Professor Kenneth Welch and his team found that hummingbirds can burn fructose equally as well as glucose, which is something other invertebrates cannot achieve. Credit: Ken Jones Enlarge

Hummingbird metabolism is a marvel of evolutionary engineering. These tiny birds can power all of their energetic hovering flight by burning the sugar contained in the floral nectar of their diet.

Now new research from the University of Toronto Scarborough shows they are equally adept at burning both glucose and fructose, which are the individual components of sugar; a unique trait other vertebrates cannot achieve.

"Hummingbirds have an optimal fuel-use strategy that powers their high-energy lifestyle, maximizes fat storage, and minimizes unnecessary weight gain all at the same time," says Kenneth Welch, assistant professor of biological sciences at UTSC and an expert on hummingbirds.

Welch and his graduate student Chris Chen, who is co-author on the research, fed hummingbirds separate enriched solutions of glucose and fructose while collecting exhaled breath samples. They found the birds were able to switch from burning glucose to fructose equally as well.

"What's very surprising is that unlike mammals such as humans, who can't rely on fructose to power much of their exercise metabolism, hummingbirds use it very well. In fact, they are very happy using it and can use it just as well as glucose," says Welch.

Hummingbird metabolism unique in burning glucose and fructose equally

A ruby-throated hummingbird takes a drink of nectar from a feeder tube in Professor Kenneth Welch's lab at the University of Toronto Scarborough. Credit: Ken Jones

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