beta-carotene and Fractures--Bone

The aim is to evaluate the effect of β-carotene for osteoporosis and provide quantitative evidence.. PubMed, Embase, Web of Science, and Cochrane Library were searched for eligible studies. Fifteen studies were included. Random-effect model was applied to pool the odds ratio (OR). The risk of osteoporosis and fracture were compared between low β-carotene intake group and high β-carotene intake group.. β-carotene may improve BMD and reduce the risk of osteoporosis and fracture. However, these effects could vary by gender and race and need to be further validated by longitudinal studies.

Topics: Asia; beta Carotene; Bone Density; Female; Fractures, Bone; Humans; Male; Osteoporosis

Vitamin A is a generic term for compounds that have biological activity similar to that of retinol and includes carotenoids like β-carotene and α-carotene. Some studies suggest high dietary intake of vitamin A can increase bone fracture risk. This investigation involved a systematic review and meta-analysis examining the association between vitamin A and fracture risk. Published literature was searched to find studies that (1) involved human participants, (2) had prospective cohort or case-control study designs, (3) contained original quantitative data on associations between dietary intake of vitamin A and fractures, and (4) provided either risk ratios (RRs), odds ratios (ORs), or hazard ratios (HRs) with 95% confidence intervals (95% CIs) comparing various levels of vitamin A consumption to fracture risk. Thirteen studies met the review criteria. Meta-analyses indicated that risk of hip fracture was increased by high dietary intake of total vitamin A (RR = 1.29; 95% CI = 1.07-1.57) or retinol (RR = 1.23; 95% CI = 1.02-1.48). Hip fracture risk was reduced by high dietary intake of total carotene (RR = 0.62; 95% CI = 0.42-0.93), β-carotene (RR = 0.72; 95% CI = 0.58-0.89), or α-carotene (RR = 0.81; 95% CI = 0.67-0.97). Total fracture risk was not associated with any vitamin A compound. High intake of total vitamin A or retinol increased hip fracture risk, while high intake of some carotenoids reduced hip fracture risk.

Topics: beta Carotene; Case-Control Studies; Fractures, Bone; Hip Fractures; Humans; Prospective Studies; Risk Factors; Vitamin A

If osteoporosis is linked with vitamin A (Vit A) A consumption, millions of people could be affected.. A MEDLINE search was performed with keywords retinol, beta-carotene, and osteoporosis.. Of 20 clinical studies, 3 were randomized controlled trials (RCTs), 14 were observational studies, and 3 were case reports. Most (8) observational studies were cross-sectional. Oral retinoyl palmitate (RP) in high doses induces fractures and radiographic osteoporosis in animals. Retinol intake from diet or supplements is negatively associated with lumbar, femoral neck, and trochanter bone mineral density (BMD). There is a graded increase in relative risk of hip fracture with increasing retinol intake, attributable primarily to retinol (either from diet or supplements) but not beta-carotene intake. Higher serum retinol levels are associated with higher risk of any fracture and with higher risk of hip fracture, whereas there is no evidence of harm associated with beta-carotene intake. The few RCTs involve serum markers of bone metabolism, not bone density or fracture outcomes. Observational studies are generally consistent in finding harm from either dietary or supplemental retinol intake on BMD and hip fracture risk. Total Vit A intake is more important than source in determining harm. Adverse effects may occur at a level of retinol intake that is only about twice the current recommendation for adult females.. It is not yet possible to set a specific level of retinol intake above which bone health is compromised. Pending further investigation, Vit A supplements should not be used with the express goal of improving bone health.

Topics: Aged; Animals; beta Carotene; Body Mass Index; Bone and Bones; Bone Density; Cohort Studies; Female; Fractures, Bone; Hip Fractures; Humans; Male; Osteoporosis; Primary Prevention; Randomized Controlled Trials as Topic; Risk Factors; Time Factors; United States; Vitamin A

Observational studies suggest that moderate intakes of retinol and increased circulating retinol levels may increase fracture risk. Easy access to supplements, combined with an aging population, makes this a potentially important association. The aim of this study was to investigate plasma retinol and total carotene concentrations in relation to fracture risk after long-term supplementation with retinol and/or beta-carotene in 998 adults between 1990 and 2007.. Participants were 663 men and 335 women in a cancer prevention program who were initially randomized to a retinol (7.5 mg RE/d) or beta-carotene (30 mg/d) supplement between 1990 and 1996. After 1996, all participants received the retinol supplement only. Plasma retinol and total carotene, medication use and various lifestyle factors were measured at annual clinic visits. Fractures were identified by self-report in 2007. The risk for any fracture or osteoporotic fracture was modeled using Cox proportional hazard models.. Over a median follow-up of 7.8 y, 123 participants with plasma samples reported an incident fracture. Although plasma retinol concentrations were markedly higher than those reported in observational studies, no association was observed between plasma retinol and risk for any fracture (hazard ratio [HR], 0.86 μmol/L; 95% confidence interval [CI], 0.65-1.14) or osteoporotic fracture (HR, 0.97 μmol/L; 95% CI, 0.66-1.43). A lower risk for any fracture was suggested with increasing plasma total carotenes (HR, 0.85 μmol/L; 95% CI, 0.71-1.01).. This study does not support earlier reports of an increased fracture risk associated with increased plasma retinol concentration. The potential for carotenes to prevent fractures deserves further investigation.

Topics: Adult; Aged; beta Carotene; Dietary Supplements; Female; Follow-Up Studies; Fractures, Bone; Humans; Incidence; Male; Middle Aged; Osteoporosis; Proportional Hazards Models; Risk Factors; Time Factors; Vitamin A; Vitamins

Although studies in animals and epidemiologic studies have indicated that a high vitamin A intake is associated with increased bone fragility, no biologic marker of vitamin A status has thus far been used to assess the risk of fractures in humans.. We enrolled 2322 men, 49 to 51 years of age, in a population-based, longitudinal cohort study. Serum retinol and beta carotene were analyzed in samples obtained at enrollment. Fractures were documented in 266 men during 30 years of follow-up. Cox regression analysis was used to determine the risk of fracture according to the serum retinol level.. The risk of fracture was highest among men with the highest levels of serum retinol. Multivariate analysis of the risk of fracture in the highest quintile for serum retinol (>75.62 microg per deciliter [2.64 micromol per liter]) as compared with the middle quintile (62.16 to 67.60 microg per deciliter [2.17 to 2.36 micromol per liter]) showed that the rate ratio was 1.64 (95 percent confidence interval, 1.12 to 2.41) for any fracture and 2.47 (95 percent confidence interval, 1.15 to 5.28) for hip fracture. The risk of fracture was further increased within the highest quintile for serum retinol. Men with retinol levels in the 99th percentile (>103.12 microg per deciliter [3.60 micromol per liter]) had an overall risk of fracture that exceeded the risk among men with lower levels by a factor of seven (P<0.001). The level of serum beta carotene was not associated with the risk of fracture.. Our findings, which are consistent with the results of studies in animals, as well as in vitro and epidemiologic dietary studies, suggest that current levels of vitamin A supplementation and food fortification in many Western countries may need to be reassessed.

Topics: beta Carotene; Body Mass Index; Dose-Response Relationship, Drug; Fractures, Bone; Hip Fractures; Humans; Longitudinal Studies; Male; Middle Aged; Multivariate Analysis; Osteoporosis; Proportional Hazards Models; Risk Factors; Vitamin A