Posted by Phillipa on October 19, 2008, at 12:23:38
In reply to quite vitamin D deficient, strange results, posted by iforgotmypassword on October 19, 2008, at 0:42:15
One study no mention of psychosis? Phillipa
Vitamin D3
Its Critical Role in Overall Health
By Jason Barker, ND
Weve come a long way in our understanding of the importance of vitamin D in health. It was only 40 years ago that scientists reasoned that vitamin D was necessary for bone health, and no other aspects of proper physiologic function. It was correctly assumed that a lack of vitamin D led to the bone condition osteomalacia, or softening of the bones in adults and presented as rickets (bowing of the legs) in children. And like much of the Recommended Daily Allowances (RDA) of the day, amounts of vitamins were based on prevention of outward disease conditions, rather than on optimal health. For instance, the RDA in 1963 for vitamin D was 400 IU for children and half that for adultsamounts shown to be just enough for prevention of osteomalacia and rickets.1 Only in the last several years has our understanding of the importance of vitamin D in other areas of health come to light.Vitamin D is made in our bodies after skin is exposed to sunlight. However, the latest medical dogma that sun exposure will cause skin cancer has caused many people to slather on the sunscreen when outdoors prior to receiving any sun exposure. This fact, along with busy work schedules that prevent us from emerging outdoors in the middle of the day, has created a widespread vitamin D deficiency linked to various forms of cancer, high blood pressure, poor blood sugar control and impaired immunity.
In this article, I will discuss a number of ways vitamin D (especially vitamin D3) is crucial to good health, emphasizing the importance of why sun-challenged individuals should consider supplementation with this important vitamin.
Vitamin D: Important Facts
When one refers to vitamin D, we must acknowledge its two main supplemental forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).Ergocalciferol can be obtained from plant sources while cholecalciferol is the form primarily synthesized in the skin by absorbing light energy from UVB rays. Vitamin D3 is considered to be the more bioavailable form of the vitamin and is the preferred form when supplementing.
Both vitamin D2 and D3 may be considered prohormones and do not have any intrinsic biological activitythey must undergo further metabolism in the liver and kidney before becoming the final active form 1,25 dihydroxycholecalciferol. The true name of Vitamin D is calciferol.
Vitamin D is not a true vitamin. Under normal circumstances, it is manufactured in the body and is not required in the diet (given adequate sun exposure at the correct intensity); its mechanism of action and structure closely resemble that of a steroid hormone.
The action for which vitamin D is best known is regulation of calcium and phosphorus concentrations in the serum. Vitamin D enhances the absorption of these two minerals in the small intestine; if dietary intake of calcium falls below adequate levels, calciferol (vitamin D) in conjunction with parathyroid hormone will mobilize calcium stores from the bones into the serum.
Possible Consequences of Vitamin D Deficiency
Vitamin D Deficiency has Been Linked to:Various forms of cancer including breast, prostate and colon cancer
Fractures
Hypertension
Heart Disease
Pain and Muscle Aches
High CRP Levels
Insulin Resistance
Decreased immunity and lowered resistance to influenza and viruses
Osteoporosis and osteomalacia
Depression
Seasonal Affective Disorder (SAD)
Lifestyle Induced Vitamin D Deficiency
Vitamin D occurs freely in relatively few foods; based on this fact and the skin-synthesis model, one must assume that this natural process instilled within the body is the preferred way for humans to obtain vitamin D from sun-stimulated conversion in the skin. While the human body is incredibly efficient at creating vitamin D from sun exposure (it is estimated that full-body exposure for a few hours will create 10,000 IU),2-3 it also has excellent control in limiting the creation of potentially toxic amounts of the vitamin as prolonged exposure also results in photodegradation of vitamin D produced in the skin.4However, many factors have compounded the irrelevance of sun exposure as a source of vitamin D. Centuries ago, humans moved northward into cold, sun-limited climates, the majority of us spend most if not all of our days inside, and clothing covers 95 percent of our skin. Even (now fortified) dietary sources are proving inadequate to offset our lack of vitamin D production. One eight-ounce glass of milk contains only 100 IU vitamin D while other dairy products have little or none of this crucial vitamin added. Cereal has 40-100 IU in each serving.5 Salmon, sardines and mackerel contain roughly 200-360 IU vitamin D per 3.5 ounce serving.6
This leaves strict vegetarians and lactose intolerant people at a disadvantage, while the elderly (inefficient conversion), the obese and dark-skinned people (additional melanin) have additional challenges producing Vitamin D.7-8 It appears now that even infants and toddlers are at risk for vitamin D deficiency. A newly released study found that 12 percent of otherwise healthy infants and toddlers in the Boston area were vitamin D deficient and 40 percent of those children had vitamin D levels that were defined as suboptimal, meaning they were at risk for rickets.9
