孕期户外活动时间与子代0～2岁婴幼儿维生素D状况的关系研究

目的探讨母亲孕期户外活动时间与子代0~2岁婴幼儿维生素D状况的关系。方法采用分层随机整群抽样的方法抽取江苏省0~2岁婴幼儿,采用自行设计的问卷调查婴幼儿基本情况、体力活动和膳食摄入情况,检测婴幼儿25-(OH) D水平。调整城乡户籍、性别、年龄、产次、出生体质量、季节、0~6个月婴儿喂养方式、6月龄内婴儿是否补充维生素D、婴幼儿近3月是否服用维生素D、婴幼儿近3月是否补充钙剂、婴幼儿户外活动时间、婴幼儿体质指数、孕期是否补充维生素D和钙剂、孕期母亲每天奶类摄入量和孕期母亲每天鱼虾摄入频率等混杂因素,采用协方差分析比较母亲孕期不同户外活动时间及其子代维生素D水平;采用Logistic回归分析母亲孕期不同户外活动时间与其子代维生素D缺乏的关系。结果本研究共调查1 384名婴幼儿,调整城乡户籍、年龄和性别等混杂因素后,孕期每天户外活动时间1 h和1 h的母亲其子代维生素D水平分别为(70. 2±31. 8) nmol/L、(75. 5±32. 4) nmol/L;与孕期每天户外活动时间1 h的母亲相比,孕期每天户外活动时间1 h的母亲其子代维生素D水平均减少5. 3 nmol/L,组间差异有统计学意义(P=0. 024)。每天户外活动时间1 h的孕妇,其子代患维生素D缺乏的风险增加1. 71倍。结论户外活动时间少的孕妇,其子代维生素D水平降低,维生素D缺乏的风险增加。     

替代鱼肝油的饮食方案

宝宝出生以后,每天维生素D的生理需要量是4001U～8001U。中国营养协会推荐。出生两周后的婴儿每天需补充维生素A15001U（国际单位）和维生素D5001U,一岁以上幼儿每天需补充维A2000～25001U和维生素D7001U,以促进婴幼儿视力的发育及预防小儿佝偻病。小儿佝偻病在我国的发病率较高,很大程度上是由于人们对孕期及婴幼儿期补充维生素D的认识不足造成的。     

0～6岁儿童血清25-(OH)D水平与佝偻病影响因素的Logistic回归分析

目的:了解北京市亚北地区0～6岁儿童血清25羟维生素D[25-(OH)D]水平,探讨佝偻病发病相关影响因素,为佝偻病防治提供依据。方法:根据临床表现,血生化及左腕关节X线摄片结果将北京市亚北地区210例0～6岁儿童分为无佝偻病组(健康组)157例和佝偻病组53例。对佝偻病发病相关因素做进一步Logistic回归分析,探讨佝偻病发病的影响因素。结果:佝偻病组与健康组儿童25-(OH)D及血清骨特异性碱性磷酸酶(NBAP)差异有统计学意义。单因素分析结果显示,发生佝偻病与母孕期腿部抽筋史、每天户外活动时间、钙剂摄入情况及维生素D补充情况、儿童每天户外活动时间、钙剂摄入情况及维生素D补充情况、患有慢性腹泻等因素相关。Logistic回归分析显示,母孕期每天户外活动时间<2 h、每天钙摄入<1 000 mg、补充维生素D<400 u、儿童每天户外活动时间<2 h、钙摄入<400 mg、补充维生素D<400 u与佝偻病发生密切相关。结论:北京市亚北地区佝偻病患儿血清25-(OH)D水平明显降低,对疑似佝偻病患儿尽可能行血清25-(OH)D检测,避免过度诊断。母孕期每天户外活动时间<2 h、每天钙摄入<1 000 mg、补充维生素D<400 u、儿童每天户外活动时间<2 h、钙摄入<400 mg、补充维生素D<400 u是佝偻病发生的危险因素。     

0～2岁婴幼儿佝偻病患病率调查

目的了解珠海市0～2岁婴幼儿佝偻病患病情况及影响因素.方法以分层随机抽样法抽取珠海市0～2岁婴幼儿405人,采用自行设计的调查表进行佝偻病及相关因素调查,运用非条件logistic回归进行多因素分析.结果珠海市0～2岁婴幼儿佝偻病患病率为13.3%.佝偻病发生与居住地区、孕末期3个月补充钙剂和维生素D、孕末期3个月进食虾皮或海带类、孕末期3个月日晒时间、孕周、儿童户外活动时间、补锌及定期检查有关.其OR值分别为0.079、6.225、0.156、3.566、0.417、0.265、5.800和9.364.结论佝偻病的发生是多因素综合作用的结果,其预防应从胎儿期开始.     

