Immune-modulating effects of amino

Immune-modulating effects of amino acids such as glutamine
and arginine have been evaluated. Ingestion of glutamine
improved nitrogen retention and lowered incidence of bacteremia
in patients with trauma, and enteral supplementation
of glutamine-enriched diet enhanced the recovery of immune
functions and reduced the length of hospital stay after surgical
operation in cancer patients (148,149). Glutamine is a nutrient
for immune cells and acts as precursor for glutathione, which
circumvents oxidant stress and improves cell-mediated
immunity. Arginine is a substrate for synthesis of nitric oxide
and improves helper T-cell numbers. Peri-operative feeding of
arginine and n-3 polyunsaturated fatty acids (PUFAs) restored
DTH and decreased infection rates in colorectal cancer
patients (150).
Nucleotides are rich in foods containing nucleic acid/
nucleoprotein and supplementation of nucleotides is important
for growth of infants. Addition of nucleotides increased the
proportion of TCR-bearing IELs through stimulating IL-7
production by IECs in mice (151), and ingestion of formula
supplemented with nucleotides augmented NK cell activity
and IL-2 production in human infants (152). It remains to be
elucidated whether immune cells may utilize ingested
nucleotides as substrates for synthesis of nucleic acids.