Development of an Instrument to Measure Dietary Supplement Health Literacy.

BACKGROUND: Health literacy is one of the important social determinants of health. OBJECTIVE: The aim of this study was to develop an instrument to measure Dietary Supplement Health Literacy (DSHL) of Iranian women. METHODS: In this psychometrics study, an initial nine-factor instrument was developed. Face validity and content validity of the instrument were evaluated. The factor structure of the instrument was explored by the Exploratory Factor Analysis (EFA) among 400 women taking Dietary supplement. Confirmatory Factor Analysis (CFA) was done to determine the underlying factor structure of the instrument in this population. The internal and external reliability of the instrument was evaluated. KEY RESULTS: According to expert panel opinions, 16 items were deleted. The results of the EFA showed that the Kaiser-Meyer-Olkin and Bartlett's test of sphericity were significant. EFA showed that 30 items could be grouped into nine factors that accounted for 60.84% of the variance. Since two items in the ability to actively engage with health care providers factor were loaded in factor 1, this factor was labeled Engaging in receiving informational supports from health care providers. In addition, one item of the dimension was loaded in factor 3. Given that the one item of factor 5 and 1 item of factor 6 were loaded in a new factor 9, this factor was labeled Applying information to decision-making. The CFA indicated that the nine-factor structure of the DSHL instrument had a poor fit. To modify indices, factor 9 with 2 items and 1 item of factor 6 were deleted. The Cronbach's alpha and intraclass correlation coefficient of the instrument were acceptable. Finally, a 27-item instrument with 8 dimensions was confirmed. CONCLUSIONS: The results of the study showed that the instrument developed was a valid tool for identifying the DSHL of Iranian women. [HLRP: Health Literacy Research and Practice. 2022;6(2):e159-e166.] Plain Language Summary: This study sought to develop and validate a multidimensional instrument to measure the health literacy of Iranian women about dietary supplements that was performed from July 2019 to May 2020 in Iran. Findings showed that the 30-item instrument developed in this study is a valid instrument to be used for identifying the health literacy of Iranian women about dietary supplements.

Effects of Calcium and Vitamin D Co-supplementation on the Lipid Profile: A Systematic Review and Meta-analysis.

PURPOSE: Calcium and vitamin D co-supplementation is common and widely used, but randomized, controlled trials (RCTs) have yielded inconclusive results concerning its impact on the serum lipid profile. METHODS: A comprehensive literature search of Medline, Web of Science, Scopus, Embase, Cochrane Central Register of Controlled Trials, and clinical trial registry databases was conducted to identify placebo-controlled RCTs that were published through September 2020 and that evaluated the impact of calcium and vitamin D co-supplementation on total cholesterol (TC), triglycerides (TGs), low- and very-low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol (HDL-C). Standardized mean differences (SMDs) were pooled using random-effects meta-analysis models. FINDINGS: Thirteen studies in a total of 2304 participants met the inclusion criteria. Calcium and vitamin D co-supplementation was associated with significant reductions in both TC (SMD, -0.81; 95% CI, -1.35 to -0.27; I2 = 94.6%) and TGs (SMD, -0.50; 95% CI, -0.91 to -0.08; I2 = 91.5%), and with a significant increase in HDL-C (SMD, 1.22; 95% CI, 0.60 to 1.83; I2 = 95.4%). However, calcium and vitamin D co-supplementation were not found to be associated with significantly decreased low-density lipoprotein cholesterol (SMD, -0.39; 95% CI, -0.78 to 0.01; I2 = 90.1%) or very-low-density lipoprotein cholesterol (SMD, -0.01; 95% CI, -0.70 to 0.69; I2 = 82.3%). IMPLICATIONS: The findings from the present systematic review and meta-analysis suggest that calcium and vitamin D co-supplementation has a beneficial effect on TC, TG, and HDL-C. Larger-scale, well-designed RCTs are needed to clarify the effect of calcium and vitamin D co-supplementation on all lipid-profile components.