北方成人普遍缺乏叶酸

北京大学生育健康教育研究所科研人员于2001年冬春季节和夏秋季节，对来自我国南方和北方的2471位年龄在35～64岁的男性和女性进行了血浆叶酸和红细胞叶酸水平的横断面调查。研究发现，北方受试者血浆叶酸和红细胞叶酸水平显著低于南方人群，而且男女性别差异明显．男性显著低于女性。南北方人群血浆叶酸水平随季节变化规律不同．南方冬春季节血浆叶酸水平高于夏秋季节．北方则夏秋季节高于冬春季节。进～步分析结果显示．南北方人群血浆叶酸缺乏率分别为6％和40％。     

我国部分地区成人血浆维生素B_(12)水平比较研究

目的:描述不同地区、季节、性别成年人血浆维生素B12水平的分布特征。方法:描述性流行病学研究;以来自南北方有代表性的城乡地区2 459份血浆标本(35～64岁)进行维生素B12检测并比较其地区、季节及性别差异。结果:南方人群调整后血浆维生素B12平均水平为260pmol/L,显著高于北方人群(189pmol/L);南北方人群血浆维生素B12水平随季节变化规律不同,南方人群夏秋季节(269pmol/L)血浆维生素B12水平高于冬春季节(252pmol/L),北方人群则夏秋季节(177pmol/L)明显低于冬春季节(200pmol/L);女性调整后血浆维生素B12水平高于男性,差异具有统计学意义。全研究人群中血浆维生素B12低于110pmol/L者占5.5%。结论:我国成年人群血浆维生素B12水平存在明显的地区和性别差异;南北方人群血浆维生素B12水平随季节变化的规律不同。     

我国部分地区35～64岁人群血浆叶酸水平与年龄性别差异比较

目的 :　了解我国部分地区 3 5～ 6 4岁人群血浆叶酸性别、年龄分布特征。方法 :　以来自南北方有代表性的城乡地区、3 5～ 6 4岁男女两性 2 5 4 5人为研究样本 ,测定血浆叶酸 ,并进行不同性别、年龄血浆叶酸水平差异比较。结果 :　 (1 )男性血浆叶酸水平显著低于女性 (9.70nmol/L vs1 4.2 nmol/L,P=0 .0 0 1 ) ,血浆叶酸缺乏率显著高于女性 (3 1 .0 % vs1 2 .5 % ,P=0 .0 0 1 )。(2 )男性血浆叶酸南方高于北方 ,城乡之间差异除北方冬春季节城市显著低于农村外 ,均不具有统计学意义 ,城乡叶酸缺乏率亦不存在显著差异 ;女性血浆叶酸亦呈南方高于北方 ,并有城市高于农村 ,北方农村叶酸缺乏率显著高于城市的分布特征。 (3 )南方男性血浆叶酸随年龄升高而增加 ,南方女性及北方男女性血浆叶酸有随年龄升高而增加的趋势 ,差异不具统计学意义。结论 :　我国 3 5～ 6 4岁人群男性血浆叶酸显著低于女性 ,缺乏率高于女性 ;男女两性血浆叶酸在城乡之间的分布特征不同 ,女性血浆叶酸城乡差异显著     

