"You couldn't reach that aerobic capacity if you were training day and night."
– Jean-Michel Weber
If only Lance Armstrong knew what the semipalmated sandpipers know, he wouldn’t have had to resort to performance-enhancing drugs or blood transfusions to win the Tour de France. Unlike the disgraced cyclist, the graceful little birds run their own three-day, non-stop endurance race every year, fuelled with nothing more than natural energy. They store that energy after stuffing themselves with mud shrimp they pluck from the Bay of Fundy at low tide.
As University of Ottawa biologist Jean-Michel Weber and his team have discovered, the process the birds use to prepare themselves for their non-stop 4,500-kilometre migration from the Fundy shore to the coast of northern Brazil is a kind of natural doping regimen.
Weber and his students knew the sandpipers spend about two weeks gorging on mud shrimp after arriving in New Brunswick and Nova Scotia in mid-July from breeding grounds in the High Arctic. Most researchers had previously focused on how much fat the birds need during their migration. But Weber’s team concentrated on what kind of fat the birds eat, wondering if the type was the secret to the birds’ amazing athletic feat.
As it turns out, mud shrimp are loaded with omega-3 fatty acids. The birds use the fatty acids as doping agents to improve their performance just before they migrate. “In addition to being a very good source of energy, these omega-3 fatty acids incorporate in the membranes of the birds’ cells, particularly in the birds’ flight muscles,” says Weber. “They accumulate there.”
The stored omega-3 acids change the membranes in the flight muscle cells. They increase aerobic capacity by activating key enzymes that boost the bird’s ability to process oxygen and to convert fat stores to adenosine triphosphate or ATP, the energy currency of living cells.
The sandpipers, which are about the size of a swallow when they arrive in the Maritimes, double their weight from 20 grams to 40 grams by the time they take off for Brazil. “To get ready for these flights, they basically become obese,” says Weber. “They have all kinds of mechanisms to encourage this obesity, which is reversible.”
By the time the birds land in Brazil, they are back to 20 grams, having used their energy reserves during the long flight. “All the mechanisms involved in making these reserves and using them in a reversible way are of great interest,” explains the biologist. “Of course they are not exactly the same mechanisms as you have in people, but we have a lot to learn from these animals.”
To test their theory that omega-3 fatty acids are natural doping agents, Weber and his team gave the most sedentary birds they could find—quails—doses of omega-3 mimicking the sandpiper diet. Then they measured the effects on the quails’ flight muscles. The couch potatoes of the bird world, which seldom fly, had increased their aerobic capacity between 50 and 90 percent, just by consuming omega-3 fatty acids.
“You couldn’t reach that aerobic capacity if you were training day and night,” says Weber.
The research confirmed that for the sandpipers, diet rather than exercise is the key to improving performance. Unfortunately for athletes like Armstrong—and for Weber—eating the same proportion of omega-3 to produce equivalent results in humans is so far impossible. “If I could replicate that kind of response in a human, I’d be rich by now,” Weber says with a laugh.
What is significant for humans is the way the fatty acids work on metabolism, by modifying cell membranes. That process is the focus of Weber’s lab research.
Researchers now know that changing cell membranes alters the behaviour of the many proteins that are embedded in that membrane, says Weber. For example, the insulin receptor is a membrane protein that can be activated by modifying membranes. When diabetics consume omega-3 fatty acids, they can greatly decrease their insulin resistance. This discovery has helped obese or diabetic people improve their glucose metabolism through simple dietary supplements of omega-3 fatty acids.
Based on this new understanding of the importance of cell membranes, Weber continues to study the ability of migrating birds and fish to mobilize the lipids they derive from their diet into increased performance, in the hope of finding more clues to the process humans may one day harness.
by Laura Eggertson