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Matti Narkia

Improved Cholecalciferol Nutrition in Rats Is Noncalcemic, Suppresses Parathyroid Hormo... - 0 views

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    Improved cholecalciferol nutrition in rats is noncalcemic, suppresses parathyroid hormone and increases responsiveness to 1, 25-dihydroxycholecalciferol.
    Vieth R, Milojevic S, Peltekova V.
    J Nutr. 2000 Mar;130(3):578-84.
    PMID: 10702588

    We conclude suppression of 1,25(OH)(2)D and PTH, and higher renal VDR mRNA and 24-hydroxylase did not involve higher free 1,25(OH)(2)D concentration or a first pass effect at the gut. Thus, 25(OH)D or a metabolite other than 1,25(OH)(2)D is a physiological, transcriptionally and biochemically active, noncalcemic vitamin D metabolite.

    When viewed from a perspective that starts with higher vitamin D nutrition, the results indicate that low vitamin D nutrition may bring about a form of resistance to 1,25(OH)2D. This situation would explain why, in humans, nutritional rickets and osteomalacia are commonly associated with normal or increased levels of 1,25(OH)2D (Chesney et al. 1981Citation , Eastwood et al. 1979Citation , Garabedian et al. 1983Citation ,Rasmussen et al. 1980Citation )-these are not like the low hormone levels associated with any other endocrine-deficiency disorder. A connection between lower vitamin D nutrition and vitamin D resistance helps to explain why the supposedly inactive compound 25(OH)D is more relevant in diagnosing nutritional rickets than is the active hormone 1,25(OH)2D.

    If the features of improved vitamin D nutrition shown here were demonstrated for any newly synthesized compound, the compound would be classified as a noncalcemic 1,25(OH)2D analogue (Brown et al. 1989Citation , Finch et al. 1999Citation , Goff et al. 1993Citation , Koshizuka et al. 1999Citation ). Thus, we contend that 25(OH)D or a metabolite of it other than 1,25(OH)2D exists as a physiological and biologically-active noncalcemic vitamin D metabolite whose effects require further examination, particularly in relationship to studies involving the synthetic analogs of 1,25(OH)2D.
Matti Narkia

NEJM -- Calcium plus Vitamin D Supplementation and the Risk of Colorectal Cancer - 0 views

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    Calcium plus vitamin D supplementation and the risk of colorectal cancer.
    Wactawski-Wende J, Kotchen JM, Anderson GL, Assaf AR, Brunner RL, O'Sullivan MJ, Margolis KL, Ockene JK, Phillips L, Pottern L, Prentice RL, Robbins J, Rohan TE, Sarto GE, Sharma S, Stefanick ML, Van Horn L, Wallace RB, Whitlock E, Bassford T, Beresford SA, Black HR, Bonds DE, Brzyski RG, Caan B, Chlebowski RT, Cochrane B, Garland C, Gass M, Hays J, Heiss G, Hendrix SL, Howard BV, Hsia J, Hubbell FA, Jackson RD, Johnson KC, Judd H, Kooperberg CL, Kuller LH, LaCroix AZ, Lane DS, Langer RD, Lasser NL, Lewis CE, Limacher MC, Manson JE; Women's Health Initiative Investigators.
    N Engl J Med. 2006 Feb 16;354(7):684-96. Erratum in: N Engl J Med. 2006 Mar 9;354(10):1102.
    PMID: 16481636

    Conclusions Daily supplementation of calcium with vitamin D for seven years had no effect on the incidence of colorectal cancer among postmenopausal women. The long latency associated with the development of colorectal cancer, along with the seven-year duration of the trial, may have contributed to this null finding. Ongoing follow-up will assess the longer-term effect of this intervention.
Matti Narkia

NEJM -- Vitamin D3 and calcium to prevent hip fractures in the elderly women - 0 views

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    Vitamin D3 and calcium to prevent hip fractures in the elderly women.
    Chapuy MC, Arlot ME, Duboeuf F, Brun J, Crouzet B, Arnaud S, Delmas PD, Meunier PJ.
    N Engl J Med. 1992 Dec 3;327(23):1637-42.
    PMID: 1331788