中国南北两县810名老年人红细胞叶酸营养状况及其地区差异调查

目的 了解中国南北方部分地区老年人的红细胞叶酸水平,评价红细胞叶酸与血浆叶酸水平的相关性.方法 在江苏省张家港市(南方)和河北省石家庄市元氏县(北方)募集810名65 ～ 74岁老年人,采集空腹静脉血标本,应用96孔板微生物法检测红细胞叶酸水平,经自然对数转换后,用t检验进行红细胞叶酸平均水平的比较;用x2检验进行红细胞叶酸缺乏率的比较.结果 南方老年人群红细胞叶酸平均水平为1083.3 nmol/L(95％CI:1034.1 ～ 1134.8),北方为489.1 nmol/L(95％CI:466.7～ 512.6),南方是北方的2.2倍(t=23.684,P＜0.001).南方老年人群红细胞叶酸缺乏率为1.0％,北方为28.9％,南北方差异有统计学意义(x2=124.06,P＜0.001).红细胞叶酸水平与血浆叶酸水平呈正相关,相关系数为0.49(P＜0.001);在控制了地区、性别、年龄组、BMI分组、文化程度、吸烟及饮酒暴露情况后,调整相关系数为0.38(P＜0.001).结论 中国65～ 74岁老年人群的红细胞叶酸营养状况有显著地区差异,南方老年人红细胞叶酸水平高于北方,但缺乏率却低于北方,红细胞叶酸水平与血浆叶酸水平呈正相关.     

中老年妇女叶酸水平分析

目的:了解无锡市中老年妇女血浆叶酸水平.方法:以年龄在35～64岁,分别来自城区和农村的623名妇女为研究对象,对其血浆叶酸水平进行统计学分析.结果:研究人群血浆叶酸平均水平为20.5 nmol/L,平均叶酸缺乏率为1.8%,城区妇女血浆叶酸平均水平高于农村妇女,冬春季节血浆叶酸水平高于夏秋季节.结论:无锡市中老年妇女血浆叶酸水平高于我国北方地区妇女,城区与农村、冬春季节与夏秋季节中老年妇女血浆叶酸水平有非常显著性差异.     

中老年妇女叶酸水平分析

目的 :了解无锡市中老年妇女血浆叶酸水平。方法 :以年龄在 35～ 6 4岁 ,分别来自城区和农村的 6 2 3名妇女为研究对象 ,对其血浆叶酸水平进行统计学分析。结果 :研究人群血浆叶酸平均水平为 2 0 .5 nmol/ L ,平均叶酸缺乏率为 1.8% ,城区妇女血浆叶酸平均水平高于农村妇女 ,冬春季节血浆叶酸水平高于夏秋季节。结论 :无锡市中老年妇女血浆叶酸水平高于我国北方地区妇女 ,城区与农村、冬春季节与夏秋季节中老年妇女血浆叶酸水平有非常显著性差异。     

天津市新婚人群血清叶酸水平现况调查及正常参考值

目的:描述天津市新婚人群血清叶酸水平的性别、年龄、地区和季节分布,取叶酸水平第5百分位点(P5)作为低叶酸水平,建立天津市不同年龄、不同性别血清叶酸水平的正常参考值,并根据检测结果指导叶酸补充,提高城市新婚人群对出生缺陷预防的认识,提高社会和家庭的优生意识。方法:选择2009年9月～2010年8月在天津各区婚姻登记处登记结婚的新婚夫妇作为调查对象,使用微生物培养法统一测定血清叶酸水平。结果:①男性叶酸水平显著低于女性(8.84 nmol/L vs12.21 nmol/L,P<0.001),男性叶酸缺乏率为29.96%,女性为13.54%;②男女血清叶酸水平随年龄增长而增加,但女性31岁以后差异不具有统计学意义(P=0.727);③男、女均以4郊区血清叶酸水平最高,滨海新区最低;④男性夏季和冬季叶酸水平均高于秋季,差异有统计学意义(夏vs秋P<0.001,冬vs秋P=0.027),男性其余季节间比较无统计学意义;女性叶酸水平以夏季最高,冬季最低,女性春季和秋季叶酸水平差异无统计学意义(P=0.079);⑤不同年龄、不同性别人群血清叶酸水平的正常参考值:≤25岁年龄段男女分别为≥3.74 nmol/L、≥4.91 nmol/L;26～30岁男女分别为≥3.71nmol/L、≥5.20 nmol/L;31～35岁男女分别为≥3.79 nmol/L、≥5.41 nmol/L;≥36岁男女分别为≥3.64 nmol/L、≥5.54 nmol/L。结论:天津市新婚人群血清叶酸水平在不同性别、年龄、地区、季节之间存在明显差异;通过对天津市新婚人群血清叶酸水平的研究,建立了天津市不同年龄、不同性别人群血清叶酸水平的正常参考值;应加强增补叶酸知识的宣教,定期监测血清叶酸水平,科学指导新婚男女双方及时补充叶酸,维持血清叶酸的正常水平,以保证母婴健康。     

