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McDonnell S.L.,GrassrootsHealth | Baggerly L.L.,GrassrootsHealth | French C.B.,GrassrootsHealth | Heaney R.P.,Creighton University | And 4 more authors.
Journal of Steroid Biochemistry and Molecular Biology | Year: 2016

Higher serum 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with lower risk of type 2 diabetes. This study compared incidence rates of type 2 diabetes among participants aged ≥20 years in two U.S. cohorts with markedly different median 25(OH)D concentrations. The median 25(OH)D concentration in the GrassrootsHealth (GRH) cohort was 41 ng/ml (N = 4933) while in the 2005-6 National Health and Nutrition Examination Survey (NHANES) it was 22 ng/ml (N = 4078) (P < 0.0001). The adjusted annual incidence rate of type 2 diabetes was 3.7 per 1000 population (95% confidence interval = 1.9, 6.6) in the GRH cohort, compared to 9.3 per 1000 population (95% confidence interval = 6.7, 12.6) in NHANES. In the NHANES cohort, the lowest 25(OH)D tertiles (<17, 17-24 ng/ml) had higher odds of developing diabetes than the highest tertile (OR: 4.9, P = 0.02 and 4.8, P = 0.01 respectively), adjusting for covariates. Differences in demographics and methods may have limited comparability. Raising serum 25(OH)D may be a useful tool for reducing risk of diabetes in the population. © 2015 The Authors. Published by Elsevier Ltd. Source


Garland C.F.,University of California at San Diego | French C.B.,GrassrootsHealth | Baggerly L.L.,GrassrootsHealth | Heaney R.P.,Creighton University
Anticancer Research | Year: 2011

Background: Studies indicate that intake of vitamin D in the range from 1,100 to 4,000 IU/d and a serum 25-hydroxyvitamin D concentration [25(OH)D] from 60-80 nglml may be needed to reduce cancer risk. Few community-based studies allow estimation of the dose-response relationship between oral intake of vitamin D and corresponding serum 25(OH)D in the range above 1,000 IU/d. Materials and Methods: A descriptive study of serum 25(OH)D concentration and self-reported vitamin D intake in a community-based cohort (n=3,667, mean age 51.3±13.4 y). Results: Serum 25(OH)D rose as a function of self-reported vitamin D supplement ingestion in a curvilinear fashion, with no intakes of 10,000 IU/d or lower producing 25(OH)D values above the lower-bound of the zone of potential toxicity (200 ng/ml). Unsupplemented all-source input was estimated at 3,300 IU/d. The supplemental dose ensuring that 975% of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d. Conclusion: Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity. Source


McDonnell S.L.,GrassrootsHealth | French C.B.,GrassrootsHealth | Heaney R.P.,Creighton University
Journal of Steroid Biochemistry and Molecular Biology | Year: 2014

Unsupplemented vitamin D status is determined by cutaneous synthesis and food inputs; however, their relative magnitudes are largely unknown. In a cohort of 780 non-supplement-taking adults with a mean serum 25-hydroxyvitamin D [25(OH)D] of 33 (±14) ng/ml we assessed the relationship between serum 25(OH)D and non-food environmental variables. Serum 25(OH)D concentration was adjusted for seasonal influence (which removed 2% of the total variance) and these adjusted values were regressed against factors involved in cutaneous synthesis. Indoor tanning use, sun exposure, and percent of work performed outdoors were significantly positively associated and body mass index (BMI) was significantly negatively associated with 25(OH)D values (P < 0.03 for each). Latitude, gender, and age were not significantly correlated (P > 0.10). Season and non-food predictors together explained 13% of the total variance in serum 25(OH)D concentration. Non-traditional food sources need to be investigated as possible vitamin D inputs. This article is part of a Special Issue entitled 'Vitamin D Workshop'. © 2013 Elsevier Ltd. Source


Heaney R.P.,Creighton University | Armas L.A.G.,Creighton University | French C.,GrassrootsHealth
Journal of Nutrition | Year: 2013

The magnitude of vitamin D inputs in individuals not taking supplements is unknown; however, there is a great deal of information on quantitative response to varying supplement doses. We reanalyzed individual 25-hydroxyvitamin D [25(OH)D] concentration data from 8 studies involving cholecalciferol supplementation (total sample size = 3000). We extrapolated individual study dose-response curves to zero concentration values for serum 25(OH)D by using both linear and curvilinear approaches and measured seasonal oscillation in the serum 25(OH)D concentration. The total basal input (food plus solar) was calculated to range from a low of 778 IU/d in patients with end-stage renal disease to a high of 2667 IU/d in healthy Caucasian adults. Consistent with expectations, obese individuals had lower baseline, unsupplemented 25(OH)D concentrations and a smaller response to supplements. Similarly, African Americans had both lower baseline concentrations and lower calculated basal, all-source inputs. Seasonal oscillation i n 4 studies ranged from 5.20 to 11.4 nmol/L, reflecting a mean cutaneous synthesis of cholecalciferol ranging from 209 to 651 IU/d at the summer peak. We conclude that: 1) all-source, basal vitamin D inputs are approximately an order of magnitude higher than can be explained by traditional food sources; 2) cutaneous, solar input in these cohorts accounts for only 10-25% of unsupplemented input at the summer peak; and 3) the remainder must come from undocumented food sources, possibly in part as preformed 25(OH)D. © 2013 American Society for Nutrition. Source


McDonnell S.L.,GrassrootsHealth | French C.B.,GrassrootsHealth | Heaney R.P.,Creighton University
Journal of Steroid Biochemistry and Molecular Biology | Year: 2014

Cutaneous synthesis and traditional food sources do not fully account for unsupplemented vitamin D status. Non-traditional food sources may be an undiscovered input. In a cohort of 780 non-supplement-taking adults with a mean serum 25-hydroxyvitamin D [25(OH)D] of 33 (±14) ng/ml we assessed the relationship between vitamin D status and selected food sources. Serum 25(OH)D concentration was adjusted for season, UVB exposures, and body size. These adjusted values were then regressed against multiple food items and combinations. Whole milk cottage cheese, eggs, red meat, and total protein were positively associated with total 25(OH)D and/or 25(OH)D3 (P < 0.05 for each), whereas fish and milk intake were not. The slope of the relationship was such that for every intake of 1 serving/day, serum 25(OH)D rose by about 2 ng/ml for eggs and 1 ng/ml for meat and total protein. For every weekly serving of whole milk cottage cheese, serum 25(OH)D rose by about 1 ng/ml. While some food sources were significant predictors of vitamin D status, their ability to explain inter-individual variability was limited. Supplementation will likely remain essential to improving vitamin D status on a population level. This article is part of a Special Issue entitled '16th Vitamin D Workshop'. © 2013 Elsevier Ltd. Source

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