Lately I've been thinking about nutrition studies. My sister is getting her PhD in nutrition and we've been talking a lot about how difficult it can be to find/do nutrition studies.
So we all know there are a lot of bogus claims out there about nutrition. Soy gives you boobs! Blueberries cure everything! And there's a general consensus about basic nutrition stuff. But in the case of most individual nutrients, we really don't know exactly what they do. It's incredibly hard to design an accurate study of nutrients, or even specific foods, because it means regulating everything people eat, which is really difficult.
If we're trying to eat as heathfully (healthily) as possible or just to discuss nutrition based on good science, how do we balance that with the possibility that we may not know for decades (if ever) what that means in terms of individual nutrients? In this case, absence of proof doesn't always mean something isn't true. Sometimes it just means it hasn't been tested. If we say, "There's no evidence of that!" when it hasn't been tested are we representing it as definitely untrue? And if we make our nutrition decisions solely on what HAS been studied, are we missing important stuff?
In no way am I saying we should fall for pseudoscience. I mean something like that there's no study definitively showing that a cup of leafy greens a day is beneficial but that doesn't mean I should decide not to eat a cup of greens a day.