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Biomedical subjects

N W Solomons

Publications and source records attributed to N W Solomons.

At least 73 records · Page 4Linked to original sources
PubMed1994

Plasma response of children to short-term chronic beta-carotene supplementation.

Plasma concentrations of beta-carotene and retinol after supplementation of children with beta-carotene in supplements and in foods were compared in Guatemalan children. The children received 6 mg/d beta-carotene [1000 retinol equivalents (RE)] as purified supplements or as carrots for 20 d and the effects on plasma beta-carotene and retinol concentrations were assessed. Plasma concentrations of beta-carotene were increased by 0.59 +/- 0.65 and 0.60 +/- 0.67 mumol/L after supplementation with beta-carotene capsules for 10 and 20 d, respectively. Addition of cooked carrots to the diet resulted in no significant change in plasma beta-carotene. Fasting plasma retinol concentrations were 1.23 +/- 0.35 mumol/L and were not significantly changed in response to supplementation with either of the carotene treatments with retinyl palmitate (1000 RE/d) for 20 d. Possible explanations for the differences in effects of plasma concentrations between the two methods of supplementation are discussed.

Biological Availability↗
PubMed1994

The interobserver reproducibility of bioelectrical impedance analysis measurements in infants and toddlers.

Although nomograms to convert readings of resistance (R) and reactance (Xc) into estimates of body composition have begun to emerge for children as well as adults, there has been reluctance to use bioelectrical impedance analysis (BIA) in very young children due to the irritability of children, measurement instability, positioning of electrodes, and, of course, reproducibility of measurements. The precision of completely independent measurements of BIA indices was evaluated by two observers by comparing a series of 40 measurements of R and Xc and 36 measurements for weight in four malnourished children on 10 different days during the course of their nutritional recuperation. For weight, the CV (coefficient of variation) was 3.5% for observer A and 3.8% for observer B. There were no differences in the means across observers with respect to weight, R, and Xc. The results obtained in this study illustrate that properly trained observers following the same standards can produce equivalent data for BIA and weight measurements even in sick children.

Body Composition↗
PubMed1993

Pathways to the impairment of human nutritional status by gastrointestinal pathogens.

Gastrointestinal pathogens are of three varieties, those that can, and often do, take the life of the host, those that infect transiently and rarely are life-threatening, and those (parasites) that establish a relatively prolonged residence or colonization of the host's alimentary tract. In the case of the second form, if infections are recurrent, both catabolic effects during the episode and failure to digest foods and/or absorb nutrients results. Similarly, catabolic wastage through activation of the acute phase response, and interference with the host's acquisition of nutrients by maldigestion, malabsorption, intestinal losses and competition with the parasite burden can impair growth and nutrition with helminthic infections. Growth and nutrition with respect to all of the macronutrients and virtually all of the micronutrients have been documented to be adversely affected by gastrointestinal pathogens. For its burgeoning importance as a worldwide health problem, both with the HIV virus as a direct intestinal pathogen and with the opportunistic gut infections occurring in the immunocompromised host, AIDS represents the emerging context of the impairment of nutritional status by intestinal pathogens.

AIDS-Related Opportunistic Infections↗
PubMed1993

Trace element intakes and dietary phytate/Zn and Ca x phytate/Zn millimolar ratios of periurban Guatemalan women during the third trimester of pregnancy.

Repeated 24-h recalls (9-14/subject) were conducted on 52 periurban Guatemalan pregnant women aged 25 +/- 5 y (means +/- SD). Intakes of energy, protein, calcium, zinc, copper, manganese, nonstarch polysaccharide (NSP), phytate, and millimolar ratios of phytate to zinc and (calcium x phytate) to zinc were calculated from food-composition values on the basis of chemical analysis and the literature. Mean (+/- SD) daily intakes were as follows: energy 8694 +/- 1674 kJ, protein 63.0 +/- 13.3 g, calcium 727 +/- 163, zinc 11.3 +/- 2.7, copper 1.3 +/- 0.3, manganese 2.8 +/- 0.6, phytate 2254 +/- 773 mg/d, NSP 26.6 +/- 6.9 g, phytate/zinc 18.8 +/- 4.2, (calcium x phytate)/zinc 706 +/- 21 mmol/MJ. Ninety-four percent had zinc intakes below the recommendations (15 mg) of WHO and the US recommended dietary allowances, assuming 20% absorption. Tortillas were a major source of zinc (46%), copper (20%), manganese (23%), calcium (39%), phytate (68%), and NSP (50%); 19% zinc from flesh foods. Thirty-eight percent had phytate-zinc ratios > 20; 94% had millimolar ratios of (calcium x phytate) to zinc per MJ > or = 22. The high prevalence of millimolar ratios of phytate to zinc and (calcium x phytate) to zinc per MJ above 20 and 22, respectively, may compromise zinc nutriture.

