Vitamin D and Its Benefits



A groundbreaking study was conducted in Nebraska on 403 postmenopausal women over a period of 4 years.  The researchers reported that the women who received 1,100 IU of vitamin D and 1,000 mg of calcium per day for 4 years reduced their risk of developing cancer of any kind by 60% compared to those women who received a placebo.

During the first year of the study, some women developed cancer, and the researchers theorized that their cancers likely had been developing before the launch of the study.  When they adjusted the statistics, removing the first year of the study, the results were even more dramatic.  Those postmenopausal women taking calcium and vitamin D had a reduced risk of any kind of cancer of 77%. 

Another finding of the same study indicated that for every 10 ng/ml increase in blood levels of vitamin D, the relative risk of cancer dropped by 35%.  Increasing blood levels of vitamin D can be easily done—Michael Holick, M.D., Ph.D., has indicated that 1,000 IU of vitamin D per day, taken for several months, raises the blood level by 10 ng/ml.

However, be warned that too much vitamin D may have the opposite effect, according to a large cross-sectional study published online in the American Journal of Cardiology[24]. The critical threshold appears to be a serum 25-hydroxyvitamin D concentration of 21 ng/mL — more than that level increases C-reactive protein (CRP), a biomarker for cardiovascular disease, but lower serum concentrations of 25-hydroxyvitamin D lower CRP levels, reported Muhammad Amer, MD, and Rehan Qayyum, MD, MHS, from Johns Hopkins University School of Medicine.


What is Vitamin D?


Vitamin D is not actually a vitamin.  By definition, a vitamin is a substance that is essential to human health but cannot be produced by the body.  Vitamin D is essential to the metabolism of calcium and phosphorous in the body.  However it is also produced by our bodies when we are exposed to UVB rays of the sun.

When the skin is exposed to the sun, the UVB light in the sun converts a form of cholesterol in the skin called
7-dehydrocholesterol into pre-vitamin D3.  The pre-vitamin D3 immediately converts into vitamin D3.  This is the vitamin D that circulates through the body, but it still is not empowered into its activated form.  In liver, vitamin D3 undergoes a process (hydroxylation), turning it into 25D (i.e., Calcidiol)  to store in your body.  In your kidneys, 25D is further converted into 1,25 D3, which is the active and potent form of vitamin D.  Its job is to circulate in your blood to ensure that you maintain appropriate levels of calcium.  This function of 1,25 D3 is vital to your health—so much so that scientists did not expect it to have other functions until recently.

In 1998, vitamin D researcher Michael Holick, M.D., Ph.D., and his colleagues discovered that the kidneys were not the only place in the body where 25D was metabolized into the potent and vital substance 1,25 D
3.  Most tissues and cells of the body have receptors for vitamin D and the ability to metabolize 25D from the liver and turn it into 1,25 D3.  This means that vitamin D circulates throughout the body and has the ability to land and affect the cells, tissues, and organs that receive the vitamin D.  

To recap, Vitamin D receptors (VDR) are found from most tissues and organs of the body[26]:


How Might Vitamin D Affect Cancer?
 
   
In its activated form (1,25D3 or calcitriol), vitamin D is a steroid hormone.  It is fat soluble and can pass through cell membranes to bind to the vitamin D receptors.    It is a powerful steroid hormone in the body, and it regulates gene expression by being able to affect approximately 200 genes in the body.

Dr. Lappe and colleagues indicated that the way vitamin D may protect against cancer is still being defined, but the current understanding shows that high levels of vitamin D may enhance the regulation of
apoptosis, cell differentiation, and cell proliferation

Based on many retrospective and/or epidemiological studies, vitamin D has been linked to the reduction of risk of 17 different types of cancer
[1,4,7-13]:
  1. colon
  2. breast[5]
  3. prostate
  4. bladder
  5. esophageal
  6. gastric
  7. ovarian
  8. rectal
  9. renal
  10. uterine
  11. cervical
  12. gall bladder
  13. laryngeal
  14. oral
  15. pancreatic
  16. and non-Hodgkin's and Hodgkin's lymphomas
Ward Off Alzheimer's[2]

In addition to fighting cancer, recent studies also suggest that upping vitamin D intake will help ward off dementia[21,22] and other factors, such as depression and cardiovascular disease[14-20], associated with dementia. 

A recent major study of 3,325 Americans over age 65 showed that being "deficient" in vitamin D raised the odds of cognitive impairment 42%, and being "severely deficient" boosted the odds 394%!  Those with the highest blood levels of vitamin D had the lowest risk.  The most exciting evidence for how vitamin D might fight Alzheimer's comes from another groundbreaking research at UCLA.  It shows that vitamin D improves the ability of the immune system's cleanup crews to go into the brain and remove bits of beta-amyloid, sticky deposits blamed for Alzheimer's destruction of neurons.  It's a big deal, since experts believe that removing the toxin should help prevent brain cell injury and death, thereby slowing Alzheimer's.