0～7岁小儿维生素D缺乏性佝偻病的影响因素调查

目的研究0~7岁小儿维生素D缺乏性佝偻病的影响因素,为临床诊疗提供依据。方法选取0~7岁小儿维生素D缺乏性佝偻病患儿103例为研究组,另外选取同期健康体检儿童103例为对照组,应用自行设计问卷调查孕妇家庭状况、孕期饮食及生活规律、分娩及婴幼儿的基本情况,应用多元Logistic回归分析法分析佝偻病的影响因素。结果孕期经常吃鱼、孕期户外活动、孕期日照时间、孕期补维生素D或钙、婴儿7个月开始服用含高钙食物、小儿晒太阳暴露皮肤的面积是影响佝偻病的相关因素(P<0.05)。结论孕期多户外运动、及时补钙、小儿7个月开始服用含高钙食物、日晒暴露皮肤面积大等是佝偻病的保护性因素,应该多进行健康宣教,早期预防、早期诊治是关键。     

早产及低出生体重与营养性佝偻病患病因素分析

维生素D缺乏性佝偻病(佝偻病)是常见的儿童营养缺乏性疾病,影响小儿骨骼健康、免疫功能和生长发育,是我国儿科重点防治的四病之一.早产、低出生体重儿是营养性佝偻病发生的高危人群,2005年长春市0～2岁早产低出生体重儿佝偻病患病率为74.46％[1].为了解本地区近五年来营养性佝偻病患病情况,影响患病的相关因素,为降低佝偻病提供依据,笔者对嘉兴市区5年间管理的早产、低出生体重婴儿进行营养性佝偻病的监测和随访,调查其患病率和相关的影响因素.     

0~2岁婴幼儿佝偻病患病率调查

目的:了解珠海市0-2岁婴幼儿佝偻病患病情况及影响因素。方法:以分层随机抽样法抽取珠海市0-2岁婴幼儿405人,采用自行设计的调查表进行佝偻病及相关因素调查,运用非条件logistic回归进行多因素分析。结果:珠海市0-2岁婴幼儿佝偻病患病率为13.3％。佝偻病发生与居住地区、孕末期3个月补充钙剂和维生素D、孕末期3个月进食虾皮或海带类、孕末期3个月日晒时间、孕周、儿童户外活动时间、补锌及定期检查有关。其OR值分别为0.079、6.225、0.156、3.566、0.417、0.265、5.800和9.364。结论:佝偻病的发生是多因素综合作用的结果,其预防应从胎儿期开始。     

泉州市7岁以下儿童维生素D缺乏性佝偻病流行病学调查

目的调查泉州市7岁以下儿童维生素D缺乏性佝偻病患病率及其影响因素.方法采用分层随机整群抽样方法,进行问卷调查、体格检查和检测血清Ca、P、AKP、拍摄左腕关节、双膝关节X线片.结果泉州市7岁以下儿童维生素D缺乏性佝偻病患病率10.54%,婴幼儿患病率21.42%,3～7岁儿童患病率4.10%.城市患病率高于农村.6个月～2岁婴幼儿患病率最高,6～7岁组最低.人工喂养、混合喂养、无服用或无规则服用鱼肝油、户外活动每天少于2 h、家庭年人均收入少于1 000元、父母文化程度初中以下、反复呼吸道感染、常患腹泻和厌食是维生素D缺乏性佝偻病患病的相关因素.结论泉州市7岁以下儿童维生素D缺乏性佝偻病患病率10.54%,须加强防治.     

