Sunshine vitamin may ease pain, reduce colon cancer risk
screened regularly for vitamin D deficiency, report authors of the
leading study in this week's Mayo Clinic Proceedings.
New research conducted at the University of Minnesota in the US found that 93 per cent of all subjects with non-specific musculoskeletal pain were vitamin D deficient. This kind of pain is the most common type of complaint seen by primary care doctors, note the authors.
A study of 150 children and adults with undetermined muscle or bone pain found that 100 per cent of African-American, East African, Hispanic, and Native American subjects were vitamin D deficient. And all study patients under the age of 30 were deficient in the vitamin. Of these, 55 per cent were severely deficient. Five patients unexpectedly had no vitamin D at all.
"These findings are remarkably different than what is taught in medical school. We would expect vitamin D deficiency in old persons or housebound persons," said Greg Plotnikoff, professor at the University of Minnesota's Center for Spirituality and Healing and lead researcher on the study.
"We found the worst vitamin D deficiency in young persons - especially women of childbearing age. We were stunned to find no vitamin D at all in five patients who had been told their pain was 'all in their head.' This study supports more routine testing for vitamin D deficiency," he added.
Vitamin D deficiency is associated with significant risks for osteoporosis, hypertension, diabetes, cancer, and auto-immune diseases such as multiple sclerosis. It also is harmful for developing foetuses and causes rickets in children. Researchers in both the US and Europe are becoming increasingly alarmed by vitamin D deficiency, which is thought to be responsible for a resurgence in rickets.
An unrelated study in the December issue of Psychosomatics found that 37 per cent of doctor's visits are for symptoms of no known cause, most frequently unexplained back, head, arm, and leg pain. Plotnikoff recommended a trial to assess management of persistent, non-specific pain by prescription of vitamin D replenishment.
And in a further study, in today's issue of the Journal of the American Medical Association, researchers confirm the important role played by the vitamin in reducing colon cancer risk. The research is one of the most comprehensive studies to date on colon-cancer risk and shows that proper intake of cereal fibre and vitamin D are associated with reduced risk of serious colon polyps that may lead to the disease.
"The finding that may surprise the scientific community is the vitamin D data," said lead investigator David Lieberman, chief of gastroenterology at the Portland VA Medical Center and Oregon Health and Science University. "Higher levels of vitamin D intake were associated with a lower risk of serious colon polyps. There have been some studies suggesting this, but our data are compelling."
In the study, which included more than 3,000 men aged 50-75, those who consumed higher amounts of cereal fibre and vitamin D - more than about 4 grams per day of fibre and more than 645 international units of vitamin D daily - were significantly less likely to have serious colon polyps, or tumours, which are often the precursor to cancer.
Exercise, calcium, folic acid and multivitamins were shown in the study to be marginally beneficial in lowering risk, as was the use of non-steroidal anti-inflammatory drugs: men who took a daily aspirin were about two-thirds less likely to have a tumour.
Smoking almost doubled the risk of having a tumour or benign polyps, which often become cancerous. The consumption of red meat and alcohol were also associated with a slightly higher risk. Body weight and cholesterol proved unrelated to cancer risk in this study.
Cancer of the colon or rectum is the second deadliest form of cancer but is also considered one of the most preventable types of cancer, as there are several dietary factors that appear to play a protective role.
"These data support relatively simple and safe recommendations that may reduce the risk of colon cancer," said Lieberman. "Stop smoking, reduce alcohol and red meat consumption, take a multivitamin, exercise regularly, and consume vitamin D, calcium and cereal fiber in your diet."
The best food sources of vitamin D include cod liver oil, salmon, mackerel, sardines, and fortified milk but sunlight, which triggers production of the vitamin, tends to be a more important source. Yet researchers are unsure how this interacts with dietary intake to provide adequate levels for cancer protection. Lieberman said his findings should prompt research to determine how regular exposure to sunlight affects the risk of colon cancer.
The sunshine vitamin made headlines in May 2002 when scientists showed in an animal study that the nutrient works to prevent colon cancer by detoxifying the body's own digestive products. But vitamin D has generally been overshadowed as a colon-cancer protector by calcium, which vitamin D helps the body use. In Lieberman's study, calcium alone showed only a minor beneficial effect.