“It is currently unknown whether increased pain is due to greater weight or poor diet quality, or both,” said Robert Sorge, Ph.D., an assistant professor in the Department of Psychology in UAB’s College of Arts and Sciences. “This study shows us the direct link between poor diet quality and increased pain.”
The study investigated the link between obesity and chronic pain and focused on the effects of the total Western Diet in particular. The western diet is defined as having fewer calories from protein and increased calories from carbohydrates and saturated and mono-saturated fats.
“They call it the Total Western Diet because it’s a common pattern in societies in our part of the world — it’s a problem particularly here in the U.S.,” said Stacie Totsch, the paper’s first author and a graduate student in Sorge’s lab. “We need to be concerned about the consequences our diet has on our bodies, and not just immediately with problems like weight gain, but also with long-term complications. That’s what we set out to investigate in this study.”
Mouse models were fed the western diet t for 13 weeks so that the researchers could investigate the functional and physiological consequences of a nutritionally poor diet in mice. the mice who consumed the western diet showed a significant increase in fat mass, decrease in lean mass, increases in pro-inflammatory cytokines, signals that promote systemic inflammation, as well as increases in serum leptin, a hormone secreted by adipose tissue that acts to regulate long-term appetite and energy expenditure.
“Most obese people have increased levels of serum leptin and pro-inflammatory cytokines, so we saw the immediate health effects that the diet had on the mice,” Sorge said. “Our next step was to look at how the unhealthy effects of the TWD corresponded to chronic pain. Did it make it any worse, and how?”
Prolonged exposure to the western diet resulted in an altered perception of pain when the mice were introduced to chronic pain, resulting in acute nociceptive sensitivity, systemic inflammation and persistent pain following chronic pain induction.
“Poor diet seems to have exacerbated the normal recovery period from this mild inflammatory insult,” said Sorge. “Because poor diet heightens hypersensitivity, patients with chronic pain who regularly practice bad diet habits are likely to experience exaggerated pain responses and recovery from injury or surgery.”
“A complete understanding of the impact of diet can aid in treatment and recovery dynamics in human clinical patients,” said Sorge. “Now that we know more about the link between diet and inflammation, we can begin thinking about applications to solve the problem.”
Stacie K. Totsch, Megan E. Waite, Ashleigh Tomkovich, Tammie L. Quinn, Barbara A. Gower, Robert E. Sorge. Total Western Diet (TWD) alters mechanical and thermal sensitivity and prolongs hypersensitivity following Complete Freund’s Adjuvant in mice. The Journal of Pain, 2015; DOI: 10.1016/j.jpain.2015.10.006