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Biomedical subjects

C E West

Publications and source records attributed to C E West.

At least 73 records · Page 4Linked to original sources
PubMed1997

Evaluation of biochemical indicators of vitamin A status in breast-feeding and non-breast-feeding Indonesian women.

Indicators of vitamin A status were evaluated in nonpregnant breast-feeding (n = 265) and nonpregnant non-breast-feeding (n = 49) Indonesian women. The concentration of vitamin A (not including provitamin A carotenoids) and fat in breast milk was 30% and 20% higher, respectively, for women with a breast-fed child 7-18 mo old than for women with an infant 3-6 mo old. The vitamin A content of milk fat was constant throughout lactation. Breast-milk vitamin A was most sensitive to changes in vitamin A status when expressed per volume. Sensitivity and specificity for detecting serum retinol concentrations < 0.70 mumol/L were < 75% for the concentration of breast-milk vitamin A and serum retinol binding protein (RBP). The modified-relative-dose-response (MRDR) method suffers from a relatively large intraindividual variation in the ratio of dehydroretinol to retinol because of vulnerability of the dehydroretinol concentration to laboratory errors and to variation in dosing and absorption. Within categories of dehydroretinol:retinol, serum retinol concentration was lower in breast-feeding women than in non-breast-feeding women. Thus, it may be necessary to use different cutoff values for the ratio and for serum retinol concentration. Serum retinol concentration, which was just above marginal (0.85 mumol/L), had the smallest within-person variation and was also the most sensitive indicator for detecting a difference between groups in change in vitamin A status postintervention, requiring only 19 subjects per group. Serum RBP concentration, breast-milk vitamin A expressed per volume or per gram milk fat, and the MRDR method required groups of 35, 36, 139, and 53 subjects, respectively.

Adolescent↗
PubMed1997

Effect of intestinal parasite treatment on the efficacy of oral iodized oil for correcting iodine deficiency in schoolchildren.

Oral supplementation with iodized oil for correction of iodine deficiency in a population has advantages over intramuscular injection but the duration of effect is shorter. The relation of intestinal parasite treatment and efficacy of oral iodized oil was examined in an intervention study in 8-10-y-old schoolchildren in Malawi. Severely iodine-deficient schoolchildren with a single parasitic infestation of Ascaris lumbricoides (n = 44), hookworm (n = 42), or Entamoeba histolytica (n = 24) were randomly allocated to receive or not receive treatment before taking a 1-mL oral supplement (490 mg I) of iodized ethyl esters from poppy seed oil. The urinary iodine concentration was measured at various time points after supplementation to define the time intervals before urinary iodine concentrations returned to 0.40 mumol/L, indicating moderate iodine deficiency. Treatment with metronidazole for E. histolytica increased the protection period from 2.0 to 21.0 wk (P < 0.05). For all untreated children together, the duration of effect was 9.2 wk shorter (P < 0.001) than that for their treated peers (16.8 wk). We conclude that intestinal parasitic infestations reduce the efficacy of oral supplementation with iodized ethyl esters by interfering with absorption.

Administration, Oral↗
PubMed1996

Supplemental vitamin A enhances the recovery from iron deficiency in rats with chronic vitamin A deficiency.

