Self-selection of a high calcium diet by vitamin D-deficient lactating rats increases food consumption and milk production

Lactating and nonlactating rats, both deficient and replete in cholecalciferol, were allowed a free selection among three diets containing 0.47% Ca, 0.3% P (normal Ca, normal P diet); 2.0% Ca, 0.3% P (high Ca diet); and 0.47% Ca, 1.0% P (high P diet). An additional group of vitamin D-deficient lactating rats was fed only the normal Ca, normal P diet. Vitamin D-deficient rats showed a strong selection preference for the high Ca diet but avoided the high P diet, whereas cholecalciferol-replete rats consumed the normal Ca, normal P diet predominantly. Compared to the nonselecting rats, the selection of the high Ca diet by the lactating rats deficient in vitamin D resulted in an increase in plasma calcium levels, hypophosphatemia, a doubling of food consumption, a reduction in maternal body weight loss and a stimulation of milk production as indicated by pup growth. These results demonstrate that vitamin D-deficient rats select a high Ca diet and that the decrease in milk production found in vitamin D deficiency results from a decrease in food consumption and that this anorexia is at least partially dependent on the hypocalcemia normally occurring in vitamin D deficiency.     

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.     

Work-induced muscle hypertrophy in vitamin D-deficient rats.

To determine if vitamin D deficiency would retard the ability of muscle to hypertrophy in response to mechanical stress, we severed the gastrocnemius tendon on one leg of rats in each of three groups, the treatment of which differed only in the amount of vitamin D in the diet. After 1 week the increased size of the soleus and plantaris in the leg in which the gastrocnemius was severed relative to that of the sham operated leg, was determined for each rat. Despite differences in body weight and serum calcium among the groups, we found no difference in the percent of muscle hypertrophy. We conclude that muscle hypertrophy can occur in response to local mechanical forces despite a deficient hormonal environment that otherwise retards growth.     

Intrauterine devices in nulliparous women

The majority of studies on the clinical events following the insertion of an intrauterine device for contraception have observed a higher frequency of adverse effects in nulliparous women. In this review, the significance of nulliparity on the occurrence of medical removal for bleeding and pain, expulsion and pelvic inflammatory disease is estimated. The possible role of the anatomy of the pregravid uterus is discussed, and results obtained through a selective measurement of the endometrial cavity in a population of nulligravidas is presented. It is concluded that IUDs should not be the first choice of contraception in nulliparous women because of an increased risk of long-term adverse effects. The relationship between the length of the intrauterine device and the length of the endometrial cavity does not seem to be of clinical significance for the performance of IUDs in nulliparous women.     

Oral glucose tolerance is unaltered in vitamin D-deficient rat

Vitamin D deficiency has been reported to result in impaired glucose tolerance and decreased insulin secretion when glucose is administered either intravenously or intraperitoneally. The aim of the present study was to study oral glucose tolerance and glucose absorption in a vitamin D-deficient rat model. Oral glucose tolerance tests were carried out in vitamin D-deficient and control rats, and this was found to be unaltered in the deficient state. Intestinal absorption of glucose was drastically reduced in the deficient animal and was found to be due to a reduction in the sodium-dependent component of glucose transport. Thus the unaltered oral glucose tolerance in the vitamin D-deficient rat is probably due to impaired absorption of glucose.     

Analyzed vitamin B-6 intakes of pregnant and postpartum lactating and nonlactating women

Daily dietary food composites were collected for three consecutive days from 36 women (23 who planned to breast feed their infants and 13 who planned to formula feed their infants) at approximately the 37th week of pregnancy and at one, three, and six months postpartum. When the food composites were collected, each woman also kept detailed food intake records. Daily protein and energy intakes were calculated from the records. Representative aliquots of the homogenized food composites were analyzed microbiologically for total vitamin B-6. The data from the composite analyses indicate that the daily dietary intakes of vitamin B-6 for both groups of women in late pregnancy through six months postpartum were substantially less than the Recommended Dietary Allowances (RDAs). During pregnancy, the women who planned to breast feed their infants consumed diets which provided 54% of the RDA. The women who planned to formula feed their infants consumed diets which provided only 44% of the RDA for vitamin B-6 for pregnant women. At one, three, and six months postpartum, the diets of the lactating women provided 61% of their RDA for vitamin B-6, and the diets of the nonlactating women provided a mean of 46%. Of the 402 daily dietary composites analyzed, only 6% met or exceeded the RDA for vitamin B-6 for the women while they were pregnant or postpartum, either lactating or nonlactating.     

