What do you call a stolen yam? A hot potato.

What do you do when a tomato goes on strike? You pick it.

How do you make a strawberry shake? Put it in the freezer until it shivers!

See how fruits and vegetables can cheer you up? And instead of talking about them, guess what happens when you eat them?

A study of 13,000 people out of the U.K.'s University of Warwick found that mental health and well-being, characterized by optimism, happiness, self-esteem, resilience and good relationships, go way up as you increase the amount of fruits and vegetables you consume!

The theory is that vitamins, minerals, polyphenols and other nutrients in produce (or the way your gut bacteria metabolize those nutrients) help your cardiovascular, endocrine and immune systems function optimally. That makes your brain and body strong.

And folks who eat healthy foods do other things that are good for them, too, such as get regular physical activity and have de-stress routines and loving interactions with others.

We say that if you're feeling down in the dumps, start thinking differently about comfort food!

Feeling blue? Eat blueberries.

Irascible? Try a radish.

Sort of sad? Snack on sweet peas.

All are genuinely effective and really good for you!

So aim for nine servings every day. It's easier than you might imagine. For example: Half a cup of blueberries, 1 cup broccoli, 1 medium baked potato, 1 medium apple, 1 cup quinoa and 1/2 cup arugula - that's NINE.

Easy as pie, and a lot better for you.

© 2014 Michael Roizen, M.D. and Mehmet Oz, M.D.
Distributed by King Features Syndicate, Inc.