A. Martha Morris, PhD, a scientist in Tufts HNRCA Nutritional Epidemiology Program who has studied protein, answers: I am wondering why you are using the whey powder. Is it for body building? Or is there some reason that you think you need a supplement? Older people may need more protein than the recommended dietary allowance of 0.8 grams per kilogram of body weight to maintain muscle mass as they age, but that doesnt necessarily mean they need to take a supplement. Perhaps you are avoiding meat but know that your body needs some protein.
There are problems with high-protein diets as well as high-meat diets, which also come with saturated fat. Excessive protein strains the kidneys. If the high-protein diet is achieved through adjustments in food intake, that usually means that it is a low-carbohydrate diet, which can result in the use of body tissues for energy and the build-up of ketones to dangerous levels, but that would not result from a normal diet supplemented with protein.
Assuming that you have a legitimate need to use a supplement (like, for example, you are vegan), the question of safety mainly rests on your resultant protein level. Does the supplement just get you to meet or slightly exceed your protein recommendation or does it result in high-protein intake? If you are not following a specific anti-animal regimen, I advise meeting your recommendation by eating lean meat, chicken and fish, and if you are not lactose-intolerant, by drinking reduced-fat milk and eating yogurt. If you cannot meet your recommendation without taking a supplement, just dont overdo it, to spare your kidneys.