Tuesday, November 06, 2007

Is taking too much vitamin D dangerous?

This post is courtesy of Ladd McNamara, M.D. and is to emphasize the importance and safety of getting at least 1,000 IU of vitamin D per day.

That's well above the US RDA of 400 IU/day, but that is what you want if you understand the benefits.

Let's start out with some good information, and move on to some really great information:

1. Recent research has shown an association between low blood levels of vitamin D and increased cardiovascular disease risk factors (high blood pressure, diabetes, and high triglycerides).

Source: Prevalence of Cardiovascular Risk Factors and the Serum Levels of 25-Hydroxyvitamin D in the United States: Data From the Third National Health and Nutrition Examination Survey, David Martins; Myles Wolf; Deyu Pan; Ashraf Zadshir; Naureen Tareen; Ravi Thadhani; Arnold Felsenfeld; Barton Levine; Rajnish Mehrotra; Keith Norris, Arch of Intern Med. 2007, Jun 11;167(11):1159

2. There are well over 89 medical studies showing that greater vitamin D blood levels reduce cancers, including cancers of the colon, rectum, breast, and prostate (some cancers are reduced as much as 50%).


Serum 25-hydroxyvitamin D and colon cancer: eight-year prospective study, Garland CF, Comstock GW, Garland FC, Helsing KJ, Shaw EK, Gorham ED, Lancet 1989, Nov 18:2(8673):1176;

Can colon cancer incidence and death rates be reduced with calcium and vitamin D?, Garland CF, Garland FC, Gorham ED, Am J Clin Nutr 1991 Jul; 54(1 Suppl)193S;

Vitamin D and prevention of breast cancer: pooled analysis. J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):708-11, Garland CF, Gorham ED, Mohr SB, et al, J Steroid Biochem Mol Biol 2007 Mar;103(3-5):708;

Vitamin D and prevention of colorectal cancer, Gorham ED, Garland CF, Garland FC, et al, J Steroid Biochem Mol Biol. 2005 Oct;97(1-2):179-94;

Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer, John EM et al, Cancer Res 2005 Jun 15;65(12):5470;

The Role of Vitamin D in Cancer Prevention, Garland et al, Am J Public Health 2006 Feb;96(2):252;

Luminal and humoral influences on human rectal epithelial cytokinetics, Thomas MG, Ann R Coll Surg Engl 1995 Mar;77(2):85.

3. In fact, the studies are numerous and convincing that it is now undeniable to be able to say that the greater one's vitamin D levels the less risk of acquiring cancer of the breast, prostate, colon, esophagus, pancreas, ovary, rectum, bladder, kidney, lung, and uterus, as well as non-Hodgkin's lymphoma and multiple myeloma.


Vitamin D status and breast cancer risk, Colston KW, Lowe LC, Mansi JL, Campbell MJ, Anticancer Res 2006 Jul;26(4A):2573;

Prohibitin is a novel target gene of vitamin D involved in its antiproliferative action in breast cancer cells, Xinjian Peng, Rajeshwari Mehta, Sheng Wang, Srikumar Chellappan and Rajendra G. Mehta, Cancer Res 2006 Jul 15:66(14);7361;

Growth inhibition of carcinogen-transformed MCF-12F breast epithelial cells and hormone-sensitive BT-474 breast cancer cells by 1-hydroxyvitamin D5, Erum A. Hussain-Hakimjee, Xinjian Peng, Rajeshwari R. Mehta, and Rajendra G. Mehta, Carcinogenesis 2006 Mar;27(3):551;

Intakes of Calcium and Vitamin D and Breast Cancer Risk in Women, Lin J, Manson JE, Lee IM, Cook NR, Buring JE, Zhang SM, Arch intern Med 2007 May 28;167(10)1050;

Prostate cancer risk and prediagnostic serum 25-hydroxyvitamin D levels (Finland), Ahonen MH et al, Cancer Causes and Control 2000 Oct;11(9):847;

Exposure to ultraviolet radiation: association with susceptibility and age at presentation with prostate cancer, Luscombe et al, Lancet 2001 Aug 25;358(9282):641;

High-dose weekly oral calcitriol in patients with a rising PSA after prostatectomy or radiation for prostate carcinoma, Beer T, Lemmon D, Lowe B, Henner W, Cancer 2003 Mar 1:97(5):1217;

Effects of vitamin D (calcitriol) on transitional cell carcinoma of the bladder in vitro and in vivo, Konety BR, Lavelle JP, Pirtskalaishvili G, et al, J Urol 2001 Jan:165(1)253

(and about 85 other medical studies that I do not intend to make this the forum to cite).