神经管畸形不同发病区婚检妇女叶酸缺乏率的研究

在我国神经管畸形(NTDs)高发的北方和低发的南方城乡地区，分别进行了婚检妇女的叶酸营养状况监测，结果发现妇女血清叶酸总缺乏率为23．6％：，红细胞叶酸总缺乏率为298．1‰。红细胞叶酸缺乏率高于血清叶酸缺乏率。南方妇女叶酸缺乏率低于北方妇女。城市妇女叶酸缺乏率低于农村。夏、秋、冬、春季妇女的叶酸缺乏率不同。叶酸营养状况与神经管畸形发病率存在着负相关。     

神经管畸形不同发病区婚检妇女叶酸缺乏率的研究

在我国神经管畸形(NTDs)高发的北方和低发的南方城乡地区,分别进行了婚检妇女的叶酸营养状况监测,结果发现妇女血清叶酸总缺乏率为23.6‰,红细胞叶酸总缺乏率为298.1‰。红细胞叶酸缺乏率高于血清叶酸缺乏率。南方妇女叶酸缺乏率低于北方妇女,城市妇女叶酸缺乏率低于农村。夏、秋、冬、春季妇女的叶酸缺乏率不同。叶酸营养状况与神经管畸形发病率存在着负相关。     

神经管畸形高、低发区农村孕早期妇女血液叶酸水平比较研究

目的 了解神经管畸形高发区与低发区农村孕早期妇女血液叶酸状况。方法 采用现况调查方法对2003年神经管畸形高发与低发两个地区共688名农村孕早期妇女的血浆叶酸与红细胞叶酸水平进行研究。结果 高发区农村孕早期妇女血浆叶酸浓度（10．53nmol／L）与红细胞叶酸浓度（389．2nmol／L）中位数明显低于低发区妇女（血浆叶酸30．39nmol/L，红细胞叶酸926．0nmol／L），差异有统计学意义；高发区妇女血浆叶酸缺乏率约为50％，红细胞叶酸缺乏率约为43％，远高于低发区妇女（血浆叶酸6％，红细胞叶酸4％），差异有统计学意义；高、低发区服用叶酸组妇女血浆叶酸水平约为不服用组的2倍，红细胞叶酸水平是不服用组的1．4倍，差异有统计学意义；高、低发区服用叶酸组孕早期妇女的血浆缺乏率均低于不服用组，相对危险度（RR）值分别为0．60（95％CI：0．36～1．01）与0．16（95％CI：0．06～0．44），差异均有统计学意义；高、低发区服用叶酸组与不服用组红细胞叶酸缺乏率之间的RR值分别为0．64（95％CI：0．36～1．13）与0．39（95％CI：0．13～1．13），差异无统计学意义；服用叶酸的孕早期妇女中，低发区血浆叶酸水平约为高发区的1．7～1．9倍，红细胞叶酸水平约为高发区的2倍，差异有统计学意义；服用叶酸的孕早期妇女中，高发区血浆叶酸与红细胞叶酸缺乏率约为低发区的10～14倍，差异有统计学意义。结论 神经管畸形高发区农村孕早期妇女血液叶酸水平很低，增补叶酸可有效提高妇女血液叶酸水平、降低妇女叶酸缺乏率，高发区育龄妇女怀孕前后每日服用0．4mg叶酸的剂量可能不足，建议增加服用剂量。     

