Review of the efficacy of green tea, isoflavones and aloe vera supplements based on randomised controlled trials

School of Food Science and Nutrition, University of Leeds, Leeds, LS2 9JT, UK.
Food & function 09/2011; 2(12):753-9. DOI: 10.1039/c1fo10101c
Source: PubMed

ABSTRACT We assess the evidence for health benefits of three commonly consumed plant food supplements (PFS), green tea, isoflavone and aloe vera, based on published systematic reviews of randomised controlled trials (RCTs). Whilst the potential benefits of green tea have been reported in a wide range of health areas, it is only in the area of the metabolic syndrome that the number of RCTs is approaching sufficient to judge such efficacy. Isoflavone supplements are widely used, and RCTs indicate that they affect bone resorption at lower doses in postmenopausal women undergoing estrogen-related bone loss, but this is only translated to attenuation of bone loss at higher doses of isoflavones. A systematic review on RCTs concluded that the effects of isoflavones on hot flashes in postmenopausal women were highly variable and no conclusions could be drawn. Despite the popularity of aloe vera as a PFS, the evaluation of its efficacy as a coadjuvant therapy for certain metabolic or digestive pathologies remains scarce; it constitutes a typical example of a naturally occurring ingredient whose efficacy in topical applications presupposes its efficacy in systemic applications. Nevertheless, its possible toxic effects on oral consumption call for caution in its utility as a PFS. Since 2007, efficacy evaluation of PFS in Europe has been covered by European Union Nutrition and Health Claims legislation. The European Food Safety Authority has adopted an approach relying on RCTs, while medicinal effects are accepted based on traditional use. In general, there are insufficient RCTs for claims to be made, and conclusive results on PFS should be obtained in the future by conducting studies with more homogeneous populations, by using supplements with optimised and measured bioavailability, and by conducting larger RCTs.


Available from: Lluis Serra-Majem, May 29, 2015
  • Recent Progress in Medicinal Plants: Analytical and Processing Techniques, 41 edited by J.N. Govil, 08/2014: chapter 4: pages 49-65; Studium Press LLC, Houston-Texas, USA., ISBN: 1-62699-078-6
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Phytoestrogens represent a diverse group of non-steroidal natural products, which seem to have some oestrogenic effects and are often marketed as food supplements. Population exposed to phytoestrogens is potentially increasing, in part because an unfavourable risk-benefit profile of Hormone Replacement Therapy (HRT) for prolonged treatments (e.g., osteoporosis prevention) highlighted by the publication of the Women Health Initiative (WHI) trial in 2002, also in part because many post-menopausal women often perceived phytoestrogens in food supplements as a safer alternative than HRT. Despite of increasing preclinical and clinical studies in the past decade, appealing evidence is still lacking to support the overall positive risk-benefit profile of phytoestrogens. The status of phytoestrogens as food supplements seem discourage studies to obtain new evidence, and the chance to buy them by user's initiative make it difficult to survey on their prevalence and pattern of use. The aim of the present review is to: (a) outline the clinical scenario underlying the increase interest on phytoestrogens, by overviewing the evolution of the evidence on HRT and its main therapeutic goals (e.g., menopausal symptoms relief, chemoprevention, osteoporosis prevention); (b) address the chemical and pharmacological features (e.g. chemical structure, botanical sources, mechanism of action) of the main compounds (e.g., isoflavones, lignans, coumestans); (c) describe the clinical evidence on potential therapeutic applications; (d) put available evidence on their risk-benefit profile in a regulatory perspective, in light of the recent regulation on health claims of food supplements.
    Current Medicinal Chemistry 10/2013; 21(4). DOI:10.2174/09298673113206660297 · 3.72 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: The metabolic effects of an aloe vera gel complex (Aloe QDM complex) on people with prediabetes or early diabetes mellitus (DM) are unknown. The goal of this study was to determine the effects of Aloe QDM complex on body weight, body fat mass (BFM), fasting blood glucose (FBG), fasting serum insulin, and Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR) in obese individuals with prediabetes or early DM who were not on diabetes medications. METHODS: Participants (n = 136) were randomly assigned to an intervention or a control group and evaluated at baseline and at 4 and 8 wk. RESULTS: The study lost six participants in the control group and eight in the intervention group. At 8 wk, body weight (P = 0.02) and BFM (P = 0.03) were significantly lower in the intervention group. At 4 wk, serum insulin level (P = 0.04) and HOMA-IR (P = 0.047) were lower in the intervention group; they also were lower at 8 wk but with borderline significance (P = 0.09; P = 0.08, respectively). At 8 wk, FBG tended to decrease in the intervention group (P = 0.02), but the between-group difference was not significant (P = 0.16). CONCLUSION: In obese individuals with prediabetes or early untreated DM, Aloe QDM complex reduced body weight, BFM, and insulin resistance.
    Nutrition 06/2013; 29(9). DOI:10.1016/j.nut.2013.02.015 · 3.05 Impact Factor