Inadequate Zn Intake Research Articles

Modeling the Contribution of Multiple Micronutrient Fortification of Salt to Daily Nutrient Intake Among the Ethiopian Population

BackgroundSalt is an affordable commodity and has wide coverage regardless of economic and social status and, hence, could be suitable vehicle for multiple micronutrient fortification. ObjectivesThis study aimed to simulate the contribution folic acid and zinc fortification of iodized salt to nutrient intake among the Ethiopian population. MethodsThe 2013 Ethiopian National Food Consumption Survey and various food composition tables were used to estimate baseline individual-level micronutrient intake. Usual intake was estimated using the Simulating Intake of Micronutrients for Policy Learning and Engagement macro tool. Discretionary salt consumption was calculated from total salt intake estimated using urinary sodium excretion. Fortificant addition rates were set to obtain maximum nutrient intake while simultaneously constraining that population with intake above the tolerable upper intake level to <5%. Addis Ababa and Somali (N = 2271), the regions with relatively the lowest and highest micronutrient deficiency prevalence in Ethiopia, were selected. ResultBaseline median intake of Zn was below the estimated average requirement for all demographic groups. Inadequate Zn intake ranged from 73% to 99%, the highest prevalence being observed among women in lower class of wealth quintiles from Somali region. Dietary folate inadequacy was as low as 2% among men in Addis Ababa but almost all (99%) women from Somali region had inadequate folate intake. Calculated discretionary salt intake was 7.5 g/d for adult men and women and 3.4 g/d for children. With addition 0.8 mg Zn and 30 μg of folic acid per gram of salt, multiple salt fortification is estimated to reduce Zn inadequacy by 38 percentage points in urban areas and19 percentage points in rural areas. Modeled reduction in folate inadequacy were 18% in urban areas and 22% in rural areas. ConclusionsMultiple salt fortification could be an effective approach to address micronutrient adequacy in Ethiopia given efficacious, technological, and economical feasibility.

Breastmilk mineral composition among well-educated mothers from Central Poland – Associations with maternal dietary intake, dietary patterns and infant psychomotor development

BackgroundMaternal dietary habits could affect breastmilk mineral composition, which may influence infant development. Mineral dietary intake or supplementation slightly affects its breastmilk concentration. However, the intake of selected food groups or dietary patterns that reflect diet complexity could have a greater impact. Hence, the aim of the study was to assess breastmilk mineral composition at one, three, and six months of lactation among mothers living in urban area of Central Poland, as well as the evaluate maternal dietary determinants and associations with infant anthropometric and psychomotor development. MethodsThe study was conducted among 43 healthy and exclusively breastfeeding mothers. In the first, third, and sixth months of lactation, we collected breastmilk samples and assessed the concentration of Ca, P, Zn, Fe, Se, Ni, As, Pb, and Cd using the ICP-MS method. Maternal dietary habits were evaluated by a food frequency questionnaire in the first month of lactation, whereas in the third and sixth by the three-day food record. Based on the collected data adherence to the Polish-adapted Mediterranean (Pl-aMED; 1 month) and the DASH diet (Mellen’s Index; 3 and 6 months) was assessed. In the third and sixth months of lactation infant anthropometric parameters and the sixth month of lactation psychomotor development were evaluated. ResultsBreastmilk Se, Ni, As, Pb, and Cd levels were under the LOQ in all the breastmilk samples at all study visits. Median breastmilk mineral concentrations of Ca, P, Zn, and Fe in the first, third, and sixth months of lactation varied from 381.9 to 332.7 mg/L, 161.6 to 139.1 mg/L, 2.2 to 0.8 mg/L, and 0.26 to 0.17 mg/L, respectively. Maternal dietary intake and supplementation did not affect breastmilk Ca, P, Zn, and Fe. Pl-aMED scores were associated with breastmilk Ca (β = 0.489, 95% CI 0.180 – 0.799, p = 0.003) and Zn (β = 0.499, 95% CI 0.199 – 0.798, p = 0.002) in the first month of lactation, whereas no association with the DASH diet were observed in the third and sixth month of lactation. Breastmilk Fe in the third month was associated with infant motor development (β = 0.420, 95% CI 0.113 – 0.727, p = 0.009) in the sixth month of life, but no other associations with anthropometric or psychomotor development were observed. Moreover, we estimated that few infants meet their adequate intake (AI) requirements for P, Zn, and Fe. ConclusionOur study showed that maternal adherence to Pl-aMED is a significant predictor of breastmilk Ca and Zn in the first month of lactation, which may be especially important considering that more than 75% of infants had inadequate Zn intake. Moreover, we found that breastmilk Fe positively influenced infant motor development, despite the majority of infants having inadequate intake. On the other hand, no infant had deficiency symptoms, which emphasizes the necessity to evaluate of AI norms for infants.