Studies with anaemic children and pregnant women from areas where vitamin A deficiency is endemic have shown a beneficial effect on Fe status of supplemental vitamin A in addition to Fe supplementation. This suggests a relationship between vitamin A and Fe status, which we attempted to mimic in rats with anaemia and chronic vitamin A deficiency. Male rats were fed on Fe-adequate diets (35 mg Fe/kg) containing different levels of vitamin A (1200, 450, 150, 75 and 0 retinol equivalent (RE)/kg feed) until they were 5 weeks old. These diets were identical to the diets fed to their mothers. Then the young male rats were transferred to diets containing the same levels of vitamin A but no added Fe. After another 2 weeks the rats were repleted with Fe (35 mg/kg feed) without or with vitamin A to a level of 1200 RE/kg feed. Increased vitamin A intake by the groups previously fed on diets with either 0 or 75 RE/kg produced a reduction in blood haemoglobin concentration, packed cell volume and erythrocyte count. In the group which had been fed on the diet without vitamin A, supplemental vitamin A raised mean cell volume, plasma Fe concentration and total Fe-binding capacity. Vitamin A supplementation during the period of Fe repletion produced a decrease in splenic and tibia Fe concentration, the effect being greater with increasing severity of previous vitamin A deficiency. The paradoxical effect of supplemental vitamin A on haemoglobin, packed cell volume and erythrocyte count can be explained by a decrease in the degree of haemoconcentration. Thus, the positive effect of supplemental vitamin A seen in humans is also observed with rats under controlled experimental conditions. We speculate that supplemental vitamin A during Fe repletion contributes to optimum erythropoiesis and Fe mobilization when baseline vitamin A status is impaired.

Anemia, Iron-Deficiency↗
PubMed1996

Dietary carotenoids and their role in combating vitamin A deficiency: a review of the literature.

OBJECTIVE: To evaluate the evidence that carotene-rich fruits and vegetables can overcome vitamin A deficiency. DESIGN: Results of studies on the relationship between dietary carotenoids and vitamin A deficiency were evaluated critically. RESULTS: Increased intake of fruits and vegetables has been shown to be related to improved vitamin A status in many cross-sectional, case-control and community-based studies, but this does not prove causality of the relationship. Many experimental studies indicating a positive effect of fruits and vegetables can be criticized for their poor experimental design while recent experimental studies have found no effect of vegetables on vitamin A status. Thus, it is too early to draw firm conclusions about the role of carotene-rich fruits and vegetables in overcoming vitamin A deficiency. Bioavailability of dietary carotenoids and their conversion to retinol are influenced by the following factors: Species of carotene; molecular Linkage; Amount of carotene in a meal; Matrix in which the carotenoid is incorporated; Absorption modifiers; Nutrient status of the host; Genetic factors; Host-related factors and Interactions (SLAMANGHI). Studies are required to quantify the impact of these factors, especially of the matrix, host-related factors and absorption modifiers. CONCLUSIONS: The effectiveness of carotene-rich foods in improving vitamin A status and ways of improving carotene bioavailability need further investigation.

Biological Availability↗
PubMed1995

Lack of improvement in vitamin A status with increased consumption of dark-green leafy vegetables.

There is little evidence to support the general assumption that dietary carotenoids can improve vitamin A status. We investigated in Bogor District, West Java, Indonesia, the effect of an additional daily portion of dark-green leafy vegetables on vitamin A and iron status in women with low haemoglobin concentrations (< 130 g/L) who were breastfeeding a child of 3-17 months. Every day for 12 weeks one group (n = 57) received stir-fried vegetables, a second (n = 62) received a wafer enriched with beta-carotene, iron, vitamin C, and folic acid, and a third (n = 56) received a non-enriched wafer to control for additional energy intake. The vegetable supplement and the enriched wafer contained 3.5 mg beta-carotene, 5.2 mg and 4.8 mg iron, and 7.8 g and 4.4 g fat, respectively. Assignment to vegetable or wafer groups was by village. Wafers were distributed double-masked. In the enriched-wafer group there were increases in serum retinol (mean increase 0.32 [95% CI 0.23-0.40] mumol/L), breastmilk retinol (0.59 [0.35-0.84] mumol/L), and serum beta-carotene (0.73 [0.59-0.88] mumol/L). These changes differed significantly from those in the other two groups, in which the only significant changes were small increases in breastmilk retinol in the control-wafer group (0.16 [0.02-0.30] mumol/L) and in serum beta-carotene in the vegetable group (0.03 [0-0.06] mumol/L). Changes in iron status were similar in all three groups. An additional daily portion of dark-green leafy vegetables did not improve vitamin A status, whereas a similar amount of beta-carotene from a simpler matrix produced a strong improvement. These results suggest that the approach to combating vitamin A deficiency by increases in the consumption of provitamin A carotenoids from vegetables should be re-examined.

