Background: Zinc is an essential micronutrient for human health and has numerous structural and biochemical roles. The search for a reliable, sensitive, and specific index of zinc status has been the subject of considerable research, which has resulted in the identification of a number of potentially useful biomarkers.

Background: Dietary selenium intakes in many countries, including the United Kingdom, are lower than international recommendations. No functional consequences of these lower intakes have been recognized, although experimental studies suggest that they might contribute to reduced immune function, increased cancer incidence, and increased susceptibility to viral disease. Objective: The objective was to assess whether administration of small selenium supplements to otherwise healthy UK subjects leads to functional changes in immune status and the rates of clearance and mutation of a picornavirus: live attenuated polio vaccine. Design: Twenty-two adult UK subjects with relatively low plasma selenium concentrations (<1.2 μmol/L, ≈60% of those screened) received 50 or 100 μg Se (as sodium selenite) or placebo daily for 15 wk in a double-blind study. All subjects received an oral live attenuated poliomyelitis vaccine after 6 wk and enriched stable ⁷⁴Se intravenously 3 wk later. Results: Selenium supplementation increased plasma selenium concentrations, the body exchangeable selenium pool (measured by using ⁷⁴Se), and lymphocyte phospholipid and cytosolic glutathione peroxidase activities. Selenium supplements augmented the cellular immune response through an increased production of interferon γ and other cytokines, an earlier peak T cell proliferation, and an increase in T helper cells. Humoral immune responses were unaffected. Selenium-supplemented subjects also showed more rapid clearance of the poliovirus, and the poliovirus reverse transcriptase–polymerase chain reaction products recovered from the feces of the supplemented subjects contained a lower number of mutations. Conclusions: The data indicate that these subjects had a functional selenium deficit with suboptimal immune status and a deficit in viral handling. They also suggest that the additional 100 μg Se/d may be insufficient to support optimal function.

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 it 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 UN sustainable development goals particularly sustainable development goal 2: end hunger, achieve food security and improved nutrition and promote sustainable agriculture. As we pass the midpoint of the UN's Decade for Action on Nutrition, it is timely to reflect on progress towards achieving sustainable development goal 2 and the strategies to reduce hidden hunger. Many low- and middle-income countries are falling behind national nutrition targets, and this has 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.

This review addresses the prevalence of zinc deficiency in Low‐ and Middle‐income Countries (LMICs) and assesses the available strategies for its alleviation. The paucity of national‐level data on the zinc deficiency in LMICs is partially a result of the lack of a reliable biomarker. Zinc deficiency appears to be a public health problem in almost all the LMICs, irrespective of the recommended indicators (plasma zinc concentration, dietary zinc adequacy and stunting prevalence) used. Based on plasma/serum zinc concentration (PZC), which is the most appropriate indicator at present, the prevalence of zinc deficiency in LMICs is of concern. Among the 25 countries for which national PZC data were available, 23 had a zinc deficiency prevalence of >20% for at least one physiological group. Zinc supplementation is largely restricted as an adjunct therapy for diarrhoea management in children, and the best platform and the most effective way of preventive zinc supplementation delivery remains to be established. Impact assessment for current zinc fortification programmes in LMICs and the effectiveness of zinc supplementation as part of a multi‐micronutrient powder is to be determined. Dietary diversification, though promising for LMICs, is in the nascent stages of development at present. Inclusion of meat and animal products can be an important way of improving zinc status. Programmatic experience with the promotion of home processing techniques to increase absorbable zinc in the diet is lacking. Conventional biofortification techniques are gaining recognition in LMICs; however, transgenic biofortification as a strategy remains controversial.

Osteoporosis is almost universal in very old age, and is a major cause of morbidity and mortality in the elderly of both sexes. Bone is lost at a rate of 0·2–0·5 %/year in both men and women after the age of 40–45 years. The causes of age-related changes in bone mass are multifactorial and include genetic predisposition, nutritional factors, endocrine changes, habitual exercise levels and body weight. Bone loss is accelerated to 2–5 % year immediately before and for up to 10 years post-menopause (Heaney, 1986). In women hormone-replacement therapy is effective in reducing the rate of bone loss caused by this peri-menopausal decrease in hormone levels (Smith & Studd, 1993); however, in men and older women (>10 years post-menopause) nutrition plays a key role in the rate of bone loss. One factor contributing to bone loss in the elderly may be a subclinical Zn and/or Cu deficiency, due to a reduced dietary intake of micronutrients and reduced absorption (Thomson & Keelan, 1986). Zn and Cu are essential cofactors for enzymes involved in the synthesis of various bone matrix constituents. Paradoxically, Ca supplementation may accentuate the problem of reduced Zn and Cu levels by impairing the absorption of simultaneously-ingested Zn and the retention of Cu (Snedeker et al. 1982; Grekas et al. 1988). The present paper will review the current literature on the potential benefits of Cu and Zn supplementation in reducing bone loss, and present new information on the effect of Ca supplementation on Zn and Cu status in post-menopausal women with osteoporosis.

Zinc could have a protective role against type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis aimed to evaluate the association between dietary, supplementary, and total zinc intake, as well as serum/plasma and whole blood zinc concentration, and risk of T2DM. Observational studies, conducted on cases of incident diabetes or T2DM patients and healthy subjects that reported a measure of association between zinc exposure and T2DM, were selected. Random effects meta-analyses were applied to obtain combined results. Stratified meta-analyses and meta-regressions were executed to assess sources of heterogeneity, as well as the impact of covariates on the findings. From 12,136 publications, 16 studies were selected. The odds ratio (OR) for T2DM comparing the highest versus lowest zinc intake from diet was 0.87 (95% CI: 0.78–0.98). Nevertheless, no association between supplementary or total zinc intake from both diet and supplementation, and T2DM was observed. A direct relationship was found between serum/plasma zinc levels and T2DM (OR = 1.64, 95% CI: 1.25–2.14). A moderately high dietary zinc intake, in relation to the Dietary Reference Intake, could reduce by 13% the risk of T2DM, and up to 41% in rural areas. Conversely, elevated serum/plasma zinc concentration was associated with an increased risk of T2DM by 64%, suggesting disturbances in zinc homeostasis.