Articles
Dietary supplementation with a combination of vitamin K with vitamin D and calcium increases bone mineral content in healthy older women: a two-year randomized controlled trial
Calcium and vitamin D supplementation have been shown to be effective in maintaining bone mineral density (BMD) or in decreasing hip fracture incidence. It is also suggested that vitamin K1 could improve bone health and prevent osteoporosis. This randomized controlled trial was conducted to establish the influence of an extra daily intake of 200 μg vitamin K1 on older women’s bone health. Its aim was also to investigate the interaction with vitamin K, of vitamin D, calcium at additional daily intakes of 400 IU and 1000 mg, respectively. In summary, results indicated that nutritional intakes of vitamin K1, vitamin D and calcium together with dietary supplementation could increase bone mineral content (BMC) where there had been evidence of bone loss at the ultradistal radius. This study suggests that taking a combined supplement may increase BMC in patients with bone loss.
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Is there a threshold where the body stops absorbing calcium, based on the amount of vitamin D being ingested? (A placebo-controlled, dose-response, randomized, double-blind study)
Maximal calcium absorption in response to vitamin D has been suggested to be a biomarker for vitamin D sufficiency. Currently, there is no evidence of a threshold for calcium absorption based on vitamin D levels. This randomized, double-blind study was conducted to answer the question: “Is there a serum 25(OHD concentration or intake of vitamin D3 above which calcium absorption no longer increases?” 71 healthy postmenopausal women completed this study. The findings indicate that increasing 25(OH)D concentrations may minimally increase calcium absorption. Calcium absorption with a serum 25(OH)D range from 40 to 130 nmol/L is not useful to determine nutritional recommendations for vitamin D.
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Evidence suggests that natto intake may help prevent bone loss in postmenopausal women: Japanese population-based osteoporosis study
Osteoporosis leads to fractures with minor or inapparent trauma in postmenopausal women. Nutrition could prevent osteoporosis but it remains unclear whether vitamin K plays a preventive role against age-related bone loss. In Japan, natto, a kind of fermented soybean which is rich in vitamin K2 (menaquinone-7), is consumed regularly and commonly because it is thought to reduce the incidence of hip fracture. This study was conducted to evaluate if taking natto regularly affects bone mineral density (BMD) and change in BMD positively in healthy Japanese women aged 20-79 years. Through the findings of this study, regular natto intake may be linked with reduced bone loss in postmenopausal women through the effects of vitamin K2, or menaquinone-7 or bioavailable isoflavones, which are richer in natto than in other soybean products.
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Concurrent calcium and vitamin D supplementation during pregnancy increases bone density in adolescent mothers: a randomized, placebo-controlled trial
Calcium demand increases during pregnancy and lactation periods, especially in young mothers. Vitamin D is important for calcium absorption and to boost bone metabolism and must be administered concurrently with calcium supplements. This randomized, placebo-controlled trial was conducted to investigate the influence of calcium plus vitamin D supplementation during the last trimester of pregnancy on bone mass and bone and calcium related hormones during lactation, in Brazilian adolescent mothers who consume low-calcium diets. The findings of this study show that taking calcium plus vitamin D supplements during pregnancy results in higher lumbar spine bone mass and a reduced rate of femoral neck bone loss during lactation. Therefore, concurrent supplementation of these two nutrients during pregnancy is highly recommended for adolescent mothers.
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