ZnO nanoparticles improve bioactive compounds, enzymatic activity and zinc concentration in grapevine

The low availability of micronutrients in the soil leads to a deficit of these micronutrients in crops, causing malnutrition in the population. Approximately 3,000 million people in the world have health problems caused by inadequate Zn intake. Agronomic biofortification is a way to produce crops rich in micronutrients and mitigate malnutrition problems. Nano biofortification with zinc oxide nanoparticles (NPs-ZnO) is a good strategy to mitigate and increase the nutritional content of the edible part of the plant. The aim was to determine the effect of foliar spraying with NPs-ZnO on yield and biosynthesis of enzymatic and non-enzymatic antioxidant compounds and their bioaccumulation. In this study, the effect of foliar fertilization with NPs-ZnO: 0, 25, 50, 75, and 100 mg L-1, on yield, the content of bioactive compounds and their bioaccumulation in grapevine berries was evaluated. The distribution of the treatments was under a completely randomized design, each treatment consisted of 10 plants, each representing one experimental unit. The treatments were applied by foliar sprays at fruit formation, in veraison and 15 days before harvest. Foliar spraying with NPs-ZnO positively modifies yield, the content of bioactive compounds, and their bioaccumulation. Doses of 50-75 mg L-1 of NPs-ZnO increased crop yield, and oenological parameters. In addition, all doses evaluated modified enzymatic and non-enzymatic antioxidants, and improving Zn concentration in grapevine berries. Foliar spraying of NPs-ZnO is an alternative to improve grape quality and yield, in addition to enriching its nutritional and antioxidant content.

Proof of concept and early development stage of market-oriented high iron and zinc rice expressing dicot ferritin and rice nicotianamine synthase genes

Micronutrient deficiencies such as iron (Fe), zinc (Zn), and vitamin A, constitute a severe global public health phenomenon. Over half of preschool children and two-thirds of nonpregnant women of reproductive age worldwide have micronutrient deficiencies. Biofortification is a cost-effective strategy that comprises a meaningful and sustainable means of addressing this issue by delivering micronutrients through staple foods to populations with limited access to diverse diets and other nutritional interventions. Here, we report on the proof-of-concept and early development stage of a collection of biofortified rice events with a high density of Fe and Zn in polished grains that have been pursued further to advance development for product release. In total, eight constructs were developed specifically expressing dicot ferritins and the rice nicotianamine synthase 2 (OsNAS2) gene under different combinations of promoters. A large-scale transformation of these constructs to Bangladesh and Philippines commercial indica cultivars and subsequent molecular screening and confined field evaluations resulted in the identification of a pool of ten events with Fe and Zn concentrations in polished grains of up to 11 μg g−1 and up to 37 μg g−1, respectively. The latter has the potential to reduce the prevalence of inadequate Zn intake for women of childbearing age in Bangladesh and in the Philippines by 30% and 50%, respectively, compared to the current prevalence. To our knowledge, this is the first potential biotechnology public-sector product that adopts the product cycle phase-gated approach, routinely applied in the private sector.

The GZnC1 variant from common wild rice influences grain Zn content.

Zinc (Zn) deficiency, caused by inadequate Zn intake in the human diet, has serious health implications. Rice (Oryza sativa) is the staple food in regions with a high incidence of Zn deficiency, so raising Zn levels in rice grain could help alleviate Zn deficiency. The wild relatives of cultivated rice vary widely in grain Zn content and thus are suitable resources for improving this trait. However, few loci underlying grain Zn content have been identified in wild rice relatives. Here, we identified a major quantitative trait locus for grain Zn content, Grain Zn Content 1 (qGZnC1), from Yuanjiang common wild rice (Oryza rufipogon Griff.) using map-based cloning. Down-regulating GZnC1 expression reduced the grain Zn content, whereas the presence of GZnC1 had the opposite effect, indicating that GZnC1 is involved in grain Zn content in rice. Notably, GZnC1 is identical to a previously reported gene, EMBRYO SAC ABORTION 1 (ESA1), involved in seed setting rate. The mutation in GZnC1/ESA1 at position 1819 (T1819C) causes delayed termination of protein translation. In addition, GZnC1 is specifically expressed in developing panicles. Several genes related to Zn-transporter genes were up-regulated in the presence of GZnC1. Our results suggest that GZnC1 activates Zn transporters to promote Zn distribution in panicles. Our work thus sheds light on the genetic mechanism of Zn accumulation in rice grain and provides a new genetic resource for improving Zn content in rice.