Anemia↗
PubMed1995

Evaluation of a two-generation rat model for vitamin A deficiency and the interrelationship with iron metabolism.

In order to induce a range of vitamin A-deficient states in young growing rats and to study the effect of vitamin A deficiency on Fe status, we designed the following two-generation experiment. Dams were fed on diets with one of five vitamin A levels from 2 weeks before and throughout pregnancy and lactation. The pups received the same diets as their mothers both before and after weaning. The five dietary levels of vitamin A were 1200, 450, 150, 75 and 0 retinol equivalents/kg feed. Vitamin A intake did not affect reproduction outcome, nor were body and liver weights of the pups affected when they were 3.5 weeks old. Male pups with normal vitamin A status had higher plasma retinol levels than female pups. Vitamin A status of the offspring was affected from 3.5 weeks onwards. Body and liver weights were decreased in the male pups given the lowest dietary vitamin A levels from week 6.5 onwards but not in the female pups. Fe status was marginally affected. Haemoglobin levels were increased and total Fe-binding capacity was decreased in the groups given no dietary vitamin A at week 9.5. Splenic Fe was increased only in the male pups given the lowest levels of dietary vitamin A. However, as a whole, Fe status was only mildly affected and subject to considerable variation. We conclude that the two-generation rat model described here is not suitable for studying effects of vitamin A deficiency on Fe metabolism.

Animals↗
PubMed1995

New model for describing urinary iodine excretion: its use for comparing different oral preparations of iodized oil.

Iodine excretion in urine after oral dosing with iodized oil is influenced by various factors involved in the retention and elimination of iodine by the body. In a study comparing different treatments of severely iodine-deficient schoolchildren from Malawi, a hyperbolic function was found to describe changes in urinary iodine concentration over time more adequately than a simple exponential function. Compared with oil A, comprising ethyl esters of iodized fatty acids, the retention and elimination of iodine from oil B, comprising triacylglycerol esters of iodized fatty acids, were significantly greater. The mean duration of effectiveness of oral iodized oil, based on urinary iodine concentrations > 0.40 mumol/L, was estimated to be 13.7, 9.9, and 52.5 wk for a single dose of iodized oil A (490 mg I), a split dose of iodized oil A (2 x 245 mg I), and a single dose of iodized oil B (675 mg I), respectively. Dividing the dose of oil A into two equal amounts given on consecutive days did not improve its efficacy.

Administration, Oral↗
PubMed1994

Comparison between time-dependent changes in iron metabolism of rats as induced by marginal deficiency of either vitamin A or iron.

To compare the changes in Fe metabolism during the development of vitamin A and Fe deficiencies, rats were given either a control diet with sufficient Fe (35 mg added Fe/kg feed) and retinol (1200 retinol equivalents/kg feed), a diet without added vitamin A or a diet with sufficient vitamin A but only 3.5 mg added Fe/kg feed. During a period of 10 weeks, indicators of vitamin A and Fe status were monitored. Neither vitamin A nor Fe deficiency produced clinical signs. Fe deficiency induced an immediate fall in blood haemoglobin concentration. Vitamin A deficiency produced a mild anaemia as the first change in Fe metabolism, pointing to impaired erythropoiesis. This effect was followed by a rise in Fe absorption and an increased amount of Fe in the spleen. By the end of the study, blood haemoglobin, packed cell volume, plasma Fe and Fe content in kidney and femur had increased above control levels, while total Fe-binding capacity had decreased. We speculate that the initial anaemia was masked later by haemoconcentration. The decrease in Fe mobilization, shown by lower total Fe-binding capacity, and the increase in Fe absorption may have caused the observed continuous rise in tissue Fe concentration in rats with vitamin A deficiency. In the rats with Fe deficiency, low tissue Fe levels coincided with high Fe absorption and high total Fe-binding capacity. Thus, changes in Fe metabolism with vitamin A deficiency differed from those with Fe deficiency.