Vitamin B-12 deficiency is prevalent in 35- to 64-year-old Chinese adults

Low vitamin B-12 status alone, or in combination with low folate status, is related to neural tube defects (NTD) and hyperhomocysteinemia, a risk factor for atherosclerotic disease, but little is known about vitamin B-12 status in Chinese adults. In a cross-sectional study, we measured plasma vitamin B-12 in 2407 apparently healthy Chinese men and women, 35-64 y old, living in the south and the north of China. Plasma vitamin B-12 concentrations were lower among the northerners than the southerners (geometric means, 209 vs. 309 pmol/L, P < 0.001). Controlling for gender, age, season (spring and fall), and area (urban and rural) had little impact on the difference. We estimated that 11% of the southerners and 39% of the northerners had plasma vitamin B-12 concentrations <185 pmol/L, a level to define vitamin B-12 deficiency. Within each region, men had lower plasma vitamin B-12 concentrations and higher prevalence of vitamin B-12 deficiency than women (279 vs. 333 pmol/L and 15 vs. 8% in the south; 192 vs. 233 pmol/L and 47 vs. 34% in the north; P < 0.001 for all the differences). Low intakes of animal-based food, especially fish and dairy products, were significantly associated with vitamin B-12 deficiency. In the north, 59% of the participants were deficient in either folate (<6.8 nmol/L) or vitamin B-12, and 17% had deficiency in both. The corresponding rates were 16 and 1% in the southerners. To our knowledge, our findings provide the first evidence that vitamin B-12 deficiency is common in 35- to 64-y-old Chinese adults, especially in the north. Further studies are needed to evaluate the health effects and possible intervention strategies in areas where B-12 vitamin deficiency is common.     

High prevalence of hyperhomocysteinemia in Chinese adults is associated with low folate, vitamin B-12, and vitamin B-6 status

Elevated plasma total homocysteine (tHcy) concentrations are associated with lower folate, vitamin B-12, and vitamin B-6 status and are considered an independent risk factor for cardiovascular disease in developed countries, but data in developing countries are limited. We conducted a cross-sectional study to explore tHcy status and its association with plasma B vitamin status in 2471 Chinese men and women aged 35 to 64 y, living in the urban and rural areas of the northern and the southern regions of China. Blood samples were also collected in 2 seasons (spring and fall). The geometric mean plasma tHcy concentration was significantly higher in the north (adjusted geometric mean, 95% CI; 13.0 micromol/L, 12.6-13.3) than in the south (9.1, 8.9-9.4) after controlling for gender, area (urban and rural), age, and season (spring and fall). Twenty-eight percent of northerners and 7% of southerners had plasma tHcy concentrations>or=16.0 micromol/L, a level used to define hyperhomocysteinemia. Within each region, men had higher plasma tHcy concentrations than women (16.1 vs. 10.6 micromol/L in the north, and 10.7 vs. 7.9 micromol/L in the south) and 40% of the northern men had hyperhomocysteinemia. Generally, individuals living in the urban areas had 30% (95% CI, 1.0-1.6) greater odds of having high tHcy levels (>or=16 micromol/L) than those living in the rural areas. Low plasma concentrations of folate, vitamins B-12 and B-6, older age, being male, and living in urban areas were all independently associated with elevated tHcy, with low folate as the strongest determinant.     

Geographical, seasonal and gender differences in folate status among Chinese adults