2013年中国2岁以下儿童母亲维生素B12营养状况及其影响因素

目的 了解中国2岁以下儿童母亲维生素Bl2营养状况的现状,并分析其影响因素.方法 利用2013年中国居民营养与健康状况监测中2岁以下儿童母亲的调查数据,采用多阶段分层抽样方法抽取中国30个省(自治区、直辖市)的55个县(市/区)2岁以下儿童母亲.最终采集2岁以下儿童母亲血液样本10331份,问卷调查收集其基本情况,通过...     

婴儿维生素D缺乏性佝偻病并外部性脑积水发病机制及预后

目的探讨维生素D缺乏性佝偻病并外部性脑积水的发病机制及预后。方法回顾性分析1995年1月～2006年1月新乡医学院第一附属医院73例维生素D缺乏性佝偻病并外部性脑积水患儿的临床资料和随访资料。结果73例维生素D缺乏性佝偻病并外部性脑积水患儿均有不同程度佝偻病表现和颅内高压征象,头颅CT显示蛛网膜下腔增宽。随访观察,发现其中一些患儿存在运动和语言发育迟缓,且随着佝偻病的恢复,上述征象及CT异常征象逐渐消失。结论维生素D缺乏性佝偻病可能是外部性脑积水的一个重要病因,其预后一般良好。     

Use of intrauterine devices in nulliparous women

Five intrauterine devices (IUDs) are available in the United States: four levonorgestrel-releasing intrauterine systems (two containing 52 mg, one containing 19.5 mg and one containing 13.5 mg) and one copper-bearing device (Copper T 380A). All IUDs have very low typical-use failure rates and high acceptability ratings, yet they are used by a minority of women, with nulliparous women less likely to do so than parous women. The objective of this clinical review is to give evidence-based recommendations for the use of IUDs in nulliparous women. Intrauterine devices are safe and effective for the majority of women including those who are nulliparous, and should be routinely included in the contraception options offered to them.     

Responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in pregnant and lactating women in Nepal

BACKGROUND: Impaired dark adaptation occurs commonly in vitamin A deficiency. OBJECTIVE: We sought to examine the responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in Nepali women. DESIGN: The dark-adapted pupillary response was tested in 298 pregnant women aged 15-45 y in a placebo-controlled trial of vitamin A and beta-carotene; 131 of these women were also tested at 3 mo postpartum. Results were compared with those for 100 nonpregnant US women of similar age. The amount of light required for pupillary constriction was recorded after bleaching and dark adaptation. RESULTS: Pregnant women receiving vitamin A had better dark-adaptation thresholds (-1.24 log cd/m(2)) than did those receiving placebo (-1.11 log cd/m(2); P: = 0. 03) or beta-carotene (-1.13 log cd/m(2); P: = 0.05) (t tests with Bonferroni correction). Dark-adaptation threshold was associated with serum retinol concentration in pregnant women receiving placebo (P: = 0.001) and in those receiving beta-carotene (P: = 0.003) but not in those receiving vitamin A. Among women receiving placebo, mean dark-adaptation thresholds were better during the first trimester (-1.23 log cd/m(2)) than during the second and third trimesters (-1.03 log cd/m(2); P: = 0.02, t test). The mean threshold of nonpregnant US women (-1.35 log cd/m(2)) was better than that of all 3 Nepali groups (P: < 0.001, t test, for all 3 groups). CONCLUSIONS: During pregnancy, pupillary dark adaptation was strongly associated with serum retinol concentration and improved significantly in response to vitamin A supplementation. This noninvasive testing technique is a valid indicator of population vitamin A status in women of reproductive age.     

Mini-pill in lactating women

A non-comparative study of the progestogen-only oral contraceptive, norgestrel 0.075 mg, in breast-feeding women was conducted at the Centro de Investigaciones Regionales, Merida, Yucatan, Mexico. The study was designed to evaluate the overall acceptability and contraceptive efficacy of norgestrel in breast-feeding women. This report includes a survey of 200 women, all of whom were less than 26 weeks postpartum at admission; 113 were interval patients and 87 were postpartum. Follow-up visits were scheduled at 2, 6 and 12 months after admission. Overall, women experienced an increase in intermenstrual bleeding, amenorrhea, vaginal discharge and breast discomfort. The discontinuation rate at 12 months was 32.5 and the corresponding lost to follow-up rate was 22.5; this is a measure of acceptability. The 12-month life-table rate for pregnancy was 3.4 with a standard error of 2.0. Three women discontinued use of the mini-pill due to accidental pregnancy. One pregnancy was attributed to user failure and the woman conceived 9 months after entering into the study; the other two were attributed to method failure, one woman conceived 3 months after admission and the other conceived 6 months after admission.     

