Calcium (Ca) is an essential nutrient for the human body. Despite lively research, there is uncertainty about Ca requirements in terms of desirable health outcomes including an upper intake level above which the potential for harm increases.The aim was to conduct a review to update requirements and desirable or harmful health effects of Ca on the current scientific evidence.We searched Medline and Swemed from January 2000 to December 2011 and included all systematic reviews that reported Ca supplementation or usual Ca intake on health outcomes. Meta-analyses, randomized clinical trials and cohort studies were included in the second search between May 2009 and March 2011 and an additional search covering studies till the end of 2011. This review concentrated on studies reporting independent effects of Ca, although a few recent trials report sole effects of Ca on health outcomes, most trials use Ca in combination with vitamin D vs. placebo.In total, we reviewed 38 studies addressing the effects of Ca on bone, pregnancy-related outcomes, cancers, cardiovascular outcomes, obesity, and mortality. There was a lot of heterogeneity in the study protocols, which made it difficult to draw any strong conclusions. According to the literature, high Ca intake seems to have a small positive effect on bone mineral content (BMC) or bone mineral density (BMD) in children and postmenopausal women. We did not find any consistent evidence on the effects of Ca on bone health in premenopausal women or men. Also, the evidence that Ca supplementation reduces fracture incidence is scarce and inconsistent. Maternal diet may influence the peak bone mass of offspring but more studies are required. There was no overall effect of Ca intake on cancers. Ca was associated with a decreased risk of breast cancer and a slightly increased risk of prostate cancer in two of the three studies. No associations were found with other cancers. We found no consistent association between cardiovascular outcomes and Ca intake except for blood pressure. A small decrease of 2-4 mmHg in systolic blood pressure was found in pregnant and in hypertensive subjects with Ca supplementation. Reviewed studies did not show consistent evidence relating Ca intake to either mortality or obesity.Based on this evidence, there is no need to change the Nordic recommendations for Ca intake. However, due to heterogeneity in the studies it is difficult to interpret the results and provide single summary statement.
Abstract. Treatment of rats with 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) 0.05 μg/kg per day for three days was without any effect on serum T 3 , T 4 or TSH concentrations, whereas serum PRL increased (20.6 ± 3.8 to 76.2 ± 19.1 μg/l, mean ± sem , N = 7–8; P < 0.01). Increased hypothalamic TRH levels (24.3 ± 3.9 to 45.7 ± 7.8 pmol/g wet weight; P < 0.01) may indicate an effect of 1,25(OH) 2 D 3 on hypothalamic TRH homeostasis. This effect could probably be due to an indirect action of 1,25(OH) 2 D 3 , mediated by the increased serum calcium (2.77 ± 0.02 to 3.16 ± 0.08 mmol/l, mean ± sem , N = 7–8; P < 0.001). This assumption was, however, not tested. Neither the pituitary TSH nor PRL was affected. The treatment decreased the serum concentration of 25-hydroxyvitamin D 3 (23.0 ± 1.3 to 16.8 ± 2.0 nmol/l, mean ± sem , N = 5–7; P < 0.01) and of 24,25-dihydroxyvitamin D 3 (3.2 ± 0.3 to 2.1 ± 0.1 nmol/l, mean ± sem , N = 3–5; P < 0.05). The results show that in this experimental design, 1,25(OH) 2 D 3 has no effect on basal hormone secretion from the pituitary-thyroid axis, and that 1,25(OH) 2 D 3 decreases the synthesis of the vitamin D 3 metabolites studied.
To evaluate the current status of dietary intakes in early pubertal girls with a special focus on milk products.Cross-sectional data using 3-day food records.Eight hundred and sixty girls, aged 10-12 years, at Tanner maturation stage I-III.The mean consumption of milk products (620 g day(-1)) was similar to that of a Finnish study in the 1980s, while the consumption of non-milk drinks (403 g day(-1)) had increased. Twelve per cent of the girls had a dairy-restricted diet and consumed significantly less milk products than girls with a non-restricted diet (465 vs. 644 g day(-1), P<0.001). Girls with low milk product consumption had the highest non-milk drinks consumption (P<0.001). The mean energy intake was 7.1 MJ day(-1). No major changes were found in the sources of nutrients. The shares of energy for nutrients were close to recommendations except for saturated fat (13.9 vs. 10% of energy) and carbohydrates (51.5 vs. 55-60% of energy). The mean calcium intake (1117 mg day(-1)) was above the recommendation, while the vitamin D intake (3.1 microg day(-1)) of 88% of the girls was below the recommendation.The diet quality of early pubertal girls is close to the recommendations and has improved with respect to fat compared with the 1980s. Consumption of milk products is high although the consumption of non-milk drinks has increased. We found a subgroup of girls who compensate their low milk product consumption with a higher consumption of non-milk drinks. Following a dairy-restricted diet is the main reason for low consumption of milk products.
