Great question yesterday by a reader (and longtime friend). I just thought I'd post it here versus responding in the comments section.
How much is too much protein? Is it hard for the body to process? Here are the answers:
- The Institute of Medicine position is that protein can be safely consumed up to 35% of calories for men and women over the age of 19 years. For a 40 year old male that is around 6 ft tall and 180 pounds, their estimated calorie needs for the day are 2300-2500 (depending on activity level). As such, 200-220 g/day of protein could be safely consumed at the upper end. That's like eating a small chicken....just to put it in perspective.
- Protein is "processed" or broken down in the kidneys. For people with normal kidney function, protein up to 35% of calories seems to be easily processed in the kidney. For people that have compromised kidney function, I certainly would consult with your doctor on how much protein to consume. Very often, people with kidney conditions are placed on a low protein diet under the care of a Registered Dietitian.
- There is a debate going on regarding the source of protein...quite a heated debate in fact...Dr. Dorks get all worked up sometimes over these things. Some feel that vegetable-based proteins (soy, pea, etc.) are more beneficial to health. There is some evidence that these proteins may be better for bone health and in general, vegetable proteins are leaner and not associated with saturated fat (like animal proteins). Other studies show that certain animal proteins (e.g., whey) may be better for stimulating muscle growth and satiety and at reasonable intakes, don't have any negative effects. However, it is not entirely clear at this point. As such, I abide by the, "a little of this, a little of that" principle and try to get protein by multiple sources. Food preferences, food allergies, and food intolerances might make one protein source less attractive than others, and that's okay too.