Adult↗
PubMed1993

Growth and body composition of periurban Guatemalan children in relation to zinc status: a cross-sectional study.

In a study of periurban Guatemalan school-children (89 males, 73 females) aged 81.5 +/- 7.0 mo (mean +/- SD), height, weight, arm circumference, and triceps-skinfold-thickness (TSF) measurements were examined in relation to plasma and hair zinc concentrations, plasma and red blood cell alkaline phosphatase activities, recognition thresholds for salt (RTS), delayed-cutaneous hypersensitivity response to seven recall skin test antigens, and cognitive measures. Children were stunted [median height-for-age (HA) Z score -1.49] but not wasted [median weight-for-height (WH) Z score 0.20], with median midarm muscle area (MAMA) and midarm-fat area (MAFA) Z scores of -0.57 and -0.35, respectively. Of the children, 63.5% of males and 44.1% of females had hair zinc < 1.68 mumol/g (P < 0.05); 12.3% of males and 1.5% of females had plasma zinc < 10.71 mumol/L (P < 0.05). Children with hair zinc < 1.68 mumol/g had higher (P < 0.05) medians for WA Z and WH Z scores, RTS, and phytic acid intake than did those with hair zinc > or = 1.68 mumol/g. Zinc status explained some of the variance in growth (HA, WA, and WH Z scores), body composition (MAFA Z scores), and taste acuity. Suboptimal zinc status arose partly from diets low in readily available zinc.

Aging↗
PubMed1993

Growth and body composition of periurban Guatemalan children in relation to zinc status: a longitudinal zinc intervention trial.

Changes in growth, body composition, and zinc indexes were evaluated after 25 wk in a double-blind zinc-supplementation study of 162 periurban Guatemalan children aged 81.5 +/- 7.0 mo (mean +/- SD). Children receiving the zinc supplement (10 mg Zn/d as amino acid chelate) for 90.1 +/- 9.2 d had higher mean fasting plasma zinc (16.2 +/- 2.9 vs 14.9 +/- 2.1 mumol/L, P < 0.01), a greater increase in median triceps skinfold Z score (0.50 vs 0.38, P < 0.05), and a smaller deficit in median midarm circumference (MAC) Z score (-0.03 vs -0.20, P < 0.05) compared with the placebo group. Initial hair zinc classified as < 1.68 and > 1.68 mumol/g was the only laboratory variable that explained some of the variance in final Z scores of midarm-muscle area (P < 0.05) and MAC (P < 0.01). Children responded to the zinc supplement with changes in indexes of body composition rather than growth.

Anthropometry↗
PubMed1993

The effect of zinc supplementation on parasitic reinfestation of Guatemalan schoolchildren.

One hundred thirty children (65-95 mo old) from a low-socioeconomic neighborhood of Guatemala City participated in a randomized, double-blind, controlled trial of zinc supplementation. One group received 10 mg Zn/d (n = 65) and the other group received a placebo (n = 65); 90 +/- 9.2 doses were given over 120-150 d. Stools were examined for prevalence and intensity of helminths and prevalence of protozoa at the beginning and end of the study. The initial prevalence was 42% for helminths and 18% for protozoa, with no differences between groups. Mebendazole was administered to all children, and protozoal infections were treated specifically at the beginning of the study. The reinfection rates were 17% (11 of 65) for helminths and 12.3% (8 of 65) for protozoa in the zinc group and 15% (10 of 65) and 10.7% (7 of 65), respectively, in the placebo group (P > 0.05). Analysis by specific parasites revealed no treatment effect. We conclude that neither plasma or hair zinc status nor oral zinc supplementation had an effect on parasite status in children.

Animals↗
PubMed1993

Prevalence of riboflavin deficiency among Guatemalan elderly people and its relationship to milk intake.

