Impact of micronutrient deficiencies on obesity

Micronutrient deficiencies have been found in obese individuals across age groups worldwide. While the effects of micronutrient deficiencies on human functions have been studied widely in different populations, there is limited information on how these micronutrient deficiencies affect obese populations. An examination of the available literature suggests associations exist between micronutrient deficiencies and obesity in different populations. These associations and possible mechanisms of the deficiencies' metabolic effects, such as their influence on leptin and insulin metabolism, are discussed here. Further studies are needed to clarify the roles of the different micronutrient deficiencies with respect to obesity and its comorbid conditions.     

控制微量营养素缺乏的历史和国际经验的借鉴

营养科学是一门生活的科学 ,它的发展和应用对人类的健康和生活质量起着重要的作用。在营养科学从营养素的发现到目前正在兴起的营养与基因研究的历史过程中 ,丰富的科学成就不断地应用于人类生活的现实 ,成为人们提高生命质量和增进健康的工具。目前的世界还存在着营养不足 ,以及越来越多的证据表明了营养与疾病、衰老、劳动能力的相关和作用 ,在社会经济发展中如何使人类最大限度地享有健康 ,将科学变成人们的生活 ,使知识成为生活的现实 ,应该是营养科学的出发点和归宿。即使是基因水平的研究 ,也必然是在解决人类健康和疾病的预防和治疗…     

Studies on micronutrient intakes and requirements in The Gambia

A series of studies are reviewed which have been undertaken to assess the impact of micronutrient deficiencies in a rural Gambian population. The purpose of these studies has been: firstly, to compare the measured 'home-food' micronutrient intakes with current knowledge of human requirements; secondly, where appropriate, to reassess requirements by controlled titration studies with specific nutrients; and thirdly, to attempt to clarify the functional significance of low intakes. Special emphasis has been placed on pregnant and lactating women, because of their increased requirements and potentially high risk status. For riboflavin, a total daily intake similar to, or slightly higher than, the current recommended daily amounts (RDA) acheived 'normal' Erythrocyte Glutathinone Reductase Activation Coefficient (EGRAC) values, with a corresponding marked improvement in the clinical picture. Ascorbate requirements of lactating women were greater than the current UK RDA. Measuerd intakes of β-carotene (or retinol) equivalents suggests a major dietary physilogical indicaes of vitamin A status were entirely within normal limits. For a variety of reasons the RDA for vitamin A seems ultra-generous, at least for adults. A newly-identified synergism between riboflavin and iron, affecting iron absorption and the mobilization of iron stores, has proved important. A multinutrient supplement has also been shown to improve work performance in children.     

Immunobiology of mild micronutrient deficiencies

Nutrition is a critical determinant of the outcome of host microbe interactions through a modulation of the immune response. Besides macronutrient malnutrition, deficiencies of several macronutrients also influence immune homeostasis and thus affect infection-related morbidity and mortality. Deficiencies of micronutrients like vitamin A, iron and zinc are widely prevalent among populations living in developing countries. Besides their severe deficiencies, subclinical deficiencies are known to impair biological functions in the host, immune function being one of them. The effects of these micronutrients on various immune mechanisms are briefly reviewed in this article.     

Effect of micronutrient supplementation on linear growth of children

This review summarizes the results of published, randomized clinical trials that have examined the impact of administration of micronutrients, singly or in combination to infants, preschool and school children on linear growth. Supplementation of single micronutrients resulted in small or no benefits on linear growth. A meta-analysis of zinc supplementation trials confirmed that zinc has a significant but small impact (0.22 sd units) on length gain in children 0-13 years of age. However, a recent study reported a substantially greater benefit (>1 sd) in stunted and non-stunted breast-fed infants 6-12 months of age. With iron supplementation, a beneficial effect was found only in anemic children. Vitamin A supplementation trials have reported little or no benefit on linear growth. Data currently available suggest some impact in children with clinical or biochemical vitamin A deficiency, but this issue needs confirmation. Few studies could be identified where a combination of micronutrients was given as a supplement or as fortified food; in the latter set of studies energy availability was assured. The impact on length without multiple micronutrient supplementation was no greater than that observed with single micronutrients. In conclusion, zinc and iron seem to have a modest effect on linear growth in deficient populations. Vitamin A is unlikely to have an important effect on linear growth. Limited available evidence does not allow us to conclude whether a combination of micronutrients, with or without additional food, would have a greater impact than that seen with zinc alone.     

