From real research to misguided meme: the case of chocolate milk

One of my bugbears is the misinterpretation and misuse of research studies. An excellent PhD Comic illustrates how a researcher’s tentative, qualified conclusion is stripped of doubt and injected with pop power by the media. Soon, it’s on everyone’s lips. Biologist Richard Dawkins called these phenomena of rapid and wide cultural diffusion memes. While many science-based memes are simply byproducts of curiosity-driven research (everyone knows what a Higg’s boson is now, right?), others are either created or latched onto for purposes of selling something.

Nowhere is science more twisted to suit marketing than nutrition. I remember reading the original paper in Science about the discovery of a compound in several edible plants that shrinks cancer tumours in mice. Oh, boy, I thought. This will be big. As a result of that study, everyone knows about resveratrol today, and it is the number one rationalization for drinking wine (since resveratrol is found in grapes). But did you know it’s also in peanuts and mulberries? No, I didn’t think you did. I’ll have another peanut butter sandwich with mulberry jam, please.

Which brings me to chocolate milk. I’m a runner, and over the past few years I keep hearing runners telling other runners to drink chocolate milk. My latest iRun magazine lists chocolate milk as a super-food for runners.

But I was skeptical. This had all the hallmarks of scientific research going meme, with no complaints I’m sure from dairy companies.

I don’t know how you spend your day, but I look up original research papers. “Chocolate milk as a post-exercise recovery aid” was published in the peer-reviewed International Journal of Sport Nutrition and Exercise Metabolism in 2006.

The study involved 9 male, healthy, highly trained cyclists. They first cycled at intervals of 90% and 50% of perceived maximal exertion (2 min each), with the hard interval progressively stepped down. They kept going until they couldn’t maintain their cycling cadence because of glycogen depletion, about 40 min. They were given recovery drinks right after the exercise and 2 h later. After 4 h loafing around the lab, they got back on the bike and cycled at 70% of their VO2 max until exhaustion, an average of 40 min.

The drinks tested were low-fat chocolate milk, Gatorade and Endurox. What the researchers looked at was how long the athletes could exercise and how much work (in physics terms) they could do in the second cycling trial. That is, which drink worked best to restore their energy?

The results showed that the athletes who drank chocolate milk could do more work than athletes drinking Gatorade (relative numbers only given ~sigh~, but it looks from a graph like about 30 kJ difference) and much more than athletes drinking Endurox (200 kJ). The athletes who drank Gatorade cycled the longest before becoming exhausted, but on average just a few minutes more than those who drank chocolate milk. Both drinks added an average 13 minutes more to the time before exhaustion compared with the Endurox.

So, doesn’t that make chocolate milk good?

Sure, in highly trained athletes exercising to exhaustion, whose glycogen is depleted and needs to be restored to do the next tough bout. According to the authors, the reason chocolate milk works so well is that it restores fluid levels and glycogen, through carbohydrates. It should also be noted that milk contains plenty of protein and vitamins, which may help account for its value.

But here’s the catch: for most of us, chocolate milk has the same nutritional value as regular milk but with two added items – fat and sugar. These athletes drank low-fat chocolate milk to avoid the fat, and the carbohydrates they were getting were from sugar.

I went down to my local store and photographed the nutritional information for regular and chocolate milk. Of course, I hang out at a healthy food store with many organic and alternative products. They stocked the low-fat chocolate milk so, if you read closely, you’ll see the chocolate milk had the same fat content as regular milk. But it had lots of sugar. 29 g per 250 mL compared with 11 g per 250 mL for regular milk. Athletes usually drink about 500 mL to recover, so they would get 58 g sugar, rather than 22 g from regular milk. Multiply that by the number of times an athlete would drink a recovery beverage during the week, and it’s getting up there.

