Michael Ristow

Ristow was born in Lübeck in the North of Germany. He graduated at the University of Bochum in 1992 and received his M.D. from University of Bochum in 1996. He was appointed to the University of Jena in 2005 as a full professor in nutritional science, as a full professor in energy metabolism at the ETH Zurich in 2013, and a full professor in Experimental Endocrinology and Diabetology at Charité Berlin in 2023, also as the director of the Institute of Experimental Endocrinology.

In 2007, Ristow’s group published evidence which could explain the basis of the observed extension of lifespan by restriction of sugar intake. In experiments on a model organism, the worm Caenorhabditis elegans, they found that lowering the availability of glucose extended the lifespan of the worms. It has been known since the 1930s that restricting calories while maintaining adequate amounts of other nutrients extends lifespan across a broad range of organisms. The mechanism has been proposed as a change in the activity of the sirtuins. Michael Ristow shows in his article that this effect can also occur independent of sirtuins, since worms deficient for sirtuins still show extended life span in states of sugar restriction.

Most importantly, Ristow's research suggests that this is a mitohormetic effect, as reviewed in. Hormesis is a controversial concept in which it has been demonstrated that the induction of low-level stress can promote health and lengthen lifespan in some species, while higher levels of the same stress exert detrimental effects. Ristow's interpretation was that in response to a decrease in glycolytic energy production, the worms have to generate ATP by oxidative phosphorylation in the mitochondria, leading to increased production of reactive oxygen species. Due to a vaccination-like response, the organism produces more defenses against oxidative stress, including increased activity of catalase. Supplementation with antioxidants abolishes the increase in lifespan, and so does disruption of an AMP-kinase but not disruption of sirtuins.

In a follow-up study that experienced significant media attention, Ristow and colleagues have shown that supplementing humans with antioxidants during physical exercise blocks the health-promoting effects of exercise, suggesting that free radicals produced during exercise are responsible and required for the effects of exercise.