Zinc Deficiency, Plasma Fatty Acid Profile and Desaturase Activities in Hemodialysis Patients: Is Supplementation Necessary?

Background: Desaturation and elongation are critical processes in endogenous metabolic fatty acid pathways. Zinc (Zn) is a cofactor for desaturases and elongases enzymes. There is limited evidence regarding the relationships between biomarkers of Zn status, nutritional intake, plasma phospholipid fatty acid profile and clinical outcomes among patients undergoing hemodialysis (HD).Objective: To examine the relationships between dietary and serum levels of Zn and Cu/Zn ratio and to explore associations of these micronutrients with PUFA profile and estimated desaturase and elongase enzyme activities in serum phospholipids among HD patients.Methods: This study included 40 adult patients undergoing hemodialysis treatment. Repeated 24-h recalls were applied for dietary intake assessment. Serum concentration of Zn and Cu were determined using inductively coupled plasma mass spectrometry and fatty acid composition by gas-liquid chromatography. Desaturase and elongase activities were calculated from product-precursor fatty acid ratios.Results: Inadequate dietary Zn intake was found in 55% of HD patients. They all had serum Zn concentration below the reference value of 60 μg/dL (mean 38.8 ± 7.72 μg/dL). Adequate zinc intake was accompanied with significantly higher intake of energy, total fats, SFA, MUFA and proteins. There was no correlation between Zn serum status and Zn intake estimates. Serum Cu/Zn ratio was high, (2.76 ± 0.68), directly and significantly associated with HD period, CRP, BMI, VFA, and inversely with Kt/V, albumin, iron, and iPTH. The n-6/n-3 ratio in plasma phospholipids was elevated (12.25 ± 3.45) and patients with inadequate Zn intake had lower n-3 PUFA intake and status compared to those with adequate intake. Serum Zn concentrations were inversely correlated with linoleic/dihomo-γ-linolenic acid ratio (LA/DGLA) (p = 0.037), related to D6-desaturase activity (p = 0.033) and directly with DGLA relative abundances (p = 0.024). Cu status was inversely associated with EPA level (p = 0.03) and estimates of elongase activity (p = 0.001). Furthermore, positive relationship was found between the Cu/Zn ratio and determined elongase value (p = 0.01).Conclusion: Findings of this study underpin the high prevalence of Zn deficiency and inadequate n-3 PUFA intake and status among subjects undergoing HD. The results obtained indicate that the assessment of Zn status should be a standard parameter of nutritional status screening in HD patients while emphasizing the importance of Cu/Zn determination. Although further research is warranted, Zn and-n-3 PUFA supplementation in HD patients might be beneficial for the prevention and attenuation of adverse health outcomes

Estimated Absorbed Zinc Intake Is Low in Breastfed 6–11.9 Month Old Infants: Data From the Feeding Infants and Toddlers (FITS) Study, 2016

ObjectivesTo calculate daily absorbed zinc (Zn) intakes, evaluate and rank dietary Zn sources, and assess the percentage of 6–11.9 month old breastfed, mixed fed, and formula fed infants at risk for inadequate absorbed Zn based on their intake and dietary Zn sources. MethodsFITS is a cross-sectional dietary survey of children aged 0–47.9 months in the U.S. For this analysis, Zn absorption factors utilized in the Dietary Reference Intake (DRI) methodology (50% for human milk, 30% for all other sources) were applied to all food sources of Zn in the 24 hour dietary recall for 6–11.9 month old infants (n = 902). The estimated amount of Zn in human milk (0.83μg/ml) and the absorbed Zn requirement for 6–12 month old infants (836μg/day) were based on DRI methodology. Dietary Zn sources were ranked according to contribution to total calculated absorbed Zn. Differences in calculated mean absorbed Zn intakes and the percentage of infants falling below the daily absorbed zinc requirement among breastfed (n = 296), mixed fed (n = 102), and formula fed infants (n = 448) were assessed by unpaired t-tests. ResultsAmong 6–8.9 month old breastfed infants, the mean absorbed Zn (0.58 μg/day) and percentage of infants falling below the daily dietary intake requirement (90.9%) were significantly different than mixed fed, (1.32μg/day and 14.5% below) or formula fed infants (2.17μg/day and 0.1% below, p < 0.0001 for all comparisons). Among 9–11.9 month old infants, the mean absorbed Zn intakes and percentage of infants falling below the daily requirement improved, but remained significantly different across all feeding types (1.00 μg/day and 33.4% of infants below in breastfed, 1.33μg/day and 13.8% below in mixed fed, 2.41μg/day and 0.0% below in formula fed, p < 0.0001 for all comparisons except difference in means for breastfed vs. mixed fed p = 0.0011). The primary sources of calculated absorbed Zn were human milk or infant formula followed by infant cereal and then meat. ConclusionsUsing established factors to account for bioavailability of dietary Zn sources, the majority of breastfed older infants are at risk for inadequate Zn intake, especially during the initial time of introduction of solid foods. Focusing on high Zn containing intake, including meat and fortified cereals may be important to assure adequate Zn intake. Funding SourcesNestlé Research, Switzerland and Nestlé Nutrition, Arlington, VA.

