The effect of calcium supplementation in people under 35 years old: A systematic review and meta-analysis of randomized controlled trials.

Background: The effect of calcium supplementation on bone mineral accretion in people under 35 years old is inconclusive. To comprehensively summarize the evidence for the effect of calcium supplementation on bone mineral accretion in young populations (≤35 years). Methods: This is a systematic review and meta-analysis. The Pubmed, Embase, ProQuest, CENTRAL, WHO Global Index Medicus, Clinical Trials.gov, WHO ICTRP, China National Knowledge Infrastructure (CNKI), and Wanfang Data databases were systematically searched from database inception to April 25, 2021. Randomized clinical trials assessing the effects of calcium supplementation on bone mineral density (BMD) or bone mineral content (BMC) in people under 35 years old. Results: This systematic review and meta-analysis identified 43 studies involving 7,382 subjects. Moderate certainty of evidence showed that calcium supplementation was associated with the accretion of BMD and BMC, especially on femoral neck (standardized mean difference [SMD] 0.627, 95% confidence interval [CI] 0.338-0.915; SMD 0.364, 95% CI 0.134-0.595; respectively) and total body (SMD 0.330, 95% CI 0.163-0.496; SMD 0.149, 95% CI 0.006-0.291), also with a slight improvement effect on lumbar spine BMC (SMD 0.163, 95% CI 0.008-0.317), no effects on total hip BMD and BMC and lumbar spine BMD were observed. Very interestingly, subgroup analyses suggested that the improvement of bone at femoral neck was more pronounced in the peripeak bone mass (PBM) population (20-35 years) than the pre-PBM population (<20 years). Conclusions: Our findings provided novel insights and evidence in calcium supplementation, which showed that calcium supplementation significantly improves bone mass, implying that preventive calcium supplementation before or around achieving PBM may be a shift in the window of intervention for osteoporosis. Funding: This work was supported by Wenzhou Medical University grant [89219029].

Osteoporosis and bone fractures are common problems among older people, particularly older women. These conditions cause disability and reduce quality of life. Progressive loss of bone mineral density is usually the culprit. So far, strategies to prevent bone weakening with age have produced disappointing results. For example, taking calcium supplements in later life only slightly reduces the risk of osteoporosis or fracture. New approaches are needed. Bone mass increases gradually early in life and peaks and plateaus around 20-35 years of age. After that period, bone mass slowly declines. Some scientists suspect that increasing calcium intake during this period of peak bone mass may reduce osteoporosis or fracture risk later in life. A meta-analysis by Liu, Le et al. shows that boosting calcium intake in young adulthood strengthens bones. The researchers analyzed data from 43 randomized controlled trials that enrolled 7,382 participants. About half the studies looked at the effects of taking calcium supplements and the other half analyzed the effects of a high calcium diet. Boosting calcium intake in people younger than age 35 improved bone mineral density throughout the body. It also increased bone mineral density at the femoral neck, where most hip fractures occur. Calcium supplementation produced larger effects in individuals between the ages of 20 and 35 than in people younger than 20. Both high calcium diets and calcium supplements with doses less than 1000 mg/d boosted bone strength. Higher dose calcium supplements did not provide any extra benefits. The analysis suggests people should pay more attention to bone health during early adulthood. Large randomized clinical trials are needed to confirm the long-term benefits of boosting calcium intake during early adulthood. But if the results are validated, taking calcium supplements, or eating more calcium-rich foods between the ages of 20 and 35 may help individuals build healthier bones and prevent fractures and osteoporosis later in life.

Ginsenoside Rd Ameliorates High Fat Diet-Induced Obesity by Enhancing Adaptive Thermogenesis in a cAMP-Dependent Manner.

