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Biomedical subjects

A Prentice

Publications and source records attributed to A Prentice.

191 records · Page 11Linked to original sources
PubMed1983

The effect of vitamin C supplementation on lactating women in Keneba, a West African rural community.

A study of vitamin C requirements was undertaken in the village of Keneba, The Gambia, during the rainy season, when the intake of vitamin C-rich foods is very low. The effect of four supplementary levels of vitamin C (0, 24, 47 and 60 mg/day), together with a milk and biscuit food supplement which provided 34 mg vitamin C/day, was studied for a five-week period. Plasma ascorbate increased from 0.25 to 0.72 mg/dl; buffy coat ascorbate increased from 14.7 to 24.3 micrograms/10(8) cells and breast milk ascorbate increased from 3.4 to 5.5 mg/dl as intake increased from 34 to 103 mg/dl. Breast milk ascorbate approached a plateau at the high intakes. A fasting plasma ascorbate of at least 0.3 mg/dl in 97.5% of the population of lactating women in Keneba would require a daily vitamin C intake of about 117 mg. No differences between vitamin C supplementation levels were observed with respect to changes in plasma iron, total iron-binding capacity or its percentage saturation. Whole blood histamine levels showed a slight downward trend as the vitamin C intake increased.

Adult↗
PubMed1982

Seasonal variations in ascorbic acid status and breast milk ascorbic acid levels in rural Gambian women in relation to dietary intake.

Vitamin C intakes from mangoes and oranges, and plasma and breast milk ascorbic acid concentrations were measured at regular intervals in a cohort of pregnant and lactating women in Keneba and Manduar, two neighbouring rural Gambian villages. Extremely wide seasonal variations in plasma ascorbic acid levels were observed, the peak during the mango season in May and June attaining mean levels of 1.4 mg/dl, while the lowest levels, averaging only 0.2 mg/dl, were observed during the rainy season, during September and October. Parallel, but less pronounced variations were observed in breast milk ascorbate levels. A vitamin-fortified milk and biscuit supplement, given first to the lactating, and later to the pregnant, mothers in Keneba, which provided about 35 mg ascorbic acid per day, failed to produce any major improvement in plasma ascorbic acid levels during the rainy season, although there was some evidence for an improvement in breast milk levels. It is therefore likely that considerably greater intakes are required to maintain satisfactory maternal circulating levels and biochemical status during this critical period.

Ascorbic Acid↗
PubMed1982

Riboflavin status in infants born in rural Gambia, and the effect of a weaning food supplement.

Riboflavin status was measured in infants between birth and two years of age, by the erythrocyte glutathione reductase (NAD(P)H2: glutathione oxidoreductase, EC 1.6.4.2) test on finger-prick blood samples. The infants were living in three rural Gambian villages: Keneba, Manduar and Kanton Kundar; those in Keneba were receiving a weaning food supplement between three and 12 months, which provided 0.15 to 0.20 mg riboflavin per day, in addition to their normal intake from breast milk and locally available weaning foods, which provided 0.13 to 0.21 mg/day over the same age range. On the basis of currently accepted criteria of biochemical normality, the unsupplemented infants were born deficient and, in the absence of a supplement, remained so throughout their first two years of life, with only a minor, short-lived improvement during the first few months. In the supplemented group, however, riboflavin status fell within normal limits for the duration of the supplement, but rapidly deteriorated again once the supplement was withdrawn. It is concluded that infants born to deficient mothers are usually deficient at birth, and remain so throughout suckling and weaning on to locally available foods. The daily requirement, to achieve satisfactory biochemical status, is thus greater than 0.13 to 0.21 mg/day, and probably approaches 0.4 mg/day, for most individuals up to the age of one year.

Child, Preschool↗
PubMed1982

Physiological tests during an improvement in riboflavin status in lactating Gambian women.

During several weeks riboflavin supplementation of lactating African women, which reduced their mean activation coefficient of erythrocyte glutathione reductase (EGRAC) from 1.65 to 1.21 and initiated an improvement in clinical deficiency signs, measurements were made of physiological functions which may be connected with riboflavin status. No specific response to the supplement could be detected in body weight, grip strength, haematological parameters, osmotic fragility and resistance to oxidative stress of erythrocytes, plasma iron levels and related indices, or plasma hormone levels. There was a cross-sectional relationship between erythrocyte distribution on Percoll density gradients and EGRAC before supplementation, and between the Percoll pattern and total haemoglobin concentration. It is not yet known, however, whether a direct causal relationship exists between these variables.

Adult↗
PubMed1981

Breast-milk fat concentrations of rural African women. 1. Short-term variations within individuals.

1. Detailed studies of variations in breast-milk fat concentrations were performed over 12 or 24 h periods on sixty rural Gambian women feeding on demand. The creamatocrit method (Lucas et al. 1978) was used. 2. The complex pattern of within-feed and between-feed changes in fat concentration was largely explained by differences in volume per feed and time interval between feeds. 3. No consistent difference in fat production between the breasts of each individual was found despite the local custom of starting all feeds on the right breast. 4. A marked diurnal variation in the mean fat concentration per feed was noted. On average the highest values occurred in the early morning, the lowest values in the late afternoon. 5. There was significantly greater between-individual than within-individual variation in the mean fat concentration per feed over 12 h (P less than 0.001). 6. A simple, rational and non-intrusive sampling procedure was devised for the estimation of whole-day mean fat levels based on the finding that the mean fat concentration of small samples of milk (0.25 ml) taken from both breasts before and after one specific feed of the day was closely correlated with 12 h and 24 h mean fat concentrations.