Colon, Breast and Prostate Health
Approximately 5,000 research papers have been written about vitamin D in the last 40 years; only recently have we begun to appreciate vitamin Ds influence on health. Epidemiologic studies are showing that cancer survival rates are lower when diagnosis occurs in months of lower vitamin D levels suggesting a protective role of the vitamin against cancer growth and development.10Research into vitamin D is being conducted on approximately 17 different kinds of cancer, the main forms being breast, prostate and colon. Research is revealing that vitamin D may stop the initiation of cancer and that treatment outcomes may be influenced by vitamin D. A recent review article estimates that 50,000 to 70,000 Americans may die prematurely from cancers due to inadequate vitamin D intake.11
Vitamin D is thought to influence cancer outcomes through several mechanisms: it promotes cell differentiation, regulates programmed cellular death (apoptosis), limits metatastic spread of cancers and growth of tumor blood supplies (angiogenesis).12
Precancerous growths (adenomatous polyps) are a colon cancer precursor that are also associated with low vitamin D and calcium intake; a recent trial showed that these polyps tend to recur more frequently in people with lower vitamin D and calcium intakes.13 Another study showed that vitamin D level at the time of colorectal cancer diagnosis had an effect on survival; lower levels were associated with poorer cancer outcomes.14 Vitamin D intake of 1,000 IU or more each day correlated with a 50 percent reduced risk of developing colorectal cancer.15
Researchers also have studied the relationship between breast cancer and vitamin D and calcium intake. Women with more dense tissue revealed on mammography (which is a stronger risk factor for breast cancer) had lower intakes of vitamin D and calcium.16 Increased amounts of vitamin D and calcium apparently affect breast tissue composition. In this particular study, women with less dense mammography had a daily intake of only 100 IU vitamin D and 750 milligrams (or more) of calcium. In the Nurses Health Study, investigators showed that over time, women with higher levels of vitamin D in their blood had a lower risk of breast cancer, and this association was stronger in women 60 years or older.17
In prostate cancer, vitamin D enhances the differentiation of new cells (poorly differentiated cells are a cancer harbinger) while it slows the ability of the cancer to proliferate, invade and spread.18 Another study showed that men without prostate cancer enjoyed more time in the sun and thus had a 50 percent decreased risk of prostate cancer compared to those who spent relatively little time in the sun. This was related to the observation that sun exposure increased synthesis of vitamin D, exerting the observed protective effect.19 In men with prostate cancer, the prostate-specific antigen (PSA -a prostate cancer marker in the blood) is followed as an indirect way to monitor cancer growth. Men who were supplemented with vitamin D had a 75 percent lengthened doubling time of their PSA, meaning that cancer growth was greatly slowed.20
Widespread Role in Health
Studies show a link between moderate sun exposure or vitamin D levels and benefits to bone health, multiple sclerosis, heart health in people with hypertension, and overall mortality.21Vitamin D deficiency is also correlated with elevated blood pressure, and vitamin D (along with calcium) can significantly lower systolic blood pressure.22-23 It is thought that these effects are carried out by vitamin Ds ability to influence the blood pressure-related hormone renin.24
C-reactive protein is an indirect measurement of general inflammation in the body and elevated levels can be associated with conditions such as heart disease. Vitamin D has been shown to have potent CRP-reducing effects.25
Another way vitamin D can influence health is through its blood-sugar-stabilizing effects. Diabetes occurs more frequently in people with lower vitamin D levels and vitamin D supplementation helps to reduce blood sugar and increase insulin sensitivity.26-27
Vitamin D may also have an effect on immune function. It is hypothesized that influenza is in part related to overall lower levels of vitamin D in the colder times of year, and this may predispose more people to the flu and other winter illnesses.28
Conclusion
Having vitamin D levels measured and monitored is important since excessively high levels are counterproductive to good health. Testing should be carried out under medical supervision.From this brief review of vitamin D, it is apparent that optimization of vitamin D levels is of paramount importance for a number of health conditions. Since sunscreen can interfere with the bodys ability to make vitamin D and since outdoor time is often limited even at this time of year, supplementation can ensure that the body achieves its optimal level of wellness.