丽水市莲都区0～15岁儿童及婴幼儿维生素D营养状况调查分析

目的调查浙江省丽水市莲都区0~15岁儿童及婴幼儿维生素D营养状况,为科学防治佝偻病提供依据。方法随机收集2012年1月~2013年5月来医院儿科门诊进行常规保健体检的0~15岁儿童及婴幼儿1 186例。采用电化学发光分析仪(竞争法)进行血清25-羟基维生素D3浓度检测,并进行统计学分析。结果丽水市莲都地区0~15岁儿童及婴幼儿血清25-羟基维生素D3平均浓度(29.63±14.40)μg/L,性别之间差异无统计学意义(F=0.072,P0.05)。随着年龄增长血清25-羟基维生素D3浓度逐渐下降;3岁以上儿童维生素D缺乏率明显增高(F=226.329,P0.01)。结论丽水市莲都区0~15岁儿童及婴幼儿维生素D水平相对偏低,应重点加强3岁以上儿童维生素D的补充,并适当控制3岁以下婴幼儿的摄入量。     

乳制品中钙、维生素D的摄入量和血压的研究

目的 :评估乳制品中钙摄入量及维生素 D摄入量与收缩和舒张血压间的关系。设计 :受检者将因高血压或心脏病而在服药的病人 ,服用钙片者 ,确诊为心血管疾病者以及孕妇除外 ,选择年龄在 2 5岁～69岁之间的 7543名男性及 80 53名女性进行分析。钙和维生素 D的摄入量由饮食频率调查表计算。结果 :排除年龄、身体状况、饮酒和喝咖啡、体育运动、吸烟以及维生素 D摄入量因素后 ,在两性中随着乳钙摄入量的增加 ,收缩压与舒张压呈显著的线性降低 (P <0 .0 5)。然而 ,在钙最高摄入量与最低摄入量的受检者中血压相差小于或等于 0 .1k Pa1～ 0 .4 k …     

Sources and determinants of vitamin D intake in Danish pregnant women

Vitamin D deficiency during pregnancy has been associated with the development of several adverse health outcomes, e.g., pre-eclampsia, gestational diabetes mellitus, preterm delivery, low birth weight, birth length, and bone mineral content. The aims of the present study were to estimate the intake and sources of vitamin D in Danish pregnant women and to examine potential determinants of vitamin D intake of the recommended level (10 μg per day). In 68,447 Danish pregnant women the mean ± SD for vitamin D intake was 9.23 ± 5.60 μg per day (diet: 3.56 ± 2.05 μg per day, supplements: 5.67 ± 5.20 μg per day). 67.6% of the women reported use of vitamin D supplements but only 36.9% reported use of vitamin D supplements of at least 10 μg. Supplements were the primary source of vitamin D for the two higher quartiles of total vitamin D intake, with diet being the primary source for the two lower quartiles. Determinants of sufficient total vitamin D intake were: high maternal age, nulliparity, non-smoking, and filling out of the Food Frequency Questionnaire (FFQ) during summer or fall. We propose that clinicians encourage vitamin D supplementation among pregnant women, with special focus on vulnerable groups such as the young, smokers and multiparous women, in order to improve maternal and fetal health both during and after pregnancy.     

Vitamin D and bone health in early life

Prolonged vitamin D deficiency resulting in rickets is seen mainly during rapid growth. A distinct age distribution has been observed in the Copenhagen area where all registered hospital cases of rickets were either infants and toddlers or adolescents from immigrant families. Growth retardation was only present in the infant and toddler group. A state of deficiency occurs months before rickets is obvious on physical examination. Growth failure, lethargy and irritability may be early signs of vitamin D deficiency. Mothers with low vitamin D status give birth to children with low vitamin D status and increased risk of rickets. Reports showing increasing rates of rickets due to insufficient sunlight exposure and inadequate vitamin D intake are cause for serious concern. Many countries (including the USA from 2003) recommend vitamin D supplementation during infancy to avoid rickets resulting from the low vitamin D content of human milk. Without fortification only certain foods such as fatty fish contain more than low amounts of vitamin D, and many children will depend entirely on sun exposure to obtain sufficient vitamin D. The skin has a high capacity to synthesize vitamin D, but if sun exposure is low vitamin D production is insufficient, especially in dark-skinned infants. The use of serum 25-hydroxyvitamin D to evaluate vitamin D status before development of rickets would be helpful; however, there is no agreement on cut-off levels for deficiency and insufficiency. Furthermore, it is not known how marginal vitamin D insufficiency affects children's bones in the long term.     