Anemia, Hypochromic↗
PubMed1994

Increasing intakes of iron reduce status, absorption and biliary excretion of copper in rats.

High intakes of Fe may impair Cu status, but the underlying mechanism is not known. Male rats, aged 7 weeks, were given purified diets adequate in Cu (8 mg Cu/kg) and containing either 7, 40 or 389 mg Fe/kg. After 6 weeks the concentrations of Fe in liver and spleen were positively related with dietary Fe level and those of Cu were negatively related with dietary Fe level. Increasing Fe intakes reduced apparent absorption and biliary excretion of Cu in a dose-dependent fashion. In individual rats, biliary Cu excretion showed a significant, positive correlation with liver Cu concentration. It is concluded that increased Fe intakes depress Cu absorption which produces a decrease in plasma and organ Cu concentrations. As a result, biliary Cu excretion is lowered which contributes to achieving Cu balance at high Fe intakes. Because the concentrations of Cu in plasma and bile, and also plasma ceruloplasmin (EC 1.16.3.1) activities, showed much greater percentage reductions with increasing Fe intake than did the concentrations of Cu in organs, it is possible that increased Fe status interferes with the mobilization of Cu stores.

Animals↗
PubMed1994

A critical appraisal of goiter assessment and the ratio of urinary iodine to creatinine for evaluating iodine status.

Iodine status can be evaluated by goiter assessment and measurement of urinary iodine concentration in either 24-h urine collections or in casual samples. It is often impossible to make 24-h collections. Therefore, iodine concentration in casual samples is often expressed in terms of urinary creatinine, assuming creatinine excretion to be constant between and within individuals. In this study large inter- and intraindividual variations were observed in the creatinine content of casual samples ranging from 0.6 to 9.87 mmol/L. Further, the urinary iodine-creatinine ratio correlated significantly with the creatinine concentration; Spearman's rank-order correlation coefficient, rs = 0.39 (P < 0.001). If creatinine is a suitable index to correct for variations in iodine excretion, no correlation would be expected. We conclude that the iodine-creatinine ratio in casual urine samples is an unsuitable indicator for evaluating iodine status in areas where large inter- and intraindividual variations in urinary creatinine excretion exist.

Child↗
PubMed1993

Supplementation with vitamin A and iron for nutritional anaemia in pregnant women in West Java, Indonesia.

Nutritional anaemia, thought to be caused by iron deficiency, affects 50-70% of pregnant women in the developing world. The influence of vitamin A and iron supplementation was studied in anaemic pregnant women in West Java, in a randomised, double-masked, placebo-controlled field trial. 251 women aged 17-35 years, parity 0-4, gestation 16-24 weeks, and haemoglobin between 80 and 109 g/L were randomly allocated to four groups: vitamin A (2.4 mg retinol) and placebo iron tablets; iron (60 mg elemental iron) and placebo vitamin A; vitamin A and iron; or both placebos, all daily for 8 weeks. Maximum haemoglobin was achieved with both vitamin A and iron supplementation (12.78 g/L, 95% Cl 10.86 to 14.70), with one-third of the response attributable to vitamin A (3.68 g/L, 2.03 to 5.33) and two-thirds to iron (7.71 g/L, 5.97 to 9.45). After supplementation, the proportion of women who became non-anaemic was 35% in the vitamin-A-supplemented group, 68% in the iron-supplemented group, 97% in the group supplemented with both, and 16% in the placebo group. Improvement in vitamin A status may contribute to the control of anaemic pregnant women.

Adolescent↗
PubMed1993

Goitre in Ethiopia.

