Before anyone gets too carried away with thinking gelatin is a cheap protein replacement for meat, eggs, and poultry it is important to be aware that gelatin lacks (or contains inadequate amounts) of many of the essential amino acids found in meat, eggs and poultry Although gelatin is 98–99% protein by dry weight, it has less nutritional value than many other complete protein sources. This from wikipedia: It is unusually high in the nonessential amino acids glycine and proline (i.e., those produced by the human body), while lacking certain essential amino acids (i.e., those not produced by the human body). It contains no tryptophan and is deficient in isoleucine, threonine, and methionine. The approximate amino acid composition of gelatin is: glycine 21%, proline 12%, hydroxyproline 12%, glutamic acid 10%, alanine 9%, arginine 8%, aspartic acid 6%, lysine 4%, serine 4%, leucine 3%, valine 2%, phenylalanine 2%, threonine 2%, isoleucine 1%, hydroxylysine 1%, methionine, and histidine <1% and tyrosine <0.5%. These values vary, especially the minor constituents, depending on the source of the raw material and processing technique.[13]
Gelatin is also a topical hemostatic. A piece of gelatin sponge of appropriate size is applied on bleeding wound, pressed for some time, and tied in bandage. Hemostatic action is based on platelets damage at the contact of blood with gelatin, which activates the coagulation cascade. Gelatin also causes a tamponading effect – blood flow stoppage into a blood vessel by a constriction of the vessel by an outside force.[14]
Scientific publications give evidence that consumption of oral gelatin has beneficial effect for some fingernail changes and diseases.[15][16][17][18]
I know wikipedia is no "bible" but it will give those reading this thread a reason to question gelatin as a complete source of protein, and look further into it. I found it interesting that the first 20 sites listed when I googled "protein in gelatin" were all either sales or quackery-type sites.