The definition of one's salad days is a " period when one is young and inexperienced." In other words: green, immature, undeveloped. There is a  positive aspect of this time we would all like to retain as we grow older and wiser; that is the mental speed and agility of youth. 

It turns out that one simple way to keep some of that youthful brain health is by Eating Your Greens! 

Nicholas Bakalar reported in the New York Time : A Salad A Day May Be Good for Brain Health 

"Those who ate the most leafy vegetables — one to two servings a day — scored the equivalent of 11 years younger on tests of mental ability than those who ate little or none. Greens contain lutein, folate, beta carotene and other nutrients known to affect aging."

The lutein found in spinach, kale and chard and lots of other leafy greens is a carotenoid pigment that helps to preserve cognitive function. Kale, spinach and dandelion greens have the highest lutein content of any foods. Other foods containing carotenoids are cruciferous vegetables like broccoli, cauliflower and brussels sprouts.

So once again our parents were right - Eat your Vegetables - Good for your Body and your Brain!

If 11 years younger isn't enough encouragement, then here is this delicious salad recipe from Bon Appetit Kale and Brussels Sprout Salad.