4a. A ground-breaking double-blind placebo controlled study was published this year in the American Journal of Clnical Nutrition. In this study involving 1,180 postmenopausal women which studied the effects of administering 1,000 IU of vitamin D (with calcium) or a placebo, the researchers found that after ONLY 4 years of taking 1,000 IU of vitamin D the risk of contracting ANY CANCER was reduced by a 60% compared to the placebo group. This was astonishing enough, however, it was about to knock the socks off the researchers.

Source: Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial, Joan M Lappe, Dianne Travers-Gustafson, K Michael Davies, Robert R Recker and Robert P Heaney, Am J Clin Nutr 2007 Jun;85(6):1586

4b. When the researchers excluded the cancers that were diagnosed during the first year of the study, which made sense because that would have included cancers that were already present when the study began (as cancers take a while to grow), a more detailed analysis of the data revealed that 1,000 IU of vitamin D (plus calcium) reduced the risk of ALL CANCERS by a whopping 77% compared to the placebo group!

5. What does this mean? If we as a society were to take 1,000 IU of vitamin D each day (with calcium, let alone any other antioxidants and minerals), as many as three-quarters (or more) of all cancers could be prevented in just four years! The impact of this double-blind, placebo controlled study is so profound that EVERYONE should be taking at least 1,000 IU of vitamin D every day!

6. Even children can benefit from greater levels of vitamin D.


Vitamin D Deficiency, Michael F. Holick, New Engl J Med 2007 Jul 19:357(3):266;

Risk factors for low serum 25-hydroxyvitamin D concentrations in otherwise healthy children and adolescents, Francis L Weng, Justine Shults, Mary B Leonard, Virginia A Stallings and Babette S Zemel , Am J Clin Nutr 2007 Jul;86(1):150

7. Vitamin D has also been shown to suppress inflammation by reducing cytokines (inflammatory molecules). Thus, taking at least 1,000 of vitamin D or more per day would help protect against inflammatory conditions such as rheumatoid arthritis, chronic muscle pain (fibromyalgia), congestive heart failure, diabetes, stroke, and mutliple sclerosis.


Vitamin D: important for prevention of osteoporosis, cardiovascular heart disease, type 1 diabetes, autoimmune diseases, and some cancers, Holick MF, South Med J 2005 Oct;98(10):1024;

Diet, nutrition, and rheumatoid arthritis, Miggiano GA, Gagliardi L, Clin Ter 2005 May;156(3):115;

Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain, Plotnikoff GA, Quigley JM, Mayo Clinic Proc 2003 Dec;78(12):1463;

Dietary Calcium, Vitamin D, and the Prevalence of Metabolic Syndrome in Middle-Aged and Older U.S. Women , Simin Liu, Yiqing Song, Earl S. Ford, JoAnn E. Manson, Julie E. Buring, and Paul M. Ridker, Diabetes Care 2005 Dec;28(12):2926;

Vitamin D supplementation improves cytokine profiles in patients with congestive heart failure: a double-blind, randomized, placebo-controlled trial, Stefanie S Schleithoff, Armin Zittermann, Gero Tenderich, Heiner K Berthold, Peter Stehle, and Reiner Koerfer, Am J Clin Nutr 2006 Apr;83(4):754

8. What About Safety of Vitamin D?

How much is Too Much?

My Doctor Told Me NOT to go above the RDA of 400 IU of vitamin D.

