Effects of zinc supplementation on glycemic control and oxidative stress in experimental diabetes: A systematic review.

INTRODUCTION: Diabetes mellitus (DM), an important public health problem worldwide, can cause imbalances in the homeostasis of trace elements such as zinc (Zn). It is possible that an adequate nutritional status related to nutrients is essential for the normal functioning of antioxidant defense systems, and any change in the concentration of these substances could increase the chances of DM complications. OBJECTIVE: To present a review on the effect of zinc supplementation on glycemic control and oxidative stress in experimental diabetes. METHODS: This is a systematic review of articles that investigated the effects of zinc supplementation on glycemic control and oxidative stress in diabetic rats. The PICOS strategy was used for the development of the research question, and the Syrcle tool for the quality assessment of the studies included in the review. Articles available in the PubMed, Scopus, and Web of Science databases were included without restriction on year of publication. The Syrcle tool was used to assess the risk of bias of the included studies. RESULTS: Fifteen studies were included in the review, seven of which evaluated glycemic control and oxidative stress after zinc supplementation, five only oxidative stress and three only glycemic control after zinc treatment. In all the studies included, diabetes was induced by the administration of streptozotocin (STZ) at doses ranging from 40 to 100 mg/kg. Zinc supplementation was made in the diet or drinking water or by gavage or intraperitoneal injection. The most used doses were 100 mg/kg of body weight by gavage and 0.32 and 0.64 g/kg in diet. The supplementation period ranged from 14 days to 8 weeks. Six studies revealed that zinc supplementation decreased fasting blood glucose as well as insulin resistance; nine studies included in this review reported decreased MDA concentration; in five studies, there was an increase in the activity of antioxidant enzymes (GPx, SOD, GSH and catalase); and one of the studies reported a reduction in glycated hemoglobin. CONCLUSION: Zinc supplementation improved hyperglycemia and revealed a protective potential against oxidative stress associated with experimental diabetes.

Functional performance, nutritional status and level of physical activity of elderly

The elderly is a risk group for changes in health conditions and as well as in functional performance related to the decline in grip strength and reduced walking speed, which can compromise the performance of activities of daily living. Based on this, the objective was to analyze the factors associated with functional performance in the elderly. For that, a cross-sectional study was developed involving a group of 179 elderly people who received medical care at an outpatient clinic of the public health network. Muscle strength and gait speed were measured. Nutritional status was determined by Body Mass Index (BMI), calf circumference (CC), waist circumference (WC) and waist-to-hip ratio (WHR). Level of physical activity was measured by the adapted version of the Minnesota Leisure Activities Questionnaire. Low muscle strength was found in 20.7% of the elderly and slow gait in 20.1%. Increased risk of cardiovascular disease was found in 40.8% considering WC, and 35.2% by WHR. Most of the elderly had low weight and no loss of muscle mass. Loss of muscle strength was associated with sex and CC and gait speed were associated with sex, age, and presence of a partner (p < 0.05). The chance of loss of muscle strength and lower gait speed was higher in elderly women. Loss of muscle mass due to CC was associated with the chance of loss of strength, and the chance of reduced walking speed was greater among the elderly individuals aged 75 years and over.

Lycopene-Rich Extract from Red Guava (Psidium guajava L.) Decreases Plasma Triglycerides and Improves Oxidative Stress Biomarkers on Experimentally-Induced Dyslipidemia in Hamsters.

This work assessed the effects of a 28-day treatment with lycopene-rich extract (LRE) from red guava fruit (Psidium guajava L.) on the lipid profile and oxidative stress in an experimental model of dyslipidemia. Male hamsters (116.5 ± 2.16 g) were fed with the AIN 93G diet containing casein (20%), coconut fat (13.5%) and cholesterol (0.1%). The animals were divided into four groups: normolipidemic control (standard feed; NC, n = 7); hypercholesterolemic control (HC, n = 7); LRE 25 mg/kg/day (LRE-25, n = 7) and LRE 50 mg/kg/day (LRE-50, n = 9). After treatment, plasma concentrations of triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL) cholesterol (LDL-c), high-density lipoprotein (HDL) cholesterol (HDL-c), malondialdehyde (MDA-p) and myeloperoxidase (MPO), as well as erythrocytic superoxide dismutase (SOD-e) and the atherogenic index, were determined. Malondialdehyde (MDA-h), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD-h) levels were assessed. Feed intake (FI) and weight gain (WG) were also determined. The LRE-25 group presented significantly lower TG levels and atherogenic index than did the HC group (p < 0.05). Both LRE-25 and LRE-50 groups presented lower levels of MDA-p and MPO than did the HC group (p < 0.05). LRE demonstrated a promising effect against dyslipidemia and oxidative stress.

Cholesterol-Lowering and Liver-Protective Effects of Cooked and Germinated Mung Beans (Vigna radiata L.).

We investigated the hypocholesterolemic and liver-protective effects of cooked and germinated whole mung beans. Hamsters were fed for 28 days on diets rich in saturated fatty acids and cholesterol, differing only in protein source (20%): casein, cooked whole mung bean, and germinated mung bean. After 28 days, we found reduced plasma concentrations of total cholesterol and non-HDL cholesterol, increased faecal cholesterol excretion, and reduced levels of asparagine aminotransferase and alanine aminotransferase enzymes in the liver. Reduction in hepatic lipid deposition was observed between each of the mung bean groups relative to the casein group. In addition, the animals of the geminated mung bean group showed a lack of inflammatory infiltrate and better vascularisation of the hepatic tissue. Results from this study show significant hypocholesterolemic and liver-protective properties of the mung bean, which are further enhanced after germination.