Nutrients are crucial modifiers of the GH/IGF-I axis. In particular, a close cross-talk between proteins and amino acids (AAs) and GH/IGF-I secretion exists.~Both AAs and proteins affect GH secretion. AAs stimulate GH secretion upon oral administration, with different potency among studies, being the combination of arginine and lysine the most powerful. Soy proteins also stimulate GH secretion when ingested either as hydrolysed proteins or free AAs. Furthermore, the acute GH response to AAs ingestion may be influenced by the daily amount of dietary protein/AAs consumption: diets high in proteins apparently increase basal GH levels.~AAs and proteins have a positive effect on IGF-I secretion as well. In general, high levels of proteins, especially animal and dairy proteins, and consumption of branched chain amino acids (BCAAs) increase serum IGF-I levels.~Considering pathological GH conditions, metabolomic analysis of acromegalic patients suggests that the main metabolic fingerprint of GH hypersecretion is a reduction in BCAAs, related to the disease activity. Moreover, there is evidence that GH, rather than IGF-I, is the main mediator of such metabolic fingerprint, which may be related to increased uptake of BCAAs by the muscles, increased gluconeogenesis, and raised consumption of BCAAs.~Thus, in acromegaly, a tailored diet is a further strategy that may contribute to blunt GH/IGF-I secretion. Indeed, some authors recently suggested that personalized or precision nutrition in some conditions and diseases could have an impact on their phenotype, combining dietary recommendations with individual's genetic makeup, metabolic and microbiome characteristics, and environment. However, studies on precision nutrition in acromegaly are still in a neonatal era.
Since protein and AAs are master regulator of GH and IGF-I secretion, we hypothesized that a low protein diet could reduce GH and IGF-I levels in acromegalic patients in addition to conventional therapy. Furthermore, we aim to explore metabolomic, microbiota, and micro-vesicle fingerprints of GH hypersecretion during conventional therapy and after a low protein diet