Vitamin D and Cancer Risk – A potential magic bullet?

Vitamin D, also known as cholecalciferol, plays an important role in bone health and muscle strength and is essential for the prevention of rickets (1). Cholesterol is a precursor of Vitamin D, which is endogenously produced in the body when ergosterol is exposed to UVB sunlight through the skin. It is also found in eggs, fatty fish and supplements (1).

A recent study by researchers in Japan found that higher levels of vitamin D may lower the risk of liver cancer. The study conducted by researchers at the Center for Public Health Sciences at the National Cancer Center in Tokyo suggests that people who suffer from low levels of Vitamin D may be at an increased risk for many different types of cancers; however the overall body of evidence is mixed (2,3).

This latest study was published in BMJ and explored biologically active forms of vitamin D in blood samples of over 30,000 middle-aged adults across Japan in the early 1990s. The follow-up for individuals was over a 16-year period. This analysis was based off a sample of 3301 participants who developed cancer during the study and 4044 randomly selected participants, of whom 450 developed cancer. The research team found higher levels of circulating vitamin D led to lower risk for cancers, overall, after controlling for age, sex, smoking status and family history of cancer. They also controlled for seasonal differences in circulating vitamin D. They did not find differences in the effect of vitamin D by sex; however, authors noted that participants in the lowest quartiles of vitamin D status had a 22% higher risk of cancer when compared to those in the highest quartiles. Additionally, they noted a 50% lower risk of liver cancers for those in the highest vitamin D group compared to the lowest, after adjusting for diet.

Vitamin D status was only measured at one point during follow-up, which serves as an important limitation. Additionally, inherent selection bias means that participants in the study may have been more health-conscious than the public at large. The number of rare cancer cases in the cohort was also small.

It is important to note that these latest findings apply primarily to Asian populations and higher levels of Vitamin D in these communities may lower risk for cancer; however, these findings cannot be translated across the board. It is important for those at risk of sun burns to avoid direct unprotected contact with the sun, which is a known risk factor for skin cancers. Additionally, lower levels of vitamin D may be an indication of poor health, overall (2,3).

Other health benefits of vitamin D have been seen in meta-analyses that have found a 31% reduction in falls among those supplemented with vitamin D. It also plays a role in improving the body’s response to infection among patients with cystic fibrosis (4). For populations in the US, vitamin D deficiency remains a problem in populations including African American communities, where according to the National Health and Nutrition Examination Survey (NHANES), 60% of people suffer from low levels (5,6). Through fortification of dairy products and supplementation, these numbers have reduced; however, greater attention including additional research is needed to reduce risk of deficiency, with added benefits to risk reduction for other health conditions, including cancers.


  • Khazai, N., Judd, S.E. & Tangpricha, V. (2008). Calcium and vitamin D: skeletal and extraskeletal health. Current Rheumatology Reports, 10(2), 110-117.
  • Budhathoki, S., Hidaka, A., Yamaji, T., Swada, N., Tanaka-Mizuno, S., Kuchiba, A., Charvat, H., Goto, A., Kojima, S., Sudo, N., Shimazu, T., Sasazuki, S., Inoue, M., Tsugane, S., Inoue, M., Tsugane, S., & Iwasaki, M. (2018). Plasma 25-hydroxyvitamin D concentration and subsequent risk of total and site specific cancers in Japanese population: large case-cohort study within Japan Public Health Center-based Prospective Study cohort. The British Medical Journal, 2018, 360.
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  • Pincikova, T., Paquin-Proulx, D., Sandberg, J.K., Flodstrom-Tullberg, & M., Hjelte, L. (2017). Clinical impact of vitamin D treatment in cystic fibrosis: a pilot randomized controlled trial. European Journal of Clinical Nutrition, 71, 203-205.
  • Jain, R.B. (2016). Recent Vitamin D data from NHANES: Variability, trends, deficiency and sufficiency rates and assay compatibility issues. Journal of Advanced Nutrition and Human Metabolism, 2.
  • Avenell, A., Mak, J.C., & O’Connell, D. (2014). Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men. Cochrane Database of Systematic Reviews, 14(4).
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Can Vitamin D Help Prevent the Development of Type 2 Diabetes?

By Banaz Al-khalidi

November is National Diabetes Month and World Diabetes Day takes place yearly on November 14 to engage millions of people worldwide in diabetes advocacy and awareness. The International Diabetes Federation estimates that 382 million adults (20-79 years old) suffered from diabetes in 2013, which equates to a prevalence of 8.3%. To provide a better perspective by nation, the 10 countries with the highest prevalence of diabetes in 2013 were as follows: Tokelau (37.5%), Federated States of Micronesia (35%), Marshall Islands (34.9%), Kiribati (28.8%), Cook Islands (25.7%), Vanuatu (24%), Saudi Arabia (24%), Nauru (23.3%), Kuwait (23.1%), and Qatar (22.9%). However, if we were to look at the 3 countries with the greatest number of people with diabetes, China ranks the highest (98.4 million), followed by India (65.1 million) and USA (24.4 million). These figures are quite alarming.

