Vegan raw vegetables on green wooden table full frame background

Editor’s note: Season 8 of the podcast Chasing Life with Dr. Sanjay Gupta gets back to basics with an in-depth examination of the brain in different states. Each episode will focus on one of those states — the distracted brain, the frightened brain, the depressed brain and others — to spotlight what is going on in our heads and how it affects our bodies.

(CNN) — Are you really what you eat? Decades of research back up the saying that you are what you eat and support the important health effects of good nutrition.

Healthy food choices increase people’s overall life expectancy and reduce the risk of developing a wide variety of medical issues, including heart disease and cancer.

The health effects of food don’t just stop at the body. They extend into the mind as well, affecting not only our risk of future brain-based conditions (such as stroke and dementia) but also our ability to think clearly in the moment as well as our mood and mental health.

But it’s not so easy to know what to eat for brain health, or even how to measure it. Many of us have been told that foods such as blueberries, salmon, nuts and leafy greens are so-called brain foods. But how do they work? Are they neuroprotective? Do they make us smarter? More alert? Less stressed? Happier?

Nutritional psychiatrist Dr. Uma Naidoo has built a career around figuring out which foods improve brain function and positively influence the way we feel. She is the director of nutritional and lifestyle psychiatry at Massachusetts General Hospital, an instructor at Harvard Medical School, an author and a personal chef.

Naidoo described the nascent and rapidly growing field as the “intersection between nutrition and mental health.”

“We’re not at the point where I can say, ‘Eat this number of blueberries in order to improve your mood.’ But we are definitely emerging and growing in the scientific evidence to be able to say, ‘You can construct a nutritional psychiatry plate for your mood,’” she told CNN Chief Medical Correspondent Dr. Sanjay Gupta recently on his podcast Chasing Life.

The number of blueberries or ounces of salmon we have to eat in a day to improve our mood is unclear, Naidoo said, but the Standard American Diet, often referred to as SAD, that so many consume is not helping our mental health.

This way of eating is called SAD for a reason, she said. It’s calorie-dense and nutrient-poor, full of refined carbs, bad fats and added sugars while lacking in fresh fruits, vegetables, whole grains and clean protein.

“Any time that we can add those leafy greens, those actual whole foods onto our plate … and step away a little bit from those processed fast foods, the healthier we are going to become as a country,” she said, adding that ultraprocessed foods are engineered to trick our brain, so that we are almost unable to stop overeating.

What can you do to nourish your brain and boost your mood? Naidoo serves up these five tips. And to learn more about the brain benefits of eating a well-balanced diet and how what you eat affects your mood, listen to Naidoo go into detail on Chasing Life.

Eat whole foods to be whole

Eighty percent of your diet should focus on real, whole, fiber-rich foods such as vegetables, fruits, nuts, seeds, legumes and lower-glycemic whole grains, healthy fats and high-quality, well-sourced protein, Naidoo said. For the remaining 20%, there is leeway for “enjoying life as it comes.”

“Following an 80/20 rule allows for dietary discipline with some flexibility. … Adopting this mindset allows us to get all the mind-calming nutrients that we need while avoiding the guilt that sometimes comes along with being inflexible,” she said.

Enjoy a rainbow of food choices

It’s something that you hear often: Eat an assortment of vegetables and fruits in a wide variety of colors.

“To optimize the nutrient quality of your diet, be sure to eat the rainbow,” Naidoo said. “Different colored plant foods contain different brain-boosting nutrients, such as plant polyphenols.”

She tells people to lean into all the different vegetables, but she’s not leading with potatoes and sweet potatoes. “I’m leading with cruciferous vegetables and leafy greens and legumes and lentils and beans.”

Don’t forget fruit to “get those natural sugars into your body rather than reaching for the candy bar that we know is not the healthiest choice,” she said. “I want people to understand we need sugar for our bodies and our brain cells, so it’s where you get the sugar that’s important.”

Naidoo said that plant-rich eating also provides plenty of fiber “to support a healthy and thriving microbiome, which influences a healthier body and mind. Similarly, fiber helps to keep inflammation down and helps calm the mind.”

Lean into green food