There is moderate scientific evidence supporting the use of whey protein to help cancer patients undergoing chemotherapy, particularly in addressing malnutrition and muscle wasting, which are common side effects. Whey protein is a high-quality, easily digestible protein source that provides essential amino acids necessary for maintaining muscle mass and supporting immune function. Several clinical trials and observational studies have explored its role in oncology nutrition.

For example, a randomized controlled trial published in Nutrition and Cancer (2013) showed that whey protein supplementation helped maintain body weight and muscle mass in patients undergoing chemotherapy for gastrointestinal cancers. Other studies have reported improvements in markers of nutritional status, decreased treatment interruptions, and enhancements in strength and quality of life.

While whey protein does not directly reduce classic chemotherapy side effects like nausea or fatigue, it can mitigate the worsening of these symptoms by preventing malnutrition and muscle loss. The scientific consensus acknowledges that nutritional support, including whey protein, is beneficial, especially for patients at risk of protein-energy malnutrition. However, it is not a replacement for standard supportive care, and the evidence is rated moderate (3/5) due to some heterogeneity in study designs and outcomes.

Overall, whey protein supplementation is considered a scientifically supported adjunct for maintaining nutritional status in chemotherapy patients, though it should be tailored to individual patient needs and under the supervision of healthcare professionals.