The relationship between zinc intake and growth in children aged 1-8 years: a systematic review and meta-analysis.

BACKGROUND/OBJECTIVES: It is estimated that zinc deficiency affects 17% of the world's population, and because of periods of rapid growth children are at an increased risk of deficiency, which may lead to stunting. This paper presents a systematic review and meta-analysis of the randomised controlled trials (RCTs) that assess zinc intake and growth in children aged 1-8 years. This review is part of a larger systematic review by the European Micronutrient Recommendations Aligned Network of Excellence that aims to harmonise the approach to setting micronutrient requirements for optimal health in European populations (www.eurreca.org). SUBJECT/METHODS: Searches were performed of literature published up to and including December 2013 using MEDLINE, Embase and the Cochrane Library databases. Included studies were RCTs in apparently healthy child populations aged from 1 to 8 years that supplied zinc supplements either as capsules or as part of a fortified meal. Pooled meta-analyses were performed when appropriate. RESULTS: Nine studies met the inclusion criteria. We found no significant effect of zinc supplementation of between 2 weeks and 12 months duration on weight gain, height for age, weight for age, length for age, weight for height (WHZ) or WHZ scores in children aged 1-8 years. CONCLUSIONS: Many of the children in the included studies were already stunted and may have been suffering from multiple micronutrient deficiencies, and therefore zinc supplementation alone may have only a limited effect on growth.

Zinc intake, status and indices of cognitive function in adults and children: a systematic review and meta-analysis.

In developing countries, deficiencies of micronutrients are thought to have a major impact on child development; however, a consensus on the specific relationship between dietary zinc intake and cognitive function remains elusive. The aim of this systematic review was to examine the relationship between zinc intake, status and indices of cognitive function in children and adults. A systematic literature search was conducted using EMBASE, MEDLINE and Cochrane Library databases from inception to March 2014. Included studies were those that supplied zinc as supplements or measured dietary zinc intake. A meta-analysis of the extracted data was performed where sufficient data were available. Of all of the potentially relevant papers, 18 studies met the inclusion criteria, 12 of which were randomised controlled trials (RCTs; 11 in children and 1 in adults) and 6 were observational studies (2 in children and 4 in adults). Nine of the 18 studies reported a positive association between zinc intake or status with one or more measure of cognitive function. Meta-analysis of data from the adult's studies was not possible because of limited number of studies. A meta-analysis of data from the six RCTs conducted in children revealed that there was no significant overall effect of zinc intake on any indices of cognitive function: intelligence, standard mean difference of <0.001 (95% confidence interval (CI) -0.12, 0.13) P=0.95; executive function, standard mean difference of 0.08 (95% CI, -0.06, 022) P=0.26; and motor skills standard mean difference of 0.11 (95% CI -0.17, 0.39) P=0.43. Heterogeneity in the study designs was a major limitation, hence only a small number (n=6) of studies could be included in the meta-analyses. Meta-analysis failed to show a significant effect of zinc supplementation on cognitive functioning in children though, taken as a whole, there were some small indicators of improvement on aspects of executive function and motor development following supplementation but high-quality RCTs are necessary to investigate this further.

A critical analysis of the content of the tools that measure breast-feeding interaction.

OBJECTIVE: To undertake a critical analysis of the content of six tools, which have been designed to evaluate the breast-feeding interaction. DESIGN: The tools are viewed as discourses and are examined in terms of the insight they give into the assumptions about and attitudes towards breast-feeding inherent in the authors who have produced them. FINDINGS: The findings indicate that there is little agreement between the existing breast-feeding assessment tools as to how to measure a successful breast feed and that the tools appear to place insufficient reliance upon the research evidence related to lactation. KEY CONCLUSIONS: The lack of commonality between evaluation tools appears to reflect a prevailing inconsistency in the advice given by health workers to breast-feeding mothers. Reports of their unreliability may be indicative of the problems inherent when attempting to impose a biomedical model upon an intrinsically natural interaction. IMPLICATIONS FOR PRACTICE: It is suggested that, if evaluations of the breast-feeding interaction are to be useful, a tool which places greater emphasis on the research evidence is called for. Otherwise, given the limitations of such tools, their use may actively hinder the establishment of successful breast feeding.

An evaluation of skills acquisition on the WHO/UNICEF Breastfeeding Management Course using the pre-validated Breastfeeding Support Skills Tool (BeSST).

OBJECTIVE: To test the hypothesis that midwives who had completed the 20-hour WHO/UNICEF Breastfeeding Management Course would score significantly higher on a validated, quantitative measure of breast-feeding support skills, the Breastfeeding Support Skills Tool (BeSST), than a control group of midwives who had not undertaken the course. DESIGN: Breast feeding support skills were assessed using a between-subjects design conducted in midwives who had not attended the course and at two weeks following the 20 hour course. PARTICIPANTS AND SETTING: Two groups, consisting of 13 pre- and 15 post-course midwives, were compared. The research was carried out at four hospital sites in the UK, three of which had undertaken the 20 hour course and one which had not adopted the course. FINDINGS: Scores on the BeSST were significantly higher in the post-course group (mean = 29.9) than in the pre-course group (mean = 19.8), t (23.39) = 2.94, P < 0.01. KEY CONCLUSIONS: It is clear that breast-feeding support skills, as demonstrated by the BeSST, are significantly improved two weeks following the 20-hour WHO/UNICEF Breastfeeding Management Course. IMPLICATIONS FOR PRACTICE: By demonstrating the effectiveness of the 20-hour course in teaching breast-feeding support skills, additional hospitals may be encouraged to adopt the course and thereby contribute further to the advancement of optimum breast-feeding practices. Furthermore, this approach to assessment may be transferred to other areas of midwifery practice enabling the effective evaluation of courses and assessment of student learning.

Cardiovascular functioning during the menstrual cycle.

Variations in cardiovascular functioning during the 'normal' menstrual cycle have been little researched. Resting-blood pressures, resting-heart rate, rate-pressure product (RPP) and a derived index of fitness (Schneider Index) were monitored throughout natural, hormonally defined menstrual cycles. Volunteers were 26 women (20-48 years) who had regular (25-35 days) cycles. Their blood pressures and heart rate (at rest and according to Schneider's protocol) were measured at the same time daily (Monday-Friday) for 5 weeks. Daily, early morning-urine samples were assayed for sex hormones enabling accurate definition of cycle phase for each woman. Resting systolic-blood pressure was significantly higher in the ovulatory phase (P < 0.05) than in the follicular or luteal phases, but resting-diastolic pressures did not differ significantly between phases. Resting-heart rate was significantly higher in both ovulatory (P < 0.01) and luteal (P < 0.01) phases than in the menstrual and follicular phases. The Schneider Index was higher during the follicular phase than during the ovulatory (P < 0.005) or luteal (P < 0.01) phases, the RPP was higher during the ovulatory phase than during the bleeding (P < 0.05) and follicular (P < 0.005) phases. These findings provide a pattern of menstrual cycle-related variation in cardiovascular functioning that can be related to established actions of the ovarian steroids.