It’s said that statistics is the art of never having to say you’re wrong.
When a much-awaited Creighton University study on vitamin D and cancer fell just a whisker short of statistical significance, principal investigator Joan Lappe, PhD, said no problem, we are not wrong.
Lappe and her Creighton research colleagues made pioneer tracks with their work on vitamin D’s relationship to cancer risk, showing a 30 percent lower incidence. Professor Robert Heaney, who died last August, helped to inspire and plan the study.
The team met the gold standard of scientific rigor through the first randomized clinical trial of the effects of vitamin D supplementation on all types of cancer combined. Their findings were published in March by the prestigious Journal of the American Medical Association (JAMA).
Funded by the National Institutes of Health (NIH), the four-year study included 2,303 healthy, older women in rural Nebraska, in which half were randomized to daily doses of 2,000 International Units (IU) of vitamin D3 and 1,500 milligrams of calcium supplements, and the rest were given placebos. Cancer struck at a 30 percent lower incidence in the supplemented group than in the control group.
While that 30 percent narrowly missed statistical significance in the study, the findings add to a critical mass of evidence that supports that vitamin D does offer important value in health promotion and disease prevention.
“It’s enough to keep me taking my vitamin D every day,” says Lappe, who is a professor of nursing and medicine and holder of the Criss/Beirne Endowed Chair in Nursing.
One of Lappe’s first research questions considered bone health in children. She and her national research partners helped to establish the normal bone density reference levels for children and to demonstrate the importance of physical activity and calcium in their bone development. The study continues to impact public health policy.
Later, Lappe worked on a project through a Department of Defense grant to look at the high risk for stress fractures among young military recruits. Finding that calcium and vitamin D supplements decreased fractures by 20 percent, the Navy implemented a new regimen for all female basic trainees. When the study appeared in the New York Times, President George W. Bush’s personal physician called Lappe to ask what supplements to suggest to the president’s wife.