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"Elimistö säätelee nesteidensä kalsiumin pitoisuutta tarkasti, sillä kalsium osallistuu lukuisin tärkeisiin aineenvaihdunnan tapahtumiin. Säätelyyn osallistuvat kilpirauhasen pinnalla sijaitsevat pienet lisäkilpirauhaset (ks. kuva «Lisäkilpirauhaset» 1) ja D-vitamiini. Ravinnon kalsiumin määrä ei merkittävästi vaikuta veren kalsiumarvoihin (ks. «Kalsium (P-Ca ja P-Ca-ion)» 1), vaikka sillä on tärkeä osuus luun lujuuden kehittymisessä."

D-vitamiinin turvallisuutta tarkasteltaessa pitää huomioida ainakin seuraavat kaksi asiaa: 1) Nykyiset saantisuositukset ja turvallisuurajat ovat aivan liian pieniä, kts. Viethin tutkimukset ja esim. Merckin manuaalista "Vitamin D toxicity". 2) On olemassa näyttöä siitä, että nykyisenkaltaisten suositusten seuraaminen voi altistaa tietyille kroonisille taudeille monia yksilöitä, joiden auringonvalon saanti on syystä tai toisesta rajoitettu (talvisaika 40 leveyasteiden ulkopuolella, liian peittävä vaatetus (musliminaiset) jne..). Tällaisia tauteja ovat mm. tyypin 1 diabetes, multippeli skleroosi ja muut autoimmuunisairaudet, monet syövät (eturauhassyövästä on aika hyvää näyttöä), reuma, osteoporoosi, korkea verenpaine, kaamosmasennus, jne .... Jättiannokset ovat myrkyllisiä, mutta liian vähäinen saantikin voi olla huomattava turvallisuusriski.

"June 29, 2009 | Shelley Wood Boston, MA - A massive, National Institutes of Health-sponsored study looking at whether vitamin-D and/or omega-3 fatty-acid supplementation can reduce the risk of developing heart disease, stroke, or cancer will get under way in January 2010, according to a website for the study. Drs JoAnn Manson and Julie Buring (Harvard Medical School/ Brigham and Women's Hospital, Boston, MA) will head up the Vitamin D and Omega-3 Trial (VITAL). The study is aiming to enroll 20 000 men and women, one-quarter of whom will be black. According to a Brigham and Women's Hospital press release, the study is intentionally aiming to illuminate a potential racial and ethnic disparity hypothesized to be linked to vitamin D [1]. "African Americans have a higher risk of vitamin-D deficiency as well as a greater frequency of diabetes, hypertension, and certain types of cancer," a press release notes. For VITAL, women need to be over age 65 to enter the study; men need to be over age 60. Study participants will be randomized to one of four groups: daily vitamin D (2000 IU) and fish oil (1 g); daily vitamin D and fish-oil placebo; daily vitamin-D placebo and fish oil; or daily vitamin-D placebo and fish-oil placebo. The trial will run for five years and is expected to cost US $20 million."

A positive dose-response effect of vitamin D supplementation on site-specific bone mineral augmentation in adolescent girls: a double-blinded randomized placebo-controlled 1-year intervention. Viljakainen HT, Natri AM, Kärkkäinen M, Huttunen MM, Palssa A, Jakobsen J, Cashman KD, Mølgaard C, Lamberg-Allardt C. J Bone Miner Res. 2006 Jun;21(6):836-44. PMID: 16753014 doi: 10.1359/jbmr.060302 We conclude that the current vitamin D recommendation for adolescent girls, at least in the northern latitudes, is too low to ensure sufficient vitamin D status during winter. Intake of vitamin D at rates of 10-15 μg/day aids to maintain stable S-25(OH)D concentrations during winter. Vitamin D induced BMC augmentation by decreasing bone resorption, but not affecting bone formation, which was reflected by the biochemical markers of bone turnover. Optimizing bone mineral gain in adolescence is crucial to the prevention of osteoporosis later in life. Increasing vitamin D intake to 10-15 μg/day aids in attaining this goal.

An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates. Grant WB. Cancer. 2002 Jan 1;94(1):272-81. PMID: 11815987 CONCLUSIONS It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.

Vitamin D deficiency is the cause of common obesity. Foss YJ. Med Hypotheses. 2009 Mar;72(3):314-21. Epub 2008 Dec 2. PMID: 19054627 doi:10.1016/j.mehy.2008.10.005

Vitamin D: In the evolution of human skin colour. Yuen AW, Jablonski NG. Med Hypotheses. 2009 Aug 28. [Epub ahead of print] PMID: 19717244

Comment: Although lower risk associated with vitamin D exposure was shown most consistently for ER+/PR+ tumors, the result might simply reflect that this tumor subtype was the most common. Nonetheless, these findings support vitamin D's beneficial effects on breast cancer risk, regardless of hormone-receptor status. Sun exposure and dietary intake (Table 1) are key sources of vitamin D.

