While whey protein is generally a well-tolerated, good source of amino acids and nutrients for most individuals, pregnant or breastfeeding women should consult their doctors before using it because there is insufficient evidence for its long-term safety, recommends WebMD. Individuals with milk allergies should not use whey protein.
Whey protein can cause allergic reactions in individuals who have sensitivities or allergies to milk. When used in high doses, whey protein can cause cramps, bloating, headache, nausea and frequent bowel movements. Kidney disease patients should consult with their doctors before adding any protein powders to their diets. Negative interactions can occur if whey protein is combined with antibiotics or certain medications used to treat osteoporosis or Parkinson’s disease.
Whey is the watery substance found in milk that separates from the curds during the making of cheese. Individuals with lactose intolerance are often able to handle whey. When used in a protein powder supplement, whey is an alternative to other protein sources that are common allergens, such as eggs and soy. Whey protein can help prevent weight loss in HIV patients and has been shown to increase muscle size and strength when added to a weight training program. While more research is needed as of 2015, whey protein may help slow the spread of metastatic cancer and may help to prevent eczema in children.