OBJECTIVE: With the discovery of thermogenic adipocytes in humans, it has been hypothesized that enhancing adaptive thermogenesis may improve obesity. Although many studies have found that ginseng can improve obesity, the beneficial effects of ginsenoside Rd on obesity and its mechanisms have not been studied. METHODS: High-fat diet-induced obese mice were used as the study subjects, with intraperitoneal injection of Rd daily at a dose of 15 mg/kg. Body weight and energy metabolism were observed. The effects of Rd on glucose tolerance, insulin sensitivity, and cold tolerance were tested. The expression of genes associated with thermogenesis was analyzed. Finally, the mechanisms by which Rd regulates adaptive thermogenesis were studied. RESULTS: Rd ameliorated obesity and insulin resistance. Rd increased cold tolerance through enhancing thermogenic gene expression in brown adipose tissue and increased the browning of white adipose tissue induced by cold stress. Rd increased intracellular cyclic adenosine monophosphate (cAMP) content. Decreasing intracellular cAMP levels by an inhibitor of adenylyl cyclase SQ22536 abolished the promoting effects of Rd on the expression of thermogenic genes. CONCLUSIONS: Rd improves obesity and insulin resistance. The upregulation of thermogenesis by Rd is dependent on the cAMP/protein kinase A signaling pathway.

Post-weaning isocaloric hyper-soybean oil versus a hyper-carbohydrate diet reduces obesity in adult rats induced by a high-fat diet.

The aim of this study was to investigate the effects of a post-weaning isocaloric hyper-soybean oil diet on later obesity and explore the underlying mechanisms. In the present study, newborn male Wistar rats were weaned on d 24, divided into CON (control), HC and HSO groups. CON was assigned to AIN-93G diet (a hypercarbohydrate diet, for short HC diet) during the entire experiment. HC and HSO were fed with HC and isocaloric hyper-soybean oil (HSO) diet for 3 wk respectively, fed with HC diet for 2 wk successively, finally administrated high fat diet (HF) for 6 wk to induce obesity. On 3,5,11 wk, the body weight, body fat content, blood glucose, blood lipid, serum insulin and leptin levels and obesity-related gene (CPT-1, FAS, UCP2, UCP3) expression levels in rats were detected. It was shown that body weight, body fat content, blood glucose and blood lipid, serum insulin and leptin levels in HSO were down-regulated on 3 and 5 wk, therefore were significantly reduced on 11 wk vs. HC. The CPT-1, UCP2, UCP3 gene expressions were up-regulated but FAS were down-regulated persistently in HSO. The study indicated that an early isocaloric HSO diet may reduce later obesity risk and reduce blood lipid and glucose abnormalities in adulthood via persistently influencing insulin and leptin sensitivity and permanent regulation of obesity-related gene expressions.

Sulforaphane, erucin, and iberin up-regulate thioredoxin reductase 1 expression in human MCF-7 cells.

Isothiocyanates (ITCs) found in cruciferous vegetables are potentially important anticarcinogenic phytochemicals for many types of cancers including breast cancer. In this study, we have shown that three isothiocyanates, sulforaphane, erucin, and iberin, are potent inducers of thioredoxin reductase 1 (TrxR1) in human breast cancer MCF-7 cells. Sulforaphane, erucin, and iberin at 1 microM induce TrxR1 mRNA 2-3-fold within 8 h of treatment, and induce mRNA 5-7-fold with 12 microM ITC treatments. Selenium did not affect sulforaphane-induced TrxR1 mRNA levels, but significantly enhanced both TrxR1 protein expression (up to 9-fold in erucin treatment) and corresponding activities. These results suggest that dietary ITCs are important factors in the regulation of redox status through the induction of the selenoprotein thioredoxin reductase.

[Effect of iron on the expression of uncoupling protein 2, 3 gene of obese rat].

In order to study the effect of iron on the expression of UCP2 in white fat and UCP3 in muscle in obese rats, a reverse transcription polymerase chain reaction (RT-PCR) technique is used to measure the expression of UCP2 and UCP3 mRNA. The results show: (1) Adequate iron improves the level of thyroid hormone in blood serum; (2) the body fat content of obese rat in 5, 10, and 20 times of iron supplement groups is lower than that of obese rats in normal iron supplement group; (3) the UCP2 and UCP3 mRNA expression of iron-deficient obese rats is low in iron-deficient obese rats; (4) iron supplement enhances the level of UCP3 mRNA expression in muscle and the level of UCP3 mRNA is the highest in the 5 times iron supplement group and about 2 times of that of basic diet group. However, there is no effect on the UCP2 mRNA expression induced by high energy diet. It suggested that adequate iron can improve the level of serum thyroid hormone, induce the UCP3 mRNA expression in muscle and mobilize fat to produce heat, but had no effect on UCP2 mRNA in white fat of obese rat.