Out of curiosity, how many different diets you know and can name? I was able to quickly come up with:
- High-fat, low-carb (and its varieties such as Atkins, Protein Power etc.)
- Low-carb, high-fat
- Vegetarian / Vegan
- Cyclical ketogenic diet
- The Zone
- Mediterranean diet
- Subway diet (!)
All claim to be better for your overall health, decrease risk of cardiovascular disease and diabetes, and help you lose weight – despite each diet giving recommendations that completely contradict each other. Now if you follow news you probably have noticed that one day high cholesterol increases risk of heart disease and the next day low cholesterol increases risk of stroke. Aspartame and other artificial sweeteners cause brain damage, but natural sweeteners damage liver! What else is there to do but stop eating altogether?
Hey, that might actually work! Studies show that calorie restriction increases lifespan in rodents, but then again not getting enough food is a stressor and therefore increases cortisol production which prevents fat mobilization and makes you lethargic… So you’re back in square one.
The question is, how can you make sense of all of this? One big part of it is to learn to read research papers (and largely ignore news in mainstream media), to be able to separate correlation from causation, and to understand statistics well enough to see if data has been manipulated to show whatever the researchers believe in. This, however, is not the topic of this article.
Nutritional science in itself is less than a 100-year old discipline. A mere baby. And like in any other area of science there are factions; people who believe differently about what we should eat. On top of the different factions the science is also very fragmented. We have a research study here and another one there, but nothing to tie them together.
For example, let’s say that there is a study that finds biological process X to be linked in cancer development. Now that biological process can be downregulated by lowering magnesium intake. Would you then go on and recommend people to take less magnesium? And by doing so ignore the hundreds of other biological processes where magnesium intake is a factor? Enter the confusion.
In order to bring all the fragmented research together and to start forming a comprehensive picture of what’s going on, a guiding paradigm is needed. In physics we have both the classical Newtonian physics and more recently Quantum Mechanics. In cosmology there’s the “Big Bang” theory. These are extremely important in providing the scientists a starting point, a perspective from which to evaluate the research they are doing. And the research either sits well in the theory or contradicts it. If enough contradictions arise the theory gets discarded, revised, or evolves into a new theory and brings us one step closer to enlightenment.
What boggles me is that even though nutritional science cannot be anything else but a subsection of biology, the guiding paradigm of biology – evolution by natural selection – is completely ignored in nutritional science. As a result we have fragmented information and no coherent way to interpret the data.
On the other hand, if you start considering nutrition research from the perspective of evolutionary theory, all the fragments of information start to suddenly make a lot more sense. As Prof. Loren Cordain puts it:
All human nutritional requirements like those of all living organisms are ultimately genetically determined. Most nutritionists are aware of this basic concept; what they have little appreciation for is the process (natural selection) which uniquely shaped our species’ nutritional requirements. By carefully examining the ancient environment under which our genome arose, it is possible to gain insight into our present day nutritional requirements and the range of foods and diets to which we are genetically adapted via natural selection. This insight can then be employed as a template to organize and make sense out of experimental and epidemiological studies of human biology and nutrition.
Maybe in the future we’ll be wiser…
Note: this article would not have happened without me reading NorCal Nutrition: Are We Crazy? which contains a very good brief by Loren Cordain.