Globe-trotting photographer Dave Krugman feels at home no matter where he is in the world. But he hasn't always felt comfortable inside his own head.

He's had issues with depression, even as he was building an Instagram following of about 300,000. "It wasn't matching up with the way I was feeling about life, which was, like, that I wasn't enjoying my day-to-day life, really," he said. "I wasn't."

He tried therapy, then anti-depressants, and finally ended up with an unconventional psychiatrist who posed an unconventional question: What did he eat for breakfast, lunch and dinner?

And thinking about what he put in his mouth really opened his eyes: "It made me realize I would just eat whatever popped into my head at that moment. Like, 'Oh, I'll go get some ramen. That sounds great.'"

"Chocolate cake?" asked correspondent Susan Spencer.

"Yeah! Yeah, chocolate cake!"

Psychiatrist Drew Ramsey, who is Krugman's doctor, said, "Food is medicine. Food is brain medicine. In your everyday life, the number one factor that you have control over in terms of your mental health is at the end of your fork."

His specialty is the daily special, and how it affects your mind. Dr. Ramsey calls this growing new field "nutritional psychiatry."

Spencer asked, "Do you treat food as you would a drug and say, this is your prescription for anchovies? And how does it work?"

"All of my patients have a sense of foods that I want them to be eating more of," said Dr. Ramsey.

Those foods? You guessed it: the Mediterranean Diet – colorful vegetables, seafood, olive oil, and lots of leafy greens.

Dr. Drew Ramsey and chef Samantha Elkrief show correspondent Susan Spencer dishes meant to improve brain and mental health. CBS News

Samantha Elkrief, a trained chef who works with Dr. Ramsey, showed Spencer how to make Thanksgiving better for your brain. Their menu included purple sweet potatoes, oven-roasted Brussels sprouts, and oysters.

"A lot of people don't like oysters," Dr. Ramsey said. "They're these raw, slimy, scary things that maybe make you sick."

Harper Wave

It's an example of what he termed "food fear."

Spencer asked Elkrief, "Would you ever sit down and eat a cheeseburger and fries?"

"Well, I wouldn't eat a cheeseburger because I don't really eat that much meat and I don't eat dairy. But I would eat, like, a salmon burger with a collard green wrap or something like that," she replied.

Unlike cheeseburgers, Dr. Ramsey says oysters have unique nutrients, making them one of the best foods for depression.

Can't you get those same nutrients out of a multivitamin?

Dr. Ramsey said there are a few reasons not to rely on multivitamins: "First of all, oyster date night is incredible. And salmon date night is incredible. And fish oil and supplement date night has never really been much fun for me.

"There's an idea that people have that we can just take supplements and be healthy. And that's simply not true," he said.

"What can you say conclusively about the impact of food on depression?" Spencer asked.

"Very conclusively, food impacts your risk of getting depressed," he responded.

Avery

And some recent research seems to back that up. In one study of people diagnosed with depression (the SMILES trial), a brain-healthy diet added to standard treatment relieved all symptoms in about a third of patients.

As for criticism that the science still is inconclusive, Dr. Ramsey said, "The evidence has really just started. We've not had any randomized clinical trials about food and the treatment of mental health until 18 months ago. So, this is very new."

"Given all the emphasis on food, what role do you see for anti-depressants?" Spencer asked.

"Anti-depressants are a great treatment for depression," he said. "The two complement each other perfectly."

While the doctor writes the prescriptions, the chef makes the house calls. Elkrief will take patients to the grocery store or farmer's market to say "this, not this," and will go to their homes and cook with them.

If you still find this whole brain-food thing hard to swallow, neuroscientist Lisa Mosconi, at New York City's Weill Cornell Medical College, says the proof is in the pictures.

She showed Spencer brain scans of a woman on the Mediterranean Diet, and of a woman who eats standard Western fare – high fat, high carbs. Her brain shows actual shrinkage, with likely cognitive decline, Mosconi says, and she blames our lousy American diet.

From "Brain Food"/Avery

Mosconi says someone thinking about their brain health should NOT eat the following: French fries; ice cream; bacon; Fruit Loops; Pop-Tarts; pizza.

What about anchovies? "Yes!" she said.

Except for those anchovies, that's mostly stuff Dave Krugman won't go near today.

"Waking up, having, like, some eggs and some avocado, I definitely just have more energy throughout the day," he said.

He is not taking medication for depression right now. "My medication is very good Italian olive oil!" he laughed.



Recipes from Dr. Drew Ramsey:



Recipes from Lisa Mosconi:

READ AN EXCERPT: "Brain Food: The Surprising Science of Eating for Cognitive Power"



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Story produced by Amiel Weisfogel.