Assessing zinc status in humans

Purpose of Review To examine the most recent literature that provides new data regarding the potential and emerging biomarkers for zinc status in individuals. Recent findings Suboptimal dietary zinc intake is estimated to affect 17% of the world’s population, however the assessment of zinc status is notoriously difficult. A systematic review and meta-analysis of studies investigating biochemical biomarkers of zinc status was conducted by the European Micronutrient Recommendations Aligned (EURRECA) network. This review summarised the data published from inception to 2007. More recently (2016), an international expert panel, convened by the Biomarker of Nutrition for Development (BOND) initiative, published an extensive review the literature addressing biomarkers of zinc status in populations and individuals and categorised the biomarkers as useful (dietary intake, serum [Zn], stunting), potentially useful (hair [Zn], urine [Zn], neurobehavioural function), and emerging (nail [Zn], oxidative stress and DNA integrity, zinc kinetics, zinc dependent proteins, taste acuity). Summary The most recent data on the potentially useful biomarkers support the further investigation of hair [Zn] and indices of neurological function, particularly those assessing memory and attention. Of the emerging biomarkers, the measurement of DNA integrity and the expression of zinc transport proteins look promising

Special considerations for vitamin D in the South Asian population in the UK

The human requirement for vitamin D is achieved primarily through the synthesis of this pre-hormone in the skin during exposure to UVB radiation, with only a minor contribution from the diet year-round. Achieving optimal vitamin D status is therefore largely dependent upon adequate exposure of the skin to sunlight, however the length of exposure required varies with latitude and season, and is also dependent upon skin pigmentation with darker skin requiring greater exposure than fair skin due to the protective effects of melanin against ultraviolet B (UVB) radiation. In northern European latitudes, where UVB radiation between the months of October and March is of insufficient intensity for the synthesis of vitamin D via this route, vitamin D deficiency is a public health concern, particularly for South Asian diaspora and other dark skinned ethnic minority communities. The consequences of vitamin D deficiency include poor bone health, including rickets and osteomalacia. In addition there is increasing awareness of an important role for vitamin D in the development and progression of chronic diseases including type 2 diabetes which is prevalent in South Asian populations. The aim of this review is to examine some of the most recent reports of vitamin D status in South Asian diaspora communities, and to explore its impact on bone health. In addition, we will examine the putative association between type 2 diabetes and vitamin D deficiency in South Asian populations and the current guidelines for treatment of vitamin D deficiency of South Asians in primary care settings

The Long Term Impact of Micronutrient Supplementation during Infancy on Cognition and Executive Function Performance in Pre-School Children

Brain growth and development are critically dependent on several micronutrients. During early development cellular activity may be sensitive to micronutrient deficiencies, however the evidence from human studies is equivocal. The objective of this study was to examine the long-term cognitive and social-emotional effects of multiple micronutrient supplementation compared with iron supplementation alone, administered during infancy. This study was a follow-up to an initial randomized, double-blind controlled trial (RCT) in 2010 in which 902 infants, aged 6-17 months, from Lima, Peru, were given daily supplements of either iron (Fe) or multiple micronutrients (MMN) including zinc (451 in each group). The supplementation period for both groups was six months. In 2012, a subsample of 184 children from the original cohort (now aged 36-48 months) was randomly selected to participate in a follow-up trial and was assessed for intelligence, working memory, inhibition, and executive function. The tests showed no significant differences between the supplementation groups though there were some gender differences, with girls displaying higher scores than boys across both groups on the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) Verbal IQ sentences subtest, the Day-Night cognitive test and on the Brief Infant-Toddler Social Emotional Assessment (BITSEA) social competency, and boys scoring higher than girls in problem behaviour. The results indicate that MMN supplementation had no long term additional effects on cognitive function compared with iron supplementation alone. The timing of supplement administration for maximum impact on a child's cognitive development requires further investigation

The Global Challenge of Hidden Hunger: Perspectives from the Field

The aim of this review paper is to explore the strategies employed to tackle micronutrient deficiencies with illustrations from field-based experience. Hidden hunger is the presence of multiple micronutrient deficiencies (particularly iron, zinc, iodine and vitamin A), which can occur without a deficit in energy intake as a result of consuming an energy dense, but nutrient poor diet. It is estimated that affects more than two billion people worldwide, particularly in low- and middle-income countries where there is a reliance on low cost food staples and where the diversity of the diet is limited. Finding a way to improve the nutritional quality of diets for the poorest people is central to meeting the United Nations Sustainable Development Goals (SDGs) particularly SDG2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture. As we pass the midpoint of the United Nations’ Decade for Action on Nutrition, it is timely to reflect on progress towards achieving SDG2 and the strategies to reduce hidden hunger. Many low- and middle-income countries are falling behind national nutrition targets, and this been exacerbated by the COVID-19 pandemic as well as other recent shocks to the global food system which have disproportionately impacted the world’s most vulnerable communities. Addressing inequalities within the food system must be central to developing a sustainable, cost effective strategy for improving food quality that delivers benefit to the seldom heard and marginalised communities

Fortification or Biofortification: Complimentary strategies or duplication of effort?

