Figure 2.

The endogenous production of fructose. Fructose is generated from glucose (its substrate) via the polyol pathway. Aldose reductase is the rate-limiting enzyme. The primary drivers for fructose production are high glucose levels, and factors that can stimulate aldose reductase activity. From a food perspective, this includes high glycaemic carbohydrates, salty foods, alcohol and umami foods such as beer. However, this pathway is also activated by stress, including ischaemia, hypoxia, dehydration and heat stress. (Online version in colour.)