Low blood folate concentrations have been associated with cardiovascular disease, neural tube defects and selected cancers, but little is known about folate status in Chinese adults. In a cross-sectional study we measured the plasma and red blood cell folate concentrations in 2422 Chinese men and women aged 35 to 64 y, living in the North and South of China, who provided blood samples either in March or September of 2001. The geometric mean concentrations of plasma and red blood cell folate were lower among Northerners than Southerners (adjusted geometric means, 8.4 and 502, and 16.7 and 811 nmol/L, respectively) controlling for age, gender, season (spring and fall), area (urban and rural), BMI, multivitamin use, alcohol intake and current smoking status. We estimated that approximately 40% of the Northerners and approximately 6% of the Southerners had plasma folate concentrations lower than the 6.8 nmol/L (3 microg/L), and approximately 30% of the Northerners and approximately 4% of the Southerners had red blood cell folate concentrations lower than the 363 nmol/L (160 microg/L), levels used to define folate deficiency. Within each region, men had lower plasma folate concentrations than women (6.9 versus 9.8 nmol/L in the North, and 14.5 versus 19.6 nmol/L in the South). In men, current smokers had a higher risk of folate deficiency compared with nonsmokers [adjusted odds ratios, 1.9 (95% CI, 1.4-2.6) for plasma folate deficiency and 2.5 (95% CI, 1.7-3.6) for red blood cell folate deficiency (P < 0.001)]. Our findings suggest that a large proportion of Chinese adults have a low folate status, especially those living in northern China where 60% of the men are plasma folate deficient in the spring. Further studies are needed to elucidate the factors that influence folate concentrations among middle-aged Chinese and to evaluate possible intervention strategies.     

Vitamin D deficiency and associated factors in adolescent girls in Beijing

BACKGROUND: Several locally published reports indicate a high prevalence of vitamin D deficiency among adolescents in China, but no systematic population-based survey has been conducted. OBJECTIVE: The objective was to determine the prevalence of vitamin D deficiency and to study associated factors in adolescent girls in Beijing. DESIGN: A cross-sectional study was conducted in a random sample of 1248 Beijing girls aged 12-14 y. Nutrient intakes, ultraviolet light exposure, anthropometric characteristics, physical activity, signs and symptoms of rickets, and plasma concentrations of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and calcium were measured and X-rays of the hand and wrist were taken. RESULTS: The prevalence of clinical vitamin D and calcium deficiency (plasma 25-hydroxyvitamin D <12.5 nmol/L, plasma calcium <2.25 mmol/L, and muscle spasm at least once per week) was 9.4% in winter. The prevalence of subclinical vitamin D deficiency (25-hydroxyvitamin D <12.5 nmol/L) was 45.2% in winter and 6.7% in summer (P < 0.0005). Logistic regression analysis showed that subclinical and clinical vitamin D deficiency in winter were associated with low plasma 25-hydroxyvitamin D concentrations (<12.5 nmol/L) in summer, low calcium intake ( x +/- SD: 280 +/- 48 compared with 440 +/- 61 mg/d), and low plasma calcium concentrations (<2.25 mmol/L) in winter. The odds ratios for these associations were 3.1, 1.5, and 1.5, respectively. CONCLUSIONS: Subclinical vitamin D deficiency was widespread among Beijing adolescent girls in winter. Low plasma 25-hydroxyvitamin D concentrations in summer, low calcium intake, and low plasma calcium concentrations in winter were the main risk factors for vitamin D deficiency in winter.     

Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors

BACKGROUND: Increased awareness of the importance of vitamin D to health has led to concerns about the prevalence of hypovitaminosis D in many parts of the world. OBJECTIVES: We aimed to determine the prevalence of hypovitaminosis D in the white British population and to evaluate the influence of key dietary and lifestyle risk factors. DESIGN: We measured 25-hydroxyvitamin D [25(OH)D] in 7437 whites from the 1958 British birth cohort when they were 45 y old. RESULTS: The prevalence of hypovitaminosis D was highest during the winter and spring, when 25(OH)D concentrations <25, <40, and <75 nmol/L were found in 15.5%, 46.6%, and 87.1% of participants, respectively; the proportions were 3.2%, 15.4%, and 60.9%, respectively, during the summer and fall. Men had higher 25(OH)D concentrations, on average, than did women during the summer and fall but not during the winter and spring (P = 0.006, likelihood ratio test for interaction). 25(OH)D concentrations were significantly higher in participants who used vitamin D supplements or oily fish than in those who did not (P < 0.0001 for both) but were not significantly higher in participants who consumed vitamin D-fortified margarine than in those who did not (P = 0.10). 25(OH)D concentrations <40 nmol/L were twice as likely in the obese as in the nonobese and in Scottish participants as in those from other parts of Great Britain (ie, England and Wales) (P < 0.0001 for both). CONCLUSION: Prevalence of hypovitaminosis D in the general population was alarmingly high during the winter and spring, which warrants action at a population level rather than at a risk group level.     

