Q: Linda – I am highly lactose intolerant as shown by the hydrogen breath test, (one of the highest they'd ever tested), so I read a lot of labels. Can you tell me if there is lactose in casein or caseinate or any variation of that?
A: Alisa – I thoroughly address lactose intolerance, milk ingredients and more in Go Dairy Free: The Guide and Cookbook, but I am happy to elaborate here on this specific and excellent question. In fact, I think the full answer may hold some surprises for many of you …
Like most foods, milk is made up of the three major components we see on nutrition labels: fat, protein, and carbohydrates. Milk fat is often referred to as butterfat. It is skimmed out in the production of reduced fat and nonfat milk, and used to make cream, butter, ghee, etc. You can read more about butter and ghee in my post about milk fat, but for this question we turn our attention to the protein and carbohydrate portions of milk.
Milk contains dozens of types of protein, but the most abundant ones are casein. Four types of casein make up about 80% of the proteins in cow’s milk (the other 20% of proteins are collectively referred to as whey proteins). When we have a food allergy, it is the protein(s) in the food that we are reacting to, which is why you may hear some people refer to their milk allergy as a casein allergy (though it is possible to have a whey protein allergy). Because of casein’s properties, it is often extracted from milk in processing to be used as a binding agent in various products, from food to paint.
Unlike plant foods, milk does not contain fiber. All of the carbohydrates in milk are sugar … otherwise known as lactose. In fact, lactose is often nicknamed milk sugar. Like casein, lactose is often extracted or isolated from milk in processing to be used in other products for texture, flavor, or even as filler in medications.
Technically speaking, lactose and casein are simply components in milk and not one in the same. Someone who is allergic to casein or another milk protein would not be allergic to lactose. Likewise, someone who is lactose intolerant would not be intolerant of casein. They do not behave the same way in the human body.
This is why you may see casein as an ingredient in some lactose-free products, such as cheese alternatives.
But, there are a few additional issues to keep in mind:
Unlike casein, whey as we see it in food does typically contain lactose. The term “whey” can actually cover more than just protein; it is made up of water, proteins, lactose, and minerals. The level of lactose in whey, whey protein concentrates, and whey protein isolates varies depending on the processing of the whey. You may spot some way protein isolates that are labeled as 100% lactose-free. In these cases, trace amounts of lactose may remain, but close to all of the lactose has been removed.
Most other milk ingredients do contain lactose, but in varying amounts. For example, butter is mostly milk fat, but it does contain small amounts of casein and lactose. Ghee is considered pure butter fat, but still may contain traces of both. See my discussion on milk fat here.
And last but certainly not least … If a product contains casein or caseinates, but not lactose, it is still possible that small amounts of lactose would remain in the product (and vice-versa where casein is the concern). Lactose and all of the proteins are dissolved in the liquid portion of milk, otherwise known as water. Processors have to work hard to separate out lactose and casein from the milk, so it would be naïve to think that these milk components are always 100% pure when added to our foods. Trace amounts of lactose are rarely a concern for lactose intolerant individuals, but there are rare cases of extreme sensitivity. Since you do note that you are highly intolerant, you may wish to err on the side of caution and avoid casein too.
Alisa Fleming is the founder of GoDairyFree.org and author of Go Dairy Free: The Guide and Cookbook for Milk Allergies, Lactose Intolerance, and Casein-Free Living. In addition to her own dairy-free lifestyle, Alisa has experience in catering to the needs of various special diets, including gluten-free, soy-free, egg-free, vegan, and multiple food allergies.