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Many of the scientific and regulatory challenges that exist in research on the safety, quality and efficacy of dietary supplements are common to all countries as the marketplace for them becomes increasingly global. This article summarizes some of the challenges in supplement science and provides a case study of research at the Office of Dietary Supplements at the National Institutes of Health, USA, along with some resources it has developed that are available to all scientists. It includes examples of some of the regulatory challenges faced and some resources for those who wish to learn more about them.

In the United States (US), the risk of hepatotoxicity linked to the widespread use of certain herbal products has gained increased attention among regulatory scientists. Based on current US law, all dietary supplements sold domestically, including botanical supplements, are regulated by the Food and Drug Administration (FDA) as a special category of foods. Under this designation, regulatory scientists do not routinely evaluate the efficacy of these products prior to their marketing, despite the content variability and phytochemical complexity that often characterizes them. Nonetheless, there has been notable progress in the development of advanced scientific methods to qualitatively and quantitatively measure ingredients and screen for contaminants and adulterants in botanical products when hepatotoxicity is recognized.

The goal of the present study was to determine whether an acute dose of a zinc-containing nutritional supplement (ZMA) has any effects on sleep and morning performance in recreationally trained males. Nineteen males participated in a repeated-measures within-subjects study to assess objective and subjective measures of sleep, completed counter-movement jumps (CMJ) and repeated sprint morning performance (RSP). Three days of baseline food intake showed no major deficiencies of zinc, magnesium or vitamin B6 for all participants (11.9 ± 3.4, 395 ± 103 and 2.7 ± 0.9 mg.day[sup.−1], respectively). Sleep (22:30–06:30 h) was assessed via actimetry, and either a control (no tablets, NoPill), dextrose placebo (PLAC) or ZMA was ingested 30–60 min before retiring to bed for two nights. The participants undertook the three conditions (NoPill, PLAC or ZMA) administered in a counterbalanced order. The data were analyzed using general linear models with repeated measures. In healthy active males who consume diets of adequate micronutrients, sleep normally and maintain good sleep hygiene (time to bed and wake times), ZMA supplementation had no beneficial effect on RSP or performance in the Stroop test (p > 0.05) but did improve CMJ height (p < 0.001) compared to that of PLAC but not NoPill (p > 0.05). Supplementation of ZMA for two nights had no effect on sleep, RSP or cognitive function. The NoPill condition elucidated the effects of the intervention under investigation.

Alzheimer's disease (AD) is the most common progressive human neurodegenerative disorder affecting elderly population worldwide. Hence, prevention of AD has been a priority of AD research worldwide. Based on understanding of disease mechanism, different therapeutic strategies involving synthetic and herbal approaches are being used against AD. Among the herbal extract, Ginkgo biloba extract (GBE) is one of the most investigated herbal remedy for cognitive disorders and Alzheimer's disease (AD). Standardized extract of Ginkgo biloba is a popular dietary supplement taken by the elderly population to improve memory and age-related loss of cognitive function. Nevertheless, its efficacy in the prevention and treatment of dementia remains controversial. Specifically, the added effects of GBE in subjects already receiving “conventional” anti-dementia treatments have been to date very scarcely investigated. This review summarizes recent advancements in our understanding of the potential use of Ginkgo biloba extract in the prevention of AD including its antioxidant property. A better understanding of the mechanisms of action of GBE against AD will be important for designing therapeutic strategies, for basic understanding of the underlying neurodegenerative processes, and for a better understanding of the effectiveness and complexity of this herbal medicine.

Millions of people in the United States consume dietary supplements hoping to maintain or improve their health; however, extensive research has failed to demonstrate the efficacy of numerous supplements in disease prevention. In addition, concerns about the safety of routine and high-dose supplementation have been raised. The Food and Drug Administration regulates dietary supplement quality, safety, and labeling, and the Federal Trade Commission monitors advertisements and marketing; still, vast enforcement challenges remain, and optimal governmental oversight has not been achieved. If the composition and quality of ingredients cannot be reliably ensured, the validity of research on dietary supplements is questionable. Moreover, the health of the US public is put at risk.