    CONCLUSIONS. Supplementation with vitamin D3 and calcium reduces the risk of hip fractures and other nonvertebral fractures among elderly women.
Matti Narkia

In vivo threshold for cutaneous synthesis of vitamin D3. - [J Lab Clin Med. 1989] - Pub... - 0 views

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    In vivo threshold for cutaneous synthesis of vitamin D3.
    Matsuoka LY, Wortsman J, Haddad JG, Hollis BW.
    J Lab Clin Med. 1989 Sep;114(3):301-5.
    PMID: 2549141
Matti Narkia

Aging decreases the capacity of human skin to produce vitamin D3. - Journal of Clinical... - 0 views

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    Aging decreases the capacity of human skin to produce vitamin D3.
    MacLaughlin J, Holick MF.
    J Clin Invest. 1985 Oct;76(4):1536-8.
    PMID: 2997282
    doi:10.1172/JCI112134

    An evaluation of surgically obtained skin (age range, 8-92 yr) revealed that there is an age-dependent decrease in the epidermal concentrations of provitamin D3 (7-dehydrocholesterol). To ascertain that aging indeed decreased the capacity of human skin to produce vitamin D3, some of the skin samples were exposed to ultraviolet radiation and the content of previtamin D3 was determined in the epidermis and dermis. The epidermis in the young and older subjects was the major site for the formation of previtamin D3, accounting for greater than 80% of the total previtamin D3 that was produced in the skin. A comparison of the amount of previtamin D3 produced in the skin from the 8- and 18-yr-old subjects with the amount produced in the skin from the 77- and 82-yr-old subjects revealed that aging can decrease by greater than twofold the capacity of the skin to produce previtamin D3. Recognition of this difference may be extremely important for the elderly, who infrequently expose a small area of skin to sunlight and who depend on this exposure for their vitamin D nutritional needs.
Matti Narkia

Vitamin D in an ecological context. [Int J Circumpolar Health. 2000] - PubMed Result - 0 views

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    Vitamin D in an ecological context.
    Björn LO, Wang T.
    Int J Circumpolar Health. 2000 Jan;59(1):26-32.
    PMID: 10850004
Matti Narkia

An Evaluation of the Vitamin D3 Content in Fish: Is the Vitamin D Content Adequate to S... - 0 views

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

    Surprisingly, farmed salmon had approximately 25% of the vitamin D content as wild salmon had. The vitamin D content in fish varied widely even within species. These data suggest that the tables that list the vitamin D content are out-of-date and need to be re-evaluated.

    Little is known about the effect of cooking on the vitamin D content in fish. When farm salmon was baked, almost all of the vitamin D content, i.e. 240 IU of vitamin D3 was recovered from 3.5 oz. of salmon. The initial concentration in the uncooked salmon was 245 IU of vitamin D3. However, when the salmon was fried in vegetable oil, approximately 50% (123 IU of vitamin D3 was recovered.)
    We also evaluated the vitamin D content in mackerel which is traditionally considered to be an excellent source of vitamin D3 because of its oily content. However, in the one sample that we tested, we only observed 24 IU of vitamin D3 in 3.5 oz.
Matti Narkia

Vitamin D2 Is as Effective as Vitamin D3 in Maintaining Circulating Concentrations of 2... - 0 views

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    Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D.
    Holick MF, Biancuzzo RM, Chen TC, Klein EK, Young A, Bibuld D, Reitz R, Salameh W, Ameri A, Tannenbaum AD.
    J Clin Endocrinol Metab. 2008 Mar;93(3):677-81. Epub 2007 Dec 18.
    PMID: 18089691

    Conclusion: A 1000 IU dose of vitamin D2 daily was as effective as 1000 IU vitamin D3 in maintaining serum 25-hydroxyvitamin D levels and did not negatively influence serum 25-hydroxyvitamin D3 levels. Therefore, vitamin D2 is equally as effective as vitamin D3 in maintaining 25-hydroxyvitamin D status.
Matti Narkia

Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does... - 0 views

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    Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2.
    Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth R.
    Am J Clin Nutr. 1998 Oct;68(4):854-8.
    PMID: 9771862

    Although the 1.7-times
    greater efficacy for vitamin D3 shown here may seem small, it is
    more than what others have shown for 25(OH)D increases when
    comparing 2-fold differences in vitamin D3 dose. The
    assumption that vitamins D2 and D3 have equal nutritional value
    is probably wrong and should be reconsidered.
Matti Narkia

Vitamin D and diabetes: Improvement of glycemic control with vitamin D3 repletion -- Sc... - 0 views

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    Vitamin D and diabetes: improvement of glycemic control with vitamin D3 repletion.
    Schwalfenberg G.
    Can Fam Physician. 2008 Jun;54(6):864-6.
    PMID: 18556494

    Conclusion

    These cases support information that is already known about VTD and its effect on the islet cell. As discussed above, this might be true only for vitamin D3 and not vitamin D2, although vitamin D2 has been shown to improve bone health. Vitamin D insufficiency or deficiency is common, and repletion might improve glycemic control early in type 2 diabetes. Diabetes is one of the fastest growing chronic diseases worldwide. Vitamin D3 is inexpensive and readily available. Well-designed clinical studies are required to ascertain if improving 25(OH)D levels from an insufficiency or deficiency to sufficiency improves glycemic control in diabetes. These studies need to be properly designed: a randomized controlled trial with VTD deficiency or insufficiency identified in diabetic patients of various ethnic
Matti Narkia

Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans -- Armas et al. 89 (11): 53... - 0 views

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    Vitamin D2 is much less effective than vitamin D3 in humans.
    Armas LA, Hollis BW, Heaney RP.
    J Clin Endocrinol Metab. 2004 Nov;89(11):5387-91.
    PMID: 15531486

    Vitamin D2 potency is less than one third that of vitamin D3. Physicians resorting to use of vitamin D2 should be aware of its markedly lower potency and shorter duration of action relative to vitamin D3.
Matti Narkia

Supplementation with cholecalciferol does not improve glycaemic control in diabetic sub... - 0 views

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    Supplementation with cholecalciferol does not improve glycaemic control in diabetic subjects with normal serum 25-hydroxyvitamin D levels.
    Jorde R, Figenschau Y.
    Eur J Nutr. 2009 Apr 16. [Epub ahead of print]
    PMID: 19370371
    10.1007/s00394-009-0020-3

    Conclusions We were not able to demonstrate that vitamin D supplementation had a significant effect on glucose metabolism in subjects with type 2 diabetes but without vitamin D deficiency. Further studies are needed in larger groups of subjects with type 2 diabetes or impaired glucose tolerance, who also exhibit low serum 25-hydroxyvitamin D levels.
Matti Narkia

Sunlight Regulates the Cutaneous Production of Vitamin D3 by Causing Its Photodegradati... - 0 views

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    Sunlight regulates the cutaneous production of vitamin D3 by causing its photodegradation.
    Webb AR, DeCosta BR, Holick MF.
    J Clin Endocrinol Metab. 1989 May;68(5):882-7.
    PMID: 2541158
    doi:10.1210/jcem-68-5-882

    Vitamin D3 proved to be exquisitely sensitive to sunlight, and once formed in the skin, exposure to sunlight resulted in its rapid photodegradation to a variety of photoproducts, including 5,6-transvitamin D3, suprasterol I, and suprasterol II.suprasterol I, and suprasterol II.
Matti Narkia

Influence of Season and Latitude on the Cutaneous Synthesis of Vitamin D3: Exposure to ... - 0 views

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    nfluence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin.
    Webb AR, Kline L, Holick MF.
    J Clin Endocrinol Metab. 1988 Aug;67(2):373-8.
    PMID: 2839537
    doi:10.1210/jcem-67-2-373

    These results quantify the dramatic influence of changes in solar UVB radiation on cutaneous vitamin D3 synthesis and indicate the latitudinal increase in the length of the "vitamin D winter" during which dietary supplementation of the vitamin may be advisable.
Matti Narkia

Pharmacokinetics of a single, large dose of cholecalciferol -- Ilahi et al. 87 (3): 688... - 0 views

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    Pharmacokinetics of a single, large dose of cholecalciferol.
    Ilahi M, Armas LA, Heaney RP.
    Am J Clin Nutr. 2008 Mar;87(3):688-91.
    PMID: 1832660

    Conclusions: Cholecalciferol (100 000 IU) is a safe, effective, and simple way to increase calcidiol concentrations. The dosing interval should be ≤2 mo to ensure continuous serum calcidiol concentrations above baseline.

