the ability to produce the enzyme lactase. Lactose (the sugar found in milk) is made up of two sugar molecules: glucose and galactose. Lactase splits the sugar for proper digestion and absorption. Without being split, the sugars are not broken down in the small intestine and pass to the colon, where they are used by bacteria for food: the byproducts can cause gas, bloating, and sometimes diarrhea.

It is now clear that lactose intolerance is a "dose dependent" issue. Everyone varies in the amount and form of dairy products they can tolerate. Here's some relevant research on lactose intolerance, from one of my Health & Nutrition Bites, and here's further information about lactose intolerance, including lactose-free recipes, on the Dr. Gourmet website.

Milk allergy is an allergic reaction to the proteins in milk and other dairy products. It is most common with cow's milk, but can be a problem for some folks consuming products made with sheep or goat milk. It is a true allergic reaction, with the body mounting an immune response, and can be quite dangerous.

It is much more common in children, and symptoms of milk allergy include nausea, vomiting, wheezing, hives, bloating, and diarrhea. It can be quite severe, causing anaphylactic shock (thus a risk of death). If your partner believes that he might have an allergy and not lactose intolerance, he should certainly visit his doctor. Here's more information about food allergies.

Thanks for writing,

Timothy S. Harlan, MD, FACP, CCMS
Dr. Gourmet