Trends in the national food supply of absorbable zinc in Ethiopia: 1990-2017.

This study analysed trends (1990-2017) in the availability of absorbable Zn in the national food supply of Ethiopia. The supply statistics of ninety-five food groups were obtained from the Ethiopian Food Balance Sheets compiled by FAO. Zn and phytate contents were determined using multiple composition databases and absorbable Zn estimated via the 'Miller' equation. Estimated average requirement cut-point method was performed to estimate proportions at risk of inadequate intake. Physiological Zn requirements set by Institute of Medicine (IOM) and International Zinc Nutrition Consultative Group (IZiNCG) were applied. Time trend was tested using Mann-Kendall statistics and Z-score and P-values are provided. Ethiopia. NA. Between 1990 and 2017, the supply of total dietary Zn was increased by 33 % from 9·8 to 13·0 mg/person/d (Z = 6·46, P < 0·001). However, that of absorbable Zn remained constant around 2·7 mg/person/d (Z = 1·87, P > 0·05). Over the period, the phytate supply was increased by 48 % from 1415 to 2095 mg/person/d (Z = 6·50, P < 0·001) and fractional Zn absorption declined from 27·0 to 20·9 % (Z = -6·62, P < 0·001). The contribution of animal source foods for bioavailable Zn was reduced by 45 % and the share of cereals raised by 11·3 %. Over the period, prevalence of inadequate Zn intake estimated using IZiNCG and IOM requirements remained constant around 10 and 50 %, respectively. Between 1990 and 2017, Ethiopia considerably increased the total supply of Zn; however, meaningful changes in bioavailable Zn and prevalence of deficiency were not observed due to proportional rise in phytate and concomitant decline in Zn absorption.

Zinc Levels and Birth Weight in Pregnant Women with Gestational Diabetes Mellitus: A Matched Cohort Study in China

Zinc (Zn) has been suggested to impact fetal growth. However, the effect may be complicated by gestational diabetes mellitus (GDM) due to its impact on fetal growth and placental transport. This study aims to investigate whether GDM modifies the association between Zn levels and birth weight. A cohort matched by GDM was established in Taiyuan, China, between 2012 and 2016, including 752 women with GDM and 744 women without. Dietary Zn intake was assessed during pregnancy. Maternal blood (MB) and cord blood (CB) Zn levels were measured at birth. Birth weight was standardized as the z score and categorized as high (HBW, >4000 g) and low (LBW, <2500 g) groups. Multivariate linear regression and multinomial logistic regression were used to examine the association between Zn levels and birth weight in offspring born to women with or without GDM. 88.8% (N = 1328) of the population had inadequate Zn intake during pregnancy. In women with GDM, MB Zn level was inversely associated with birth weight (β = -.17; 95% confidence interval (CI), -0.34 to -0.01), while CB Zn level was positively associated with birth weight (β = .38; 95% CI, 0.06-0.70); suggestive associations were observed between MB Zn level and LBW (odds ratio 2.01; 95% CI, 0.95-4.24) and between CB Zn level and HBW (odds ratio 2.37; 95% CI, 1.08-5.21). GDM may modify the associations between MB and CB Zn levels and birth weight in this population characterized by insufficient Zn intake. These findings suggest a previously unidentified path of adverse effects of GDM.

Dietary habits of newcomer children in Canada.

