By Jeffrey P. Haibach, Ph.D., Mph, Health Science Officer, U.S. Department Of Veterans Affairs
Research supporting the benefits of eating produce is endless, yet new reports come out regularly with added support. There is overwhelming research that eating a diet high in produce is associated with better health — physical, mental and possibly even spiritual. There is further research on inverse associations between produce and addictions, where high produce intake is associated with lower addiction. Other research connects addiction and poorer mental health.
In one study, we assessed these phenomena of triangulation between produce intake, mental health, and addiction. Looking specifically at depression and cigarette smoking, smokers with a depression history have lower odds of quitting; depression symptoms mirror smoking withdrawal symptoms, and higher produce intake is known to have an inverse association with both depression and smoking. In our study we found produce intake (measured as fruits and vegetables) moderated the association between depression and cigarette smoking. That is, among persons with higher produce intake, depressive symptom history appeared to be removed as an impediment to smoking cessation over a four-year follow-up period.
We found the threshold for these results to be fairly low, where eating produce at least once per day seemed to make the difference in removing depression symptoms associated with quitting smoking over time. In another statistical model, we found the association between depression symptoms and smoking frequency to be mitigated at eating produce about five times per day. This produce intake frequency threshold is interesting, as it mirrors the five servings per day recommendation, which could merely be coincidental. There also may be an underlying biological basis that transcends various health benefits at that frequency or volume. In a prior study in a different study sample, we also found similar thresholds for smoking frequency and smoking cessation based on produce intake.
There are many limitations to this, and in our prior study, they were largely observational health studies of smokers on various health-related factors. In the latest study, when smokers were followed up four years later, we assessed whether or not they had quit smoking based on their level of fruit and vegetable consumption and depressive symptoms at baseline. To ensure our findings weren’t explained by higher health consciousness by those who ate more produce simply explaining a higher quit likelihood, we adjusted for overall health-related lifestyle via exercise, heavy alcohol use, and illicit drug use, and the associations persisted.
Overall, the results of this study paired with other studies cited in our research paper and suggest opportunities to promote produce consumption to help improve mood, mental health and reduce addictions. In looking at the underlying neurobiology, both smoking and consumption of sweet-tasting foods, such as fruit, promote dopamine release and feelings of pleasure (positive effect) and reduce negative affect. This promotes or inhibits some depressive symptoms. Either behavior could reduce the desire to consume the other, such as has been observed where eating fruit can reduce perceived enjoyment of a subsequent cigarette (e.g., make the cigarette taste worse).
Chemicals in fruit also interact with the dopaminergic system. Serotonin is further known to mediate the effect of dopamine and moderate mood and feelings of negative effect. Both fruits and vegetables and smoking have been found to be monoamine oxidase inhibitors (MAO), which increase levels of dopamine and serotonin by inhibiting the action of monoamine oxidase. Higher fruit and vegetable intake could be hypothesized to act as an alternative MAO to smoking, thereby attenuating or possibly eliminating the smoking depression association.
In considering the underlying neurobiology, higher produce intake may buffer the depressive withdrawal symptoms of smokers, thus reducing withdrawal symptoms as an impediment to cessation. Smokers are also known to reach for a cigarette when having negative feelings, whereas fruit intake can promote positive feelings. Thus, if a person eats fruit in moments of negative or depressive feelings, he/she may be less likely to reach for a cigarette. In essence, eating produce may make it easier for smokers to quit, especially those who struggle with depression or intense withdrawal symptoms when trying to quit.
Overall, the concept of improving mood and quitting harmful habits such as cigarette smoking could help promote produce intake. The business of produce may be the anti-cigarette. There are so many reasons to promote produce; it’s a good business.
Jeffrey Haibach, Ph.D., MPH, is a Health Science Officer and Scientific Program Manager. Prior to his transfer to the central office of the U.S. Department of Veteran Affairs, he served at the VA HSR&D Center for Health Equity Research and Promotion in Pittsburgh. In other federal positions, he served in research with the U.S. Department of Agriculture and on active duty in the U.S. Army as a senior non-commissioned officer. He has conducted collaborative research and other work in diverse settings, including clinical, community and public health venues with associates from governmental, academic, faith-based, corporate for-profit and non-profit organizations. His primary research interests are in health promotion, multiple health behavior changes and the potential of wellness approaches for addiction prevention, treatment, and recovery.