The German Federal Institute for Risk Assessment has established maximum recommended intake levels for the consumption of leucine, isoleucine and valine through food supplements. These essential amino acids are more commonly referred to as the branched chain amino acids (BCAA) and often found in sport supplements.
In order to support safe use of BCAA, the German Institute has derived indicative maximum consumption intake levels from the outcomes of toxicological studies performed on animals arguing there is insufficient human data available to support the adoption of the reference intakes.
The recommendation holds that the total intake of BCAA should not exceed 8.2 grams per day. Although the findings suggest that BCAAs should be taken into combination, the following individual limits should be observed:
Leucine: 4.0 grams per day
Isoleucine: 2.2 grams per day
Valine: 2.0 grams per day
The recommendations do not support BCAA supplementation for children, adolescents, pregnant women and nursing mothers as data is insufficient to support the extraction of relevant intakes for these population groups. Likewise, the reference values should be disregarded by people with impaired kidney functioning and people on a low protein diet. Overall, the institute advises to consult with the doctor prior to the consumption of isolated amino acids.
BFR - NahrungsergÃ¤nzungsmittel - Isolierte verzweigtkettige AminosÃ¤uren kÃ¶nnen bei hoher Aufnahme die Gesundheit beeintrÃ¤chtigen - link