Let's look at it this way. Take chicken soup for an example.
Please do not take this as advice to eat raw meat, but it should be obvious that raw chicken meat does not taste the same as cooked meat in soup - for a lot of reasons.
One reason is that a fraction of proteins are hydrolyzed during cooking - broken down into polypeptides and into some single amino acids. Polypeptides are short chains of amino acids. So in a sense every time you have chicken soup you are consuming some amino acids.
Food intolerance and allergenic responses are a lot more complex. And
@Buzz Bloom is correct in saying that by consuming protein as straight amino acids things may change. But not necessarily for the worse.
Some infant formulas (EHF's) are made from extensively hydrolyzed cow's milk proteins. Note this means lots of different polypeptides. This paper cites using pure amino acid mixtures in lieu of EHF for EHF sensitive infants. The take away is that the immune system does not see the amino acids as allergenic, but does react to a few of the huge panoply of polypeptides present in EHFs.
(abstract only behind a paywall )
http://www.sciencedirect.com/science/article/pii/S0022347697701045?np=y
This is in counterpoint to what
@Buzz Bloom was mentioning. IMO, it is possible to have adverse effects from changing diet, yes. It is something to expect? probably no.
Plus, so-called branched chain amino acids (leucine, isoleucine and valine) are routinely used as a supplement by weight lifters and some endurance athletes.
There are data to support this application:
http://jn.nutrition.org/content/136/1/269S.short
http://journals.lww.com/nsca-jscr/Abstract/2006/08000/The_Effects_of_Protein_and_Amino_Acid.28.aspx
http://download.springer.com/static/pdf/322/art%253A10.1186%252F1550-2783-9-20.pdf?originUrl=http%3A%2F%2Fjissn.biomedcentral.com%2Farticle%2F10.1186%2F1550-2783-9-20&token2=exp=1460469593~acl=%2Fstatic%2Fpdf%2F322%2Fart%25253A10.1186%25252F1550-2783-9-20.pdf*~hmac=e8c4ad9bced2d6f81a4105accead693a6f7518406c19495a1393656ad79e76e7
However let's not go off on the whole supplement thing. Please.