Oral contraceptives and premenopausal breast cancer in nulliparous women

Characteristics of women with potential for modifying the relationship between use of oral contraceptives (OCs) and the risk of premenopausal breast cancer were investigated using data from the Cancer and Steroid Hormone study, a population-based, case-control study conducted in eight geographic areas of the United States. Cases consisted of 2945 women who were premenopausal and 20-54 years of age when breast cancer was diagnosed between December 1, 1980, and December 31, 1982; controls consisted of 2646 women with no history of breast cancer who were also premenopausal and 20-54 years of age when selected during the same period. Results are presented with the cases and controls divided into eight groups on the basis of age at diagnosis on selection (20-44, 45-54), parity (0, greater than or equal to 1), and age at menarche (less than 13, greater than or equal to 13). Among nulliparous women who experienced menarche before age 13, the relative risk of developing breast cancer in the age interval 20-44 years is estimated to be 1.0 for never-users of OCs (reference), 1.3 for greater than 0-3 years of use (95% confidence intervals 0.7-2.4), 1.3 for 4-7 years (95% CI 0.7-2.6), 2.7 for 8-11 years (95% CI 1.2-6.3), and 11.8 for 12 years or longer (95% CI 1.4-95.7). OC use is not significantly related to the risk of breast cancer among women in any of the other seven groups. These findings suggest that prolonged OC use may accelerate the onset of breast cancer for a small group of susceptible women while having no appreciable impact on overall risk. The findings should be regarded as tentative, however, since they are based upon numerous comparisons and because age of menarche was stratified at 13 years to highlight the concentration of breast cancer risk apparent in our data.     

Normalization of serum calcium restores fertility in vitamin D-deficient male rats.

We performed experiments to determine whether treatment with vitamin D or 1,25-dihydroxycholecalciferol could reverse male infertility caused by vitamin D deficiency. Additionally, an attempt was made to distinguish between a direct and an indirect effect of 1,25-dihydroxycholecalciferol on reproductive tissue. Vitamin D-deficient male rats with impaired fertility were treated with vitamin D and 1,25-dihydroxycholecalciferol for 3 wk, then mated. Secondly, vitamin D-deficient male rats were made normocalcemic by increasing dietary calcium, and their fertility was compared with that of vitamin D-deficient, hypocalcemic rats. The fertility of male rats was restored by treatment with either vitamin D or 1,25-dihydroxycholecalciferol. However, fertility was also restored in vitamin D-deficient animals by feeding them a diet supplemented with high levels of calcium. These results indicate that the influence of vitamin D and its active metabolite, 1,25-dihydroxycholecalciferol, on male fertility is indirect. Vitamin D and 1,25-dihydroxycholecalciferol seemed to influence male fertility by acting on classic target tissues and regulating levels of calcium in reproductive tissues.     

Calcium metabolism in lactating women

During lactation the main source of the breast-milk calcium seems to be maternal bone. The women who breast-fed, lost bone mineral content, which is recovered once breast-feeding ceased. Breast-milk calcium do not depend on an increase in calcium intake by the lactating mother. Calcium demand during lactation is associated with adjustments in the calcium metabolism, such as a decrease in urinary calcium excretion and mobilization of calcium from maternal bone. The classical calciotropic hormones concentrations (PTH and 1,25-dihydroxyvitamin D) are not associated with bone turnover markers or with changes in bone mineral content in the lactating women. However, serum estradiol is strongly associated with calcium balance, bone loss and calcium milk content.     

Weekly vitamin A and iron supplementation during pregnancy increases vitamin A concentration of breast milk but not iron status in Indonesian lactating women

Studies on the effect of vitamin A and iron supplementation during pregnancy on maternal iron and vitamin A status postpartum are scarce. We investigated whether retinol and iron variables in breast milk and in serum postpartum were enhanced more with weekly vitamin A and iron supplementation during pregnancy than with weekly iron supplementation. During pregnancy, subjects were randomly allocated to two groups and received either (n = 88) a weekly supplement of iron (120 mg Fe as FeSO(4)) and folic acid (500 microg) or (n = 82) the same amount of iron and folic acid plus vitamin A [4800 retinol equivalents (RE)]. Transitional milk (4-7 d postpartum) had higher (P < 0.001) concentrations of retinol and iron than mature milk (3 mo postpartum). Compared with the weekly iron group, the weekly vitamin A and iron group had a greater (P < 0.05) concentration of retinol in transitional milk (as micromol/L) and in mature milk (as micromol/g fat). Although serum retinol concentrations approximately 4 mo postpartum did not differ significantly, the weekly vitamin A and iron group had significantly fewer (P < 0.01) subjects with serum retinol concentrations < or = 0.70 micromol/L than the weekly iron group. Iron status and concentrations of iron in transitional and mature milk did not differ between groups. We have shown that weekly vitamin A and iron supplementation during pregnancy enhanced concentrations of retinol in breast milk although not in serum by approximately 4 mo postpartum. However, no positive effects were observed on iron status and iron concentration in breast milk.     

