hdwkt: the science behind nutritional advice

9 Nov

The past few years I’ve been teaching biochemistry of the macromolecules (Chapter 3 in Campbell Concepts and Connections) alongside enzymes and digestion (Chapters 5 and 21 respectively). To me, these topics fit together tighter than a-bungarotoxin at the neuromuscular junction. I wish more textbooks would organize themselves this way, rather than oh so unoriginal small – big sequence of topics. Start with atoms, end with ecology…clever. But that’s another day.

A few items recently caught my eye regarding nutritional advice, and I’m mulling over how to implement these into the classroom along the lines of hdwkt (how do we know this?). One is a video a student showed me of  a 4 year old McDonald’s hamburger that looks pretty much like a 4 hr old hamburger (there’s lots of other videos on this same theme).

While her props are indeed provocative, this isn’t really fair to the burger or fries. Before I start, I’m not in any way suggesting that McDonald’s is healthy or great for you, or that any burger and fries are great for you. However, I do take issue with her illogical argument for avoiding McDonald’s.

Her argument goes something like this:

McDonald’s burger doesn’t rot
Food rots
Therefore, McDonald’s burger is not food

Her corollary to that seems to be:

McDonald’s non-food burger doesn’t break down easily in the open air under normal household conditions
If non-food burger can’t break down outside the body, it can’t break down inside the body
If the burger can’t break down, your body stores it (in your thighs)

There’s lots of ways this line of reasoning is flawed. Skipping over the philosophical debate over a definition of ‘food’, even a rudimentary working knowledge of the digestive system would tell you that the environment in your stomach or small intestine is quite different from sitting on the kitchen counter. I think this provides a great opportunity for students to critically evaluate an argument such as this and apply knowledge they’ve acquired.

Another issue here is the lack of a proper experiment. Simply holding up one McDonald’s burger doesn’t tell us much when we don’t have another burger to compare it to. Similarly, slices of raw potato don’t make a great control for a McDonald’s french fry longevity study aimed at demonstrating how un-foodlike McDonald’s products are. What would make a better control? What types of experiments could we design?

Today I stumbled across a blog post from J.Kenji-Lopez (SeriousEats.com) who seems to have taken issue with this pseudoscience of burger preservation and tried to approach it more scientifically. Read more about the experiments and analysis here. I like the comparison of % change in mass over time graph, interesting stuff.

This provocative video lecture, “Sugar: The Bitter Truth” by a scientist from UCSF argues that fructose is treated by our bodies as a poison and responsible for the modern obesity epidemic. Lots of great biochemistry too. This isn’t exactly a mainstream, FDA position, but that’s the point. How do we evaluate these types of claims? It gets even harder when it’s a scientist from a reputable university, and he’s using lots of formulas! How does the FDA make their guidelines? When you take a look at the obesity epidemic, obviously something about or recommendations isn’t working…

Another food related article illustrates the uncertainty in our scientific understanding of world. The headline ‘Twinkie diet helps nutrition professor lose 27 pounds” is definitely an attention grabber. There’s lots of room for questioning in here. Why do we eat the foods we do? A great food choice related infographic appeared in the NYTimes the other week highlighting ways we can subtly alter school cafeterias to increase positive choices. Reminded me of the book ‘Nudge’ a bit, but how do we know what is ‘good’?

Everyone is faced with food choices every day of their life. How can we better inform our choices? My students will soon be heading off to college and, for many of them, it will be the first time in their lives when they’re entirely responsible for what to eat. Yikes.

Michael Pollan has written extensively on food and nutrition and I really enjoy his perspective. His book, “In Defense of Food,” has a nice and simple message, “Eat food, mostly plants, not too much.” Word.

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One Response to “hdwkt: the science behind nutritional advice”

  1. Holly January 4, 2012 at 9:45 pm #

    “I think this provides a great opportunity for students to critically evaluate an argument such as this and apply knowledge they’ve acquired.”

    Very interesting examples from the media and I love the idea of bringing this into the classroom. So often I hear my students saying “I heard this…I heard that…” followed by something outrageous or nonsensical. Teaching students how to think critically about the information presented to them is an important life skill. Thanks for the reminder.

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