Of those suffering from diabetes, type 2 diabetes comprises almost 90% of people with diabetes around the world. As such, type 2 diabetes is one of the fastest growing health problems in the world. So what could be driving this epidemic?

Evidence from observational studies have consistently shown us that low blood levels of vitamin D are associated with an increased risk of type 2 diabetes. The results of numerous observational studies led to speculation that the development of type 2 diabetes is associated with vitamin D insufficiency. Going back to the figures presented earlier, if vitamin D insufficiency is a risk factor for type 2 diabetes, one might also speculate that countries with higher prevalence of diabetes are facing a coexisting problem of type 2 diabetes and vitamin D insufficiency. For example, Tokelauans (the nationals of Tokelau) who have the highest prevalence of type 2 diabetes, may also be at risk for vitamin D insufficiency despite having a tropical and marine climate. The question then becomes, could vitamin D be a causal factor in the development of type 2 diabetes? While this might sound too simplistic, I assure you it’s not.

Interpretation of evidence on vitamin D and type 2 diabetes is complicated for a number of reasons. First and foremost, observational studies do not tell us anything about the cause-effect relationship between vitamin D and type 2 diabetes because of possible uncontrolled confounding factors, such as physical activity, that may affect both vitamin D levels and the risk of type 2 diabetes. Second, observational studies cannot inform us about reverse causation. In other words, which comes first, the chicken or the egg? Third, there are a myriad of factors that affect vitamin D levels, including environmental, cultural, genetic and physiological factors. It remains unclear then whether there is a causal link between vitamin D and type 2 diabetes.

To answer this question, a large genetic study published in The Lancet Diabetes and Endocrinology journal looked at the causal association between low blood levels of vitamin D and risk of type 2 diabetes. The study concluded that the association between vitamin D and type 2 diabetes is unlikely to be causal. The research, which was a Mendelian randomization study, examined the link between type 2 diabetes risk and vitamin D, by assessing the genes that control blood levels of vitamin D. Most importantly, the design of this study has a powerful control for confounding factors and reverse causation which are issues of concern in observational studies. This may partly explain the discrepancy between results from earlier observational studies and this study in question. However, we still need to be cautious about interpreting the results from mendelian randomization studies as some of the underlying assumptions in the study might remain untested.

The take home message is that no special recommendations could be made about vitamin D levels or supplementation for people with type 2 diabetes. However, long-term randomized trials of vitamin D supplementation remain important to elucidate vitamin D’s role in type 2 diabetes.

As we recognize National Diabetes Awareness this month, it is important to remind patients that diabetes is a progressive chronic lifestyle disease that can be controlled by making healthy lifestyle changes- such as partaking in regular physical activity, eating a balanced diet, maintaining a healthy body weight, taking prescribed medications, joining a smoking cessation program, and improving sleeping patterns.

Zheng Ye, Stephen J Sharp, Stephen Burgess, Robert A Scott, Fumiaki Imamura, Claudia Langenberg, Nicholas J Wareham, Nita G Forouhi. Association between circulating 25-hydroxyvitamin D and incident type 2 diabetes: a mendelian randomisation study. The Lancet Diabetes & Endocrinology, 2014; DOI: 10.1016/S2213-8587(14)70184-6.

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Nutritional Interventions in Treatment of Major Depressive Disorder

By Chris Sovey, RN, BSN

Do you know someone who is depressed? You probably do, whether you realize it or not. Major Depression is a crippling mood disorder currently affecting over 26.2% of the adult population in the United States (U.S.) (NIMH, 2005, NIMH 2008). The prevalence of Major Depression in the U.S. has increased by a factor of ten fold in the last two decades (Ilardi, 2009). It is expected to continue to rise. The National Institute of Mental Health estimates that 1 in 4 Americans will meet the diagnostic criteria for major depression during their lifetime (NIMH, 2008). Medicare claims of those suffering with depression tend to incur charges an average of $2,409 greater per medical incident than their non-depressed counterparts (NIMH, 2009).

There is a significant body of literature supporting the use of nutritional interventions in the treatment of depression. Because of the increasing prevalence of this troublesome disorder, my goal is to briefly outline four nutritional supplements that have demonstrated safety and at least some efficacy in research. Keep in mind that research surrounding these particular items is still controversial.