维生素D和维生素D缺乏性佝偻病的研究

进入21世纪,维生素D缺乏性佝偻病又出现了上升趋势.该文探讨了其病因:纯母乳喂养时间过长而未添加维生素D,尤其是那些摄入母亲自身是维生素D缺乏者乳汁的婴儿;由于各种原因造成婴儿日照时间减少,从而使得婴儿体内由皮肤转化的内源性维生素D的量大大减少;在很多温带地区移民人群中佝偻病的高发病率.因此,维生素D缺乏可能是一项国际妇幼保健问题,需再次强调对儿童及孕妇额外补充维生素D及日照的重要性.     

Incidence and characteristics of vitamin D deficiency rickets in New Zealand children: a New Zealand Paediatric Surveillance Unit study

Objective: To investigate the incidence and characteristics of vitamin D deficiency rickets in New Zealand (NZ). Methods: Prospective surveillance among paediatricians of Vitamin D Deficiency Rickets was conducted by the New Zealand Paediatric Surveillance Unit (NZPSU) for 36 months, from July 2010 to June 2013, inclusive. Inclusion criteria were: children and adolescents <15 years of age with vitamin D deficiency rickets (defined by low serum 25‐hydroxyvitamin D and elevated alkaline phosphatase levels, and/or radiological rickets). Results: Fifty‐eight children with confirmed vitamin D deficiency rickets were identified. Median age was 1.4 (range 0.3–11) years, 47% were male, and 95% of the children were born in NZ; however, the majority of the mothers (68%) were born outside NZ. Overall annual incidence of rickets in children aged <15 years was 2.2/100,000 (95%CI 1.4–3.5); with incidence in those <3 years being 10.5/100,000 (95%CI 6.7–16.6). Skeletal abnormalities, poor growth and motor delay were the most common presenting features, with hypocalcaemic convulsion in 16% of children. Key risk factors identified were: darker skin pigment, Indian and African ethnicity, age <3 years, exclusive breast feeding, and southern latitude, particularly when combined with season (winter/spring). Of the patients reported, none had received appropriate vitamin D supplementation. Conclusions: Vitamin D deficiency rickets remains a problem for NZ children. Key risk factors remain similar to those identified in the international literature. Preventative targeted vitamin D supplementation, as per existing national guidelines, was lacking in all cases reported. Implications: Vitamin D deficiency rickets is the most significant manifestation of vitamin D deficiency in growing children. To reduce the incidence of this disease among those at high risk, increasing awareness and implementation of current public health policies for targeted maternal, infant and child supplementation are required.     

Vitamin D Supplementation during Pregnancy: An Evidence Analysis Center Systematic Review and Meta-Analysis

BackgroundGiven the high rates of vitamin D deficiency among pregnant women and possible effects on offspring health, a systematic review on this topic was conducted to help inform future practice guidelines.ObjectiveTo evaluate associations between maternal vitamin D supplementation, maternal 25-hydroxyvitamin D (25(OH)D) concentrations, and health outcomes.MethodsA PubMed literature search was conducted to identify studies that examined the health effects of vitamin D supplementation during pregnancy on maternal and infant health outcomes published from 2000 to 2016. Among 976 identified publications, 20 randomized clinical trials met the inclusion criteria. The initial search was extended to include five studies published between July 2016 and September 2018.Main outcome measuresMaternal and infant 25(OH)D concentrations, gestational diabetes, preeclampsia or gestational hypertension, cesarean section, maternal parathyroid hormone and calcium concentrations, and infant gestational age, birth weight, and birth length.Statistical analysesMean differences, odds ratios, and 95% CIs were calculated, only for the initial search, using separate random-effects meta-analyses for each outcome.ResultsEvidence was good or strong that maternal vitamin D supplementation significantly increased maternal (13 studies, n=18, mean difference, 14.1 ng/mL [35.2 nmol/L]; 95% CI=9.6-18.6 ng/mL [24.0-46.4 nmol/L]) and infant (nine studies, n=12; 9.7, 5.2, 14.2 ng/mL [24.2, 12.9, 35.5 nmol/L]) 25(OH)D concentrations, although heterogeneity was significant (I²=95.9% and I²=97.4, respectively, P<0.001). Evidence was fair that vitamin D supplementation significantly decreases maternal homeostatic model assessment-insulin resistance (five studies, n=7; −1.1, −1.5, −0.7) and increases infant birth weight (nine studies, n=11, 114.2, 63.4, 165.1 g), both had insignificant heterogeneity. A null effect of maternal supplementation on other maternal (preeclampsia, cesarean section) and infant (gestational age, birth length) outcomes was found.ConclusionsResults show vitamin D supplementation during pregnancy improves maternal and infant 25(OH)D concentrations and may play a role in maternal insulin resistance and fetal growth. To further inform practice and policies on the amount of vitamin D, which supports a healthy pregnancy, high quality dose-response randomized clinical trials, which assess pregnancy-specific 25(OH)D thresholds, and appropriately powered clinical outcomes are needed.     