Micronutrient deficiencies continue to be a global concern, with the most common deficiencies being vitamin A, iron, zinc and B vitamins (folate and B12). Addressing this requires strategies that are scalable and equitable such that they reach all members of a population irrespective of socioeconomic status and geography. Fortification and biofortification offer potential large-scale solutions, however each have strengths and limitations depending on the context, particularly the cultural and political factors that may create barriers or opportunities for effectiveness. Planning how to target scarce resources for maximum impact requires an in-depth knowledge and understanding of local food systems and market dynamics, alongside strong government policy and legislative support. A food fortification programme was launched in Pakistan in 2016, supported by UK Aid and designed to address the high prevalence of vitamin A, iron and zinc deficiency, particularly in women and children. In the same year the first zinc biofortified variety of wheat, Zincol-2016, was released in Pakistan, supported and developed through the HarvestPlus programme in collaboration with the Pakistan National Agriculture Research Centre. This review explores the challenges faced by fortification and biofortification, initiated independently, (but around the same time) in Pakistan

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

The relationship between zinc intake and serum/plasma zinc concentration in adults: a systematic review and dose–response meta-analysis by the EURRECA Network

Dietary zinc recommendations vary widely across Europe due to the heterogeneity of pproaches used by expert panels. Under the EURRECA consortium a protocol was designed to systematically review and undertake meta-analyses of research data to create a database that includes “best practice” guidelines which can be used as a resource by future panels when setting micronutrient recommendations. As part of this process, the objective of the present study was to undertake a systematic review and meta-analysis of previously published data describing the relationship between zinc intake and status in adults. Searches were performed of literature published up to February 2010 using MEDLINE, Embase, and Cochrane Library. Data extracted included population characteristics, dose of zinc, duration of study, dietary intake of zinc, and mean concentration of zinc in plasma or serum at the end of the intervention period. An intake-status regression coefficient was estimated for each individual study, and pooled meta-analysis undertaken. The overall pooled for zinc supplementation on serum/plasma zinc concentrations from RCTs and observational studies was 0.08 (95% CI 0.05, 0.11; p<0.0001; I2 84.5%). An overall of 0.08 means that for every doubling in zinc intake, the difference in zinc serum or plasma concentration is (20.08 = 1.06), which is 6%. Whether the dose-response relationship, as provided in this paper, could be used as either qualitative or quantitative evidence to substantiate the daily zinc intake dose necessary to achieve normal or optimal levels of biomarkers for zinc status, remains a matter of discussion

Dietary Calcium Intake, Vitamin D Status, and Bone Health in Postmenopausal Women in Rural Pakistan

The high prevalence of osteoporosis in Pakistan is of public-health concern. However, there is a paucity of information regarding nutrition and bone density in rural communities. The purpose of this study was to evaluate the dietary and lifestyle factors that impact bone health in Nahaqi. Data were collected from 140 postmenopausal women using an interviewer-administered 24-hour dietary recall questionnaire. Bone mineral density was estimated using the quantitative ultrasound index (QUI). Serum 25(OH)D was measured in fasting blood samples. The QUI scores revealed that 42% and 29% of the women had T-scores, indicative of osteopaenia and osteoporosis respectively. The mean calcium intake was 346 mg/d, which is less than 50% of the recommended daily intake. The QUI correlated with 25(OH)D after controlling for age (p=0.021, r=0.41, r2=0.168). Vitamin D deficiency and low intake of dietary calcium are two key factors contributing to poor bone health in this population

Effect of zinc intake on growth in infants: A meta-analysis

A systematic review and meta-analysis of available randomized controlled trials (RCTs) was conducted to evaluate the effect of zinc (Zn) intake on growth in infants. Out of 5500 studies identified through electronic searches and reference lists, 19 RCTs were selected after applying the exclusion/inclusion criteria. The influence of Zn intake on growth was considered in the overall meta-analysis. Other variables were also taken into account as possible effect modifiers: doses of Zn intake, intervention duration, nutritional status, and risk of bias. From each select growth study, final measures of weight, length, mid upper arm circumference (MUAC), head circumference, weight for age z-score (WAZ), length for age z-score (LAZ), and weight for length z-score (WLZ) were assessed. Pooled β and 95% confidence interval (CI) were calculated. Additionally, we carried out a sensitivity analysis. Zn intake was not associated with weight, length, MUAC, head circumference, and LAZ in the pooled analyses. However, Zn intake had a positive and statistically effect on WAZ (β = 0.06; 95%CI 0.02 to 0.10) and WLZ (β = 0.05; 95%CI 0.01 to 0.08). The dose–response relationship between Zn intake and these parameters indicated that a doubling of Zn intake increased WAZ and WLZ by approximately 4%. Substantial heterogeneity was present only in length analyses (I2 = 45%; p = 0.03). Zn intake was positively associated with length values at short time (four to 20 weeks) (β = 0.01; CI 95% 0 to 0.02) and at medium doses of Zn (4.1 to 8 mg/day) (β = 0.003; CI 95% 0 to 0.01). Nevertheless, the effect magnitude was small. Our results indicate that Zn intake increases growth parameters of infants. Nonetheless, interpretation of these results should be carefully considered