Effects of Zinc supplementation on serum lipids: a systematic review and meta-analysis.

Zinc is a mineral that plays a vital role in many biological processes and plays an important role in insulin action and carbohydrate metabolism. It may also have a protective role in the prevention of atherogenesis. Numerous studies have evaluated the effects of Zinc supplementation on serum lipids in humans and have demonstrated varying results. We systematically evaluated the literature and performed a meta-analysis on the effects of Zinc supplementation on serum lipids. A five staged comprehensive search of the literature was conducted in the following databases; PubMed, Web of Science and SciVerse Scopus for studies published before 31st December 2014. All controlled clinical trial in humans, that included a Zinc supplement intervention, either alone or in combination with other micronutrients and evaluated effects on serum lipids (total cholesterol [TC], triglycerides [TG], LDL cholesterol [LDL-c] and HDL cholesterol [HDL-c]). A meta-analysis of selected studies was performed using RevMan v5.3. The Jaded scale was used to assess the methodological quality of the trials included in the systematic review. A total of 24 studies were included in Meta analysis, which included a total of 33 Zinc interventions, in a total of 14,515 participants in the Zinc intervention or control group. The duration of Zinc supplementation ranged from 1 month to 7.5 years. The dose of elemental Zinc supplemented ranged from 15-240 mg/day. The pooled mean difference for TC between Zinc supplemented and placebo groups from random effects analysis was -10.92 mg/dl (95 % CI: -15.33, -6.52; p < 0.0001, I(2) = 83 %), while for HDL cholesterol it was 2.12 mg/dl (95 % CI: -0.74, 4.98; p = 0.15, I(2) = 83 %). The pooled mean difference for LDL-c between Zinc supplemented and placebo group from random effect analysis was -6.87 mg/dl (95 % CI: -11.16,-2.58; p < 0.001, I(2) = 31) and for TG it was -10.92 mg/dl (95 % CI: -18.56, - 3.28; p < 0.01, I(2) = 69 %). In conclusion, Zinc supplementation has favourable effects on plasma lipid parameters. Zinc supplementation significantly reduced total cholesterol, LDL cholesterol and triglycerides. Therefore it may have the potential to reduce the incidence of atherosclerosis related morbidity and mortality.

Waist to height ratio: a better anthropometric marker of diabetes and cardio-metabolic risks in South Asian adults.

AIMS: Obesity associated metabolic diseases have reached epidemic levels in many South Asian countries. Conventional anthropometric indices have poor sensitivity and specificity for detecting people with increased metabolic risks. The aim of this study was to investigate and compare WHtR (Waist to Height Ratio) as a marker of diabetes and cardio-metabolic risks with existing classical anthropometric indices such as; Body Mass Index (BMI), Waist Circumference (WC) and Waist to Hip Ratio (WHR) in a large sub-population of ethnic South Asians. METHODS: A total of 5000 subjects recruited from a nationally representative community-based sample using multi-stage random cluster-sampling method. Anthropometric, biochemical and clinical parameters were measured. Receiver-operating characteristic (ROC) curves were performed and area under the curve (AUC) was calculated for each anthropometric index. RESULTS: Sample size was 4485. The mean WHtR in all adults was 0.496 (±0.077), males (0.477±0.065) had a significant lower WHtR than females (0.508±0.081) (p<0.001). WHtR had the highest correlation with metabolic parameters. In all adults, males and females the AUC of WHtR was significantly higher than that of BMI, WC and WHR in diabetes mellitus, pre-diabetes, hypertension, metabolic syndrome and hypercholesterolemia. Mean age, fasting blood glucose, 2-h post prandial blood Glucose, total cholesterol, LDL cholesterol, triglycerides, systolic blood pressure and diastolic blood pressure were all significantly higher among all adults, males and females with WHtR≥0.5. CONCLUSIONS: WHtR is a simple and effective anthropometric index to identify obesity associated metabolic risks among Sri Lankan adults.

Efficacy and safety of 'true' cinnamon (Cinnamomum zeylanicum) as a pharmaceutical agent in diabetes: a systematic review and meta-analysis.

AIMS: Diabetes is a leading cause of morbidity and mortality worldwide. Studies have frequently looked at dietary components beneficial in treatment and prevention. We aim to systematically evaluate the literature on the safety and efficacy of Cinnamomum zeylanicum on diabetes. METHODS: A comprehensive search of the literature was conducted in the following databases; PubMed, Web of Science, Biological Abstracts, SciVerse Scopus, SciVerse ScienceDierect, CINAHL and The Cochrane Library. A meta-analysis of studies examining the effect of C. zeylanicum extracts on clinical and biochemical parameters was conducted. Data were analysed using RevMan v5.1.2. RESULTS: The literature search identified 16 studies on C. zeylanicum (five in-vitro, six in-vivo and five in-vivo/in-vitro). However, there were no human studies. In-vitro C. zeylanicum demonstrated a potential for reducing post-prandial intestinal glucose absorption by inhibiting pancreatic α-amylase and α-glucosidase, stimulating cellular glucose uptake by membrane translocation of glucose transporter-4, stimulating glucose metabolism and glycogen synthesis, inhibiting gluconeogenesis and stimulating insulin release and potentiating insulin receptor activity. The beneficial effects of C. zeylanicum in animals include attenuation of diabetes associated weight loss, reduction of fasting blood glucose, LDL and HbA(1c) , increasing HDL cholesterol and increasing circulating insulin levels. Cinnamomum zeylanicum also significantly improved metabolic derangements associated with insulin resistance. It also showed beneficial effects against diabetic neuropathy and nephropathy, with no significant toxic effects on liver and kidney and a significantly high therapeutic window. CONCLUSION: Cinnamomum zeylanicum demonstrates numerous beneficial effects both in vitro and in vivo as a potential therapeutic agent for diabetes. However, further randomized clinical trials are required to establish therapeutic safety and efficacy.