stevie667

Not in the slightest.

Proteins, fats and carbohydrates are all biologically important molecules, without which we have the unfortunate problem of keeling over dead.
Now, if we eat a lot of these molecules, we simply get big (what type of big you get is dependant on what you eat and if/how you exercise). There isn't any kind of negative feedback mechanism in the body that stops you absorbing protein later in life because you eat loads now.
Any degredation in your bodies ability to absorb protein as you grow old is most likely just due to old age affecting the digestive system.


Now, for the original question.
Why exactly do you want to use protein supplemenation? If it's for post-workout shakes after weightlifting, then look for whey proteins (produced as a by product of cheese making). They are absorbed into the body faster, and have more bio-available amino acids. Because it is more quickly absorbed, whey protein isn't best for non-post workout shakes.
If your looking for a general protein supplement because your diet is lacking for whatever reason, then try ceasin protein (the main protein in milk) as it is slower acting, and therefor will give you steady protein release over a period of time. For this reason it is advisable not to use ceasin after a workout.

There are other types of protein out there, but those two are the main ones.

Remember though, don't get the majority of your protein intake from supplements, get it from real food.