Vitamin D intake to attain a desired serum 25-hydroxyvitamin D concentration.
Aloia JF, Patel M, Dimaano R, Li-Ng M, Talwar SA, Mikhail M, Pollack S, Yeh JK.
Am J Clin Nutr. 2008 Jun;87(6):1952-8.
PMID: 18541590
The mean daily dose was 86 microg (3440 IU). The use of computer simulations to obtain the most participants within the range of 75-220 nmol/L predicted an optimal daily dose of 115 microg/d (4600 IU). No hypercalcemia or hypercalciuria was observed. CONCLUSIONS: Determination of the intake required to attain serum 25(OH)D concentrations >75 nmol/L must consider the wide variability in the dose-response curve and basal 25(OH)D concentrations. Projection of the dose-response curves observed in this convenience sample onto the population of the third National Health and Nutrition Examination Survey suggests a dose of 95 microg/d (3800 IU) for those above a 25(OH)D threshold of 55 nmol/L and a dose of 125 microg/d (5000 IU) for those below that threshold.
Randomized comparison of the effects of the vitamin D3 adequate intake versus 100 mcg (4000 IU) per day on biochemical responses and the wellbeing of patients.
Vieth R, Kimball S, Hu A, Walfish PG.
Nutr J. 2004 Jul 19;3:8.
PMID: 15260882
doi:10.1186/1475-2891-3-8
CONCLUSION: The highest AI for vitamin D brought summertime 25(OH)D to >40 nmol/L, lowered PTH, and its use was associated with improved wellbeing. The 100 mcg/day dose produced greater responses. Since it was ethically necessary to provide a meaningful dose of vitamin D to these insufficient patients, we cannot rule out a placebo wellbeing response, particularly for those on the lower dose. This work confirms the safety and efficacy of both 15 and 100 mcg/day vitamin D3 in patients who needed additional vitamin D.
Clinical Responses to a Mega-dose of Vitamin D3 in Infants and Toddlers With Vitamin D Deficiency Rickets.
Soliman AT, El-Dabbagh M, Adel A, Ali MA, Aziz Bedair EM, Elalaily RK.
J Trop Pediatr. 2009 Jun 8. [Epub ahead of print]
PMID: 19506025
doi:10.1093/tropej/fmp040
Conclusion: An IM injection of a mega dose of cholecalciferol is a safe and effective therapy for treatment of VDD rickets in infants and toddlers with normalization of all the biochemical parameters and healing of radiological manifestations. Measurement of serum 25(OH)D level is highly recommended in all short children with a clear need for a general vitamin D supplementation for all infants and young children in Qatar.
Together, the earlier data and the data of Heaney et al indicate that an oral dose of vitamin D2 or vitamin D3 would lead to a comparable increase in circulating 25(OH)D concentrations in children and adults when the initial 25(OH)D3 concentrations in the groups are similar and when equivalent oral vitamin D doses expressed per kilogram body weight/d are given.
Serum 25-hydroxyvitamin D response to oral vitamin D intake in children.
Zittermann A.
Am J Clin Nutr. 2003 Sep;78(3):496-7.
PMID: 12936937
How much vitamin D3 do the elderly need?
Viljakainen HT, Palssa A, Kärkkäinen M, Jakobsen J, Lamberg-Allardt C.
J Am Coll Nutr. 2006 Oct;25(5):429-35.
PMID: 17031013
Conclusions: A clear dose response was noted in S-25-OHD to different doses of vitamin D3. The recommended dietary intake of 15 µg is adequate to maintain the S-25-OHD concentration around 40-55 nmol/L during winter, but if the optimal S-25-OHD is higher than that even higher vitamin D intakes are needed. Interestingly, subjects with lower vitamin D status at baseline responded more efficiently to supplementation than those with more adequate status
Conclusion: Vitamin D3 at doses equivalent to 2000 IU/d for 1 yr is safe in adolescents and results in desirable vitamin D levels.
Short- and long-term safety of weekly high-dose vitamin D3 supplementation in school children.
Maalouf J, Nabulsi M, Vieth R, Kimball S, El-Rassi R, Mahfoud Z, El-Hajj Fuleihan G.
J Clin Endocrinol Metab. 2008 Jul;93(7):2693-701. Epub 2008 Apr 29.
PMID: 18445674
doi:10.1210/jc.2007-2530
Conclusions: Healthy men seem to use 3000-5000 IU cholecalciferol/d, apparently meeting > 80% of their winter cholecalciferol need with cutaneously synthesized accumulations from solar sources during the preceding summer months. Current recommended vitamin D inputs are inadequate to maintain serum 25-hydroxycholecalciferol concentration in the absence of substantial cutaneous production of vitamin D.
Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol.
Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ.
Am J Clin Nutr. 2003 Jan;77(1):204-10. Erratum in: Am J Clin Nutr. 2003 Nov;78(5):1047.
PMID: 12499343
Dose response to vitamin D supplementation among postmenopausal African American women.
Talwar SA, Aloia JF, Pollack S, Yeh JK.