To explore the dietary habits, nutrient adequacies and dietary change experiences of immigrant and refugee children. Mixed-methods cross-sectional design. Children completed three 24 h dietary recalls to determine nutrient inadequacies. Parents and service providers were interviewed to capture dietary practices. Healthy Immigrant Children study, Saskatchewan, Canada. Three hundred immigrant and refugee children aged 3-13 years and twenty-two parents who lived in Regina or Saskatoon for less than 5 years; twenty-four newcomer services providers. Immigrant children had higher mean intakes of meat and alternatives, milk and alternatives, and whole grains; and consumed more vitamin B12, folate, Ca, vitamin D, Fe and Zn compared with refugee children. Refugee children were at higher risk of having inadequate intakes of folate (37 %) and Fe (18 %). Both immigrant and refugee children were at high risk of inadequate vitamin D (87 and 93 %, respectively) and Ca intakes (79 and 80 %), and a substantial portion were at risk for inadequate Zn intake (21 and 31 %). Participants mentioned challenges with maintaining a healthy traditional diet in the midst of a busy schedule, while responding to their children's demands for foods high in fat and sugar. Newcomer children are at risk for inadequate intakes of vitamin D, Ca and Zn, while refugee children are at additional risk for inadequate folate and Fe intakes. Newcomers to Canada may experience subtle or drastic changes in their food environment leading to dietary acculturation that includes increased consumption of foods high in sugar, salt and fat.

The influence of food consumption and socio-economic factors on the relationship between zinc and iron intake and status in a healthy population.

To examine Zn and Fe nutritional status of a healthy population by means of anthropometric, dietary and biochemical measurements and to investigate the relationship of usual Zn and Fe dietary intakes to Zn and Fe status. In addition, to examine the impact of food choices and socio-economic factors on Fe and Zn dietary intakes and status with the aim to identify groups at risk of dietary deficiency and suggest factors that may influence the status of these nutrients. Food consumption was assessed by 24 h recall questionnaires. Twenty biochemical parameters were measured, of which Hb, haematocrit, erythrocyte count and plasma concentrations of Fe and Zn were directly related to Fe and Zn nutrition. The prevalence of study participants with inadequate micronutrient intakes was calculated using the Estimated Average Requirement cut-point method. Serbia, Europe. Apparently healthy adults (25-65 years of age). Mean daily Zn and Fe intakes were 9·1 mg and 11·6 mg for males and 7·3 mg and 9·4 mg for females, respectively. Five per cent of the study population had inadequate dietary Fe intake and 15-25 % had inadequate Zn intake. Lower Hb concentrations were measured in women with lower Zn intakes. No differences in Fe and Zn intakes and status among various socio-economic groups were observed, except for Fe intake between the low-income and affluent groups. Regular follow-ups are needed to ensure that potential deficiencies of Zn and Fe do get recognized and addressed in a timely manner.

Zinc supplement use and contribution to zinc intake in Australian children.

The aims of the present study were to examine the Zn intake and characteristics of Zn supplement users and non-users and to survey Zn supplements that are commercially available. Cross-sectional national nutrition survey (2007 Australian Children's Nutrition and Physical Activity Survey) and a review of commercially available Zn supplements. Australia. Children (n 4834) aged 2-16 years. Zn supplement use was associated with younger age, being female, having a lower BMI and consuming a vegetarian or modified diet. Supplement users had significantly higher intakes of Zn than non-users in all age and gender subgroups. Adolescent boys aged 14-16 years who did not use Zn supplements were at highest risk of inadequate Zn intake (15 % compared with 1 % of users). Conversely, children aged 2-3 years were at highest risk of exceeding the recommended upper limit of Zn intake (86-87 % of users and 64-71 % of non-users), followed by children aged 4-8 years (9-29 % of users and 3-12 % of non-users). The most common sources of Zn supplements consumed by children were multi-vitamin and mineral preparations (92 %), followed by Zn-only supplements (5 %) and Zn-containing cold and flu, or cold sore supplements (3 %). A survey of commercially available Zn supplements revealed that the median elemental Zn content was 2 and 25 mg for multi-vitamin and mineral preparations and Zn-only supplements, respectively. Based on these data, widespread Zn supplement use among young children is unlikely to be warranted. The impact of exceeding the upper limit of Zn intake on biomarkers of Zn toxicity requires further investigation.

A historical review of progress in the assessment of dietary zinc intake as an indicator of population zinc status.