Frankly, most doctors are not aware of the research over the last 20 years showing the 100 of thousands of lives that could be spared just in the U.S. alone if every American took just 1,000 IU of vitamin D per day... (and, we haven't even touched on a full spectrum of the other vitamins, minerals, or antioxidants ...which would naturally push that number up beyond measure.)

So, let's alleviate the safety concern. Is it possible to get too much vitamin D? The answer is YES! But, how much is too much?

Vitamin D status can be assessed by a blood test. BUT DON'T go by reference ranges, because they only compare you to the "normal population," who are DEFICIENT ... you don't want to be in that category. Optimal levels of vitamin D (25-hdroxyvitamin D) should be in the range of 30 - 50 ng/ml (or 75 - 125 nmol/L).

A study was performed to see how much oral vitamin D was required to increase one's vitamin D levels. Taking 1,000 of vitamin D only increases your blood level of vitamin D by 11.5 ng/ml (that's increases it by that much, not establishes it at that level). The bottom line is this: A daily oral intake between 1,000 to 4,000 IU of vitamin D (depending upon your baseline vitamin D blood levels) is ideal.

9. Vitamin D toxicity does not occur until blood levels reach 150 ng/ml or more; which would generally take an oral dose of 50,000 IU per day! Therefore, doses up to 10,000 IU of vitamin D per day would appear to be safe, and certainly half that much (5,000 IU per day) would absolutely be safe!

Source: Vitamin D Deficiency, Michael F. Holick, N Eng J Med 2007 Jul 19;357(3)266

To make it clear: In order to achieve an optimal serum blood level of vitamin D of approximately 60 ng/ml, a 154 pound (70 kg) person with a baseline vitamin D level of 20 ng/ml would have to take 5,000 of vitamin D to increase their blood levels to the desired levels of 60 ng/ml.

10. The authors of a review study in the July 19, 2007 edition of the New England Journal of Medicine calculate the rates of various diseases affected by vitamin D status and have come up with the following numbers:

a) 78% Reduction in Type I diabetes in children taking 2,000 IU/day of vitamin D in their FIRST YEAR of life.

b) 200% Increase in Type I diabetes in Vitamin D-deficient children

c) 33% reduction in Type II diabetes in those taking 800 IU/day plus calcium

d) 72% reduction in number of falls in elderly people taking high-dose vitamin D (that's well over 1,000 IU/day)

e) 30-50% more cancers in vitamin D-deficient people

f) 42% reduction in multiple sclerosis in women taking MORE than 400 IU/day of vitamin D

The article goes on to state:

1. Human diets do NOT provide sufficient vitamin D
2. Minimum vitamin D blood levels needed to reduce disease risk are 30 ng/ml (and as stated above optimal levels are 60 ng/ml).

The authors then go on to point out that the US government recommendations of 200 IU/day for children, 400 IU/day for adults, and 600 IU/day for those over 70 years old are horribly outdated.

Source: Vitamin D Deficiency, Michael F. Holick, N Eng J Med 2007 Jul 19;357(3)266


The evidence is clear. Vitamin D is both safe and effective in reducing the risk of many chronic degenerative diseases. The old governmental recommendations are outdated. Everyone should be getting at least 1,000 IU/day of vitamin D. Vitamin D, taken up to 5,000 IU/day is safe, and should be safe even up to 10,000 IU/day. However, if one is going to be taking more than 5,000 IU/day it would be prudent to follow blood tests to aim for the optimal blood level of 60 ng/ml. (Toxicity does not occur until blood levels reach 150 ng/ml ... so the range of safety is wide.)

There is much too much TRUE HEALTH to be obtained from taking optimal levels of vitamin D, along with a full spectrum of nutrients, along with a proper diet and a healthy lifestyle.

I hope this has been a help to those who have been worried, or told not to take more than 400 IU/day! Frankly, your health depends upon you being informed that you must take more than that!

Thanks and good health,

Ladd McNamara, M.D.

Source: Ladd McNamara, M.D. - expert in nutraceutical and anti-aging medicine, Ladd McNamara blog, www.laddmcnamara.com