Cobalamin and folate status in infants and young children in a low-to-middle income community in India

BACKGROUND: Population-based data on the prevalence of cobalamin and folate deficiency in India are lacking. OBJECTIVE: The objective was to measure the prevalence of cobalamin and folate deficiency among children aged 6-30 mo residing in a low-to-middle income community in North India. DESIGN: Children aged 6-30 mo (n = 2482) were identified through a community survey in a low-to-middle socioeconomic area in New Delhi, India. Non-fasting venous blood samples were collected before enrollment in another trial. RESULTS: The median (interquartile range; IQR) cobalamin concentration in 6-11-mo-old children was substantially lower in breastfed (183; 120-263 pmol/L) than in nonbreastfed (334; 235-463 pmol/L) children. Cobalamin concentrations decreased progressively with increasing age in the nonbreastfed children. Median (IQR) plasma folate concentrations in the 6-11-mo-old group were higher in breastfed (20.3; 11.7-34.4 nmol/L) than in nonbreastfed (5.3; 3.4-7.7 nmol/L) children (P < 0.001). Folate concentrations decreased with increasing age in the breastfed children. In the nonbreastfed children, folate concentrations increased with increasing age. Low concentrations of plasma cobalamin (<150 pmol/L) were detected in 36% of breastfed and 9% of nonbreastfed children (P < 0.001). The proportions of children with plasma folate concentrations <5 nmol/L in these 2 subgroups were 6% and 33%, respectively (P < 0.001). CONCLUSIONS: In north Indian preschool children, cobalamin and folate concentrations were commonly low and were associated with elevated total homocysteine and methylmalonic acid concentrations. Because low cobalamin and folate concentrations have functional consequences, population-based measures for improving cobalamin and folate concentrations need to be seriously considered.     

Anemia and deficiencies of folate and vitamin B-6 are common and vary with season in Chinese women of childbearing age

Little is known about the micronutrient status of Chinese women of childbearing age. We assessed nonfasting plasma concentrations of folic acid, vitamin B-12, vitamin B-6 (as pyridoxal-5'-phosphate), hemoglobin (Hb), ferritin and transferrin receptor (TfR) in 563 nonpregnant textile workers aged 21-34 y from Anqing, China. All women had obtained permission to become pregnant and were participating in a prospective study of pregnancy outcomes. Mean (SD) plasma concentrations were 9.7 (4.1) nmol/L folic acid, 367 (128) pmol/L vitamin B-12, 40.2 (15.8) nmol/L vitamin B-6, 108 (12. 9) g/L Hb, 42.6 (34.2) microgram/L ferritin and 5.2 (2.7) mg/L TfR. Twenty-three percent of women had biochemical evidence of folic acid deficiency, 26% were deficient in vitamin B-6 and 10% had low vitamin B-12. Overall, 44% of women were deficient in at least one B vitamin. Although anemia (Hb < 120 g/L) was detected in 80% of women, only 17% had depleted iron stores (ferritin < 12 microgram/L); 11% had elevated TfR concentrations. Distinct seasonal trends were observed in the prevalence of moderate anemia (Hb < 100 g/L) and deficiencies of folic acid and vitamin B-6, with significantly lower concentrations of folate and Hb occurring in summer and lower concentrations of vitamin B-6 occurring in winter and spring than in other seasons. We conclude that deficiencies of folic acid, vitamin B-6 and iron were relatively common in this sample of Chinese women of childbearing age and were contributing to the high prevalence of anemia. Without appropriate supplementation, these deficiencies could jeopardize the women's health and increase their risk of adverse pregnancy outcomes.