Sarcopenia is common in lung cancer patients. It is one of the significant factors affecting the overall survival, radiotherapy and chemotherapy efficacy, and quality of life of patients with lung cancer. Previous studies have shown that increased protein intake can stimulate postprandial muscle synthesis, and improve muscle mass, strength, function, and overall survival. However, most previous studies have focused on the intervention of whey protein, while the protective effect of soybean protein on lung cancer-related sarcopenia (LCRS) has not yet been fully explored and reached an agreement.

So, this study aims to explore the effects of soy and whey protein on muscle, gut microbiota, and clinical outcomes among patients with lung cancer-related sarcopenia, to provide a reference for further nutrition treatment.

This study will last 6 months. For the duration of the study, an anticipated total of 90 participants will be randomly assigned to receive either a 30-gram protein supplement or a placebo daily. There will be a total of 5 study visits, and dietary records, questionnaires, blood and stool collection, and functional testing will occur at all study visits. Intention-to-treat analysis (ITT) and per-protocol analysis (PP) will be conducted in statistical analysis.

Inclusion Criteria:

• age>=18years old
• Patients with lung cancer and sarcopenia
• ECOG<=2
• Patients are able to provide written informed consent.

Exclusion Criteria:

• People who are allergic to soy protein and whey protein.
• Participants received any drugs or supplements known to influence effcet size, such as protein powder, anabolic steroids, or glucorticosteroid before the 3 months preceding the study.
• Participants with gastrointestinal bleeding, enterotomy or gastric bypass surgery before the 3 months preceding the study.
• Concurrent severe cardiac disease, liver and renal failure, which may significantly interfere with study compliance.
• Participants with electronic or mental device.