Healthy pregnant women in Canada are consuming more dietary protein at 16- and 36-week gestation than currently recommended by the Dietary Reference Intakes,primarily from dairy food sources

Adequate dietary protein intake throughout pregnancy is essential to ensure healthy fetal development. Insufficient and excessive maternal dietary protein intakes are both associated with intrauterine growth restriction, resulting in low birth weight infants. The aim of this study was to analyze the dietary protein intake patterns of healthy pregnant women in Vancouver, British Columbia, during early and late gestation. We hypothesized that women would be consuming higher protein during late stages of pregnancy compared with early stages of pregnancy. Interviewer-administered food frequency questionnaires were collected prospectively from 270 women at 16- and 36-week gestation; food frequency questionnaires from 212 women met study criteria. Maternal anthropometrics at both stages and infant weight at birth were collected. Wilcoxon signed rank tests were used to determine significant gestational differences in protein intakes. Spearman correlation was used to determine the influence of protein intakes and maternal anthropometrics on pregnancy outcomes. Median (25th and 75th percentiles) protein intakes adjusted for body weight were 1.5 (1.18 and 1.79) and 1.3 (1.04 and 1.60) g/kg per day at 16- than 36-week gestation, respectively. Primary protein sources were identified as dairy products. Protein intakes were negatively correlated with birth weight (P < .05), whereas maternal height, weight, body mass index, and weight gain to 36-week gestation were positively correlated with birth weight (P < .05). This study provides current dietary protein intake patterns among healthy Canadian women during pregnancy and indicates higher intakes than current Dietary Reference Intakes recommended dietary allowance of 1.1 g/kg per day, especially during early gestation.     

Breast milk vitamin B-12 concentrations in Guatemalan women are correlated with maternal but not infant vitamin B-12 status at 12 months postpartum

In our previous studies, one-third of lactating Guatemalan women, infants, and children had deficient or marginal serum vitamin B-12 concentrations. Relationships among maternal and infant status and breast milk vitamin B-12, however, have not, to our knowledge, been investigated in such populations. Our purpose was to measure breast milk vitamin B-12 in Guatemalan women with a range of serum vitamin B-12 concentrations and explore associations between milk vitamin B-12 concentrations and maternal and infant vitamin B-12 intake and status. Participants were 183 mother-infant pairs breastfeeding at 12 mo postpartum. Exclusion criteria included mother <17 y, infant <11.5 or >12.5 mo, multiple birth, reported health problems in mother or infant, and mother pregnant >3 mo. Data collected on mothers and infants included anthropometry, serum and breast milk vitamin B-12, and dietary vitamin B-12. Serum vitamin B-12 concentrations indicated deficiency (<150 pmol/L) in 35% of mothers and 27% of infants and marginal status (150-220 pmol/L) in 35% of mothers and 17% of infants. In a multiple regression analysis, breast milk vitamin B-12 concentration was associated (P < 0.05) with both maternal vitamin B-12 intake (r = 0.26) and maternal serum vitamin B-12 (r = 0.30). Controlling for the number of breastfeeds per day and vitamin B-12 intake from complementary foods, infant serum vitamin B-12 was associated with maternal serum vitamin B-12 (r = 0.31; P < 0.001) but not breast milk vitamin B-12, implicating a long-term effect of pregnancy status on infant vitamin B-12 status at 12 mo postpartum.     

