Using food as medicine dates back at least to 400 BC, when the Greek physician Hippocrates wrote, “Let food be thy medicine, and medicine be thy food.”¹ The wise doctor understood that good nutrition helps us maintain health. Even so, many of us miss the profound connections between food and our mental and physical health. For it turns out that everything from your mood, mental sharpness, clarity, and energy to healthy weight and protection from chronic illness are influenced by food.^2,3,4 There is even a new field called “foodomics”, which looks at food-health interactions at the molecular level.⁵ 

“We really want to link food and medicine, and not just give away food,” Dr. Rita Nguyen, medical director of Healthy Food Initiatives at Zuckerberg San Francisco General Hospital told NPR in 2017. “We want people to understand what they’re eating, how to prepare it, the role food plays in their lives.”⁶

A whole food, unprocessed diet that emphasizes healthy protein and fats, vegetables, fruits, whole grains and legumes, and lean meats or fish, is consistently linked to better health.⁷ These foods contain the many nutrients and micronutrients needed for the optimal functioning of our body and brain. In addition, the soluble and insoluble fiber in these diets helps support healthy gut flora, which has been linked to both mental and physical well-being.

But how specifically do healthy foods work their magic? Read on for just a few fascinating examples of the power of food as medicine.

Dietary Neurotransmitters

Neurotransmitters help regulate the function of neurons throughout the body. They include molecules such as GABA, dopamine, glutamate, serotonin, and acetylcholine, which help regulate mood, memory, cognition and sleep. Not only can our bodies produce them, from raw materials found in food, but these neurotransmitters are also abundantly present in foods. These neurotransmitters are present in meat, fish, fruits, vegetables, roots and herbs 

Acetylcholine stimulates muscles to contract and plays an important role in memory and cognition.⁸ Foods that contain acetylcholine include spinach, squash, mung beans, wild strawberries, peas, and radishes. Botanicals that contain this molecule include nettles.

Glutamate is the most abundant excitatory neurotransmitter in our nervous system and is responsible for sending signals between nerve cells. Glutamate stimulates neurons to fire, therby playing a key role in most brain activity. Glutamate is present in a wide array of foods, especially those high in protein. That includes meats, seafood and cheese. It’s also present in mushrooms, tomato products, caviar, spinach, soy sauce, seaweeds, fermented beans and even instant coffee. 

GABA (Gamma-aminobutyric acid) is an amino acid and neurotransmitter that balances glutamate. While glutamate is excitatory, GABA is inhibitory, slowing nerve impulses and helping calm the body and brain. This molecule is found in many foods, including cruciferous veggies like broccoli and cauliflower, soybeans and other beans, peas, tomatoes, spinach, mushrooms, buckwheat, rice, oat, wheat, barley, and chestnuts. It is also found in herbs such as valerian and St. John’s wort.

Dopamine plays a role in pleasure and the reward system of the brain. Our brain releases it when we eat delicious food or during sex, or even if someone compliments us or we achieve a goal. It’s found in bananas, plantains, avocados, oranges, apples, eggplants, spinach, peas, beans and tomatoes.

Serotonin helps regulate eating, sleep, mood and gut motility. Serotonin is also a building block for melatonin, the hormone that helps regulate sleep and waking. Serotonin is found in a wide variety of foods from papaya to banana, plantain, passion fruit, pineapple, plum, strawberries, wild rice, spinach, tomatoes, coffee, hazelnuts, kiwis, potatoes, lettuce, green onions and herbs such as nettles and paprika.

Histamine is a molecule that has many functions. It helps modulate allergic reactions and increases inflammation. It also functions as a neurotransmitter and helps regulate arousal, attention and reactivity. Dairy products, including cheese, yogurt, sour cream, and milk contain histamine, as well as many fermented products such as soy sauce and sauerkraut. It can be found in sardines, anchovies and herring.

Can Food Help Fight Depression?

To function well, the brain needs an abundant supply of neurotransmitters and nutrients. A diet high in unhealthy trans-fatty acids, refined carbohydrates, and processed ‘junk foods’ has been shown to increase the risk for depression. For instance, researchers found a link between obesity, poor mood and diet in the Nurses’ Health Study, which looked at close to 44,000 women aged 50-77 over a period of 12 years. One analysis of this study found that an unhealthy, inflammatory diet raised the risk of depression.⁹ 

Even short-term, unhealthy foods can lead to a negative mood. When 44 college students kept a seven-day record of the foods they ate and their moods, higher nutrition foods were associated with positive moods two days later.¹⁰ The more calories, saturated fat, and sodium they ate, the more negative mood their moods became two days later. Results suggest that foods come first, then mood follows.

Conversely, a diet high in health-promoting, nutrient-rich fruits, and vegetables, along with healthy fats and proteins, has been linked to better mental health. ¹¹ It’s also been associated with an improved microbiome. A healthy microbiome, with ample amounts of probiotics, has been shown to produce nutrients we need and promote a healthy mood. The gut and brain are so strongly connected that gut bacteria that influence mood are called psychobiotics.

Changing your diet can improve mood relatively quickly. In one 12-week, randomized controlled study, 67 individuals with moderate to severe depression received either seven individual nutritional consulting sessions with a registered dietician or one-on-one social support sessions. The group receiving nutritional counseling experienced significantly greater improvement in depression, as well as anxiety.¹² And in another two-week study in 171 young adults who had low fruit and vegetable consumption, two extra servings a day of fruit and vegetables improved vitality and motivation.¹³

Weight Gain and Ultra-Processed Foods

We all know that excess calories—especially in the form of junk foods full of sugar, processed carbohydrates, and unhealthy fats—puts on weight. There is a long list of such foods, from chips to cheerios, bakery goods, candy, and ‘tv’ dinners. But, independent of calories and sugar, research suggests that ultra-processed foods themselves put on more weight. That may be because they are engineered to be incredibly tasty, high in fat, sugar, and salt. They often use designer molecules to recreate or mimic natural flavors—ones that seem to spur us to eat even more.

In one intriguing month-long study of twenty adults, individuals who ate ultra-processed foods consumed more and gained more weight in comparison to those who ate a healthier, higher-fiber, less sugary diet. Those on an ultra-processed diet ate about 500 calories more per day and gained two pounds over a two-week period. Their counterparts on an unprocessed, healthier diet, lost about two pounds over the same period.¹⁴

There were also changes in hunger-related hormones in the two groups. Those eating an unprocessed, healthy diet had higher levels of an appetite-suppressing hormone, a pancreatic polypeptide. They also had lower levels of ghrelin, a hunger hormone.  But those on the ultra-processed food diet showed the exact opposite, which led them to eat more.

Finally, those eating tasty ‘junk foods’ ate faster. Junk foods are often easy to chew and swallow—a soft cupcake goes down much more quickly than a crunchy carrot. It’s possible that eating so quickly allowed them to pack in more food and calories before their stomachs could give a signal to the brain that they were full. 

It seems that highly processed foods shift our metabolism and appetite, leading directly to weight gain.

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