Optimism Linked to Higher Antioxidant Levels

Megan Brooks

January 15, 2013

Middle-aged adults who are more optimistic about their future tend to have higher serum antioxidant levels than their less optimistic peers, new research suggests.

Investigators at Harvard University in Boston, Massachusetts, found that for every standard deviation increase in optimism, there was an increase in carotenoid concentrations of 3% to 13% in age-adjusted models.

Dr. Julia Boehm

"In other words, individuals with greater optimism tended to have greater levels of carotenoids such as beta-carotene," study investigator Julia K. Boehm, PhD, research fellow, Department of Society, Human Development, and Health, Harvard School of Public Health, told Medscape Medical News.

"This is the first study of its kind to report a relationship between optimism and healthier levels of carotenoid concentrations," she added.

The study is published in the January issue of Psychosomatic Medicine.

Links between psychological and physical health, she explained, have long been recognized, but most research has focused on poor psychological functioning such as being depressed or anxious.

"Increasing research suggests that positive psychological functioning such as being optimistic or having purpose in life may be good for health," Dr. Boehm said. "Antioxidants are good examples of positive functioning because they help to inhibit other molecules from producing free radicals that damage cells and contribute to disease."

Positive Outlook Good for Health

The investigators evaluated the cross-sectional association between optimism and antioxidant concentrations in 982 men and women in the Midlife in the United States (MIDUS) study, conducted between 1994 and 2005 to understand a range of factors that influence the mental and physical health of Americans as they age.

Primary measures were optimism (ie, the general expectation that the future will be favorable), assessed with the well-validated 6-item revised Life Orientation Test and measurements of serum concentrations of 9 different antioxidants (carotenoids and vitamin E).

Although optimism was associated with an increase in carotenoids, there was no link between optimism and vitamin E levels — a finding that is in line with other studies reporting null associations between psychological factors and tocopherols.

Tocopherols may be more strongly dependent on other factors, such as lipids, which may make it difficult to detect the direct effects of psychosocial variables, they note.

The relationship between optimism and carotenoid levels was only partially explained by the fact that more optimistic people tended to engage in healthier behaviors such as eating fruits and vegetables and avoiding cigarette smoking. Including these healthy behaviors did not completely explain all of the variance in the relationship, the researchers point out.

"This study was cross-sectional, so we can't conclusively determine whether optimism leads to healthier levels of antioxidants or vice versa," said Dr. Boehm. However, "our findings indicate a promising association between optimism and protective biological markers."

"Replication of these findings and a more nuanced understanding of relevant pathways may indicate that enhancing psychosocial assets such as optimism could provide effective strategies for promoting health," the authors conclude.

Findings Not Surprising

Reached for comment on the study, Alexandra J. Fiocco, PhD, assistant professor, Department of Psychology, Ryerson University, Toronto, Ontario, Canada, said that it is an "interesting study" and that the findings are "important but not surprising."

"Apart from being associated with decreased depression, cardiovascular disease, and rate of mortality, we know that optimists are more likely to engage in health-promoting behaviors, such as healthier food choices," she said. "We also know that eating foods rich in antioxidants is associated with increased serum antioxidants."

"This study confirms that having a positive predisposition is associated with making healthier life choices [and] shows that this is not only evidenced by subjective self-reports of health behaviors but can also be objectively shown by way of biological measures," Dr. Fiocco said.

She believes "future research should evaluate what determines optimism — is it hereditary, is it determined by environmental circumstance?"

In current study, those with higher socioeconomic status were more likely to score high on optimism.

The study was supported by the Robert Wood Johnson Foundation through a grant, "Exploring the Concept of Positive Health," to the Positive Psychology Center of the University of Pennsylvania. The authors and Dr. Fiocco have disclosed no relevant financial relationships.

Psychosom Med. 2013;75:2-10. Abstract