The book itself is summarized succinctly on the cover: "Eat food. Not too much. Mostly plants." It sounds like reasonable advice, and inside he makes the case for the pithy slogan. He argues that much of what we eat is not food and attacks the Western Diet and the nutritionism movement that focuses on individual compounds and not on whole foods. He describes what he calls "The American paradox": despite a preoccupation with health and nutrition, the US increasingly unhealthy, and proposes some dietary changes to address that fact, elaborating on the cover's mantra. (There's no reason to think this doesn't apply to Canadians as well)
Unfortunately, this book got under my skin right from the start. From the beginning, there is an anti-science tone, even putting the word in scare quotes, "advising you to reject the advice of science and industry" and arguing that current limitations of scientific understanding mean it's not enough to go by when deciding what to eat. Well, if not science then what? "Tradition and common sense" is the answer. That sounds good, and may even be a reasonable starting point but outside scientific rationalism, tradition and common sense can lead down the path to pseudoscience. And we see this fairly often with unproven traditional medicines that "have been used for thousands of years!"
In fairness, he's mostly speaking about science in a narrower sense and uses some science to back his arguments, but the opening tone feels otherwise. The real science he's attacking is reductionist nutritionism, the kind of thinking that gives us 'trans-fats are bad', 'eat more omega-3s', etc., distilling food down into more basic elements. It's not hard to be frustrated by reports of what's good or bad for you changing seemingly daily, and he makes a reasonable case for rethinking that approach. Unfortunately, this poses another problem for Pollan. He attempts to debunk nutritional science but at the same time depends on it to support his own arguments about what kind of food we should be eating. The inconsistency is obvious, and Pollan himself is aware of it. He does attempt to address this problem, but never really succeeds at doing it satisfactorily (at least for me).
This isn't the only logical flaw in his thesis. He appeals to tradition, but what gets traditions started? How did our ancestors know what works and what doesn't? How do we figure it out to start new traditions? Trial and error is one way, and historically possibly the main way, these things have been worked out. For example, one complaint is that our bodies aren't used to the new Western diet and its manufactured foods, we get sicker because of it (eg. increased rates of obesity and diabetes) and we should move back to eating "real" food. This may well be true, but as he also notes, the same thing happened when cow (and other animal) milk was introduced to the human diet. Now, milk seems as natural and wholesome a food as any other, but would Pollan have argued against milk as a food if he were around back then? "We've adapted!" seems like a probable defense, but how do you adapt or learn or improve without trying new things?
While this all seems quite negative, the book was interesting and easy-to-read, even if some of the support for the thesis had holes. Despite some flawed argumentation, In Defense of Food does offer some food for thought regarding our philosophy towards food - what it is and how to think about it - even if you walk away not agreeing.
In Defense of Food by Michael Pollan