Dietary components influencing zinc (Zn) bioavailability were implicated in the first cases of human Zn deficiency in the Middle East in the 1960s. It was not until the 1980s that isotope tracer studies in humans quantified the effects of the type and/or quantity of Zn, protein, iron, and phytate (myo-inositol hexaphosphate) on Zn absorption in humans and confirmed the dose-dependent inhibitory effect of phytate on Zn absorption. This led to further analysis of the Zn and phytate content of foods. The use of phytate-to-Zn molar ratios as likely estimates of absorbable dietary Zn followed together with an assessment of their relationship with Zn biomarkers in low-income countries (LIC). In the 1990s, increasing knowledge of factors governing Zn-absorption diets led to refinements of Zn requirements and algorithms to estimate dietary Zn bioavailability. Their use highlighted that inadequate Zn intake from plant-based diets were a major etiological factor in morbidity and stunting in LIC, prompting the need to identify indicators of the population's Zn status. Major advances in analyses of dietary data pioneered by Beaton in 1980s led to the endorsement in 2007 of a dietary Zn indicator based on the prevalence of the population with usual Zn intake below the estimated average requirement for Zn. Risk of Zn deficiency is a public health concern when the prevalence of inadequate Zn intake is >25%. Recent findings that Zn bioavailability from high-phytate, whole-day diets is lower than previous estimates suggest that revision of Zn estimated average requirement for LIC may be warranted.

Zinc deficiency in neuronal biology

Adverse nutritional and environmental conditions during early development can irreversibly affect the nervous system. Zinc (Zn) deficiency associated with inadequate Zn intake and undernutrition is frequent throughout the world. Increasing evidence indicates that developmental Zn deficiency can lead to alterations in neonate and infant behavior, cognitive and motor performance that persist into adulthood. This review will address current knowledge on the events that are triggered in neuronal cells when Zn availability decreases and discuss their consequences on neuronal function and development. In neuronal cells, Zn deficiency induces oxidative stress, alters the normal structure and dynamics of the cytoskeleton, affects the modulation of transcription factors AP-1, NF-betaB and NFAT and induces a decreased cell proliferation and increased apoptotic death. Thus, these closely associated events can affect neuronal function and critical developmental events (neuronal proliferation, differentiation, plasticity and survival) when Zn availability decreases.

Zinc metabolism in animals: Pathology, immunology and genetics

Deficiency of dietary Zn rapidly reduces both appetite and growth, the latter effect being apparently caused by a failure of cell replication. Diagnosis of presymptomatic Zn deficiency depends largely on estimation of plasma Zn concentration but is complicated by reductions of it during a range of stressful conditions. In the latter cases, the decrease in plasma Zn concentration does not appear to be associated with inadequate Zn intake. Only two genetic defects of Zn metabolism are known in animals. One is associated with lethally inadequate concentrations of Zn in the milk of mice, the other with the A46 trait in Friesian cattle. A46 is a recessively inherited defect of Zn absorption which is lethal in the absence of major Zn supplementation of the diet. The characteristics of the disease are very similar to those of acrodermatitis enteropathica in man.

Zinc deficiency and the zinc requirements of calves and lambs.

1. The effects of changes in zinc intake on weight gain, plasma Zn concentration and the development of clinical lesions of Zn deficiency have been studies in Zn depletion and repletion studies with calves and lambs.2. A basal diet, the principal components of which are urea, dried egg white, starch, glucose, cellulose and arachis oil has been developed for trace element deficiency studies with ruminants.3. Weight gain ceased abruptly in both calves and lambs when either the unsupplemented basal diet was given or when Zn supplements provided only 0.05 mg Zn/kg live weight per day. Mean plasma Zn concentrations in these animals fell from pre-experiment values of between 0.8 and 1.2 μg Zn/ml to below 0.4 μg Zn/ml after 1 week on these treatments.4. Supplements providing 0.2 mg Zn/kg live weight per day were sufficient to maintain a good rate of growth but insufficient to prevent a fall in plasma Zn.5. Growth arrest occurring within 2 weeks and a rapid fall in plasma Zn occurring within 1 week after Zn supplements were withheld from calves and lambs that had previously received 0.7 mg Zn/kg live weight per day for 6 and 14 weeks respectively indicated that these species have only a limited capacity to store Zn in a form that can be utilized during periods of inadequate Zn intake.6. Tentative estimates are presented of the Zn requirements of calves maintained on this type of basal diet and the influence of ration composition of Zn availability is discussed.7. The possible value and the limitations of plasma Zn determination as an aid to the field diagnosis of Zn deficiency are considered.