This seems to surprise people when considering how any science changes. Most theories are just that theories, often manipulated for ego, profit, or politics.
Remember when eggs were all but outlawed and vilified in the 80s? Now they are a superfood. In the 70s all the nutritional experts were pushing high carb diets then it switched to high protein. Now the fads are vegetarian and organic. For the longest time nutritionists had everyone terrified of coconut oil, later we found out they had been bought out by oil producers to push cheap canola oil (which is a made-up thing). Many people still think and are taught that canola oil is better for you.
Not everything you eat is perfect for your friend, brother, neighbour, teacher, or anyone else. Diet and nutrition often times is extremely personalized. Food is also extremely diverse. An apple picked from your local orchard may be nutritiously different than the ones pre-sliced and sold in packages. And the same goes for many other foods.
If you asked most people about foods that are “good” or “bad” for you, you’d get a dozen different answers. You’d find people who vehemently argue that eggs are both good or bad for you, that sodium does and doesn’t contribute to hypertension, or that carbs do or don’t make you sick. In general, you’ll find a lot of laypeople with opinions that may or may not be based in real science. Researchers, however, generally have some pretty solid opinions on these issues and are quick to note where their own shortcomings are.
Nutrition research is very difficult to conduct. While studies about a nutrient’s impact on health can be conducted in a highly controlled environment, the isolation of a laboratory with set meals, supplements and controlled activity is a far cry from life in the real world.
Conducting studies with subjects eating, working and playing in the real world presents an array of issues, including fluctuations in behaviour or misremembered accounts of intake or physical activity. Statisticians help researchers to tease out the confounding factors to determine the significance of a study’s outcomes and interpret the results. However, for these reasons and more, nutrition research must repeat until a large enough body of evidence exists that the broader scientific community agrees on a nutrient’s relationship to health. Even then, there could be special exceptions to the rule.
Because we are all different. We have varying degrees of health. We have different levels of hormones and metabolism; different body composition or body type; different genetic predispositions and different responses to foods. We live different lifestyles in different environments, and we endure different stress levels. We have different ethnic backgrounds. For instance, those with Japanese heritage or who come from coastal people will need more fish and fish oil. These wide differences account for so many different diets.
Be cautious about what you read in the media and read well beyond the headline. If you have time, find the original research article to see what the researchers actually concluded. You can also Google search to see if other reputable sources are commenting or debating the interpretation of the results.
Don’t treat anecdotal evidence as consensus science. Just about everyone knows of someone that lived to a ripe age breaking every health rule. It’s likely you also know of someone that died prematurely of a massive heart attack from the same regimen. Trust the consensus when it comes to saturated fat, omega-3 fats, and refined carbohydrates.
Be mindful of the way you feel during and after you eat. I like to trust my body and the positive feeling I have when I eat a balanced, minimally processed diet, with plenty of plant-based foods and desserts in moderation (for my sweet tooth!).
In nutrition, the hypotheses are speculations about what foods or dietary patterns help or hinder our pursuit of a long and healthy life. The ingenious and severe attempts to refute the hypotheses are the experimental tests — the clinical trials and, to be specific, randomized controlled trials. Because the hypotheses are ultimately about what happens to us over decades, meaningful trials are prohibitively expensive and exceedingly difficult. It means convincing thousands of people to change what they eat for years to decades. Eventually, enough heart attacks, cancers, and deaths have to happen among the subjects so it can be established whether the dietary intervention was beneficial or detrimental.
No matter what book you read, keep in mind that you have to eat the diet that works for you. Don’t substitute anyone else’s judgment for your own. It takes years of trial and error while listening to your body and its reactions to foods to figure out the best diet suited to you (i.e. the amount of protein you need). Then once you get it figured out, your needs change due to age and health status! This is a lifelong journey.
