No one is saying to cut out the Vitamin C, but a report in this week's Science New Online suggests that folks with generally positive outlooks about their lives develop fewer colds than do individuals whose emotional style tends to be more depressed, hostile, or anxious. This is not the first study to demonstrate the impact of emotional styles on physical health.
Psychologist Sheldon Cohen and his colleagues at Carnegie Mellon University in Pittsburgh theorized that positive emotions stimulate symptom-fighting substances in the body the exact nature of which is unknown.
The study, published in the current issue of Psychosomatic Medicine (Sheldon Cohen, et al (2006). Positive Emotional Style Predicts Resistance to Illness After Experimental Exposure to Rhinovirus or Influenza A Virus, Psychosomatic Medicine, Vol. 68, pp. 809-815. [Abstract]) replicates prior similar research and rules out the possibility that psychological traits related to a positive emotional style, rather than the emotions themselves, guard against cold symptoms.
For purposes of the study, a "positive" emotional style was defined as "being happy, lively, and calm;" and a "negative" emotional style was defined as "characterized by being anxious, hostile, and depressed."
So smile when you drink your orange juice!