Omega-3’s– Omega-3 supplementation comes highly recommended by a growing number of practitioners as an integral part of depression treatment. Dr. Neil Nedley, MD and Stephen S. Ilardi, PhD claim that diets high in omega-3’s may assist in the treatment of both major depression and bipolar disorder. Because the Western American Diets tend to lack foods containing omega-3’s, it may be beneficial to find a supplemental source, such as fish oil or flaxseed. Some authors claim that the alpha-linolenic acid (ALA) found in flax is not a bio-available source of Omega-3 fatty acids. Fish oil may be another viable option. Walnuts also contain a relatively high level of Omega-3’s. Regardless of source, omega-3 supplementation has consistently demonstrated a reduction in depressive symptoms in the literature (Riediger, et al 2009).

Folate and Vitamin B-12 – Depressed patients tend to demonstrate higher deficiency levels of vitamin B-12. Folate levels typically are lower in depressed patients (Bodner, 2005). It has been suggested that a deficiency in either of these vitamins may impair methylation in the central nervous system that is necessary to produce monoamine neurotansmitters (Penninx, 2000). This may in turn lead to the impaired mood symptoms evident in depression.

Vitamin D – Serum 25-hydoxyvitamin D levels tend to be low among depressed individuals. Some authors argue that there may be a causal link between depression and Vitamin D deficiency (Jorde, et. al 2008), while others maintain that the evidence is not strong enough at this point. Even more confusing is the lack of an established dosage to treat various disorders. This includes depression. Some studies suggest a dose of 2000 IUs / day for general intake (Vieth, 1999). In the treatment of depression, some studies have used dosages as high as 20,000 – 40,000 IUs / day! (Jorde, et. al 2008) Regardless of whether or not there is a direct causal relationship, it appears that some studies are yielding positive results in reducing depressive symptoms.

St. John’s Wort – Hypericum perforatum L. (St. John’s Wort) is currently a hotspot for research. It is widely popular in Europe, and used as a front-line treatment for mild to moderate depression. The United States is a little more hesitant to adopt this herb into the realm of psychotherapy, as it comes with several drug interactions. Many systematic reviews present confusing and contradictory results. A meta-analysis by Linde, et al. found Hypericum to be as effective as standard antidepressants to decrease depressive symptoms in mild to moderately severe depression (Linde, 1996). It is likely that more research will need to be completed before St. John’s Wort becomes an accepted treatment for depression in the U.S.

I want to stress that when applied correctly, an appropriate regimen of nutritional interventions in addition to other therapies for depression may yield profound results in mood and other symptoms. You must work the details out with your healthcare provider.

Lastly, if you’re reading this out of sheer curiosity, pass this information on to someone who is struggling with depression. Maybe it is a family member. Maybe it is you. Sometimes things can seem pretty hopeless in our darkest moments. But there is always hope. Finding the correct information and acting upon it is the first step to recovery.

Disclaimer: These interventions are not meant to serve as medical advice. Please consult with your healthcare provider. Supplements, and even foods, may cause interactions with your current medications.


Bodnar, L., & Wisner, K. (2005). Nutrition and depression: Implications for improving mental health among childbearing-aged women.Biological Psychology, 58, 679-685. Retrieved from

Ilardi, S. (2010). The depression cure. Da Capo Press. 1999. Philadelphia, PA.

Jorde, R., Sneve, M., Figenschau, Y., Svartberg, J., & Waterloo, K. (2008). Effects of vitamin d supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial. Journal of Internal Medicine,264(6), 599-609. Retrieved from

Linde, K., Ramirez, G., Mulrow, C., Pauls, A., Weidenhammer, W., & Melchart, D. (1996). St john’s wort for depression—an overview and meta-analysis of randomised clinical trials. British Medical Journal, 313(253), Retrieved from

NIMH. (2009, February 13). Health care costs much higher for older adults with depression plus other medical conditions. Retrieved from

NIMH. (2005). Major depressive disorder among adults. Retrieved from

NIMH. (2008, June 26). The numbers count: Mental disorders in america. Retrieved from

Penninx, B., Guralnik, J., Ferrucci, L., Fried, L., Allen, R., & Stabler, S. (2000). Vitamin b12 deficiency and depression in physically disabled older women: Epidemiologic evidence from the women’s health and aging study. American Journal of Psychiatry, 157, 715-721. Retrieved from

Riediger, N., Othman, R., Miyoung, S., & Moghadasian, M. (2009). A systemic review of the roles of n-3 fatty acids in health and disease. American Dietetic Association, 109, 668-679.

Vieth, R. (1999). Vitamin d supplementation, 25-hydroxyvitamin d concentrations, and safety.American Journal of Clinical Nutrition, 69(5), 842-856. Retrieved from