For millennia humans have, in fact, been surprisingly adept at discerning patterns; it's something hard-wired in our brains to help us survive in a hostile environment. Mothers did their best to raise their children to be healthy and strong, based on the anecdotal evidence in the lives of those around them and the advice their own mothers passed down to them. And I can easily pull up many sources of historic nutritional advice, including advice from famous philosophers.
- Hippocrates is very quotable.
- Mother Knows Best (1953 Campbell's Soup TV ad).
- Slikke Hans (old Danish children's song).
- Confucius Tells You How to Eat.
But the post-World War II era saw the emergence of the first large-scale studies of our diet. Most famous was perhaps the Framingham Heart Study, in which 5,209 people in a small Massachusetts town were followed for many years, starting in 1948, in an attempt to uncover risk factors for heart disease. The study of Korean War soldiers followed it, along with many more. But the conclusions drawn from these studies weren't always justified.
Every time a well-intentioned study has come along, revealing some new connection between diet, exercise and health, there has always been a pattern:
- New information is cautiously (usually) presented to the scientific establishment, suggesting a possible link between whatever and our health.
- The conclusion from the new study is presented in a simplified format to the general public.
- The media jumps on the simplified conclusion, simplify it even more, and emphasize the most controversial aspect of it.
- People overreact to the media stories and demonize or praise the whatever.
- The food industry is happy to "feed" the hype in order to sell higher-margin products.
- A backlash occurs, people start to question even the initial cautious scientific conclusion, and they revert back to their previous behavior.
- Eventually things calm down and a more sober assessment of the data results in a more nuanced approach to the whatever.
That's what happened with the war on fat: After some initial hype resulted in a decline in fatty diets and a commensurate decline in heart disease, we instead had a huge increase in type 2 diabetes as people ate/drank more carbs in place of fatty foods. Eventually people came to understand that not all fats are bad, and some are essential to our health, in moderation.
Then we had the war on cholesterol: Since cholesterol was the sticky substance that was blocking our arteries, it seemed obvious that reducing the amount of it in our diets would be beneficial, right? Well, since 75% to 80% of the cholesterol in our blood is produced by our own livers, not from the food we eat, that idea has declined in recent years as scientists have instead uncovered evidence suggesting it is really much more complicated than that, and it may be far more inflammation of the arteries that allows this blockage to occur.
That was followed by the war on carbs: After the low-fat, low-cholesterol diets resulted in type 2 diabetes people started to revert back to higher-fat diets. When the initial euphoria associated with unlimited fat intake died down (along with some of its adherents), people realized that not all carbs are bad and avoiding them altogether was not improving our health. Who would argue that the carbs from fresh fruit are unhealthy?
That's happening now with the war on gluten: After the the initial discovery of yet another culprit in our poor health, people are now questioning the value of the war on gluten. Soon all of those expensive gluten-free foods at the store will be gone, and people will revert back to regular old wheat. Yet, perhaps gluten really isn't essential to our health, and perhaps we can get the nutrients in grains from other, healthier food sources?
The wars on alcohol, coffee, high-fructose corn syrup, artificial sweeteners and more continue unabated, more or less.
I believe the biggest source of this pattern of hype/rejection is that the "causality" of the issue is oftentimes ignored. That is, the conclusions from scientific studies often don't truly separate the causes from the effects. Example: Is it the eating of cholesterol in food that causes coronary artery blockage? Or is the blockage caused by something else, that in turn allows the cholesterol to accumulate? The human body is exceedingly complex, as is nutrition... when you combine those two very complex subjects into one subject you can imagine how the complexity must increase tremendously. We will probably never fully be able to separate cause and effect, but we can certainly narrow down the possible answers.
The old saying "Don't throw out the baby with the bath water" still holds true: Within those large cycles in popular and scientific opinion there are always some truths that don't change. We shouldn't rely on the popular media, our friends, family and personal trainers for advice about diet. We should rely on a cautious examination of the best possible scientific evidence when making decisions that affect our health. That means we should read the original scientific studies rather than rely on the simplified message we get from the media or others trying to profit from the conclusions.
That said, I don't pretend to read the full texts of the many scientific studies, but like all humans I am hard-wired to find patterns, and when I see a pattern I try to learn from it.
Good luck, we need it!