Methylglyoxal (MGO) is responsible for the pronounced antibacterial activity of manuka honey, where it may reach concentrations up to 800 mg/kg. As MGO formed in vivo is discussed to play a role for diabetic complications, the metabolic transit of dietary MGO was studied within a 3 day dietary recall with 4 healthy volunteers.

Determination of MGO in 24h-urine was performed with GC-MS after derivatization with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine and D lactate was quantified enzymatically. Following a diet virtually free from MGO and other glycation compounds, a defined amount of MGO (500µmol in manuka honey) was administered in the morning of day 2. Renal excretion was between 0.1 and 0.4 µmol/day for MGO and between 50 and 220 µmol/day for D-lactate. No influence on excretion of both compounds was observed following administration of MGO. To investigate the stability of MGO under physiological conditions, a simulated in vitro gastrointestinal digestion was performed with MGO-containing honey. After 8 h in vitro digestion, only 5 - 20 % of the initial methylglyoxal was recovered.

This indicates that dietary MGO is rapidly degraded during the digestion process in the intestine, and, therefore, exerts no influence on the MGO level in vivo.