Vitamin D insufficiency is associated with risks of cardiovascular diseases (CVD) and cancer in observational studies, but evidence for benefits with vitamin D supplementation is limited. To investigate the effects of vitamin D3 supplementation on CVD and cancer incidences. The study was a 5-year, randomized, placebo-controlled trial among 2495 male participants ≥60 years and post-menopausal female participants ≥65 years from a general Finnish population who were free of prior CVD or cancer. The study had 3 arms: placebo, 1600 IU/day, or 3200 IU/day vitamin D3. Follow-up was by annual study questionnaires and national registry data. A representative subcohort of 551 participants had more detailed in-person investigations. The primary endpoints were incident major CVD and invasive cancer. Secondary endpoints included the individual components of the primary CVD endpoint (myocardial infarction, stroke, and CVD mortality), site-specific cancers, and cancer death. During the follow-up, there were 41 (4.9%), 42 (5.0%), and 36 (4.3%) major CVD events in the placebo, 1600 IU/d (compared with placebo: HR: 0.97; 95% CI: 0.63–1.49; P = 0.89), and 3200 IU/d (HR: 0.84; 95% CI: 0.54–1.31; P = 0.44) arms, respectively. Invasive cancer was diagnosed in 41 (4.9%), 48 (5.8%), and 40 (4.8%) participants in the placebo, 1600 IU/d (HR: 1.14; 95% CI: 0.75–1.72; P = 0.55), and 3200 IU/d (HR: 0.95; 95% CI: 0.61–1.47; P = 0.81) arms, respectively. There were no significant differences in the secondary endpoints or total mortality. In the subcohort, the mean baseline serum 25-hydroxyvitamin D concentration was 75 nmol/L (SD, 18 nmol/L). After 12 months, the concentrations were 73 nmol/L (SD, 18 nmol/L), 100 nmol/L (SD, 21 nmol/L), and 120 nmol/L (SD, 22 nmol/L) in the placebo, 1600 IU/d, and 3200 IU/d arms, respectively. Vitamin D3 supplementation did not lower the incidences of major CVD events or invasive cancer among older adults, possibly due to sufficient vitamin D status in most participants at baseline.
The present cross-sectional study was designed to evaluate the vitamin D status in three groups of women in Bangladesh by using serum 25-hydroxyvitamin D (S-25-OHD), alkaline phosphatase (S-ALP), calcium (S-Ca) and phosphate (S-P). Sampling was undertaken at three locations in the city of Dhaka, Bangladesh. Representative subjects of three groups of women aged 18-60 years were studied. Study subjects included nonveiled young women = group A (N = 36, mean+/- SD age 22.3 +/- 1.9 years), veiled women =group B (N = 30, mean+/- SD age 47.7+/- 9.4 years) and nonveiled diabetic women = group C (N = 55, mean +/- SD age 50.2 +/- 5.9 years). The mean value of S-25-OHD was not significantly different in the groups. The distribution of S-25-OHD concentration in all groups was shifted overall toward the lower limit of the normal range. Vitamin D deficiency (serum 25-OHD level <25 nmol/l) was detected in 39% of young women (university students), 30% in veiled women and 38% in diabetic women, respectively. Vitamin D insufficiency defined as serum 25-OHD concentration <40 nmol/l was detected in 78% of group A, 83% in group B and 76% in group C, respectively. As indicated, prevalence of vitamin D insufficiency was a bit higher in group B compared with the other groups studied although it was not statistically significant (P > 0.05). In the present study, there were several independent predictors of serum 25-OHD, i.e. both increasing parity (r = 0.286; P < 0.005) and increasing time spent outdoors (r = 0.515; P < 0.001) were associated with significant increase in serum 25-OHD. A strongly significant inverse correlation between serum ALP and 25-OHD (r = -0.303;P<0.001) was observed. The results showed that women in Bangladesh, regardless of different age-groups, lifestyle and clothing, were at risk of developing hypovitaminosis D. The results emphasize the appropriate health message for vitamin D needs in Bangladeshi women, since vitamin D insufficiency significantly affects bone integrity.
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