"Many of these 'superfoods' also work to boost glutathione in the body: an amino acid in charge of detoxification. So superfoods nourish and detoxify, and in this way, they combat stress," said stress expert Pete Sulack, author of "Unhealthy Anonymous," a book about stress management and overall wellness.
The top superfoods that are recommended to munch on when feeling anxious are kale, broccoli, leafy greens, celery, nuts, oily fish like salmon, fermented foods like kimchi, herbs and spices, and organic berries high in vitamin C.
"In animal studies, vitamin C fed to rats who were undergoing stress both prevented an increase in cortisol levels and ... known signs of physical and/or emotional stress like losing body weight. Animals that didn't receive the vitamin C had three times the level of cortisol in their bodies," Sulack said. Stress can increase levels of the hormone cortisol, which manages stress in the body.
"Human studies have been done as well," he said.
A small study published in the journal Psychopharmacology
in 2001 suggests that ascorbic acid, or vitamin C, can help reduce stress hormone levels
For the study, 60 healthy young adults were given daily doses of vitamin C over a 14-day period, while 60 others were given a placebo.
Then, the researchers measured each person's blood pressure and cortisol levels by taking saliva samples. They discovered that, compared with the placebo group, the adults consuming vitamin C had lower systolic blood pressure, lower diastolic blood pressure and greater cortisol recovery, and they reported experiencing less psychological stress.
How do these foods influence our mood? That's an active topic of research, said Kate Brookie, a PhD candidate studying nutritional psychology at the University of Otago in New Zealand.
"While there are biologically plausible ways that diet can influence our state of mental health, the exact mechanisms of action are still being investigated," she said.
"Whole foods, especially fruit and vegetables, provide your brain with the nutrients necessary for key processes involved in mood and well-being," she said.
For instance, vitamin C is involved in the production of dopamine, a feel-good hormone associated with motivation and drive, Brookie said, adding that B vitamins and carbohydrates are associated with the synthesis of serotonin, a neurotransmitter that plays a role in our daily moods.
"It could be that eating a high-quality, whole-food diet, rich in fruits and vegetables, provides the nutrients for these systems to function more optimally, leading to better mental health," Brookie said.
Meanwhile, there are some other foods that might do the opposite.
Foods to avoid when stressed
"Innately as humans, we know that food can relieve stress. That's why we refer to 'comfort foods,' " Sulack said. "The only problem is that most 'comfort foods' like french fries, ice cream and macaroni and cheese offer some release of brain chemicals that make us feel good for the moment but in the long run cause the body more stress and the brain more distress."
Foods that may stress the body, he said, are processed foods such as deli meat and foods high in sugar and high in caffeine, like some energy drinks or sugary sodas for example.
"One of the biggest causes of stress is your blood sugar. When blood sugar is between the glucose levels of 75 to 95 nanograms per deciliter, the body functions well. The more time you spend outside that range, the more your body feels stressed," Sulack said.
"Excessive caffeine consumption can induce heart palpitations, shaking and difficulty sleeping, all a recipe for triggering the stress response," he added. "It's not just enough to look at the foods you eat but also the ingredients in those foods."
Ingredients to limit include sugar, saturated fats and trans fats, refined carbohydrates, casein-containing items, such as processed foods, and the artificial sweetener aspartame, Sulack said. Also, watch your alcohol consumption
"Diets made up of high-fat, high-sugar and processed foods, often referred to as a 'Western diet,' are becoming increasingly associated with poor mental health outcomes, as well as a number of physical detriments," Brookie said. "While it is not always easy to make healthy choices during times of stress, I would advise people to reach for whole, nourishing foods that help the body -- and mind -- in the long run."
When to seek help
Sometimes, difficulty managing stress and negative emotions have both been implicated as contributors to eating disordered behaviors, such as binge eating, said Julie Friedman, vice president of the Eating Recovery Center's compulsive overeating recovery effort program in Chicago.
In those cases, it is important to consult with a doctor and seek support.
"What we know is that a significant percentage of binge eating disorder patients actually have a co-occurring or co-morbid anxiety disorder. They also tend to have high stress responsivity profiles, meaning they have greater physiological response to stress. This can include a higher heart rate and higher respiration," Friedman said.
"Many people experience stress from being overwhelmed from the demands of their life and not being able to deal with everything coming their way," she said. "Being able to lean on others helps you manage things. Sleep also plays a role with stress. ... In addition, finding something that you find pleasurable and enjoy doing can help you be less stressed."