Protein Quality

• Collagen is not a complete protein because it is lacking in the amino acid tryptophan. A Protein Digestibility Corrected Amino Acid Score (PDCAA) of a complete protein is 1.0. Collagen's PDCAA score is 0.08.
  
  

Amino Acid Content

• Collagen is highest in the amino acids glycine and proline. Glycine releases oxygen to the cells. Proline is important for proper functioning of joints and tendons.
  
  

Calories

• Collagen protein supplements contain 15 grams of protein per serving. Each gram of protein provides 4 calories, contributing 60 calories overall.
  
  

Vitamins and Minerals

• Many protein supplements have vitamins and minerals added. The most common vitamins added are B vitamins, which are essential for energy and metabolism. Choline may also be added to increase lipid metabolism.
  
  

Benefits of Collagen Protein

• While collagen protein cannot be used as a sole source of protein, a 24-week study from the journal Current Medical Research and Opinion found that collagen hydrolysate may be beneficial for patients with joint pain due to osteoarthritis.
  
  

Are there vegetarian sources of collagen?

• Most collagen protein supplements are made from animal tissue. However, some products that use agar (seaweed) as a source of collagen would be suitable for vegetarians.