Eating well has many known benefits. But a good diet may not be able to counteract all the ill effects of stress on our bodies.
A new study, published in Molecular Psychiatry, suggests stress can override the benefits of making better food choices.
To evaluate the interactions between diet and stress, researchers recruited 58 women who completed surveys to assess the kinds of stress they were experiencing. The women also participated in what researchers call a "meal challenge," where they were each given two different types of meals to eat, on different days.
One meal was high in saturated fat, the type of fat linked to cardiovascular disease. The other meal was high in a plant-based oil, which is considered more healthful.
"When women were not stressed and they got the healthier meal, their inflammatory responses were lower than when they had the high saturated fat meal," explains study author Janice Kiecolt-Glaser, director of the Institute for Behavioral Medicine Research at the Ohio State University. She says this was not a big surprise.
But here's the part that may seem counterintuitive: "If a woman was stressed on a day when she got the healthy meal, she looked like she was eating the saturated fat meal in terms of her [inflammation] responses," Kiecolt-Glaser explained.
In other words, the more healthful meal was no better in terms of its impact on inflammation. "The stress seemed to boost inflammation," Kiecolt-Glaser explained.
The kinds of stressful events the women experienced weren't life-threatening. Rather, they're the sorts of events that make us feel overwhelmed or out of control, such as a child care scramble or caring for an elderly, sick parent.
The researchers measured several markers of inflammation in the body, including C-reactive protein, or CRP.
Over a lifetime, higher inflammation levels are linked to an increased risk of a range of diseases, including "cardiovascular disease, Type 2 diabetes, arthritis, some cancers," Kiecolt-Glaser explains. "It's an ugly list of possibilities."
The findings add to the evidence that stress is a powerful player when it comes to influencing our health. Kiecolt-Glaser's prior research has shown that people who are stressed heal wounds more slowly. She has also demonstrated that stress can promote weight gain by altering metabolism and slowing down calorie-burning.
Kiecolt-Glaser says there's still a lot that's unknown. For instance, in this new study, she's not sure how the inflammation levels of stressed-out women would have been influenced by an ultra-healthful meal — say, an avocado with greens on a piece of whole-grain toast. She points out that both of the meals the women ate for this study were very high in calories and had about 60 grams of fat.
Now, if you're looking for the upside in this line of research, rest assured: There are a whole range of strategies that have been shown to help manage stress.
"Close, personal relationships are perhaps the world's greatest stress reducer," Kiecolt-Glaser says. Studies of mindfulness meditation and yoga have also been shown to be effective.
And as we've reported, even doing nice things for others can help keep stress in check.
When I was reporting this story, I asked stressed-out Georgetown University law students what they do to manage stress. They pointed to a range of activities — from salsa dancing to listening to hip-hop to going to the gym. "I really enjoy exercising when I'm stressed. It gives you an outlet to distract you," Marina Smith told me.
And it seems these students are on to some good strategies, says Aric Prather, an assistant professor at the University of California, San Francisco School of Medicine, who studies how lifestyle choices influence health. "Exercise and social connectedness," he says, "are effective in improving people's well-being and their ability to cope with stress."