Am J Clin Nutr. 2007 Dec;86(6):1657-62.
PMID: 18065583
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.
Serum vitamin D concentration and prostate cancer risk: a nested case-control study.
Ahn J, Peters U, Albanes D, Purdue MP, Abnet CC, Chatterjee N, Horst RL, Hollis BW, Huang WY, Shikany JM, Hayes RB; Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Project Team.
J Natl Cancer Inst. 2008 Jun 4;100(11):796-804. Epub 2008 May 27.
PMID: 18505967
doi:10.1093/jnci/djn152
CONCLUSION: The findings of this large prospective study do not support the hypothesis that vitamin D is associated with decreased risk of prostate cancer; indeed, higher circulating 25(OH)D concentrations may be associated with increased risk of aggressive disease.
In summary, results from this large prospective study of men who underwent standardized prostate cancer screening in the context of a screening trial do not support the hypothesis that higher serum vitamin D status is associated with decreased risk of prostate cancer. The study showed no association of vitamin D level with nonaggressive disease; however, it raises the possibility that higher vitamin D level may be associated with increased risks for aggressive disease, although a clear monotonic dose-response relationship was lacking. Along with recent reports of adverse associations for higher vitamin D status and risk of pancreatic (32) and esophageal (33,34) cancer, caution should be taken in recommending high doses of vitamin D or sunlight exposure to the general public for prostate cancer prevention. Future analyses are warranted to confirm these results and to further clarify the effects of vitamin D on aggressive prostate cancer.
BACKGROUND: To determine the effect of vitamin D binding protein (DBP) genotypes on 25-hydroxyvitamin D [25(OH)D] changes with vitamin D supplements, we studied 98 adults receiving 600 or 4000 IU/d vitamin D(3) for one year. METHODS: The DBP functional variant, T436K, was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: Mean 25(OH)D increases were 97% for TT (n=48), 151% for TK (n=31) and 307% (n=6) for KK genotypes (p=.004). CONCLUSIONS: As with baseline 25(OH)D, T436K genotype predicts 25(OH)D changes after long-term vitamin D supplementation.
Common genetic variants of the vitamin D binding protein (DBP) predict differences in response of serum 25-hydroxyvitamin D [25(OH)D] to vitamin D supplementation.
Fu L, Yun F, Oczak M, Wong BY, Vieth R, Cole DE.
Clin Biochem. 2009 Jul;42(10-11):1174-7. Epub 2009 Mar 18.
PMID: 19302999
"So why is Dr Vieth so frustrated? You might think he'd have cause for celebration. But for him and other vitamin D researchers around the world, the good news comes with a bitter aftertaste. They believe they can prove vitamin D could help millions live longer and be healthier and yet they have not been able to convince their own governments.
In the US and Canada, official vitamin D policy is set by the Institute of Medicine. And in the opinion of Vieth, the current recommendations - 200 International Units per day for people under 50, 400 for people aged 51-70, and 600 for those 71 and older - are outrageously low. Bruce Hollis, professor of paediatrics at the Medical University of South Carolina, calls 400 IU a day "a joke". That's because the best research suggests that to achieve the higher vitamin D blood levels associated with disease prevention, most adults in the US would need to take 1,000-2,000 IU a day: five to 10 times more than the current official recommendation for adult
In 1999, Reinhold Vieth (pictured right) published a review of vitamin D research in response to the IOM conclusions. In it, he argued that there was no evidence that amounts lower than 20,000 IU a day could be toxic. "Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D," Vieth wrote.
Studies have since shown 10,000 IU a day of vitamin D to be safe. While any substance will become toxic in excess, vitamin D researchers today accept that the current vitamin D recommendations could be more than quadrupled with no fear of toxicity.!
Estimation of the dietary requirement for vitamin D in free-living adults >=64 y of age.
Cashman KD, Wallace JM, Horigan G, Hill TR, Barnes MS, Lucey AJ, Bonham MP, Taylor N, Duffy EM, Seamans K, Muldowney S, Fitzgerald AP, Flynn A, Strain JJ, Kiely M.
Am J Clin Nutr. 2009 May;89(5):1366-74. Epub 2009 Mar 18.
PMID: 19297462
doi:10.3945/ajcn.2008.27334
Conclusion: To ensure that the vitamin D requirement is met by the vast majority (>97.5%) of adults aged ≥64 y during winter, between 7.9 and 42.8 µg vitamin D/d is required, depending on summer sun exposure and the threshold of adequacy of 25(OH)D. .
Vitamin D and Cancer Mini-Symposium: The Risk of Additional Vitamin D.
Vieth R.
Ann Epidemiol. 2009 Apr 11. [Epub ahead of print]
PMID: 19364661
doi:10.1016/j.annepidem.2009.01.009
Vitamin D for cancer prevention: global perspective.
Garland CF, Gorham ED, Mohr SB, Garland FC.
Ann Epidemiol. 2009 Jul;19(7):468-83. Review.
PMID: 19523595