A stratified goitre survey was conducted on 35,635 schoolchildren and 19,158 household members in all Regions of Ethiopia except Eritrea and Tigrai. The gross goitre prevalence (mean of male and female values) among schoolchildren and household members was 30.6 and 18.7% respectively, while that of visible goitre was 1.6 and 3.2% respectively. Prevalence was higher in females (27.3% in household members and 36.1% in schoolchildren) than in males (10.1% in household members and 25.1% in schoolchildren) and increased with age more in females than in males. The prevalence rates at higher altitudes were higher than those at lower altitudes in both schoolchildren and household members. Using an epidemiological model the consequences of iodine deficiency, including cretinism and maternal wastage, have been estimated.

Adolescent↗
PubMed1993

Interrelationship between vitamin A, iodine and iron status in schoolchildren in Shoa Region, central Ethiopia.

A total of 14,740 schoolchildren in seven provinces of Shoa Administrative Region in Central Ethiopia were surveyed for the prevalence of goitre, xerophthalmia and anaemia. Haemoglobin and packed cell volume were assessed in 966 children in one province while an in-depth study was conducted on 344 children in the same province and two others. Goitre, xerophthalmia (Bitot's spots) and clinical anaemia were observed in 34.2, 0.91 and 18.6% respectively of the children. Most biochemical variables were within the normal range while those of haemoglobin (Hb), mean corpuscular Hb concentration (MCHC) and urinary I excretion were lower, and mean corpuscular volume, mean corpuscular Hb (MCH), and immunoglobulins G and M were higher. Hb was strongly correlated with retinol, ferritin, MCHC, MCH, packed cell volume and erythrocyte count while retinol formed a triad with transthyretin (TTR) and retinol-binding protein (RBP) which were all correlated with one another. Total and free thyroxin and total and free triiodothyronine were positively correlated as were the concentrations of the total and free hormones. Thyrotropin (TSH) was negatively correlated with total and free thyroxin and positively correlated with free triiodothyronine. Thyroxin and triiodothyronine in both free and combined forms were all correlated with thyroxin-binding globulin which in turn was negatively correlated with the triad retinol, RBP and TTR. The triad was also negatively correlated with C-reactive protein. Urinary I excretion was positively associated with total thyroxin and negatively associated with TSH. The anaemia found was not nutritional in origin but due to the effect of infestation with intestinal parasites and malaria.

Adolescent↗
PubMed1993

Iron status in rats fed on diets containing marginal amounts of vitamin A.

Severe vitamin A deficiency in rats is known to cause anaemia associated with growth retardation and impaired water retention. However, study of the effect of marginal vitamin A intake is of more interest because such intake may mirror the situation in humans in many developing countries. Therefore, in two experiments, the effect of marginal vitamin A deficiency on Fe status was investigated in male rats. After 28 d of feeding either low- or high-vitamin A diets (0 or 120 v. 1200 retinol equivalents/kg feed), body weight and feed intake were not influenced by the level of vitamin A in the diet. Liver weight was lowered by vitamin A deficiency. Water intake was not influenced in rats fed on a low-vitamin A diet. Plasma retinol concentrations were decreased in rats fed on diets low in vitamin A. Marginal vitamin A deficiency produced slightly lower blood haemoglobin concentrations; it did not systematically affect packed cell volume. The concentration of Fe in liver was significantly higher when diets low in vitamin A were fed, but hepatic Fe mass was not affected. Significantly lower Fe levels were observed in femurs of rats with vitamin A deficiency. The effects on liver and femur Fe concentrations were seen with diets adequate in Fe but not with diets deficient in Fe. The efficiency of apparent Fe absorption was significantly increased by low intakes of vitamin A, provided that the dietary Fe concentration was adequate. It is speculated that depressed uptake of Fe by bone marrow is the primary feature of altered Fe status in rats with marginal vitamin A deficiency.

Animals↗