Tryptophan depletion in context of the inflammatory and general nutritional status of a low-income South African HIV-infected population

Background: the essential amino acid tryptophan cannot be synthesised in the body and must be acquired through dietary intake. oxidation of tryptophan,due to immune induction of the enzyme indoleamine 2,3-dioxygenase (ido),is considered to be the main cause of tryptophan depletion in hiv infection and aids. methods: this cross-sectional study included 105 hiv-positive patients recruited from the kalafong hospital in pretoria,south africa,and 60 hiv-negative controls. results: patient tryptophan levels were in general markedly lower than those reported for developed countries. in contrast to reports from developed countries that showed tryptophan levels on average to be 18.8 % lower than their control values,tryptophan levels in our study were 44.1 % lower than our controls (24.4 ± 4.1 vs. 43.6 ± 11.9 μmol/l; p < 0.001). tryptophan levels correlated with both cd4 counts (r = 0.341; p = 0.004) and with pro-inflammatory activity as indicated by neopterin levels (r = -0.399; p = 0.0001). nutritional indicators such as albumin and haemoglobin correlated positively with tryptophan and negatively with the pro-inflammatory indicators neopterin,interleukin 6 and c-reactive protein. the most probable causes of the lower tryptophan levels seen in our population are food insecurity and higher levels of inflammatory activity. conclusions: we contend that inflammation-induced tryptophan depletion forms part of a much wider effect of pro-inflammatory activity on the nutritional profile of hiv-infected patients. © 2016 bipath et al.