Vitamin D deficiency strongly exaggerates the craving for and effects of opioids, potentially increasing the risk for dependence and addiction, a new study suggests.
The findings suggest that addressing the common problem of vitamin D deficiency with inexpensive supplements could play a part in combating the ongoing scourge of opioid addiction.
"Our results suggest that we may have an opportunity in the public health arena to influence the opioid epidemic," said researcher David E. Fisher from the Massachusetts General Hospital.
For the study, published in the journal Science Advances, the research team addressed the question from dual perspectives.
In one arm of the study, they compared normal laboratory mice with mice that were deficient in vitamin D (either through special breeding or by removing vitamin D from their diets).
Importantly, when the mice were conditioned with modest doses of morphine, those deficient in vitamin D continued seeking out the drug, behaviour that was less common among the normal mice.
When morphine was withdrawn, the mice with low vitamin D levels were far more likely to develop withdrawal symptoms.
The study also found that morphine worked more effectively as a pain reliever in mice with vitamin D deficiency.
The lab data suggesting that vitamin D deficiency increases addictive behaviour was supported by several accompanying analyses of human health records.
One showed that patients with modestly low vitamin D levels were 50 per cent more likely than others with normal levels to use opioids, while patients who had severe vitamin D deficiency were 90 per cent more likely.
Another analysis found that patients diagnosed with opioid use disorder (OUD) were more likely than others to be deficient in vitamin D.
Back in the lab, one of the study's other critical findings could have significant implications, said Fisher.
"When we corrected vitamin D levels in the deficient mice, their opioid responses reversed and returned to normal," he said.
In humans, vitamin D deficiency is widespread, but is safely and easily treated with low-cost dietary supplements, notes Fisher.