Scientists have long known that poor nutrition is linked to higher levels of perceived stress, but many past studies on the topic have looked at overall indicators of nutrition, rather than specific components like fruits and vegetables. For the latest study, researchers were interested in looking more closely at the relationship between fruit and vegetable intake and measures of psychological stress. They used data from a large study called the Australian Diabetes, Obesity and Lifestyle Study to look at this relationship, as well as to look at blood levels of carotenoids — substances found in many fruits and vegetables — and other nutrients linked to fruit and vegetable consumption.
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A total of 8,689 participants took a detailed food frequency questionnaire, along with a questionnaire on perceived stress. A subset of 1,187 had blood samples taken to look at carotenoids and other substances. The average age of participants was 47.4, and the group was almost perfectly evenly split between men and women.
Fruits and vegetables linked to lower perceived stress
The researchers found that participants with the highest fruit and vegetable intake — at least 470 grams (16.6 ounces) of fruits and vegetables daily — had stress index scores that were, on average, 10% lower compared with participants with the lowest fruit and vegetable intake — less than 230 grams (8.1 ounces) daily. When the researchers broke the results down to look at intake of fruits and vegetables separately, they found similar results to the overall numbers, indicating that total fruit and vegetable intake — rather than intake of just fruits or just vegetables — is linked to lower stress. When the researchers broke the results down by age groups, though, they found that higher fruit and vegetable intake was linked to lower perceived stress in middle-aged adults — those ages 45 to 64 — but not in younger or older study participants, those younger than 45 or at least 65 years old. Higher blood levels of carotenoids were linked to lower stress levels before adjusting for age and other factors, but not after this adjustment.
As noted in a Medical Dialogues article on the study, these results strengthen what we know about the relationship between fruit and vegetables intake and stress, but are complicated by the fact that past studies have found this relationship to exist in younger adults — in contrast with the current study, which found a link only in middle-aged adults. Since the relationship between blood levels of carotenoids and stress levels was somewhat weaker than the overall relationship between fruit and vegetable intake and stress, it’s likely that carotenoids are only one factor out of many that play a role in this relationship, the researchers noted — and more research is needed to get a more complete picture of the nutrients in fruits and vegetables that are linked to lower stress levels. In the meantime, it can’t hurt to consume a variety of fruits and vegetables, both for potential stress reduction and for the numerous other health benefits these foods may offer.
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