Determinants of Knowledge About Dietary Supplements Among Polish Internet Users: Nationwide Cross-sectional Study

Abstract

Background An accurate understanding of dietary supplements (DS) is a prerequisite for informed decisions regarding their intake. However, there is a need for studies on this understanding among the public based on validated research tools. Objective This study aims to assess the knowledge about DS among Polish internet users with no medical education and to identify its determinants and design an appropriate predictive model. Methods The study protocol was prospectively registered with a statistical analysis plan. Polish users of a web-based health service and a social networking service were administered a survey consisting of the recently developed questionnaire on knowledge about DS, the questionnaire on trust in advertising DS, the beliefs about medicines questionnaire, and several other health-related single-item measures and sociodemographic questions. The results were subjected to general linear modeling. Results A total of 6273 participants were included. Of the 17 yes or no questions in the questionnaire of knowledge about DS, the mean number of correct responses was 9.0 (95% CI 8.9-9.1). Health service users performed worse than social networking users by 2.3 points (95% CI 2.1-2.5) in an analysis adjusted for potential confounders. Internet users had fewer true beliefs about DS if they presented higher trust in their advertising (adjusted β=−.37; 95% CI −.39 to −.34), used DS (adjusted β=−.14; 95% CI −.17 to −.12), experienced their positive effect (adjusted β=−.16; 95% CI −.18 to −.13), were older or younger than 35 years (adjusted β=−.14; 95% CI −.17 to −.12), expressed interest in the topic of DS (adjusted β=−.10; 95% CI −.13 to −.08), reported getting information about the products from friends (adjusted β=−.13; 95% CI −.15 to −.11), and believed that medicines are harmful (adjusted β=−.12; 95% CI −.15 to −.10). The proposed 5-predictor model could explain 31.2% of the variance in knowledge about DS. The model appeared resistant to overfitting and was able to forecast most of the observed associations. Conclusions Polish internet users with no medical education exhibit some false beliefs regarding DS. Trusting the advertising of DS appears to conflict with knowledge about them. There is an urgent need for effective web-based educational campaigns on DS and the promotion of advertising literacy. After the proposed predictive model is externally validated, it may help identify the least informed target audience.

Decrease in Salivary Serotonin in Response to Probiotic Supplementation With Saccharomyces boulardii in Healthy Volunteers Under Psychological Stress: Secondary Analysis of a Randomized, Double-Blind, Placebo-Controlled Trial

“…Parametric analyses were applied, although some of the variables were ordinal. This was to allow more flexible modeling and was justifiable as such analyses are usually closely compatible with non-parametric ones ( 57 ). While testing multiple hypotheses, Benjamini and Hochberg procedure was used to control the false discovery rate at the level of 0.3.…”

Use of Dietary Supplements and Perceived Knowledge among Adults Living with Fibromyalgia in Norway: A Cross-Sectional Study

“…Furthermore, to determine the participants’ current knowledge of DS, they were asked to answer whether they agreed or disagreed with nine different health claims [ 21 ]. Table 4 shows the frequency of correct answers for the health claims based on the current evidence.…”

“…Regarding reliability, another strength is that the survey was built on validated instruments and scales [ 21 , 25 ], and the list of DS was chosen due to its common use in nutritional studies such as NORKOST 3 and NAFKAM 2018 [ 22 , 23 ]. Furthermore, among the predefined list of 32 DS, the option “other” was also included, allowing the participants to report any other DS not mentioned in the list.…”

“…Therefore, uncritical use of DS could be a risk rather than a benefit for the health of potential users, such as those individuals living with FMS or other rheumatic and/or musculoskeletal disorders. Therefore, an accurate understanding of DS appears to be a prerequisite for making informed DS choices, especially considering the fact that health claims in the media may provide an uncritically positive image of DS that shapes DS intake patterns [ 21 ].…”

Dietary Supplements—For Whom? The Current State of Knowledge about the Health Effects of Selected Supplement Use

“…The primary reasons for supplement use in the United States are for overall health and wellness and to fill nutrient gaps in the diet [10], while in Poland, among the elderly it is a need to boost the immune system, and among younger people, use is related to improving the health and condition of skin and hair [7]. Moreover, more than 40% of Poles surveyed believe that taking vitamin and mineral supplements prevents diseases in healthy people, and almost 70% claim that the use of antioxidants prevents the development of cancers [11,12].…”