补充微量营养素对艾滋病人免疫状态影响的研究

摘要:目的　研究补充微量营养素对艾滋病人免疫状态的影响。方法　选择艾滋病人,试验组服用复合微量营养素片,对照组服用安慰剂。研究开始及结束时分别进行体格测量、免疫状态的测定。结果　试验前各组对象的身高、体重和微量营养素摄入、细胞免疫及体液各项指标水平均无统计学差异（P＞0.05）。6 个月后,艾滋病人试验组免疫细胞及体液免疫指标均高于对照组,2组差异有统计学意义（P＜0.05）。结论　补充微量营养素能增进艾滋病人细胞免疫功能,并能提高艾滋病人体内IgA、IgG、IgM、补体C3水平。     

Efficacy of multiple micronutrient supplementation for improving anemia, micronutrient status, and growth in South African infants

Growth faltering, anemia, and multiple micronutrient deficiency are common during infancy in developing countries. This South African trial was part of a multicenter study aimed at testing the efficacy of multiple micronutrient supplementation on growth, anemia, micronutrient status, and morbidity during infancy across 4 countries. A total of 265 infants aged 6-12 mo were individually randomized to 1 of 4 intervention groups: a daily multiple micronutrient supplement (DMM), a daily placebo supplement (P); a multiple micronutrient supplement 1 d of the week and placebo supplement on the other days of the week (WMM), and a daily iron supplement (DI). For 6 mo, the blinded supplements were provided to mothers at monthly health clinic sessions, and consumption was verified during weekly household visits by community health workers, when morbidity was also checked. Weight and height of the infants were measured monthly, and blood samples were taken at the beginning and at the end for assessing the infants micronutrient status. There were no significant differences in nutritional status of the groups at baseline with 40% of infants with anemia (hemoglobin < 110 g/L), 16% vitamin A deficiency (plasma retinol < 0.7 micromol/L), 47% zinc deficiency (plasma zinc < 10.7 micromol/L), 2% underweight, and 11% stunting. There was no difference in growth or morbidity between the micronutrient supplemented groups and the P group during the 6-mo study. The DMM was the most effective intervention tested, not only for improving anemia but also for improving iron, zinc, riboflavin, and tocopherol status.     

A comparison of micronutrient inadequacy and risk of high micronutrient intakes among vitamin and mineral supplement users and nonusers in Canada

Although supplement use is prevalent in North America, there is little information on how supplements affect the prevalence of nutrient adequacy or risk of intakes greater than the tolerable upper intake level (UL). The objectives of this study were to compare the prevalence of nutrient adequacy and percent of intakes greater than the UL from diet alone between supplement users and nonusers and determine the contribution of supplements to nutrient intakes. Dietary intakes (24-h recall) and supplement use (previous 30 d) from respondents ≥1 y in the Canadian Community Health Survey 2.2 (n = 34,381) were used to estimate the prevalence of nutrient adequacy and intakes greater than the UL. Software for Intake Distribution Evaluation was used to estimate usual intakes. The prevalence of nutrient adequacy from diet alone was not significantly higher among supplement users than nonusers for any nutrient. Based on diet alone, children 1-13 y had a low prevalence of nutrient adequacy (<30%) except for vitamin D and calcium. Among respondents ≥14 y, inadequacies of vitamins A and D, calcium, and magnesium were >30%. For other nutrients, there was a low prevalence of nutrient adequacy. There were no nutrient intakes greater than the UL from diet alone, except zinc in children. When supplements were included, ≥10% of users in some age/sex groups had intakes of vitamins A and C, niacin, folic acid, iron, zinc, and magnesium greater than the UL, reaching >80% for vitamin A and niacin in children. In conclusion, from diet alone, the prevalence of nutrient adequacy was low for most nutrients except for calcium, magnesium, and vitamins A and D. For most nutrients, supplement users were not at greater risk of inadequacy than nonusers; supplement use sometimes led to intakes greater than the UL.     

Assessment and interpretation of micronutrient status during pregnancy

Accurate assessment of maternal micronutrient status is critical to the prevention of suboptimal micronutrient status and anaemia during pregnancy. Measurement of Fe, folate and vitamin B12 status is complicated by adaptive changes to maternal and placental physiology that markedly affect concentrations of circulating micronutrients and their functional biomarkers. Validation of new assessment methods by comparison with gold standards is often prevented by ethical considerations. Antenatal screening in the UK is predominantly concerned with the detection of anaemia, although estimation of maternal Fe stores by serum ferritin at the start of antenatal care may be a more effective preventive strategy. Functional assessment of maternal anaemia is highly problematic, so instead reference data are used for its definition. The effect of mild-to-moderate anaemia on pregnancy outcome is unclear because of the crude nature of its assessment and the influence of confounding factors. Fe-deficient erythropoiesis may be detected by assessment of erythrocyte Zn protoporphyrin and reticulocyte Hb, although such measures may be unavailable in many clinical laboratories. Serum soluble transferrin receptor is highly responsive to tissue Fe deficiency and is less affected by inflammation than most other indicators. Direct inter-assay comparison of serum and erythrocyte folate values is inadvisable since recovery rates differ greatly between methods. Serum total homocysteine is a useful functional biomarker of both folate and vitamin B12 status but during pregnancy is influenced by other factors that reduce its sensitivity. Isotope-dilution liquid chromatography-tandem MS and serum holo-transcobalamin provide new opportunities to gain detailed data of folate species and vitamin B12 fractions in large samples.     

