Scientists and nutritionists may never identify an optimum human diet.
When it comes to the human body and its interaction with the world, we face unknown unknowns; we don’t know the scope of our ignorance and we’re constantly discovering greater complexity.
This epistemological problem is laid out in Colin Campbell’s new book, Whole. According to Campbell, the body is not a machine that can be broken down to component parts to be fully understood, as most Western “reductionist” thinking believes. Instead it is a fluid system that is intertwined with our environment, and is constantly reacting to it.
Nutrition resists reductionist thinking.
“Daily recommended values” for specific nutrients don’t make sense for these three reasons:
- Our bodies don’t follow a script; they improvise. There’s almost no direct correlation between the amount of a nutrient eaten and the amount that reaches its main site of action in the body – what is called bioavailability – because the body takes only what it needs at that moment.
- There’s natural, unpredictable variability in food. The quantity of a single vitamin, for example, can vary dramatically from one fruit to another. Factors that affect the vitamin content of fruits can include production factors and climate conditions, maturity stage of fruits (species and variety), handling and storage, and type of container they’re stored in.(1) The swings can be extreme; one peach, for example, may contain forty times more beta-carotene than another, even though they look and taste identical.
- The foods we eat interact with one another. Some nutrients work to enhance, inhibit, or change how the body absorbs other nutrients. For example, calcium decreases iron’s bioavailability by up to 400%. Many nutrient pairs interact.
But it gets even more complex when we consider ethnicity, age, stress levels, activity, etc., all factors influencing how we absorbs nutrients. Whatever experts may claim, nutrition resists certainty.
But some diets lead to proven outcomes, right?
Yes, many diets do have very good short-term outcomes. Each of the popular diet trends – Mediterranean, Paleo, South Beach, Whole-Food Plant-Based (WFPB), Ornish Diet, and gluten-free – has its credentialed advocates who wield impressive supporting evidence and its equally qualified critics armed with contradictory evidence. Paleo and plant-based dieters acknowledge that both diets have their strengths, but disagree on their respective weaknesses.
It’s really easy to poke holes in scientific studies on diet.
It’s easy to poke holes because no study can capture or control for all the variables that might effect an entire group of people over the long term. The problem is that we don’t know with statistical certainty which elements are driving those outcomes as it’s really hard to run a controlled long-term study and isolate each variable to find out (in humans). But looking at individual variables is probably the wrong approach; it’s likely that a constellation of factors – not just one or two variables – come together to create a healthy outcome.
You don’t need to be right. You need to be different.
Over 74% of American adults are overweight or obese today. Americans eat a diet rich in meat, salt, sugar, oil, and all sorts of processed foods. Start by eating less of all of those foods, and eat more of what Americans are missing: fruits and leafy greens. If you want to look dramatically different from most Americans, you’ll have to eat dramatically different. Here’s what we recommend.
Prioritize conscience over nutritional science.
2014 was the hottest year in recorded human history. Methane from livestock causes more greenhouse gases than all the world’s transportation(2). Our seas are on the verge of mass extinction due to overfishing and pollution(3).
Maybe we shouldn’t be looking so much to researchers to tell us what to eat as to Mother Nature.