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.
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."
ROBERT SIEGEL, HOST:
We are used to leading busy lives. But if things get too busy, too hectic, we can feel overwhelmed. That is stress. Stress can hurt our bodies in ways that scientists are just beginning to understand. A new study suggests it can even reduce the benefits of a good diet. NPR's Allison Aubrey reports.
ALLISON AUBREY, BYLINE: If you're curious about how stress influences your body and what you can do to handle it better, there's a lot to be learned from the research of Janice Kiecolt-Glaser. She's been studying this a long time.
The Ohio State professor has demonstrated that stress can alter metabolism, leading people to burn fewer calories. She's also shown that stress makes wounds heal more slowly.
JANICE KIECOLT-GLASER: My major theme has been the effects that stress has on your body.
AUBREY: In her latest study, she's looking at the interactions between stress and diet. And she wants to know if a certain kind of meal could counter the effects of stress on the body. To answer this, she got about 60 women who were experiencing different kinds of stress in their lives to participate in what she calls a meal challenge.
KIECOLT-GLASER: You're giving people a meal - in this case, two different meals. And you're looking to see how the two different meals might have different kinds of effects.
AUBREY: Now, one meal was very high in saturated fat, the type of fat most linked to heart disease. The other meal was made with fat similar to olive oil, which is considered better for health. The idea is that the healthier of the two meals would protect against the harmful effects of stress, specifically inflammation levels in the body. And here's what she found.
KIECOLT-GLASER: 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.
AUBREY: Not really a surprise - but on days when women were stressed, experiencing things like a child care scramble, an unmet deadline or caring for an elderly, sick parent, eating the healthier meal did not help.
KIECOLT-GLASER: The stress appeared to boost inflammation.
AUBREY: Meaning when the women ate the healthier meal, their inflammation was just as high. Kiecolt-Glaser says over time, higher inflammation in the body can increase the risk of a range of diseases.
KIECOLT-GLASER: Cardiovascular disease, type 2 diabetes, arthritis, some cancers - it's an ugly list of possibilities.
AUBREY: The findings may seem like a bummer. It's easy to interpret as, hey, maybe a good diet doesn't really matter. But Aric Prather of UC, San Francisco, who studies how lifestyles influence health, says this would be the wrong conclusion.
ARIC PRATHER: No, I don't think this study shows of how you eat doesn't matter.
AUBREY: What it does suggest is that, in some cases, the power of stress can overwhelm diet choices. But if you combine a good diet with other effective strategies, Prather says, you can protect the body against the effects of stress - for instance, exercise.
MARINA SMITH: Like, I really enjoy exercising when I'm stressed because it gives you some sort of outlet to distract from all of the stress.
AUBREY: That's law student Marina Smith (ph). I caught up with her and a group of friends as they were taking a study break. They agreed that one of their top stress relievers is just hanging out together.
SMITH: Friends are great because when you're able to talk with them, you're able to get the stress out so it's not bottled up inside of you.
AUBREY: UC, San Francisco's Aric Prather says Smith's strategies are two of the best.
PRATHER: Yeah, absolutely. Exercise and social connectedness are effective in kind of improving people's well-being and their ability to cope with stressors during the day.
AUBREY: Since we can't just wish stress away, Prather says the more of these habits we have to unwind, the better. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.