There are several different components of milk that some individuals react to. If you have a bad reaction when you drink milk or eat dairy products, you could be lactose intolerant. Alternately, however, you could have a milk allergy, which is a reaction to one or more of the proteins in milk. Whey is an example of a milk protein to which you could be allergic.
Lactose Intolerance
In their book "Biochemistry," Drs. Reginald Garrett and Charles Grisham explain that lactose intolerance arises from an inability of an individual to produce lactase, the enzyme your digestive tract uses to break down lactose. Lactose is the chemical name for milk sugar, a carbohydrate in dairy that you can't absorb unless you break it into its constituent components, glucose and galactose. If you are lactose intolerant, lactose from dairy passes into your large intestine, where bacteria break it down. This produces large quantities of gas, leading to cramping and bloating symptoms.
Whey
Whey is quite different from lactose -- it's a protein rather than a carbohydrate, and is one of several proteins found in milk. Most people can ingest whey without any difficulty, but some individuals have an allergic reaction to whey. Allergies aren't the same as digestive intolerances; they don't result from the lack of an enzyme. Instead, they occur when your immune system mistakes whey or another dietary protein for an invader and attacks. This leads to symptoms including hives, itching, and difficulty breathing, in addition to possible digestive symptoms, explains MayoClinic.com.
Determining the Problem
If you have a bad reaction after consuming milk or dairy, you may be lactose intolerant, allergic to whey, both, or neither. If your reaction is very serious and includes respiratory difficulty or hives, it's likely that you're allergic to milk. Only a doctor can help you determine whether the allergy is specific to whey, and it's best not to experiment on your own. If you have digestive upset upon consuming dairy, you might be lactose intolerant or have a milk allergy. Try consuming lactose-free milk -- if you can handle it without difficulty, you're lactose intolerant. If you still react badly, you likely have an allergy to whey or another milk protein.
Foods
Once you know if you're lactose intolerant or allergic to whey, you can make food decisions. Lactose intolerant individuals can use lactase supplements, which are sold under several brand names including Lactaid. You can also consume lactose-free milk and other lactose-free dairy products. These products still contain whey, however, so they're not appropriate for you if you're allergic to whey. If you have a whey allergy, you'll need to use milk substitutes, such as soy or almond milk.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- MayoClinic.com: Milk Allergy