Vitamin D Deficiency

The dark skin of people indigenous to southern India, Africa, and other tropical regions protects against excessive UV light exposure from the sun. On the other hand, dark skin interferes with the formation of vitamin D in the skin, which requires UV light. Thus, dark-skinned people in northern latitudes are often vitamin D-deficient.


Two Types of Vitamin D Supplements

There are two main types of vitamin D supplements:
  1. Vitamin D2 (also known as ergocalciferol)
  2. Vitamin D3 (also known as cholecalciferol)
Research has shown that vitamin D2 is less effective in raising human vitamin D levels than vitamin D3.  Vitamin D3 is naturally produced in humans and animals when sunlight hits the skin, fur or feathers.  It is the raw material from which all potent forms of vitamin D are produced in the body.  It is also known that vitamin D3 is generally considered safer than vitamin D2, which has more reported cases of overdose or toxicity.

In his recent book The
UV Advantage, vitamin D researcher Dr. Michael Holick said, "Can you imagine what would happen if one of the drug companies came out with a single pill that reduced the risk of cancer, heart attack, stroke, osteoporosis, PMS, seasonal affective disorder, and various autoimmune disorders[25]?  These would be a media frenzy the likes of which has never been seen in response to a medical breakthrough!"  Such a pill exists!  It is called vitamin D. 

Try
Citracal which provides 630 mg Calcium Citrate and 500 IU Vitamin D3 per serving (i.e., 2 caplets).  Harvard Medical School researcher Eric Rimm, ScD, offers this rule of thumb: each 100 IU of vitamin D per day increases blood levels by 1 ng/mL; a blood level over 21 ng/mL is excessive[24].  If you decide to take high dosage of vitamin D and calcium, please consult with your doctor first especially when you have other health complications such as kidney stone problem.


References

  1. The Vitamin D Revolution by Soram Khalsa, M.D.
  2. 100 Simple Things You Can Do to Prevent Alzheimer's by Jean Carper
  3. Building Strong Bones
  4. Colon Cancer and Its Prevention
  5. Breast and Prostate Cancer News
  6. The UV Advantage by Michael Holic, MD
  7. Giovannucci E ,Liu Y ,Rimm EB ,Hollis BW ,Fuchs CS ,Stampfer MJ ,Willett WC (2006) J Natl Cancer Inst 98:451–459.
  8. Garland CF ,Garland FC ,Gorham ED ,Lipkin M ,Newmark H ,Mohr SB ,Holick MF (2006) Am J Public Health 96:252–261.
  9. Skinner H ,Michaud D ,Giovannucci E ,Willett W ,Colditz G ,Fuchs C (2006) Cancer Epidemiol Biomarkers Prev 15:1688–1695.
  10. Gorham ED ,Garland CF ,Garland FC ,Grant WB ,Mohr SB ,Lipkin M ,Newmark HL ,Giovannucci E ,Wei M ,Holick MF (2005) J Steroid Biochem Mol Biol 97:179–194.
  11. Grant WB (2006) Prog Biophys Mol Biol 92:65–79.
  12. Grant WB ,Garland CF (2006) Anticancer Res 26:2687–2699.
  13. van der Rhee HJ ,de Vries E ,Coebergh JW (2006) Eur J Cancer 42:2222–2232.
  14. Heaney RP (2006) Am J Clin Nutr 84:471–472.
  15. Holick MF (2004) Am J Clin Nutr 80:1678S–1688S.
  16. Cantorna MT ,Mahon BD (2004) Exp Biol Med (Maywood, NJ) 229:1136–1142.
  17. Pittas AG ,Dawson-Hughes B ,Li T ,Van Dam RM ,Willett WC ,Manson JE ,Hu FB (2006) Diabetes Care 29:650–656.
  18. Zittermann A (2006) Prog Biophys Mol Biol 92:39–48.
  19. Munger KL ,Zhang SM ,O'Reilly E ,Hernan MA ,Olek MJ ,Willett WC ,Ascherio A (2004) Neurology 62:60–65.
  20. Luong KV ,Nguyen LT (2006) Curr Med Chem 13:2443–2447. 
  21. Kalueff AV ,Tuohimaa P (2006) Curr Opin Clin Nutr Metab Care.
  22. Mackay-Sim A ,Feron F ,Eyles D ,Burne T ,McGrath J (2004) Int Rev Neurobiol 59:351–380. 
  23. 維他命D對孕婦的重要性
  24. Vitamin D: Too Much May Erase Heart Benefit
  25. Extra Vitamin D May Ease Crohn's Symptoms
  26. Vitamin D in pregnancy, birth and later life - Dr Elina Hypponen (Video)
  27. Vitamin D Deficiency (NEJM)
  28. Vitamin D Heart Risk Mediated by Race
    • The risks and benefits of vitamin D supplementation should be evaluated carefully across race and ethnicity.

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