[sp3000]

One of the commonalities between the longest lived people on earth: they eat food that is macronutrient poor, but micronutrient rich (think lots of vegetables, but not too many calories). This is the opposite of people who live the shortest: macronutrient rich, but micronutrient poor (think modern processed foods high in calories).

A typical fruit or vegetable can have hundreds of phytonutrients and other chemical compounds that are just very hard to recreate in processed foods. This is in addition to the 30 or so micronutrients that we already know of that are essential for certain biological processes. In the black hole that is nutritional research, population and epidemiological studies simply show people who do include a lot of vegetables in their diet tend to have better health outcomes. It's likely you might draw a different conclusion from that research than people involved in the field, but it's probably one of the safest bets we can make when it comes to staying healthy.

[JesseMReeves]

These are good points. The Japanese (and probably many Chinese) cuisines certainly fall into the micronutrient-rich category (with seaweed, fish, etc.), have seemingly been tested for centuries and are awesome. Difficult to have these diets in the Western world though.

As for the science factor, I am a bit suspicious of people who have made nutrition their life topic. I get vibes of eating disorders or very controlling food choices. Like the formerly obese or anorexic person who becomes a dietitian because they did not manage to get rid of the cognitive addiction (they chose a profession where they can talk about food all the time). This might explain the tendency for these research areas to go with diet fads, or promote food very poor in nutrients like lettuce while rarely talking dangers like pesticides or issues how you should even come close to the daily recommended values with modern-grown veggies.

Also, there are some shoddy science practices in highly promoted studies. They often seem to work with mindless questionnaires („how many grams of potato did you eat last week?“). Then there is a huge correlation vs. causation problem. In some countries only rich and educated people have time and money to cook or even think about their food choices.