Ageing may be sweet

ageing affected by taste in flies
Fly taste affects ageing. Image André Karwath. Sourced from Wiki Commons.

Eating too much sugar contributes to many age-related diseases such as Diabetes and heart disease. But a recent study showed that just tasting sugar may affect ageing, at least in flies. Flies have taste bristles, their version of taste buds, on their mouthparts, legs and wings. In this study, flies were genetically engineered to be missing some or most taste bristles. The flies missing taste bristles only on their mouthparts lived longer than wild type flies. This effect was more pronounced in females than males. If taste bristles were also removed from wings and legs, the flies didn’t live any longer than wild type. So some taste is needed for longer life.

Animals on calorie restricted diets live longer – this is true for yeast, worms, flies, mice and monkeys. But the tastebud-less long-lived flies actually ate more and weighed more than their wild type friends. They also had the same blood sugar level (haemolymph triacylglyceride level) and were just as fertile as wild type flies. So the anti-ageing effects in these animals were not due to less food.

Sugars are metabolised by the insulin pathway in both humans and flies. Some of the genes involved in the pathway were up-regulated in the flies without mouth tastebuds, even though their blood sugar level was unchanged. When the insulin pathway was inhibited in these flies, they didn’t live any longer than wild-type. This suggests that some of the lifespan extension was due to insulin signalling.

So the ability to taste sugar could affect how we age. If only sugar wasn’t so delicious.

The Scientific Paper:
Ostojic et al. Positive and negative gustatory inputs affect Drosophila lifespan partly in parallel to dFOXO signaling. PNAS. 2014 

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