People who have high blood levels of healthy plant compounds, known as carotenoids, also tend to be more optimistic about the future, a new study has found.
Links between psychological health and physical health have long been recognized by researchers. However, most research has focused on poor psychological functioning, such as how being depressed or anxious may be bad for health, according to lead study author Julia Boehm, a research fellow at the Harvard School of Public Health.
Researchers wanted to test whether positive psychological functioning, such as being optimistic or having a purpose in life, might be good for health.
"This study is the first of its kind to report a relationship between optimism and healthier levels of carotenoids," Boehm said.
Previous studies have shown that high blood levels of antioxidants may be a marker of good health. Antioxidants help keep other molecules in the body from producing free radicals, which can damage cells and contribute to disease. Carotenoids, including beta-carotene, a pigment found in high levels in orange produce and some green veggies such as spinach and collards, are antioxidants.
The current study evaluated blood concentrations of nine different antioxidants, including carotenoids such as beta-carotene and vitamin E in nearly 1,000 American men and women ages 25 to 74. They also measured the degree of optimism in the same group. The participants filled out a questionnaire about their life attitudes and provided blood samples to the researchers.
Researchers found that people who were more optimistic had up to a 13 percent increase in carotenoid concentrations in their blood compared with people who were less optimistic. The researchers believe that higher levels of fruit and vegetable consumption among more optimistic people may at least partially explain the results. They found that people who ate two or fewer servings of fruits and vegetables a day were significantly less optimistic than people who ate three or more servings a day.
Conversely, the researchers found no association between vitamin E, an antioxidant found in high levels in oils made from safflower, sunflower and wheat germ as well as nuts and nut oils. The results were published in January in the journal Psychosomatic Medicine.
Because the researchers measured each person’s antioxidant and optimism levels only once, rather than following them over time, it remains unclear whether optimism leads to higher blood levels of carotenoids or whether people who eat more fruits and vegetables just tend to be more optimistic, said the researchers.
A 2009 study of more than 100,000 U.S. women, published in the journal Circulation, found that optimists live longer and healthier lives, with fewer cancer- and heart-disease-related deaths. "The current study adds a valuable piece of information to this larger picture about how optimists go about getting healthier," said Dr. Hilary Tindle, a doctor of internal medicine at the University of Pittsburgh.
"Our findings can be partially explained by the fact that more optimistic people tend to engage in healthier behaviors such as eating fruits and vegetables and avoiding cigarette smoking," said Boehm.
"Right now, it’s a question of which came first, the chicken or the egg. This study lays the groundwork for future research," said Emily Nicklett, a professor of social work at the University of Michigan who was not involved in the current study. However, "this question needs to be answered before any dietary recommendations should be made," she added.
The American Heart Association currently recommends that most adults eat 4.5 cups of fruits and vegetables in a variety of colors daily. According to the Centers for Disease Control and Prevention, a diet rich in fruits and vegetables may reduce the risk of cancer and other chronic diseases — reason enough for produce lovers to look on the bright side.
Pass it on: Eating more fruits and vegetables may help people look on the bright side.
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