完全母乳喂养婴儿维生素D补充剂的应用现状

【目的】 对山东省完全母乳喂养婴儿维生素D补充剂的应用现状进行调查,并分析其影响因素。 【方法】 选取2010年11月-2011年1月来预防接种门诊进行计划免疫与健康保健的0~3岁儿童903例,以生后4个月内完全母乳喂养儿612例作为研究对象。采用自制的调查问卷对儿童抚养人进行维生素D补充剂应用方面的调查。 【结果】 完全母乳喂养婴儿维生素D补充剂的应用率为76.6%,开始添加维生素D补充剂的时间、停用时间是生后30.0(30.0)d、9.0(7.0)月,其中生后1周内、1~2周、2~4周、>4周开始添加的儿童分别占1.7%、3.4%、9.3%、85.5%;78.4%婴儿1岁以内停用了维生素D补充剂,1~2岁停用者占16.6%,2~3岁停用者占5.1%;多因素Logistic回归分析发现儿童年龄、家庭收入水平、母亲文化程度和孕期使用微营养素等是影响维生素D补充剂应用的因素(OR=0.673,0.706,1.651,1.646)。 【结论】 维生素D补充剂在完全母乳喂养婴儿中的应用普遍,但应用不合理,不符合国内外维生素D补充剂应用指南的要求。年龄、母亲文化水平、收入水平等多种因素影响维生素D补充剂的应用状况。     

Intake of vitamin D by Finnish children aged 3 months to 3 years in relation to sociodemographic factors

OBJECTIVE: To study the total daily intake of vitamin D from food and supplements among Finnish children aged 3 months to 3 years, the dietary sources of vitamin D and the association between vitamin D intake and sociodemographic factors. SUBJECTS AND METHODS: The subjects are participants in the Finnish Type I Diabetes Prediction and Prevention Nutrition Study born between October 1997 and October 1998. At the age of 3 and 6 months, 1, 2 and 3 years, 342 (72% of the invited families), 298 (63%), 267 (56%), 233 (49%) and 209 (44%) families, respectively, participated in the present study. Food consumption was assessed by a 3-day food record. A structured questionnaire was used to record the parents' socioeconomic status. RESULTS: The mean dietary vitamin D intake exceeded the recommendation (10 microg/day) at the age of 3 (11.0 microg) and 6 months (12.0 microg), but decreased thereafter being 9.8, 5.0 and 4.1 microg at 1, 2 and 3 years of age, respectively. Among the children 91, 91, 81, 42 and 26% used vitamin D supplements at the age of 3 and 6 months, and 1, 2 and 3 years, respectively. In children not using vitamin D supplements, vitamin D intake was less than 10 microg/day at all ages. Vitamin D intake from food did not differ in children who used and did not use vitamin D supplements. Vitamin D supplements were the main source of vitamin D intake in all age groups studied, followed by vitamin D-fortified infant formula in 3-month-olds and infant formula and baby foods in 6-month-olds. After the age of 1 year, the most important food sources of vitamin D were margarine, fish, baby foods, low-fat milk and eggs. Sociodemographic factors, especially the number of children in the family and maternal age, were associated with the total vitamin D intake and vitamin D supplement use. CONCLUSION: Vitamin D supplements are not used according to the dietary recommendations in a substantial proportion of Finnish children.     

Meat consumption reduces the risk of nutritional rickets and osteomalacia

Endogenous vitamin D deficiency (low serum 25(OH)D3) is a necessary but insufficient requirement for the genesis of vitamin D-deficiency rickets and osteomalacia. The magnitude of the independent contributions of dietary factors to rachitic and osteomalacic risk remains uncertain. We reanalysed two weighed dietary surveys of sixty-two cases of rickets and osteomalacia and 113 normal women and children. The independent associations of four dietary variables (vitamin D, Ca, fibre and meat intakes) and daylight outdoor exposure with rachitic and osteomalacic relative risk were estimated by multivariate logistic regression. Meat and fibre intakes showed significant negative and positive associations respectively with rachitic and osteomalacic relative risk (RR; zero meat intake: RR 29.8 (95 % CI 4.96, 181), P<0.001; fibre intake: RR 1.53 (95 % CI 1.01, 2.32), P=0.043). The negative association of meat intakes with rachitic and osteomalacic relative risk was curvilinear; relative risk did not fall further at meat intakes above 60 g daily. Daylight outdoor exposure showed a significant negative association with combined relative risk (RR 0.33 (95 % CI 0.17, 0.66), P<0.001). Operation of the meat and fibre risk factors was related to sex, age and dietary pattern (omnivore/lactovegetarian), mainly determined by religious affiliation. The mechanism by which meat reduces rachitic and osteomalacic risk is uncertain and appears independent of revised estimates of meat vitamin D content. The meat content of the omnivore Western diet may explain its high degree of protection against nutritional rickets and osteomalacia from infancy to old age in the presence of endogenous vitamin D deficiency.