Protein shakes offer an easy, convenient way to supplement your daily protein intake. Since most protein shakes are made using a type of dairy protein called whey, people who are lactose intolerant tend to have difficulty digesting them. Additionally, some people may have an uncommon genetic defect that limits their ability to process the waste products generated from protein digestion. For best results, keep your protein intake restricted to the recommended 46 to 56 grams per day.

Definition

Whey protein is a highly digestible form of milk protein, according to MayoClinic.com. In addition to its use in protein shakes and supplements, whey protein is included in a variety of food and beverage products, including ice cream, bread and infant formulas. Due to its prevalence of muscle-building essential amino acids, whey protein is a popular supplement among athletes and weightlifters. Additionally, medicinal applications of whey protein may be effective at reducing some symptoms associated with diabetes and allergies.

Whey Protein and Digestion

As your body begins to break down the whey protein from your shake, a number of byproducts are released into your digestive system. One of these byproducts is the toxic chemical ammonia. Once ammonia is created it is transferred to your liver, where it is processed into a chemical called urea and excreted in your urine. For most healthy adults, this process happens automatically and without any unpleasant side effects. However, one in 8,000 Americans has a genetic defect that disables the ability to process ammonia, causing it to accumulate and become potentially life-threatening, according to Medical News Today.

Lactose Intolerance

A much more common reaction to whey protein is lactose intolerance. According to the U.S. Food and Drug Administration, an estimated 30 million to 50 million Americans are thought to be lactose intolerant. Since whey protein is derived from milk, it contains part of a natural dairy sugar called lactose. This sugar requires an intestinal enzyme called lactase in order to be fully digested. Individuals with a deficiency or shortage in lactase are more likely to have difficulty digesting protein shakes made with whey protein.

Safety Concerns

In addition to whey protein, protein shakes may contain a number of ingredients that can cause digestive problems. People with diabetes or hypoglycemia may respond negatively to the added sugar in some protein shakes. If you experience severe abdominal pain or other worrying symptoms, stop drinking protein shakes and seek medical attention.