Tuesday, 28 March 2017

Minerals in the News Vol. 15, No. 3 (March 2017)

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Association Between Antioxidant Intake/Status and Obesity: a Systematic Review of Observational Studies

Biol Trace Elem Res. 2017 Feb;175(2):287-297. doi: 10.1007/s12011-016-0785-1. Epub 2016 Jun 22.
Hosseini B, et al.

Abstract
(AA) The global prevalence of obesity has doubled in recent decades. Compelling evidences indicated that obesity was associated with lower concentrations of specific antioxidants which may play a role in the development of obesity-related diseases such as cardiovascular disease. The present review aimed to synthesize the evidence from studies on the association between obesity and antioxidant micronutrients in a systematic manner. Data bases including MEDLINE, Science Direct, and Cochrane were searched from inception to October 2015. Thirty-one articles were reviewed using the MOOSE checklist. Lower concentrations of antioxidants have been reported in obese individuals among age groups worldwide. Circulatory levels of carotenoids, vitamins E and C, as well as zinc, magnesium, and selenium were inversely correlated with obesity and body fat mass. However, studies demonstrated inconsistencies in findings. Lower status of carotenoids, vitamins E and C, zinc, magnesium, and selenium appears to be associated with adiposity. Intervention studies may be needed to establish the causality of these associations. 
 
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The unresolved role of dietary fibers on mineral absorption

Crit Rev Food Sci Nutr. 2017 Mar 24;57(5):949-957. doi: 10.1080/10408398.2014.953030
Baye K, et al.

Abstract
(AA) Dietary fiber is a complex nutritional concept whose definition and method of analysis has evolved over time. However, literature on the role of dietary fiber on mineral bioavailability has not followed pace. Although in vitro studies revealed mineral binding properties, both animal and human studies failed to show negative effects on mineral absorption, and even in some cases reported absorption enhancing properties. The existing literature suggests that dietary fibers have negative effects on mineral absorption in the gastrointestinal tract largely due to mineral binding or physical entrapment. However, colonic fermentation of dietary fibers may offset this negative effect by liberating bound minerals and promoting colonic absorption. However, existing studies are limited since they did not control for more potent mineral absorption inhibitors such as phytates and polyphenols. Animal studies have mostly been on rats and hence difficult to extrapolate to humans. Human studies have been mostly on healthy young men, who likely to have an adequate store of iron. The use of different types and amounts of fibers (isolated/added) with varying physiological and physicochemical properties makes it difficult to compare results. Future studies can make use of the opportunities offered by enzyme technologies to decipher the role of dietary fibers in mineral bioavailability.
 
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Zinc's role in the glycemic control of patients with type 2 diabetes: a systematic review

Biometals. 2017 Jan 30. doi: 10.1007/s10534-017-9996-y. [Epub ahead of print]
de Carvalho GB, et al.

Abstract
(AA) Past research has shown the importance of zinc in several metabolic processes, such as the glucidic metabolism. The present systematic review aims to discuss zinc's participation in the glycemic control of type 2 diabetes mellitus (DM2) patients. In order to accomplish that, a systematic search was performed in the Pubmed database using the following indexed and theme-related descriptors: "zinc" AND "type 2 diabetes mellitus", AND MeSH terms related to glycemic control combined with the boolean operator OR. In total, 1078 articles were retrieved from the research, of which 15 articles of original studies conducted with DM2 patients were included, with three being about the effect of mineral supplementation and 12 reporting observational studies. The main findings of these studies consisted of low body contents of zinc and high excretion of zinc in urine. Hyperglycemia was one of the mechanisms that caused these alterations owing to its interference in zinc reabsorption via renal cells. Another evidence was the negative correlation between the glycated hemoglobin percentage (%HbA1c) and the plasma zinc levels. Additionally, it has been observed that zinc supplementation in DM2 patients has improved glycemic control, since the %HbA1c significantly reduced in these individuals. This present review shows the positive effect of adequate zinc levels on glycemic control, whether it is through dietetic ingestion or supplementation, since its role in insulin homeostasis is clear.
 
