Take home message first
If oneâ€™s health goal is to stay healthy or slow the progression of most diseases, then consumption of at least 2000 IU of vitamin D is a good start.
Vitamin D 101 â€“ for the layperson
Vitamin D does a whole lot more than sustain healthy bones by assisting in the absorption of calcium. There are receptors throught out the body that attach to vitamin D and regulates DNA.
In the past 20 years, vitamin D deficiency has been associated with:
- Heart disease
- Metabolic syndrome (combination of hypertension, fat deposit in blood vessels, diabetes, blood glucose imbalance and fat around the belly)
- Cancer â€“ especially colorectal cancer
- Autoimmune diseases
- Overall non-specific death (Melamed et al., 2008)
Who needs vitamin D supplementation the most?
Darker skin people, the obese and those who live in regions away from the equator where there is low ultraviolet B radiation from sunlight are in higher need of vitamin D supplementation. Yes, that’s pretty much all of us
It may not be a coincidence that cancer occurs more frequently in dark-skinned people, the obese, and in regions with limited exposure to ultraviolet B radiation from sunlight. Each of these factors is associated with low blood levels of vitamin D. Furthermore, cancer survival rates are lower when the diagnosis occurs in months of lower sunlight levels, suggesting a protective role of vitamin D. Studies suggest that vitamin D protects against numerous forms of cancer, including widely prevalent cancers such as those affecting the colon, prostate, breast, and lung. (Giovanucci 2005)
The cancer / vitamin D link
Colon cancer â€“ A study of studies (meta-analysis) revealed that out of 35,000 people studied, those with normal vitamin D levels had lower risk of colon / bowel cancer. Other studies suggest that high calcium (1000mg) with 400IU of vitamin D a day offers no protection. To note, 400 IU a day is a ancient lower suggested dose that plays no role in modern nutrition. For most, 2000 IU is the minimum on should take.
Breast cancer – Also, a meta-analysis regarding vitamin D and the prevention of breast cancer demonstrated a 45% decrease in breast cancer risk for those in the higher blood levels of vitamin D compared with those at the lowest. (Hu et al, 2009) A clinical randomized trial, the gold standard, looking at over 1100 women,Â showed that the incidence of breast cancer was lowered by daily supplementation with 1000Â IU of vitamin D plus calcium in postmenopausal women (Lappe et al. 2007).
Prostate cancer â€“ epidemiological studies, that is, a study designed to examine large group of people and its associations with its increase the risk of disease, indicate a strong link between vitamin D deficiency and prostate cancer. Test tube studies and animal studies do as well. Human studies with consumption of vitamin D have been inconsistent (Barnett et al. 2011) We yet do not know objectively what blood levels of vitamin D are most adequate (normal is between 30ng/ml â€“ 100ng/ml) or what dosage is best for daily consumption for prostate cancer prevention or adjuvant treatment.
Governmental agencies like the Institute of Medicine, IOM, fall short in their recent daily recommendations of vitamin D. After â€œcarefulâ€ review of the literature, researchers from the IOM increased the daily dosage of vitamin D from 400IU to a marginal 600IU. Since most people have insufficient if not deficient levels of vitamin D, 600 units will not get virtually anyone to normal levels.
The absolute best way to determine adequate levels of vitamin D is to get a 25-hydroxy-vit D blood test from your practitioner and make sure levels are between 50ng/ml to 90ng/ml (mid to high normal.) A Calcium blood test is also adequate to assure hypercalcemia ( too much blood calcium) which can also cause problems. Based on my clinical experience, no one should take anything less than 2000 units of vitamin D3 a day with food or fish oil – anything higher should be monitored by a physician. This is particularly true for those who are obese, dark skin color or one who is not out in the sun much. By the way, if you are out in the sun and use sunscreen, all bets are off, no vitamin D production for you either.
In Optimal Health ,
M.L. Melamed, E.D. Michos, W. Post and B. Astor, 25-hydroxyvitamin D levels and the risk of mortality in the general population, Arch Intern Med 168 (2008), pp. 1629â€“1637
Giovannucci E. The epidemiology of vitamin D and cancer incidence and mortality: a review (United States). Cancer Causes Control. 2005 Mar;16(2):83-95.
P. Chen, P. Hu, D. Xie, Y. Qin, F. Wang and H. Wang, Meta-analysis of vitamin D, calcium and the prevention of breast cancer, Breast Cancer Res Treat 121 (2009), pp. 469â€“477.
J.M. Lappe, D. Travers-Gustafson, K.M. Davies, R.R. Recker and R.P. Heaney, Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial, Am J Clin Nutr 85 (2007), pp. 1586â€“1591.
Barnett, C.M, Beer, T;Prostate Cancer and Vitamin D; what does the evidence really suggest?; Urologic Clinics of North America; Volume 38, Issue 3 , August 2011, Pages 333-342