Throughout In Defense of Food, Pollan exposes and critiques scientific reductionism. Pollan argues that American society has been sold the ideology of nutritionism, which is the idea that when people eat, what matters are the individual essential nutrients found in the food (macronutrients such as protein, and micronutrients such as Omega 3). This ideology is the product of scientific reductionism, which is the scientific method taken to extreme. This approach seeks to determine truth by studying individual elements in isolation, treating each as a variable in a scientific equation. Such an approach works admirably well in contexts where the factors can be isolated in such a fashion, Pollan notes, but it does not work in arenas where the factors cannot be successfully isolated because they are part of a larger context.
This particularly applies to food for several reasons. First and most simply, nutrition sciences are strikingly limited. Even scientists working in the field aren’t sure about the effects of individual nutrients on the human metabolism. Second, outside of the lab, nutrients are not consumed in isolation. They are consumed as part of complex biological entities: plants, animals, and so forth. Third, in many cases, nutrients whose function is known do not necessarily function the same way in isolation or in synthetic forms as they do when consumed as part of plants or animals. Fourth, the nutrient qualities of those vegetables and meats are changed depending on the context in which they’re grown. Fifth and finally, people’s eating habits are shaped by many factors beyond science, such as culture and advertising. Closely related to idea that the science employed by nutrition scientists is more ideology than science are two other related themes: hubris and bias.
Hubris is an overweening pride, a conceit that allows one to overlook the seeds of one’s own downfall in one’s very actions. Pollan’s critique of contemporary nutrition science shows a discipline distorted by this very sort of hubris. From relatively humble scientific beginnings early in the nineteenth century to a complete domination of key government policies and economic and individual decisions about what to eat, the rise of nutrition science has been nothing short of meteoric. However, a glimpse at the way theories move in fads through the nutrition world will show just how little this rise is based on actual science, and the numerous sweeping dictates about what to eat and what to avoid, which are then followed by equally sweeping reversals, are closer to the mercurial...
(The entire section is 1079 words.)