Vitamin A supplements are used by many people, and the number of newly registered dietary supplements is continuously increasing. The preparations fall under food law and are not subject to the strict controls of pharmaceuticals. Risk indications and maximum quantity recommendations, e.g., from the Bundesinstitut für Risikobewertung (BfR) and the U.S. Food and Drug Administration (FDA) are not binding, which means that overdoses and potentially serious health problems can easily occur. The hepatotoxicity and teratogenicity of vitamin A are well documented, and other negative effects of high doses of vitamin A are also being discussed. Nevertheless, preparations with exorbitantly high doses are freely available for sale and unrestricted. In this study, 75 supplements containing vitamin A available in Germany and 26 available in the USA were critically examined on the basis of various parameters such as the recommended daily dose according to the manufacturer, daily therapy costs (DTC), the presence of warnings about overdose, use during pregnancy and breastfeeding, and information on adverse effects/interactions. The aim was to gain insights into their risk potential and to examine the need for closer monitoring and stricter guidelines for these preparations. The results show some considerable country-specific differences. Overall, there are serious deficiencies in compliance with the labeling requirements for both the German and the US preparations, and the dosages are often far too high in view of the applicable expert recommendations. Overall, these deficits can pose a risk for consumers that is difficult to assess in its entirety, especially for vulnerable consumer groups. It should be noted that the US preparations perform better overall than the German preparations. This suggests better regulation of dietary supplements in the US market. Based on the available data and literature research, it is doubtful whether the intake of vitamin A-containing preparations, without a diagnosed vitamin A deficiency, has a positive health benefit. Furthermore, it should be examined whether vitamin A should continue to be offered over-the-counter as a food supplement.

The aim of the study was to evaluate widespread dietary supplements (DSs) use among the military population. There is no recent study to comprehensively evaluate the prevalence of DS use among the military population. Therefore, this systematic review and meta-analysis aimed to present an overview and estimate of the overall prevalence of DSs use among the military population. PubMed, Scopus, Web of Science, and Google Scholar databases were searched up to September 2023 using relevant keywords. All original articles written in English evaluating the prevalence of DSs use among the military population were eligible for this study. The risk of bias assessment of the included studies was done using the Joanna Briggs Institute critical appraisal checklist. The meta-analysis was performed utilizing a random-effects model and STATA software. In total, 32 cross-sectional studies were included in this review. The prevalence rate of DS use in the overall military population was 57% (95% CI: 49-64); this rate was higher in the studies that were carried out in the USA and the studies with a sample size lower than 10,000 members. Eleven studies reported adverse effects (AEs) following DSs use in the military population, the pooled effect size of them was 13.0% (95% CI: 6-20). The most common AEs reported by military personnel were abdominal pain, nausea, vomiting, and diarrhoea, however, they did not include any serious complications. The findings indicate that the prevalence of DSs use among the military personnel was high. Moreover, some studies reported AEs following DSs use such as gastrointestinal symptoms. Promotion of knowledge and informed attitudes regarding the DSs use in the military population could be useful.

