This article is just an example - there have been many other studies that point to the same. Personally, I think the proven lower IQ levels of people from the continent of Africa might be because they don't have as much meat in their diets when their brains are developing. The constant malnutrition is also a problem. I think this is also Israel's long term strategy with the Gaza strip - starve them stupid and they'll forget what they're fighting for or just become obsolete as a people.
But it's all good, what makes YOU feel good is what's important!