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Inadequate dietary intake of minerals: prevalence and association with socio-demographic and lifestyle factors

Br J Nutr. 2017 Jan 23:1-11. doi: 10.1017/S0007114516004633. [Epub ahead of print]
Sales CH, et al.

Abstract
(AA) This cross-sectional, population-based study aimed to estimate the prevalence of dietary mineral inadequacies among residents in urban areas of Sao Paulo, to identify foods contributing to mineral intake and to verify possible associations between socio-demographic and lifestyle factors and mineral intake. Data were obtained from the 2008 Health Survey of Sao Paulo (n 1511; mean age 43·6 (sd 23·2), range 14-97 years). Dietary intake of minerals was measured using two 24-h dietary recalls. Socio-demographic and lifestyle data were collected. The prevalence of inadequate intake was estimated according to Dietary Reference Intakes methods. Associations between mineral intake and baseline factors were determined using multiple linear regression. Na, Ca and Mg showed the highest dietary inadequacies. Some age/sex groups had lower intakes of P, Zn, Cu and Se. Rice, beans and bread were the main foods contributing towards mineral intake. Female sex was negatively associated with K, Na, P, Mg, Zn and Mn intakes. All age groups were positively associated with the intakes of K, P, Mg and Mn. Family income above one minimum wage was positively associated with Se intake. Living in a household whose head completed ≥10 years of education was positively associated with Ca and negatively associated with Na intake. Former smoker status was negatively associated with Ca intake. Current smoker status was inversely associated with K, Ca, P and Cu intakes. Sufficient physical activity was positively associated with K, Ca and Mg intakes. Overall, the intakes of all major minerals were inadequate and were influenced by socio-demographic and lifestyle factors.
 
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Dietary adequacy of Egyptian children with autism spectrum disorder compared to healthy developing children

Metab Brain Dis. 2017 Jan 10. doi: 10.1007/s11011-016-9948-1. [Epub ahead of print]
Meguid NA, et al.

Abstract
(AA) Although the etiology and pathology of autism spectrum disorder (ASD) is still poorly understood, a number of environmental, anthropological, neurobiological and genetic factors have been related to the pathophysiology of ASD, even the impact of oxidative stress response related to the environment and nutrition intake. Usual recommended dietary habits are based on the combination of behavioral and dietary or nutraceutical interventions together with pharmacotherapy. Investigations about a reliable relationship between diet and ASD are still lacking. The present study aimed at comparing dietary regimens and habits of normally developing apparently healthy children, without diagnosed ASD, with a pediatric population of individuals affected by autistic disorder. Assessments of nutritional and anthropometric data, in addition to biochemical evaluation for nutrient deficiencies, were performed. A total of 80 children with autistic disorder and 80 healthy, normally developing pediatric individuals were enrolled in the study. Parents were asked to complete the standardized questionnaire regarding the different types of food and the proportion of a serving for their children. Biochemical analysis of micro- and macronutrients were also done. Plotting on the Egyptian sex-specific anthropometric growth (auximetric) chart, absolute weights as well as weight-related for age classes, were significantly higher in cases than healthy controls. No differences between groups were observed in regard to total kilocalories (kcal), carbohydrates, and fat intake. A total of 23.8% of children with autistic disorder vs. 11.3% in the healthy control group had a nutrient intake with features below the Recommended Dietary Allowance (RDA) of protein. Children with autistic disorder showed low dietary intake of some micronutrients; calcium (Ca), magnesium (Mg), iron (Fe), selenium (Se) and sodium (Na), also they had significantly high intake of potassium (K) and vitamin C compared to healthy controls. Serum Mg, Fe, Ca, folate and vitamin B12 in children with autistic disorder were significantly low compared with healthy children. Significant positive correlations between serum Mg, Fe, Ca, vitamin B12 and folate and their levels in food were present. These results confirmed that different nutritional inadequacy was observed in Egyptian children with autistic disorder. The evidence reported in the present study should recommend screening of the nutritional status of ASD children for nutrient adequacy to reduce these deficiencies by dietary means or by administering appropriate vitamin and mineral supplements. Nutritional intervention plan should be tailored to address specific needs.