Environmental risk factors for autism: Do they help cause de novo genetic mutations that contribute to the disorder? Kinney DK, Barch DH, Chayka B, Napoleon S, Munir KM. Med Hypotheses. 2009 Aug 20. [Epub ahead of print] PMID: 19699591

Vitamin D and multiple sclerosis. Hayes CE, Cantorna MT, DeLuca HF. Proc Soc Exp Biol Med. 1997 Oct;216(1):21-7. Review. PMID: 9316607

Vitamin D treatment in multiple sclerosis. Myhr KM. J Neurol Sci. 2009 Jun 22. [Epub ahead of print] PMID: 19549608 doi:10.1016/j.jns.2009.05.002 Epidemiological evidence combined with clinical and laboratory analyses, and experimental animal models, suggest a possible influence of vitamin D on MS susceptibility as well as clinical disease activity. Supplement with vitamin D may reduce the risk of developing MS. An intervention may also reduce the risk of conversion from a first clinical event suggestive of MS to clinical definite MS, as well as reduce the relapse rate among patients with relapsing remitting MS. More studies are, however, needed to determine optimal dose and serum level for vitamin D, as well as target populations and optimal timing for intervention.

Vitamin D, nervous system and aging. Tuohimaa P, Keisala T, Minasyan A, Cachat J, Kalueff A. Psychoneuroendocrinology. 2009 Aug 4. [Epub ahead of print] PMID: 19660871

Serum levels of vitamin D metabolites and breast cancer risk in the prostate, lung, colorectal, and ovarian cancer screening trial. Freedman DM, Chang SC, Falk RT, Purdue MP, Huang WY, McCarty CA, Hollis BW, Graubard BI, Berg CD, Ziegler RG. Cancer Epidemiol Biomarkers Prev. 2008 Apr;17(4):889-94. Epub 2008 Apr 1. PMID: 18381472 doi: 10.1158/1055-9965.EPI-07-2594 In this prospective study of postmenopausal women, we did not observe an inverse association between circulating 25(OH)D or 1,25(OH)2D and breast cancer risk, although we cannot exclude an association in younger women or with long-term or earlier exposure

Dairy and bone health. Heaney RP. J Am Coll Nutr. 2009 Feb;28 Suppl 1:82S-90S. PMID: 19571166

Calcidiol and prostate cancer. Tuohimaa P, Golovko O, Kalueff A, Nazarova N, Qiao S, Syvälä H, Talonpoika R, Lou YR. J Steroid Biochem Mol Biol. 2005 Feb;93(2-5):183-90. Epub 2005 Jan 22. Review. PMID: 15860261

Vitamin D intoxication associated with an over-the-counter supplement. Koutkia P, Chen TC, Holick MF. N Engl J Med. 2001 Jul 5;345(1):66-7. PMID: 11439958

Vitamin D's days of obscurity seem pretty much over. Once just an afterthought to most people-relegated to the sides of milk cartons and the pages of medical texts-it's now on the cusp of becoming a full-fledged disease prevention star. Although vitamin D has long been known as an important factor in bone health, a quickly growing body of evidence now shows that it may also help lower the risk of cancer, heart disease, and even premature death.[1], [2] Not surprisingly, scientists and the public have started to take note, particularly of vitamin D's potential to protect against cancer

Use of vitamin D in clinical practice. Cannell JJ, Hollis BW. Altern Med Rev. 2008 Mar;13(1):6-20. PMID: 18377099 The recent discovery--from a meta-analysis of 18 randomized controlled trials--that supplemental cholecalciferol (vitamin D) significantly reduces all-cause mortality emphasizes the medical, ethical, and legal implications of promptly diagnosing and adequately treating vitamin D deficiency. Not only are such deficiencies common, and probably the rule, vitamin D deficiency is implicated in most of the diseases of civilization. Vitamin D's final metabolic product is a potent, pleiotropic, repair and maintenance, seco-steroid hormone that targets more than 200 human genes in a wide variety of tissues, meaning it has as many mechanisms of action as genes it targets. One of the most important genes vitamin D up-regulates is for cathelicidin, a naturally occurring broad-spectrum antibiotic. Natural vitamin D levels, those found in humans living in a sun-rich environment, are between 40-70 ng per ml, levels obtained by few modern humans. Assessing serum 25-hydroxy-vitamin D (25(OH)D) is the only way to make the diagnosis and to assure treatment is adequate and safe. Three treatment modalities exist for vitamin D deficiency: sunlight, artificial ultraviolet B (UVB) radiation, and vitamin D3 supplementation. Treatment of vitamin D deficiency in otherwise healthy patients with 2,000-7,000 IU vitamin D per day should be sufficient to maintain year-round 25(OH)D levels between 40-70 ng per mL. In those with serious illnesses associated with vitamin D deficiency, such as cancer, heart disease, multiple sclerosis, diabetes, autism, and a host of other illnesses, doses should be sufficient to maintain year-round 25(OH)D levels between 55 -70 ng per mL. Vitamin D-deficient patients with serious illness should not only be supplemented more aggressively than the well, they should have more frequent monitoring of serum 25(OH)D and serum calcium. Vitamin D should always be

An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?\nLu Z, Chen TC, Zhang A, Persons KS, Kohn N, Berkowitz R, Martinello S, Holick MF.\nJ Steroid Biochem Mol Biol. 2007 Mar;103(3-5):642-4. Epub 2007 Jan 30.\nPMID: 17267210 \ndoi:10.1016/j.jsbmb.2006.12.010 \n

The same annual dose of 292 000 IU of vitamin D(3) (cholecalciferol) on either daily or four monthly basis for elderly women: 1-year comparative study of the effects on serum 25(OH)D(3) concentrations and renal function. Pekkarinen T, Välimäki VV, Aarum S, Turpeinen U, Hämäläinen E, Löyttyniemi E, Välimäki MJ. Clin Endocrinol (Oxf). 2009 May 25. [Epub ahead of print] PMID: 19486025 DOI: 10.1111/j.1365-2265.2009.03637.x