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Visa fullständig version : Nypublicerad forskning om D-vitamin


Eddie Vedder
2011-09-08, 15:19
Senaste volymen av European Journal of Clinicil Nutrition har flera artiklar om D-vitamin och olika hälsoaspekter. Här är de för den intresserade:

Under normal circumstances, vitamin D is mainly obtained from skin through the action of ultraviolet B irradiation on 7-dehydrocholesterol. It is further metabolized to 25-hydroxyvitamin D (25OHD), the major circulating vitamin D compound, and then to 1,25-dihydroxyvitamin D, the hormonal form. The major function of vitamin D compounds is to enhance active absorption of ingested calcium (and phosphate). This assists in building bone at younger ages and ensures that despite obligatory urinary losses, bone does not need to be resorbed to maintain blood calcium concentrations. Vitamin D compounds appear to have direct effects to improve bone and muscle function, and there is good, although not entirely consistent, evidence that supplemental vitamin D and calcium together reduce falls and fractures in older individuals. On the basis of calcium control and musculoskeletal function, target levels for 25OHD in blood are at least 50–60 nmol/l and there may be a case for higher targets of 75–80 nmol/l. There are vitamin D receptors in most nucleated cells and some evidence, although not consistent, that adequate vitamin D levels may be important in reducing the incidence of, or mortality from, some cancers and in reducing autoimmune disease. Adequate vitamin D may also allow for a normal innate immune response to pathogens, improve cardiovascular function and mortality and increase insulin responsiveness. Vitamin D levels are maintained better in the presence of adequate calcium intakes, more exercise and less obesity. Genetic variation may have an effect on vitamin D blood levels and response to treatment with vitamin D.

http://www.nature.com/ejcn/journal/v65/n9/full/ejcn2011105a.html

Mason RS, Sequeira V, Gordon-Thompson C (2011). Vitamin D: the light side of sunshine. Eur J Clin Nutr 65, 986–993.

Background/Objectives:
The goal of this work is to estimate the reduction in mortality rates for six geopolitical regions of the world under the assumption that serum 25-hydroxyvitamin D (25(OH)D) levels increase from 54 to 110 nmol/l.
Subjects/Methods:
This study is based on interpretation of the journal literature relating to the effects of solar ultraviolet-B (UVB) and vitamin D in reducing the risk of disease and estimates of the serum 25(OH)D level–disease risk relations for cancer, cardiovascular disease (CVD) and respiratory infections. The vitamin D-sensitive diseases that account for more than half of global mortality rates are CVD, cancer, respiratory infections, respiratory diseases, tuberculosis and diabetes mellitus. Additional vitamin D-sensitive diseases and conditions that account for 2 to 3% of global mortality rates are Alzheimer's disease, falls, meningitis, Parkinson's disease, maternal sepsis, maternal hypertension (pre-eclampsia) and multiple sclerosis. Increasing serum 25(OH)D levels from 54 to 110 nmol/l would reduce the vitamin D-sensitive disease mortality rate by an estimated 20%.
Results:
The reduction in all-cause mortality rates range from 7.6% for African females to 17.3% for European females. Reductions for males average 0.6% lower than for females. The estimated increase in life expectancy is 2 years for all six regions.
Conclusions:
Increasing serum 25(OH)D levels is the most cost-effective way to reduce global mortality rates, as the cost of vitamin D is very low and there are few adverse effects from oral intake and/or frequent moderate UVB irradiance with sufficient body surface area exposed.

http://www.nature.com/ejcn/journal/v65/n9/full/ejcn201168a.html

Grant WH (2011). An estimate of the global reduction in mortality rates through doubling vitamin D levels. Eur J Clin Nutr 65, 1016–1026.

