D-aspartic acid (D-asp) ... It's made in the body and found in certain foods—like spinach, beets, and strawberries—as well as supplements. Takeaway.

Lactic acid is found in pickled vegetables, sourdough bread, beer, wine, sauerkraut, kimchi, and fermented soy foods like soy sauce and miso. It’s responsible for their tangy flavor ( 4 ).

There are also 11 non-essential amino acids—alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine—that can be produced by ...