Breast Feeding↗
PubMed1981

Breast-milk fat concentrations of rural African women. 2. Long-term variations within a community.

1. Long-term variations in breast-milk fat concentration of mothers feeding on demand were studied in 120 rural West African women over a 12-month period. 2. The over-all mean 12 h breast-milk fat concentration was 39.3 g/l. 3. Mean breast-milk fat concentrations were affected by season in a manner which was correlated with seasonal changes in maternal subcutaneous fat stores (P less than 0.05) but which was unrelated to seasonal variations in maternal energy intake and breast-milk output. 4. Breast-milk fat concentrations were highest in early lactation, decreasing to a constant level during the first year. 5. There was significantly greater between-mother than within-mother variation in breast-milk fat concentrations measured in successive months, after correcting for season and stage of lactation (P less than 0.001). 6. Breast-milk fat concentrations were highest for primiparous mothers, decreasing to a constant level at parity 4 and higher. 7. A mother's relative breast-milk fat concentration was not correlated with her levels of dietary energy intake and breast-milk output but was positively correlated with her relative subcutaneous fat deposits (P less than 0.01).

Energy Intake↗
PubMed1981

The influence of G-6-PD activity on the response of erythrocyte glutathione reductase to riboflavin deficiency.

Erythrocyte NAD(P)H2 glutathione oxidoreductase (EC 1.6.4.2.) activation coefficients (EGR AC) and D-glucose-6-phosphate: NADP 1-oxidoreductase, EC 1.1.1.49 (G-6-PD) activities were measured in 155 West African women to determine whether heterozygous G-6-PD deficiency produces false negative results in the EGR test for riboflavin deficiency. A positive correlation was found between EGR AC and G-6-PD activity demonstrating that heterozygous G-6-PD deficiency does result in abnormally depressed EGR AC values when G-6-PD activity is significantly reduced. However, heterozygous deficient genotypes with normal G-6-PD activity showed undepressed EGR AC values. These results indicate that, in its present form, the EGR test is not a suitable index of riboflavin status in subjects whose G-6-PD activity is less than 9 IU/g Hb when measured by the WHO-37 degrees assay.

Adult↗
PubMed1980

Dietary supplementation of Gambian nursing mothers and lactational performance.

A dietary supplement, resulting in a mean net increase in energy intake of over 700 kcal/day, was supplied to all nursing mothers in a West African village for 12 months. The supplement produced a slight initial improvement in maternal body weight and subcutaneous fat stores but did not increase breast-milk output or fat content.

Body Weight↗
PubMedDate not supplied

Breast milk as a source of vitamins, essential minerals and trace elements.

Human breast milk provides all of the vitamins and essential minerals and trace elements (micronutrients) that are required by the normal term infant, until weaning. With a few exceptions, excessive micronutrient supplies to the mother, or a moderate deficiency in her diet, do not greatly alter the supply to the infant. Thus, the infant is well-protected by maternal homeostatic processes, although the mechanisms of these are not yet well understood. Considerable progressive changes in concentration occur for some of the micronutrients during the course of lactation. Because the concentration of these nutrients, and of other substances that modify their absorption by the infant, such as binding proteins, differs considerably between human milk, animal milk and, hence, commercial milk formulae, there is great interest in the quantitative significance of micronutrient supplies, and their variability in breast milk, in the quest for improvement of commercial formulations. The aim of this review is to summarize the available information about the factors that determine breast milk contents of micronutrients.

Breast Feeding↗
PubMedDate not supplied

An investigation of ethnic differences in bone mineral, hip axis length, calcium metabolism and bone turnover between West African and Caucasian adults living in the United Kingdom.

The aim of the study was to investigate factors relating to calcium and bone metabolism which might explain the low incidence of osteoporotic fracture among Africans. Adult bone mineral status, hip axis length and biochemical indices were investigated in 20 Caucasians (10 male, 10 female) and 19 Gambians (12 male, 7 female) living in the UK. Bone mineral content (BMC), bone mineral density (BMD) and BMC adjusted for bone area, body weight and height (size-adjusted BMC) were measured for the whole-body, lumbar spine, femoral neck, trochanter, radius shaft and radius wrist using dual-energy X-ray absorptiometry. There were no significant differences in whole body or regional BMC; values tended to be lower in the Gambians. Gambian men had higher size-adjusted BMC at the femoral neck (Gambian-British = 21%, 95% CI = 6 to 36%, p < 0.01), associated with a smaller bone area (Gambian-British = -11%, 95% CI = -20 to -2%, p = 0.02). BMD was affected similarly. No other significant differences in BMD or size-adjusted BMC were observed. Gambians had shorter hip axis length (Gambian British, after accounting for sex, = -5%, 95% CI = -9 to -1%, p = 0.02). There were no significant differences in bone turnover (osteocalcin, bone isoenzyme of alkaline phosphatase, urinary deoxypyridinoline) or calciotropic hormone levels (parathyroid hormone, 1,25-dihydroxyvitamin D, calcitonin). Gambian men had lower 25-hydroxyvitamin D concentrations (Gambian = 26.3 SD 12.0 nmol/L, British = 55.5 SD 13.9 nmol/L, p < 0.0001), a difference not seen among the women. Gambian men and women excreted significantly less phosphate and potassium than British subjects by 30-60%; urinary calcium and sodium excretion were similar in the two groups. This study revealed few ethnic differences that could account for the disparity in osteoporotic fracture rates between Africans and Caucasians, with the possible exception of anatomical differences in the hip.

Absorptiometry, Photon↗