Protein

Protein consists of charcoal, oxygen and nitrogen and is built up by amino acids. There are a total of 23 amino acids, from which 14 that the body produces and 9 that has to be brought by the food. The latter 9 are called the essential amino acids. A complete protein consists of at least these 9 essential ones and an incomplete misses at least one of them.
It’s important to get all of the essential amino acids at the same meal, since they need each other. Animal protein consists of all 9 and is therefore the best protein source. Algae and soy are the only complete plant proteins, but be sure to choose fermented soy. All other plant proteins are incomplete but you can still get all 9 by eating from different sources. Be sure to know which amino acid to find where.