New studies suggest that a high level of Vitamin D in the blood may improve our mood during the winter months, and may also protect against colds and flu.

This is my discovery of the season! I’ve already written about the importance of maintaining a strong level of vitamin D3 in the blood, to protect against cancer. This works in cancer prevention, but it’s also very likely to have an impact in slowing the progress of cancer. We’re now learning that women with a high level of vitamin D3 have the lowest risk of developing breast cancer, and that if they do develop cancer, they have a lower risk of cancer progression (Abbas et al. 2009 ; Goodwin, 2008).

This beneficial effect of vitamin D3 seems likely to extend to non-small-cell lung cancer too. In one study, people with the highest blood levels of vitamin D3 had an average survival rate that was double those who had the lowest blood levels of vitamin D3 (Zhou et al., 2005). Similar data also exists for cancers of the colon and prostate cancers (Freedman et al. 2007, Woo et al., 2005).

Indeed, researchers into vitamin D believe that it slows the progress of all forms of cancer, at least during its early phases (Cannell et Hollis, 2008).

What’s new is that it seems that adequate levels of vitamin D3 -- comparable to the levels observed during the summer months in people who enjoy moderate exposure to the sun – may also protect from colds and winter flu (Laaksi et al., 2007), and may additionally contribute to maintaining a positive mood, acting as a kind of antidote to falling energy levels during the cold, dark winter months (Wilkins et al. 2006). Two doctors of integrative medicine have recently published an article on the subject (Cannell and Hollis, 2008), and they conclude that we should maintain our blood-levels of vitamin D3 above 50 ng/ml (in Europe, where this is usually measured in nmol/l, this corresponds to about 125 nmol/l) and below 70 ng/ml (175 nmol/l). (To convert ng/ml to nmol/l, multiply by 2.498).

You should note that, in the absence of large-scale, long-term research into survival rates, Dr Jean-Claude Souberbielle, who has been studying vitamin D for 25 years at the Necker Hospital in Paris, recommends a blood level above 30 ng/ml (roughly 90 nmol/l), and under 50 ng/ml (125 nmol/l), in order to minimize the risk of side-effects such as the development of developing kidney stones due to excessive absorption of calcium.

The best way to move forward on this is to talk to your doctor about the importance of analyzing your level of vitamin D3. (Many doctors do this regularly, but others have no knowledge of this field). You may also need to take appropriate supplements. Vitamin D experts recommend taking daily supplements of 1,000 – 5,000 International Units (remember that our skin manufactures 10,000 IU after 15 to 20 minutes of exposure to midday sun in the summer), or single doses of 100,000 units of vitamin D3, once or twice a month (each dose costs no more than $1.50). However, it’s usually better NOT to take ergocalciferol (also known as vitamin D2), which some experts think may be more toxic.

RISKS The only possible risks associated with excessive intake of vitamin D3 – particularly in people who have cancer – are, firstly, that kidney stones may develop due to excessive calcium in the urine, and, secondly, hypercalcemia (excessive levels of calcium in the bloodstream). Hypercalcemia may in some cases be lethal to people with cancer. It is therefore recommended that you measure blood levels of vitamin D3 (25 OH cholecalciferol) and calcium, before you begin supplements, and roughly every three months during treatment.

Acknowledgment Thanks to Thierry Souccar and his team at for having alerted me to the recent article by Cannell and Hollis.

Bibliography: Souberbielle J-C, Prié D, Couberbaisse M, et al. News on the effects of vitamin D and the evaluation of vitamin D status. Annals of Endocrinology 2008;69:501-10. Abbas S, Chang-Claude J, Linseisen J. Plasma 25-hydroxyvitamin D and premenopausal breast cancer risk in a German case-control study. Int J Cancer 2009;124(1):250-5. Goodwin PJ. Frequency of vitamin D (Vit D) deficiency at breast cancer (BC) diagnosis and association with risk of distant recurrence and death in a prospective cohort study of T1-3, N0-1, M0 BC. In: Annual Meeting of the American Society of Clinical Oncology; 2008. Zhou W, Suk R, Liu G, et al. Vitamin D is associated with improved survival in early-stage non-small cell lung cancer patients. Cancer Epidemiology, Biomarkers & Prevention 2005;14(10):2303-9. Freedman DM, Looker AC, Chang S-C, Graubard BI. Prospective Study of Serum Vitamin D and Cancer Mortality in the United States. J Natl Cancer Inst 2007;99(21):1594-602. Woo TCS, Choo R, Jamieson M, Chander S, Vieth R. Pilot study: potential role of vitamin D (Cholecalciferol) in patients with PSA relapse after definitive therapy. Nutr Cancer 2005;51(1):32-6. Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev 2008;13. Laaksi I, Ruohola J-P, Tuohimaa P, et al. An association of serum vitamin D concentrations < 40 nmol/L with acute respiratory tract infection in young Finnish men. American Journal of Clinical Nutrition 2007;86(3):714-7. Wilkins CH, Sheline YI, Roe CM, Birge SJ, Morris JC. Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. American Journal of Geriatric Psychiatry 2006;14(12):1032-40.