Efficacy of multiple micronutrient supplementation for improving anemia, micronutrient status, growth, and morbidity of Peruvian infants

Anemia, micronutrient deficiencies, and growth faltering are still common in Peru. The study objective was to determine the efficacy of different micronutrient supplements in preventing growth failure, anemia, and micronutrient deficiencies in Peruvian infants. Three hundred and thirteen infants aged 6 to 12 mo participated in a double-blind, masked, controlled trial in which they were randomly assigned to receive either a daily dose of iron (DI), a daily dose of multiple micronutrients (DMM), a weekly dose of multiple micronutrients, or a placebo (P) for 6 mo. None of the supplements tested prevented growth faltering or the morbidities common during infancy. Anemia and plasma homocysteine concentrations fell significantly in all groups during the study, but the mean change of plasma homocysteine during the trial period was significantly smaller in the DI group than in other groups, and the increase in hemoglobin concentrations was smaller in the P group than the micronutrient treatment groups. Plasma ferritin concentrations decreased least in the groups taking daily micronutrient supplements containing iron (DI and DMM). There were no significant differences among groups in mean final values or changes in plasma zinc, retinol, tocopherol, or riboflavin. Although the DMM intervention was the most efficacious for preventing anemia, iron, and zinc deficiencies, 15%, 20%, and 50% of this group still remained anemic, zinc deficient, and iron deficient, respectively, at the end of the study. Further research thus should investigate whether higher doses of iron and zinc, together with infection control measures, are more efficacious.     

Efficacy of twice-weekly multiple micronutrient supplementation for improving the hemoglobin and micronutrient status of anemic adolescent schoolgirls in Bangladesh

BACKGROUND: Although iron deficiency is a major cause of anemia, other micronutrient deficiencies may also play a role. OBJECTIVE: We examined whether multiple micronutrient supplementation is more efficacious than is supplementation with iron and folic acid alone for improving the hemoglobin and iron status of anemic adolescent girls in Bangladesh. DESIGN: Anemic (hemoglobin < 12.0 g/dL) girls (n = 197) aged 14-18 y from rural schools in Dhaka District were entered into a randomized double-blind trial and received twice-weekly supplements of iron and folic acid (IFA group) or multiple micronutrients (15 micronutrients, including iron and folic acid; MMN group) for 12 wk. RESULTS: At recruitment, the characteristics of the girls in the 2 groups were not significantly different, except for family size and body mass index. At the end of the study, although both groups benefited significantly from supplementation, mean changes in hemoglobin and serum ferritin concentrations were not significantly different between groups. Compared with the IFA group, girls in the MMN group had significantly greater increases in mean serum vitamin A, plasma vitamin C, red blood cell folic acid, and riboflavin concentrations (assessed as erythrocyte glutathione reductase activation coefficient). After 12 wk of supplementation, only the prevalence of vitamins A and C and riboflavin deficiencies decreased more significantly in the MMN group than in the IFA group. CONCLUSIONS: Twice-weekly MMN supplementation for 12 wk significantly improved the status of the micronutrients assessed but was not more efficacious than was supplementation with iron and folic acid alone in improving the hematologic status of anemic adolescent girls. More frequent doses may be needed to achieve full benefit.     

母体补充复合微量营养素对妊娠时间及新生儿体质量的影响

目的 探讨母体补充复合微量元素与妊娠时间及新生儿体质量的关系.方法 选择在本院接受产前护理的单胎妊娠孕妇作为研究对象,将受试孕妇随机化分为两组:常规补充铁-叶酸组(对照组,n=75)和补充15种维生素和矿物质的复合微量营养素组(试验组,n=75),分析母体补充复合微量营养素对妊娠时间及新生儿体质量的影响.结果 对照组孕妇妊娠时间为(9.3±0.8)周,试验组孕妇妊娠时间(9.5±0.6)周,平均相差0.2周,两组比较无显著性差异(P＞0.05);对照组新生儿体质量为(2 763.3±419.5)g,试验组新生儿体质量(2 870.4±461.6)g,平均相差97.1g,两组比较存在显著性差异(P＜0.05).结论 母体通过补充复合微量营养素对妊娠时间无影响,但可改善新生儿体质量,效果优于常规铁和叶酸制剂的补充疗法,值得推广.