Can surgery patients eat their way to less postoperative pain?

A recent study by French researchers suggests that a diet low in polyamines can reduce pain after spinal surgery, with few side effects.

“There have been some data to show that a polyamine-deficient diet decreased pain in rats,” said Jean-Pierre C. Estebe, MD, PhD, professor of anesthesiology at University Hospital of Rennes in Rennes, France, who led the latest work. “This effect is likely due to polyamine’s modulation of the N-methyl-_D-aspartate (NMDA) receptors. But no data are available on the potential efficacy of a polyamine-deficient diet on perioperative pain, so we decided to undertake a prospective, randomized trial with chronic pain patients with high levels of pain.”

Dr. Estebe and his colleagues enrolled 64 spine surgery patients into the study. Patients were randomized to one of two diets. Those on the polyamine-deficient diet ate a low-polyamine breakfast supplemented with six 250-mL low-polyamine drinks per day.

“Just to drink that, they received around 10,000 kcal per day,” Dr. Estebe said. Controls had a partial polyamine-deficient diet comprising two of the drinks each day plus regular food. “The study group received less than 10 micromoles per day of polyamine, while controls received an average of more than 400 micromoles per day,” Dr. Estebe explained.

The diets were initiated seven days before spine surgery and continued until five days after the procedure. The primary end point was pain at rest and with motion. Researchers also monitored compliance, side effects and quality-of-life scores. Patients in both groups were demographically similar, and had comparable levels of preoperative pain.

As Dr. Estebe reported at the 2013 annual meeting of the American Society of Anesthesiologists (abstract 2067), patients in the study group demonstrated a trend of decreasing pain at rest in the seven days before surgery (P=0.144), which became significant thereafter (P=0.022). The French team found a trend toward decreased postoperative pain with motion in these patients, but it did not reach statistical significance (P=0.128).

The effect of the low-polyamine diet became significant when the investigators analyzed the subset of patients experiencing more severe pain at rest and with motion (P=0.0135 and 0.0093, respectively). No reduction in pain was observed in controls.

Quality-of-life scores were significantly improved in the low-polyamine diet patients immediately before surgery (P=0.046), and continued as a trend five days after surgery (P=0.0629). Hospital length of stay was similar for both groups of patients.

“In terms of compliance, it’s very interesting to note that 100% of the study group completed the diet for the seven days before surgery, compared with 83% thereafter,” Dr. Estebe said. “By comparison, 83% and 71% of controls consumed both drinks each day before and after surgery, respectively. The only side effect was minor gastrointestinal intolerance. So a low-polyamine diet could be useful for surgery because pain is decreased, compliance is high and adverse effects show no difference between the two groups.”

Eugene R. Viscusi, MD, professor of anesthesiology and director of acute pain management at Thomas Jefferson University, in Philadelphia, called the study “fascinating.”

“Some diets can promote inflammation, which might have a role in pain. Here, the authors identified another familiar pathway involving the NMDA receptor, which is well known to have a role in chronic pain, particularly in the presence of chronic opioid use. There is a resurgence of interest in ketamine—a potent NMDA receptor antagonist—in patients with opioid tolerance, and this drug is now commonly used in this setting. So it is entirely possible that modulation of diet in a way that modulates the NMDA receptor might have an effect on pain.”

Yet Dr. Viscusi raised several questions about the study. “The experimental group not only had polyamine restriction but also received what appears to be a markedly different caloric load during the study,” he said. “One has to question whether this alone, or perhaps the type of calories, made the difference.

“One thing is for sure: We generally do not pay close enough attention to the diets of our perioperative patients,” Dr. Viscusi added. “Perhaps careful preoperative and postoperative feeding may have a far greater impact than we ever imagined.”

—Michael Vlessides