Whey supplements provide high-quality dietary protein with little or no fat. However, in addition to their benefits, they carry drawbacks, including digestive problems, depending on how you use them and on your personal physiology. As with any supplement, seek the advice of a dietitian before adding whey protein to your diet, and consult with your health care provider if whey causes you digestive problems.
Whey protein derives from milk as a component of the liquid remaining from the cheese-manufacturing process. Whey protein, which contains all of the amino acids essential to your diet, is available in supplement form as concentrates, isolates or hydrolysates. Whey concentrates are minimally processed, containing at least 30 but not more than 90 percent protein, with variable levels of lactose and little fat. Isolates have no lactose or fat and offer a minimum of 90 percent protein. Hydrolysates are further processed to predigest some of the protein for easier absorption. The degree to which whey supplements are processed may affect the digestive problems they can cause. According to MuscleandStrength.com, the average intake for whey is 1 to 2 grams per pound of body weight. More is often consumed by those trying to build muscle mass.
Before you can benefit from the nutrients in whey protein, your body must digest it until the food components are small enough for absorption. Your digestive system is equipped to handle a certain volume of food, but if you consume too much at once, you may overwhelm the capacity of your gastrointestinal tract to process it. Similarly, if you take in too much of any one macronutrient -- for example, whey protein -- the total volume of food may be fine but your digestive enzymes specific to that macronutrient may not be able to keep up. The resulting backlog of whey can cause indigestion, with symptoms of abdominal pain or bloating, until your body processes the accumulated protein.
The milk sugar lactose consists of a glucose molecule and a galactose molecule joined together. Your small intestine secretes a digestive enzyme called lactase that splits lactose into its two individual sugars for absorption. If your digestive system produces too little lactase, or none at all, you cannot properly digest lactose. This condition, called lactose intolerance, causes abdominal pain, gas and diarrhea as undigested lactose passes through your gut. Whey protein concentrates contain lactose and may trigger digestive upset if you suffer from this condition.
Most animal sources of protein contain little dietary fiber, and whey is no exception. Fiber, although undigested by your body, contributes to your gastrointestinal health by providing bulk to the waste products moving through your intestines. Sufficient dietary fiber helps keep your bowels regular and decreases your risk of developing constipation. Whey provides no fiber to your diet, and excessive consumption may lead you to experience constipation unless you consume high-fiber foods in addition to whey.