References
1. Park EA. The therapy of rickets. JAMA.1940;115(5):370-9.
2. Shearer MJ. The roles of vitamins D and K in bone health and osteoporosis prevention. Proc Nutr Sci. 1997;56:915-37.
3. Gesensway D. Vitamin D and sunshine. Ann Int Med. 2000;133:319-20.
4. Holick MF. Sunlight and vitamin D: both good for cardiovascular health. J Gen Intern Med. 2002;17:733-5.
5. Holick MF, Shao Q, Liu WW, Chen TC. The vitamin D content of fortified milk and infant formula. N Engl J Med. 1992 Apr 30;326(18):1178-81.
6. Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc. 2006 Mar;81(3):353-73.
7. Zadshir A, Tareen N, Pan D, Norris K, Martins D. The prevalence of hypovitaminosis D among US adults: data from the NHANES III. Ethn Dis. 2005;15(4 Suppl 5):S5-101.
8. Wortsman J, Matsuoka LY, Chen TC, Lu Z, Holick MF. Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr. 2000 Sep;72(3):690-3.
9. Gordon CM, Feldman HA, Sinclair L, et al. Prevalence of Vitamin D Deficiency Among Healthy Infants and Toddlers. Archives of Paediatric Medicine. June 2008, Vol 162, No. 6.
10. Porojnicu AC, Dahlback A, Moan J. Sun exposure and cancer survival in Norway: changes in the risk of death with season of diagnosis and latitude. Adv Exp Med Biol. 2008;624:43-54.
11. Grant WB, Holick MF. Benefits and requirements of vitamin D for optimal health: a review. Altern Med Rev. 2005 Jun; 10(2):94-111.
12. van den Bemd GJ, Chang GT. Vitamin D and vitamin D analogs in cancer treatment. Curr Drug Targets. 2002 Feb;3(1):85-94.
13. Hartman TJ, Albert PS, Snyder K, et al. The association of calcium and vitamin D with risk of colorectal adenomas. J Nutr. 2005 Feb;135(2):252-9.
14. Giovannucci E. The epidemiology of vitamin D and colorectal cancer: recent findings. Curr Opin Gastroenterol. 2006 Jan;22(1):24-9.
15. Gorham ED, Garland CF, Garland FC, et al. Vitamin D and prevention of colorectal cancer. J Steroid Biochem Mol Biol. 2005 Oct;97(1-2):179-94.
16. Berube S, Diorio C, Verhoek-Oftedahl W, Brisson J. Vitamin D, calcium, and mammographic breast densities. Cancer Epidemiol Biomarkers Prev. 2004 Sep;13(9):1466-72.
17. Bertone-Johnson ER, Chen WY, Holick MF, et al. Plasma 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D and risk of breast cancer. Cancer Epidemiol Biomarkers Prev. 2005 Aug;14(8):1991-7.
18. Lou YR, Qiao S, Talonpoika R, Syvala H, Tuohimaa P. The role of Vitamin D3 metabolism in prostate cancer. J Steroid Biochem Mol Biol. 2004 Nov;92(4):317-25.
19. John EM, Schwartz GG, Koo J, Van Den BD, Ingles SA. Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer. Cancer Res. 2005 Jun 15;65(12):5470-9.
20. Woo TC, 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.
21. Moan J, et al Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure Proceedings of the National Academy of Sciences 2008; 05: 668-673.
22. Pfeifer M, Begerow B, Minne HW, Nachtigall D, Hansen C. Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women. J Clin Endocrinol Metab. 2001 Apr;86(4):1633-7.
23. Lind L, Hanni A, Lithell H, et al. Vitamin D is related to blood pressure and other cardiovascular risk factors in middle-aged men. Am J Hypertens. 1995 Sep;8(9):894-901.
24. Li YC. Vitamin D regulation of the renin-angiotensin system. J Cell Biochem. 2003 Feb 1;88(2):327-31.
25. Timms PM, Mannan N, Hitman GA, et al. Circulating MMP9, vitamin D and variation in the TIMP-1 response with VDR genotype: mechanisms for inflammatory damage in chronic disorders? QJM. 2002 Dec;95(12):787-96.
26. Martins D, Wolf M, Pan D, et al. 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. Arch Intern Med. 2007 Jun 11;167(11):1159-65.
27. Zittermann A. Vitamin D and disease prevention with special reference to cardiovascular disease. Prog Biophys Mol Biol. 2006 Sep;92(1):39-48.
28. Cannell JJ, Vieth R, Umhau JC, et al. Epidemic influenza and vitamin D. Epidemiol Infect. 2006
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thread:858207
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