A new US study suggests that most older American women are not taking enough Vitamin D and calcium and if they were to increase their intake this would substantially reduce their risk of getting cancer.
The study, which was funded by the US National Institutes of Health, is published in the American Journal of Clinical Nutrition.
Researchers at Creighton University School of Medicine in Omaha, Nebraska, US, conducted a four-year (from 2000 to 2005), double-blind randomized placebo-controlled trial on 1,179 healthy, postmenopausal women aged over 55 who were living in rural eastern Nebraska. A double-blind trial meant nobody knew who was on the active agents and who was on the placebos, including the administrators.
All the women were Caucasian and had been cancer free for at least ten years before enrollment.
The participants were randomly assigned to three groups. One group took only 1,400 to 1,500 mg a day of supplemental calcium (Calcium-only group). Another group took the supplemental calcium plus a 1,100 IU dose of vitamin D per day (Calcium plus Vit D group) and the third group took a placebo.
The US government’s Recommended Daily Amount (RDA) of vitamin D for people aged 50 to 70 is 400 IU per day.
The results showed that women in the Calcium plus Vit D group had a 60 per cent drop in their cancer risk over the four years compared to the women in the placebo group.
In order to eliminate the possibility that some women may have started the trial with undiagnosed cancers, the researchers re-analysed the results leaving out the first year’s figures. This showed an even bigger 77 per cent reduction in cancer risk in the Calcium plus Vit D group compared with the placebo group.
The analysis (excluding the first year) showed no significant difference in cancer risk between the placebo and the Calcium-only group.
50 women developed non-skin cancers during the course of the study. These included breast, colon, and lung cancers.
Dr Joan Lappe, Professor of Medicine at Creighton and who led the research said:
“The findings are very exciting. 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,” she added.
Lappe and colleagues said that further research is needed to see whether these findings are true of men and women of all ages and ethnicity.
More and more studies are coming out in support of Vitamin D for preventing and treating cancer and other diseases such as high blood pressure, diabetes, MS, fibromyalgia and rheumatoid arthritis.
Exposure to sunlight helps humans to make vitamin D, but sunscreens tend to block this. According to Lappe, it only takes 10 to 15 minutes of bright summer sun to make large amounts of Vitamin D, but she said people should be careful because sunlight has ultraviolet B (UVB) rays that cause skin cancer.
It appears that the further you are from the equator the harder it is to get enough sunlight to make Vitamin D naturally. For instance, Omaha, where the research was conducted, is near the 41st parallel, just 4 degrees too far north, to give its residents enough sun in the winter to make Vitamin D. Also, people with light skin make Vitamin D more easily than people with dark skin.
While generally in agreement that the government’s RDA for vitamin D should be raised, experts disagree about how much.
There are two types of Vitamin D available in supplement form, D2 and D3. The scientists at Creighton recommend the latter because it is more active.
“Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.”
Joan M Lappe, Dianne Travers-Gustafson, K Michael Davies, Robert R Recker and Robert P Heaney.
American Journal of Clinical Nutrition, Vol. 85, No. 6, 1586-1591, June 2007.
Click here for more information on dietary supplements (US National Institutes of Health).
Written by: Catharine Paddock
Writer: Medical News Today