A lot can happen when you clean up your diet: You may lose weight, minimize your risk of disease and feel like you have enough energy to conquer your entire to-do list. Plus, a bevy of recent studies suggest you might find yourself in a cheerier mood, too.
The reason? There's a brain-gut connection in play, meaning what you put into your body doesn't just fill your stomach and ease hunger pangs; it also affects the way your brain behaves and the emotions you experience. That's primarily because more than 90 percent of your serotonin, which is often called a "happy hormone" because of its role in mood regulation, comes from your gastrointestinal tract, according to a 2015 study published in Cell.
The connection between mood and food is being studied in a growing field called nutritional psychology, which is centered on the idea that nutrition plays a role in the incidence of mental disorders, according to a 2015 study published in Lancet Psychiatry.
But researchers aren't yet able to prescribe a feel-good diet. "We are studying effects of certain nutrients and cognition, mood and attitude — namely omega-3 fatty acids, vitamin D and fermented foods — but it's too soon to give any definitive recommendations on that front," says Monica Auslander Moreno, RD, LDN, a nutrition consultant for RSP Nutrition.
She also warns not to give the link between mood and diet too much weight. "It's far-fetched to say that certain foods or diet alone can 'cure' mental health conditions," she stresses. But, she says, eating cleaner in general and cutting back on processed foods may make you feel better overall, which can encourage a happier and more positive outlook.
Here are five things researchers have found so far regarding the link between food and mood.
1. Healthy Food Might Help Reduce Depressive Symptoms
Switching from an unhealthy diet to a healthier one, even for a short amount of time, leads to fewer symptoms of depression, according to a new study published October 2019 in PLoS ONE.
The study researchers split a group of 76 university students who exhibited symptoms of depression into two groups. The first group made healthy changes to their diets, such as eating more fruits, vegetables, fish and olive oil rather than processed foods. The second group didn't change their diets at all. After three weeks, the healthy eaters had fewer depressive symptoms, with depression scores moving into the normal range. The control group, on the other hand, saw no changes.
Similarly, an analysis published November 2019 in BMC Psychiatry found that depression is linked to nutrition in middle age. Researchers looked at data from more than 27,000 adults and concluded that eating fruits and vegetables was protective against depression, and omega-3 polyunsaturated fats were inversely associated with depression among men.
2. A Heathier Diet Is Linked to Lower Anxiety Levels
The Mediterranean diet, specifically, has been associated with lower anxiety levels. That's what a January 2017 study published in BMC Medicine found.
Over the course of 12 weeks, 33 study participants followed a Mediterranean diet that was rich in whole grains, fish, nuts and vegetables, while a second group of 34 participants stuck to their regular diet but received social support in the form of conversing with trained personnel. After three months, the diet-based intervention group saw greater improvements to their scores of both depression and anxiety.
3. Unhealthy Foods Can Put You in a Bad Mood
It's important to consider whether causation or correlation is responsible for the link between food and mood. For instance, does a person who eats unhealthy food become unhappy because of their diet, or are they unhappy in the first place and think they'll find comfort in reaching for sugary, highly processed foods?
Researchers behind an April 2012 study published in Appetite concluded that food can influence one's mood. Their study involved 44 people and found that the more calories, saturated fat and sodium someone consumed, the more negative the mood he or she reported two days later.
4. A Diet Rich in Fruits and Vegetables May Lead to Greater Life Satisfaction
A 2016 American Journal of Public Health study involving more than 12,000 Australians found that diets rich in fruits and veggies led to greater levels of happiness, life satisfaction and overall well-being. In fact, increasing one's intake of fruits and vegetables by eight servings per day led to a life satisfaction increase equivalent to what one would expect from becoming employed after being unemployed.
Plus, you don't have to stick to a healthy diet for decades to reap the benefits. The researchers found these improvements became evident within two years of adopting a healthier diet.
- Cell: “Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis”
- Lancet Psychiatry: “Nutritional medicine as mainstream in psychiatry”
- BMC Medicine: “A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial)”
- Appetite: “Which comes first in food-mood relationships, foods or moods?”
- Pediatrics: “The Mediterranean Diet and ADHD in Children and Adolescents”
- American Journal of Public Health: “Evolution of Well-Being and Happiness After Increases in Consumption of Fruit and Vegetables”
- PLoS ONE: "A brief diet intervention can reduce symptoms of depression in young adults – A randomised controlled trial"
- BMC Psychiatry: "Depression in middle and older adulthood: the role of immigration, nutrition, and other determinants of health in the Canadian longitudinal study on aging"