Vitamin D linked to colon cancer protection: Meta-analysis

High blood levels of vitamin D are associated with a reduced risk of colorectal cancer, according to a new meta-analysis of observational studies from an international team of researchers.

Analysis of data from nine studies revealed that, for every 10 nanograms per milliliter increase in levels of vitamin D (25-hydroxyvitamin D) the associated risk of colorectal cancer decreased by 15 percent.

On the other hand, no association was observed between vitamin D levels and the risk of breast or prostate cancer, say results published in the International Journal of Cancer.

Shining light on the sunshine vitamin

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are transformed in the liver and kidneys into 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.

D and the big C

The link between vitamin D intake and protection from cancer dates from the 1940s when Frank Apperly demonstrated a link between latitude and deaths from cancer, and suggested that sunlight gave "a relative cancer immunity".

Since then there have been numerous studies suggesting associations between vitamin D and lower risks of certain cancers.

There is growing evidence that 1,25(OH)2D has anticancer effects, but the discovery that non-kidney cells can also hydroxylate 25(OH)D had profound implications, implying that higher 25(OH)D levels could protect against cancer in the local sites.

The new meta-analysis, led by Philippe Autier from the International Prevention Research Institute (IPRI) in Lyon, France, adds to the subject, while also showing the relationship between vitamin D and cancer is ambiguous, depending on the type of cancer.

Indeed, a recent meta-analysis published in the European Journal of Cancer (doi: 10.1016/j.ejca.2010.03.037) concluded that the association between vitamin D and breast cancer is still ambiguous.

New analysis

Dr Autier and his co-workers analyzed data from 35 epidemiological studies of 25(OH)D levels and colorectal, breast and prostate cancer.

The analysis showed that for every 10 nanograms per milliliter increase in 25(OH)D levels the associated risk of colorectal cancer decreased by 15 percent, while the risk of breast cancer was associated with an 11 percent decrease. However, when the researchers restricted their analysis to prospective studies only, the breast cancer risk was decreased by only 3 percent, whereas data from case-control studies indicated a risk reduction of 17 percent.

“A non-significant decreased risk of breast cancer risk was associated with higher serum 25-hydroxyvitamin D, but results from prospective studies only did not support an association between vitamin D status and breast cancer,” said the researchers.

No association between vitamin D levels and prostate cancer were observed at all.

“If additional observational studies of vitamin D and cancer are proposed, they should adopt different designs, such as assessment of serum 25-hydroxyvitamin D colorectal at different points in time, or longer follow-up of subjects,” wrote the researcher.

“To assess whether vitamin D status is a risk factor or a risk marker for colorectal cancer, it is likely that new randomized trials will need to be organized to test whether increasing the 25-hydroxyvitamin D level changes the risk of colorectal cancer, and to determine how much of an increase is required to change the risk of cancer sufficiently to be useful as a public health measure,” they concluded.

Source: International Journal of Cancer
15 March 2011, Volume 128, Issue 6, pages 1414–1424
“Meta-analysis of observational studies of serum 25-hydroxyvitamin D levels and colorectal, breast and prostate cancer and colorectal adenoma”
Authors: S. Gandini, M. Boniol, J. Haukka, G. Byrnes, B. Cox, M.J. Sneyd, P. Mullie, P. Autier



Vitamin D supplement use increases 50% among US users; herbs slide, finds survey

Vitamin D penetration has jumped 50% in the past two years in the US, according to a new survey of 6000 supplement buyers conducted by product tester and market scrutineer, ConsumerLab.com, that also recorded dwindling herbal interest.

Its 105-page report found vitamin D use had skyrocketed, especially among women who also were more likely to use calcium and probiotics, and that omega-3 fish oil supplements were exerting a “growing dominance”, used by 75.7 percent of respondents as opposed to 74 percent in 2009.

Unlike many of the other 31 supplement types that featured in the survey, fish oil consumption was ubiquitous among all age groups and both genders.

ConsumerLab.com found 56.2 percent of people surveyed were vitamin D supplement users, compared to 47.9 percent in the 2009 survey and 36.9 percent in 2008 – a 52 percent hike.

“In contrast to fish oil, vitamin D use increased with age and by gender – 61 percent of women used vitamin D compared to 51 percent of men,” ConsumerLab.com president, Tod Cooperman told NutraIngredients-USA.com

Multivitamin consumption rates dropped slightly to 70.1 percent from 72 percent in 2009 among those polled – taken from ConsumerLab’s e-newsletter subscription list.

Botanicals took a hit in 2010 with only 37.6 pecent or respondents reporting using them compared with 44 percent in 2009. Glucosamine/chondroitin fell from 38.5 percent to 35.3 percent.

Online outlets were the most popular with 46.5 percent of people using them, compared to 44.1 percent in 2009 and 39.9 percent in 2008. Vitamin stores, mass merchants and direct distributors registered a small drop in patronage.

Other findings included:

• Men were more likely than women to have taken coQ10, herbs and extracts, glucosamine/chondroitin, vitamin E, resveratrol, amino acids, nutrition drinks and powders.
• Younger adults (35-44) were more likely than older adults (75-84) to have used multivitamins, amino acids, nutrition/protein drinks and powders, green tea, nutrition bars and iron.
• Older adults were more likely to have used vitamin D, calcium, CoQ10, vitamin C, vitamin E, resveratrol, vitamin K, and red yeast rice.

Calcium passed CoQ10 to become the fourth most popular supplement with use rising from 51.2 percent in 2009 to 55.3 percent last year. CoQ10 dropped from 55.3 percent to 51.2 percent over the same period.