Obesity often coexists with low calcium intake and vitamin D insufficiency. There is emerging evidence of a role for these nutrients in the regulation of body weight. However, it is unclear whether increasing intakes of calcium and/or vitamin D during energy restriction, is a better strategy for weight and fat loss. We searched the literature from 2000 to date for randomized controlled trials (RCTs) on weight loss that had increased calcium or vitamin D per se, or in combination. Primary and secondary studies were included for this analysis. A total of 15 RCTs on calcium with or without vitamin D and seven on vitamin D alone met our criteria. Two studies reported that supplemental calcium significantly increased fat loss during caloric restriction by 1.8 and 2.2 kg, three found differences between 1 and 3.5 kg but were statistically nonsignificant, while nine trials were equivocal (±0.7 kg). The data on vitamin D supplementation during weight loss were too few to make firm conclusions. Current evidence from RCTs did not consistently support the contention that calcium and vitamin D accelerated weight or fat loss in obesity. There were studies that favoured the hypothesis but lacked the statistical power. There is a need for RCTs to examine the influence of vitamin D on body fat.

http://www.nature.com/ejcn/journal/v65/n9/full/ejcn2011106a.html

Soares MJ, Chan She Ping-Delfos W, Ghanbari MH (2011). Calcium and vitamin D for obesity: a review of randomized controlled trials. Eur J Clin Nutr 65, 994–1004.

Background/Objectives:
Vitamin D may modify the risk of type 2 diabetes mellitus. The aim of this review was to examine the association between vitamin D status and incident type 2 diabetes, and the effect of vitamin D supplementation on glycemic outcomes.
Methods:
We performed a systematic review of English-language studies using MEDLINE through February 2011. Longitudinal cohort studies reporting associations between vitamin D status and incident type 2 diabetes, and randomized controlled trials (RCTs) of vitamin D supplementation, were included. Study characteristics and results were extracted, and study quality was assessed.
Results:
A total of 8 observational cohort studies and 11 RCTs were included. In meta-analyses of observational studies, vitamin D intake >500 international units (IU)/day decreased the risk of type 2 diabetes by 13% compared with vitamin D intake <200 IU/day. Individuals with the highest vitamin D status (>25 ng/ml) had a 43% lower risk of developing type 2 diabetes (95% confidence interval 24, 57%) compared with those in the lowest group (<14 ng/ml). In post hoc analyses from eight trials among participants with normal glucose tolerance at baseline and in three small underpowered (n=32–62) trials of patients with established type 2 diabetes, there was no effect of vitamin D supplementation on glycemic outcomes. In two trials among patients with baseline glucose intolerance, vitamin D supplementation improved insulin resistance.
Conclusions:
Vitamin D may play a role in type 2 diabetes; however, to better define the role of vitamin D in the development and progression of type 2 diabetes, high-quality observational studies and RCTs that measure blood 25-hydroxyvitamin D concentration and clinically relevant glycemic outcomes are needed.

http://www.nature.com/ejcn/journal/v65/n9/full/ejcn2011118a.html

Mitri J, Muraru MD, Pittas AG (2011). Vitamin D and type 2 diabetes. A systematic review. Eur J Clin Nutr 65, 1005–1015.

Vitamin D has an important role in pregnancy in promoting fetal skeletal health. Maternal dietary intake is a key factor influencing both maternal and fetal status. There are limited data available on food groups contributing to vitamin D intake in pregnancy. The aim of this study was to determine dietary intakes of vitamin D throughout pregnancy in 64 women and to determine the main food groups contributing to vitamin D intake. Results showed that median dietary intakes of vitamin D ranged from 1.9–2.1 μg/d during pregnancy, and were 80% below the current recommendation. The principal food groups contributing to vitamin D intake were meat, egg and breakfast cereal groups. Oily fish, the best dietary source of vitamin D, was consumed by <25% of women. These data call for more education; they question the role of vitamin D supplementation and highlight the contribution of other food groups more frequently consumed, namely, breakfast cereals, meat and eggs.

http://www.nature.com/ejcn/journal/v65/n9/full/ejcn2011110a.html?WT.ec_id=EJCN-201109

C A McGowan, J Byrne, J Walsh and F M McAuliffe (2011). Insufficient vitamin D intakes among pregnant women. Eur J Clin Nutr 2011 65: 1076-1078

Sk1llz
2011-09-08, 15:29
Tack som fan!