Protein powder (whey, casein or plant-based) is a convenient way to increase protein intake, supporting muscle maintenance and growth, satiety and recovery. It is a food product rather than a supplement in the traditional sense, useful mainly for people who struggle to reach adequate protein through food alone.
The value of adequate protein for muscle maintenance, particularly with age and alongside resistance training, is well established. Protein powder is simply a practical tool to reach that intake, and there is nothing magical about the powdered form versus protein from food; convenience is the main benefit.
Generally safe for most people. Whey and casein are dairy-derived, an issue for those with dairy intolerance or allergy. Very high total protein intake needs care in people with kidney disease. Product quality and additives vary.
If you have kidney disease, protein intake (from any source) should be guided by a doctor or dietitian. Check ingredients for allergens and unnecessary additives.
Moderate, sold by weight. Cost per serving is often comparable to or cheaper than equivalent protein from some whole foods.
Research on protein intake, muscle maintenance and ageing. Educational information only.