Dietary intake of total and glycosylated vitamin B-6 and the vitamin B-6 nutritional status of unsupplemented lactating women and their infants

The mean dietary intakes of total and glycosylated vitamin B-6, determined from analysis of 3-d diet composites collected from 30 lactating women, were 8.63 +/- 4.04 and 1.33 +/- 0.85 mumol/d (mean +/- SD), respectively. A comparison of linear regression models that either included or excluded dietary glycosylated vitamin B-6 content indicates that the intake of glycosylated vitamin B-6 had little, if any, effect upon maternal plasma pyridoxal 5'-phosphate concentration and maternal urinary excretion of total vitamin B-6 and 4-pyridoxic acid. On the basis of guidelines from the literature for evaluating biochemical indices of vitamin B-6 nutriture, the women appeared to be consuming adequate amounts of the vitamin. The mean breast-milk concentrations of total and glycosylated vitamin B-6 were 733 and 18 nmol/L, respectively. Infant plasma pyridoxal 5'-phosphate concentration was 54 +/- 44 nmol/L (mean +/- SD) and all infants had lengths and weights appropriate for age.     

Copper IUDs,PID, and fertility in nulliparous women

Some authors have suggested that use of IUDs (intrauterine contraceptive devices) in nulliparous women should be contraindicated because of the risk for PID (pelvic inflammatory disease); others have found nulliparous women to be suitable candidates for IUD use. Clinical studies of copper IUDs in which parous and nulliparous women have been compared with regard to risk of PID often point to young age as a risk factor, regardless of parity. Vital statistics of PID rates also show this trend. An overall PID rate of 1.49/100 woman-years (WY) was calculated from data contained in 28 of the clinical studies reviewed in this paper. These studies included 25,674 women, of whom 42.5% were nulliparous. Studies of fertility following use of copper IUDs indicate that fertility is not impaired by their use.

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Resumen Ciertos autores han sugerido que el empleo de DIU (dispositivos anticonceptivos intrauterinos) en las mujeres nulíparas debía estar contraindicado a causa del riesgo de enfermedades pélvicas inflamatorias (EPI); otros han considerado que estos dispositivos eran convenientes para las mujeres nulíparas. Los estudios clínicos realizados con DIU de cobre en los que se comparó el riesgo de EPI en las mujeres con hijos y en las mujeres nulíparas revelaron frecuentemente que la edad joven era un factor de riesgo, sea cual fuere la paridad. Las estadísticas vitales relativas a la proporción de API también indican esta tendencia. Se calculó un porcentaje total de EPI de 1.49 por cada 100 años-mujer a partir de los datos extraídos de 28 estudios clínicos examinados en este documento. Estos estudios comprendieron a 25,674 mujeres, de las cuales el 42.5% eran nulíparas. Los estudios relativos a la fecundidad tras el empleo de DIU de cobre indican que la fertilidad no se ve afectada por el empleo di dicho dispositivo.

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Resumé Certains auteurs ont suggéré que l'usage des DIU (dispositif intra-utérin de contraception) chez les femmes nullipares devrait être contre-indiqué à cause du risque de maladies pelviennes inflammatoires (MPI); d'autres ont trouvé que ces dispositifs convenaient fort bien pour les femmes nullipares. Des études cliniques effectuées avec des DIU au cuivre, où l'on a comparé, en étudiant le risque de MPI, des femmes ayant eu des enfants et des femmes nullipares, ont souvent révélé que le jeune âge était un facteur de risque, quelle que soit la parité. Les statistiques vitales sur le taux de MPI ont aussi fait apparaître cette tendance. Un pourcentage total de MPI de 1.49 pour 100 année/femme a été calculé à partir des données extraites de 28 études cliniques examinées dans ce document. Ces études portaient sur 25,674 femmes, dont 42.5% étaient des nullipares. Des études relatives à la fécondité après usage du DIU au cuivre montrent que celle-ci n'est pas compromise par l'utilisation de ce dispositif.

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This paper is based on a presentation given at the Seventh International Meeting of the Scoiety for the Advancement of Contraception, which was held in Singapore on 4–11 November, 1990.