Nutrition "science" is so inconsistent and contraindicatory that as much as we want to have some reliable data, there is nothing we can hold on to. All we get is more confusion and misleading information.
Let's take the humble egg. In the late 1970s, it began to be a dangerous source of all evil - super high in cholesterol, the culprit of heart attack and stroke. Yet, in the last few years, there has been some kindness shown towards the poor egg - described in many publications as a great source of protein, unparalleled antioxidants like lutein and zeaxanthin, source of many vitamins and minerals, including riboflavin and selenium, and of course relatively low in calories.
And here we go again. In March a study published in JAMA has shown that the amount of cholesterol in two eggs a day was associated with an increased risk of cardiovascular disease and death by 17 percent and 18 percent, respectively. The study was really large with nearly 30,000 participants so by no means fairly reliable.
What's the take-home message then? Is the egg good or bad for health? We still don't know.
Nutrition research tends to be unreliable and confusing simply because the vast majority of it is based on observational studies. These studies are basically surveys which are imprecise, have no control groups, and don’t follow any experimental method. And to be fair with the researchers, it's nearly impossible to design a proper nutrition study for many reasons.
We are all snowflakes, all different. Our way of living, our metabolism, our emotions and daily stresses shape the way we eat and the speed we metabolise food. Unless we take each of us personally the nutrition research will stay where it is now. In a mess.