Background Dietary supplements (DSs) are commercially available products consumed as an addition to the usual diet and are frequently ingested by athletes. Objective Our objective was to examine the prevalence of DS use by athletes. Data Sources PubMed, Ovid MEDLINE, OVID Healthstar, and Cumulative Index to Nursing and Allied Health were searched for original research articles published up to August 2014. Search terms included specific sports, specific DSs, and other terms. Study Selection Studies were selected if they were written in English, involved athletes, and provided a quantitative assessment of the proportion of athletes using specific DSs. Summary Measure Percent of athletes using specific DSs. Synthesis of Data Methodological quality of studies was assessed by three reviewers using an 8-point scale that included evaluations for sampling methods, sampling frame, sample size, measurement tools, bias, response rate, statistical presentation, and description of the participant sample. Where there were at least two investigations, meta-analysis was performed to obtain summary (pooled) prevalence estimates (SPEs) on (1) DS use prevalence by sport and sex, (2) DS use prevalence by elite versus non-elite athletic status, and (3) specific DS prevalence for all athletic groups combined. Meta-analyses included evaluations of homogeneity and publication bias. Results A total of 159 unique studies met the review criteria. Methodological quality was generally low with an average ± standard deviation of 43 ± 16 % of available rating points. There was low homogeneity for SPEs when compiled by sport, athletic status, and/or specific DSs. Contributing to the lack of homogeneity were differences in studies’ objectives and types of assessments used (e.g., dietary surveys, interviews, questionnaires). Despite these limitations, the data generally indicated that elite athletes used DSs much more than their non-elite counterparts. For most DSs, use prevalence was similar for men and women except that a larger proportion of women used iron while a larger proportion of men used vitamin E, protein, and creatine. No consistent change in use over time was observed because even the earliest investigations showed relatively high use prevalence. Conclusion It was difficult to generalize regarding DS use by athletes because of the lack of homogeneity among studies. Nonetheless, the data suggested that elite athletes used dietary supplements far more than their non-elite counterparts; use was similar for men and women with a few exceptions; use appeared to change little over time; and a larger proportion of athletes used DSs compared with the general US population. Improvements in study methodology should be considered in future studies especially (1) defining DSs for participants; (2) querying for very specific DSs; (3) using a variety of reporting timeframes (e.g., daily, 2–6 times/week, 1 time/week and <1 time/week); (4) reporting the sampling frame, number of individuals solicited, and number responding; (5) reporting characteristics of volunteers (and non-volunteers, if available); and (6) using similar methods on several occasions to examine possible temporal trends among athletes.

Kidney stones are one of the oldest known and common diseases in the urinary tract system. Various human studies have suggested that diets with a higher intake of vegetables and fruits play a role in the prevention of kidney stones. In this review, we have provided an overview of these dietary plants, their main chemical constituents, and their possible mechanisms of action. Camellia sinensis (green tea), Rubus idaeus (raspberry), Rubia cordifolia (common madder), Petroselinum crispum (parsley), Punica granatum (pomegranate), Pistacia lentiscus (mastic), Solanum xanthocarpum (yellow-fruit nightshade), Urtica dioica (stinging nettle), Dolichos biflorus (horse gram), Ammi visnaga (khella), Nigella sativa (black-cumin), Hibiscus sabdariffa (roselle), and Origanum vulgare (oregano) have received considerable interest based on scientific evidence. Beside these dietary plants, phytochemicals—such as catechin, epicatechin, epigallocatechin-3-gallate, diosmin, rutin, quercetin, hyperoside, and curcumin—as antioxidant dietary phyto-phenols were found to be effective for the prevention of urolithiasis (the process of stone formation in the urinary tract). The main underlying mechanisms of these dietary plants and their isolated phytonutrients in the management of urolithiasis include diuretic, antispasmodic, and antioxidant activity, as well as an inhibitory effect on crystallization, nucleation, and aggregation of crystals. The results as presented in this review demonstrate the promising role of dietary plants and phytophenols in the prevention and management of kidney stones. Further investigations are required to confirm the safety and efficacy of these compounds.

Medicinal properties of turmeric (Curcuma longa L.), a plant used for centuries as an anti-inflammatory, are attributed to its polyphenolic curcuminoids, where curcumin predominates. Although “curcumin” supplements are a top-selling botanical with promising pre-clinical effects, questions remain regarding biological activity in humans. To address this, a scoping review was conducted to assess human clinical trials reporting oral curcumin effects on disease outcomes. Eight databases were searched using established guidelines, yielding 389 citations (from 9528 initial) that met inclusion criteria. Half focused on obesity-associated metabolic disorders (29%) or musculoskeletal disorders (17%), where inflammation is a key driver, and beneficial effects on clinical outcomes and/or biomarkers were reported for most citations (75%) in studies that were primarily double-blind, randomized, and placebo-controlled trials (77%, D-RCT). Citations for the next most studied disease categories (neurocognitive [11%] or gastrointestinal disorders [10%], or cancer [9%]), were far fewer in number and yielded mixed results depending on study quality and condition studied. Although additional research is needed, including systematic evaluation of diverse curcumin formulations and doses in larger D-RCT studies, the preponderance of current evidence for several highly studied diseases (e.g., metabolic syndrome, osteoarthritis), which are also clinically common, are suggestive of clinical benefits.