Low levels of the sunshine vitamin, vitamin D, may contribute to chronic pain among women, scientists believe.
The link does not apply to men, suggesting hormones may be involved, according to a study published in the Annals of Rheumatic Diseases said.
The team from the Institute of Child Health in London said studies were now needed to see if vitamin D supplements can guard against chronic pain.
About one in 10 people are affected by chronic pain at any one time in the UK.
The causes are not well understood and much of the focus to date has been on emotional factors.
Dr Elina Hypp�nen and colleagues believe, at least in women, vitamin D levels could play a role in some cases of chronic pain.
Sunshine vitamin
The nutrient, essential for healthy bones, is produced in the body when exposed to sunlight and is also found in oily fish, egg yolks and margarine.
Among the 7,000 men and women aged 45 from across England, Scotland and Wales that they studied, those who were smokers, non-drinkers, the overweight and the underweight all reported higher rates of chronic pain.
Among the women, vitamin D levels also appeared to be important.
This finding was not explained by gender differences in lifestyle or social factors, such as levels of physical activity and time spent outdoors, say the authors.
Women with vitamin D levels between 75 and 99 mmol/litre - a level deemed necessary for bone health - had the lowest rates of this type of pain, at just over 8%.
Women with levels of less than 25 mmol/litre had the highest rates, at 14.4%.
Severe lack of vitamin D in adults can lead to the painful bone disease osteomalacia.
But the researchers said osteomalacia did not account for their findings.
Dr Hypp�nen said work was needed to evaluate whether vitamin D supplements could help prevent chronic pain.
In the meantime, she advised: "If I had chronic pain I would certainly check I was getting enough vitamin D."
Kate MacIver of the Pain Research Institute at Liverpool University cautioned: "Taking too high a dose of Vitamin D supplements as a means of preventing or treating chronic pain could result in Vitamin D toxicity and high blood calcium levels."
Most people should be able to get all the vitamin D they need from their diet and by getting a little sun.
However, if you are pregnant or breastfeeding you should take 10 micrograms (0.01 mg) of vitamin D each day, the Food Standards Agency recommends.
Older people should also consider taking 10 micrograms (0.01 mg) of vitamin D each day.
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