NMU 94 –Higher Vitamin D level Lowers Colorectal Cancer Risk (2018 update study)

Nutrition / Natural Medicine Update No 94 (July 5, 2018)

with Dr. James Meschino

Topic: Higher Vitamin D level Lowers Colorectal Cancer Risk (2018 update study)

Source: Journal of the National Cancer Institute (2018)

An important 2018 study in the journal of the National Cancer Institute has provided compelling evidence that more optimal blood levels of vitamin D provide significant protection against colorectal cancer development. Colorectal cancer is the third leading cause of cancer-related death in North America and in many developed countries, and diet and lifestyle may be able to prevent 70-90% of cases according to the published data. The evidence points very strongly to the fact that in most cases the development of colorectal cancer is most strongly tied to faulty nutrition and lifestyle factors, whereby lifestyle factors include such things as inadequate physical activity, being overweight, smoking and moderate to heavy alcohol consumption.

Although a variety of nutritional factors are linked to colorectal cancer, over the years studies have suggested that vitamin D, as one of those factors, may help prevent colorectal cancer, but more definitive data was required. As such, researchers compiled data from 17 cohort studies, comprising over 5,000 colorectal cancer case participants and over 7,000 control participants. The combination of these 17 studies, following 12,000 individuals, showed that during the average follow-up period of 5.5 years, individuals who initially registered a blood vitamin D level above 50-63 nmol/L (20 – 25 ng/mL) had a 22% lower risk of developing colorectal cancer than individuals whose initial vitamin D blood levels were within the range of 50-63 nmol/L (20 – 25 ng/mL).

We know that vitamin D is required to prevent osteoporosis, and with respect to prevention of osteoporosis, most authorities suggest that maintaining a vitamin D blood level between 50-63 nmol/L (20-25 ng/mL) is adequate and sufficient. However, from the standpoint of colorectal cancer prevention, it appears that a year-round vitamin D blood level higher than this value is required to achieve an additional 22% reduction in risk of colorectal cancer. I normally suggest to patients that they strive to achieve a vitamin D blood level of at least 85 nmol/L (34 ng/mL), and in some high-risk cases up to 150 nmol/L (60 ng/mL).

In the same study, researchers also found that individuals who had an initial vitamin D blood level below 30 nmo/L (12 ng/mL) had a 31% higher risk of colorectal cancer than did individuals whose initial vitamin D blood levels were between 50-63 nmol/L. (20-25 ng/mL). Many previous studies have shown various ways in which vitamin D reduces the risk of colorectal cancer. For example, human and experimental studies have shown the following anti-cancer effects of vitamin D on colorectal cancer development:

• Vitamin D slows down the rate of division of the cells that line the colon. Slowing down cell replication leads to fewer genetic mistakes in genes linked to cancer.
• Vitamin D encourages programmed cell death of emerging cancer cells – a process scientists call apoptosis
• Vitamin D helps new cells fully mature, a process called cellular differentiation, which makes cells less prone to cancer development
• Vitamin D blocks an important pathway in colon cancer development known as the Wnt pathway.
• Vitamin D also reduces inflammation, which is known risk factor for many cancers
• Vitamin improves immune function, another important aspect in cancer prevention
• Vitamin D reduces the synthesis of some key factors that are linked to colon cancer metastasis, such as the molecule VEGF, which increases new blood vessel formation to feed tumors.

The authors of the study make the point that this 2018 review of vitamin D and colon cancer, published in the Journal of the National Cancer Institute, should be taken quite seriously by individuals and by health agencies, such as Cancer Societies, when establishing guidelines for the public. The evidence suggests that most adults should aim for a blood vitamin D level above 63 nmol/L (25 ng/mL), as one means by which to help prevent colorectal cancer. This can be achieved by eating fish twice per week, the ingestion of low-fat, vitamin D fortified dairy products, usually combined with the use of vitamin D supplements and exposure of the skin to ultra-violet light. However, excess exposure to UV-light (from the sun or tanning beds) may also increase risk of skin cancer, and thus, the researchers encourage dietary and supplemental vitamin D as the main strategies in which to optimize vitamin D status. Once again, the consideration here is to get your vitamin D blood level above 63 nmol/L (25 ng/mL).

I have included a link to the research study in the text below

Reference:

McCullough ML, Zoltick ES, Weinstein SJ, Fedirko V, Wang M et al. Circulating vitamin D and colorectal cancer risk: An international pooling project of 17 cohorts. JNCI. June 2108 https://academic.oup.com/jnci/advance-article-abstract/doi/10.1093/jnci/djy087/5035027?redirectedFrom=fulltext

Eat Smart, Live Well, Look Great

Dr. Meschino