08/06/2007 – A growing body of scientists believes that most Americans and Europeans do not receive enough vitamin D, and according to the latest study this could be putting them at a significant risk of developing cancer.
Researchers from the Creighton University School of Medicine, in the United States found during a study of 1,179 healthy, postmenopausal women that those taking large amounts of vitamin D3 in conjunction with calcium had a 60 per cent or higher chance of not getting cancer than their peers.
The women, from rural Nebraska, supplemented their diet for four years with calcium and a quantity of vitamin D3 nearly three times the US government’s recommended daily amount (NRV) for middle-age adults.
“The findings are very exciting,” said Joan Lappe, the study’s lead researcher. “They confirm what a number of Vitamin D proponents have suspected for some time but that, until now, have not been substantiated through clinical trial. Vitamin D is a critical tool in fighting cancer as well as many other diseases.”
The women, who were all 55 years or older and free of known cancers for at least 10 years prior to entering the study, were randomly assigned to take daily dosages of 1,400-1,500 mg supplemental calcium, 1,400-1,500 mg supplemental calcium plus 1,100 IU of vitamin D3, or placebos.
Over the four-year trial, women in the calcium/vitamin D3 group experienced a 60 per cent decrease in their cancer risk compared to the group taking placebos.
Since some women may have entered the study with undiagnosed cancers, researchers eliminated the first-year results and examined the last three years of the study.
The latter years showed even more dramatic results with the calcium/vitamin D3 group showing a 77 per cent cancer-risk reduction, claimed the researchers.
There was, however, no statistically significant difference in cancer incidence between participants taking placebos and those taking just calcium supplements, they added.
During the study, 50 participants developed non-skin cancers, including breast, colon and lung cancers.
Lappe said further studies were needed to determine whether the results applied to other populations, including men, women of all ages and different ethnic groups – all the participants in this study were Caucasian.
Interest in vitamin D has been increasing around the world for all age groups, with calls to increase vitamin D intake growing louder.
Fifteen experts from universities, research institutes and university hospitals around the world recently called for international agencies to “reassess as a matter of high priority” dietary recommendations for vitamin D because current advice is outdated and puts the public at risk of deficiency (The American Journal of Clinical Nutrition, Vol. 85, pp. 860-868).
A review of the science reported that the tolerable upper intake level for oral vitamin D3 should be increased five-fold, from the current tolerable upper intake level (UL) in Europe and the US of 2000 International Units (IU), equivalent to 50 micrograms per day, to 10,000 IU (250 micrograms per day).
There is also evidence that a higher intake of vitamin D may be helpful in preventing and treating diseases other than cancer, such as high blood pressure, fibromyalgia, diabetes mellitus, multiple sclerosis and rheumatoid arthritis.
Vitamin D refers to two biologically inactive precursors – D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive. The latter is derived from plants and only enters the body via the diet, from consumption of foods such as oily fish, egg yolk and liver.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active ‘storage’ form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body
The researchers for this study chose vitamin D3 because it is more active and thus more effective in humans, they explained.
The research was funded by the National Institutes of Health.
Source: American Journal of Clinical Nutrition
“Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial”
June 8, Volume 85, Issue 6, Pages 1586-1591
Authors: J. Lappe, D. Travers-Gustafson, K. Davies, R. Recker, R. Heaney