    Our study highlights that 100 000 IU cholecalciferol is a safe, efficient, and cost-effective means to increase calcidiol concentrations in the elderly. From this study we can safely recommend 100 000 IU cholecalciferol dosed every 2 mo in persons with moderate baseline calcidiol concentrations. However, in those persons with baseline calcidiol concentrations < 20 ng/mL, even this large dose will not adequately raise their calcidiol concentrations.
Matti Narkia

25-Hydroxylation of vitamin D3: relation to circulating vitamin D3 under various input ... - 0 views

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    25-Hydroxylation of vitamin D3: relation to circulating vitamin D3 under various input conditions.
    Heaney RP, Armas LA, Shary JR, Bell NH, Binkley N, Hollis BW.
    Am J Clin Nutr. 2008 Jun;87(6):1738-42.
    PMID: 18541563

    Conclusions: At physiologic inputs, there is rapid conversion of precursor to product at low vitamin D3 concentrations and a much slower rate of conversion at higher concentrations. These data suggest that, at typical vitamin D3 inputs and serum concentrations, there is very little native cholecalciferol in the body, and 25(OH)D constitutes the bulk of vitamin D reserves. However, at supraphysiologic inputs, large quantities of vitamin D3 are stored as the native compound, presumably in body fat, and are slowly released to be converted to 25(OH)D.
Matti Narkia

eMJA: Annual intramuscular injection of a megadose of cholecalciferol for treatment of ... - 0 views

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    Annual intramuscular injection of a megadose of cholecalciferol for treatment of vitamin D deficiency: efficacy and safety data. Diamond TH, Ho KW, Rohl PG, Meerkin M.
    Med J Aust. 2005 Jul 4;183(1):10-2.
    PMID: 15992330

    Conclusions: Once-yearly intramuscular cholecalciferol injection (600 000 IU) is effective therapy for vitamin D deficiency. While this therapy appears to be safe, the potential for developing hypercalciuria needs to be examined in a large randomised controlled trial.
Matti Narkia

Aging decreases the capacity of human skin to produce vitamin D3. - J Clin Invest. 198... - 0 views

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    Aging decreases the capacity of human skin to produce vitamin D3.
    MacLaughlin J, Holick MF.
    J Clin Invest. 1985 Oct;76(4):1536-8.
    PMID: 2997282
Matti Narkia

High-dose oral vitamin D3 supplementation in the elderly. - [Osteoporos Int. 2009] - Pu... - 0 views

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    High-dose oral vitamin D3 supplementation in the elderly.
    Bacon CJ, Gamble GD, Horne AM, Scott MA, Reid IR.
    Osteoporos Int. 2009 Aug;20(8):1407-15. Epub 2008 Dec 20.
    PMID: 19101755

    Sixty-three elderly participants were randomized to three regimens of vitamin D supplementation: a 500,000-IU loading dose; the loading dose plus 50,000 IU/month; or 50,000 IU/month.

    CONCLUSIONS: Large loading doses of vitamin D(3) rapidly and safely normalize 25OHD levels in the frail elderly. Monthly dosing is similarly effective and safe, but takes 3-5 months for plateau 25OHD levels to be reached.
Matti Narkia

Vitamin D and calcium supplementation reduces cancer risk: results of a randomized tria... - 0 views

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    Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.
    Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP.
    Am J Clin Nutr. 2007 Jun;85(6):1586-91. Erratum in: Am J Clin Nutr. 2008 Mar;87(3):794.
    PMID: 17556697

    Conclusions: Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.
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