Regular 1% milk nutritional information
Regular 1% milk. Note sugar content

Chocolate milk nutritional information
Low-fat chocolate milk. Note sugar content

For the average recreational runner, who may be trying to eat healthy and watch his or her weight, it is really not good to consume extra fat and sugar. You don’t need the extra carbohydrates unless you are exercising again in a few hours; those are only for endurance athletes or athletes in high-performance training.
If you want a really good recovery drink, low-fat milk has protein and fluids.
The moral of the story: studies in one group (high-performance athletes) should not be generalized to other groups (recreational runners); studies in one situation (repeated bouts of exhausting exercise) should not be generalized to other situations (recreational exercise).
Oh, there is one use for chocolate milk: getting children who don’t like milk to drink it for the value of the other nutrients. But you’re all grown up now, aren’t you?

What will be the legacy of International Polar Year?

A selection of the Canadian contributions to International Polar Year appear in the November 2012 issue of the journal Climatic Change, available free online. Guest editor of this special issue, Tanuja Kulkarni, told me that the choice of journal reflects one of the main concerns of Canadian research during the year (really two years): how Canada’s arctic is changing and adapting (or not) to warming temperatures. (In the interests of full disclosure, Tanuja is a friend, and I’m proud of her role in this important publication.)

But the second main thrust for the IPY research was the health and well-being of northern communities. While there have been three other IPYs in history, they have focussed on hard sciences, whereas this one brought in the social aspects. As well, community knowledge played a role in many of the research projects, including those collecting scientific evidence.

As the authors point out in the introduction, past IPYs dating from the 1880s to the 1950s broke new scientific ground. From them, we learned about the jet stream and the ozone layer, among other discoveries. They also fostered international collaboration instead of competition, which allowed sharing of new knowledge that would not otherwise have been possible. They set the stage for the continuing international scientific exploration of Antarctica, as an example.

So what will come out of Canada’s work on the 2007-2008 IPY? A few years ago, I attended a symposium by IPY-funded researchers as part of the annual Canadian ecology and evolution conference. They were doing important research on the changing tree line, which in some places is moving northward year over year as the climate warms, with important effects on albedo and ecology. Others were studying what happens as permafrost melts, releasing additional greenhouse gases such as methane into the atmosphere, in a vicious circle that exacerbates climate change.

Climate, ecology, community — the interdependence of these systems is becoming increasingly apparent. A holistic view of our north is one of the positive legacies, certainly. Understanding the global effects of what happens in northern Canada is another. We will hear more in years to come about what is called the “cryosphere”: snow, permafrost and ice. These play a much more influential role in world climate and ecology than we ever imagined.

And, if we learn anything at all, we will learn that Canada has a challenge shared with only a few other arctic countries as guardian and steward of the north. There is a danger with the end of IPY funding that we will lose the momentum of this important research. We need to continue to explore the land — and sea — that are now less mysterious and more complex than previously thought.

Commercial solar energy: in my lifetime

I’ve been hearing about solar power all my life. And I was getting pretty cynical. Yeah, yeah, solar power. And world peace, tricorders, an end to disease and so on.

So I was surprised to read in recent reports from the International Energy Agency that there is a real shot at commercially viable solar power within the next decade.

Why now? The hurdle until recently was the high cost of photovoltaics, the systems to turn solar energy into electric current and put it on the grid. While sunshine is free, the cells that trap it rely on a certain grade of silicon (expensive to produce). Then land must be found for solar plants, and then the cells must be mounted in large glass installations. Power generated is often direct current at an inappropriate voltage. So transformers and other equipment are involved to produce alternating current at an appropriate voltage and add it to the existing grid.

However, there have been recent technical achievements that have resulted in lower-cost cells based on technologies such as cadmium telluride.

To encourage “green” energy solutions, many governments (including Ontario’s) have supported solar energy through feed-in tariffs, in which providers are paid a premium price (a form of incentive or subsidy) under long-term contracts. The price often reflects the cost of production, rather than the market cost of electricity.

However, with costs coming down, experts are talking about the magical moment of “grid parity,” when the cost of providing power from photovoltaics matches the market cost of electricity. At that sweet spot, solar power becomes commercially viable. This has actually been achieved in some international systems. As the new technologies come on stream, it will be more and more common. In the same way that lofty windmills are a familiar sight in the Gaspe, arrays of glass-plated solar-catchers will appear on abandoned industrial land (brownfields) or next to cow pastures. And the world will become a better place.