Six groups of elderly subjects from central Guatemala were assessed for riboflavin status by using the erythrocyte glutathione reductase activity coefficient (EGRAC). The prevalence of riboflavin deficiency ranged from 50% to 76% among the free-living rural elderly subjects. Milk intake data that were collected from some of the subjects showed a significant correlation (P < 0.0001) between frequency of milk intake and riboflavin status. In a short-term riboflavin supplementation experiment in which nine riboflavin-deficient subjects were given 10 mg riboflavin/d for 3 d, all the subjects' EGRACs were normalized by the supplementation. However, they returned to a state of deficiency within 2 wk while consuming their usual diets without supplementation. It appears that the high prevalence of riboflavin deficiency in elderly Guatemalan people is caused by inadequate intake of riboflavin-rich foods such as dairy products, and that sufficient amounts of riboflavin need to be ingested regularly to maintain satisfactory riboflavin status.

Aged↗
PubMed1993

Riboflavin requirement of healthy elderly humans and its relationship to macronutrient composition of the diet.

The riboflavin requirements of two groups of riboflavin-deficient, but otherwise healthy, Guatemalan elderly persons over the age of 60 y were studied by varying the fat:carbohydrate ratio in two diets. The first group consumed a diet similar in macronutrient content to a Western-type diet with low carbohydrate and high fat; the second group consumed a typical Guatemalan diet with high carbohydrate and low fat. Energy and protein intakes of both groups were similar. Riboflavin status was monitored by weekly measurements of erythrocyte glutathione reductase activity coefficient (EGRAC) and urinary riboflavin excretion. Increasing increments of riboflavin were added to the subjects' diets until their status was normalized, as indicated by EGRAC of < 1.34 and a sharp increase in urinary riboflavin excretion. Using the EGRAC method, the mean value of riboflavin intake at which the subjects' EGRAC reached the limit of normality was 1.37 +/- 0.03 mg/d in the first phase and 1.29 +/- 0.03 mg/d in the second phase. The sharp increase in urinary excretion occurred at riboflavin intakes of 1.13 and 1.03 mg/d for Groups 1 and 2, respectively. Thus, the differences between the two groups suggest that diets with a lower fat:carbohydrate ratio can decrease the dietary need for riboflavin. The dietary requirement of riboflavin, as estimated by the more reliable urinary excretion method, was 1.1-1.3 mg/d for those consuming the Western-type diet, which is similar to values found over 40 y ago in young adults. We conclude that the dietary requirements of riboflavin in the elderly do not differ from those of young adults.

Adult↗
PubMed1993

Plant sources of provitamin A and human nutriture.

Hypovitaminosis A is a problem in many parts of the developing world. Beyond the stop-gap measures of capsule distribution and food fortification, increased consumption of accessible sources of vitamin A, specifically of the carotenoid provitamin A in yellow, orange, and green plants, has been promoted as the sustainable, long-term solution. However, a search of the available literature reveals few examples of human studies to support the effectiveness of this solution. Evidence from feeding studies shows an almost universally poorer uptake of intact carotenoids from plant sources as opposed to pure, chemical sources. With notable exceptions, the bioconversion of plant carotenoids to preformed vitamin A also seems to be inefficient. Epidemiologic observations in poor Third World populations and in vegetarians in an industrialized nation indicate a relatively greater potency for animal sources of vitamin A. In developing countries, low fat intakes, intestinal roundworms, recurrent diarrhea, and tropical enteropathy all may contribute to reduced utilization of plant provitamin A. The accepted 6:1 equivalency of beta-carotene to preformed vitamin A must be challenged and reexamined in the context of dietary plants. The consequences of operating on a miscalculation could be serious indeed for public health programs designed to alleviate and eradicate hypovitaminosis A.

Adult↗
PubMed1993

The underprivileged, developing country child: environmental contamination and growth failure revisited.

A major public health challenge to human populations in developing countries is poor linear growth and failure to maximize genetic potential in final adult stature. It is now clear that this process occurs in early life, and neither genetics nor dietary intake, or both, is the complete determinant. We suggest that a situation similar to the phenomenon of impaired growth of poultry and livestock reared under unsanitary conditions occurs in children from underprivileged countries. Recent advances in cell biology and immunology suggest that the intermittent or continuous activation of the acute-phase response with the consequent mediation of catabolic and antitrophic metabolic processes is responsible for the antibiotic-responsive growth impairment of chicks raised in unhygienic environments. Ongoing epidemiological studies in poor Third World children provide evidence for a prevalence of acute-phase response activation in the absence of overt clinical signs. The consequences of this immunostimulation of the growing infant or toddler could represent an important additional factor in the failure of children in developing countries to manifest adequate growth and to achieve their genetic potential for adult stature.

Acute-Phase Reaction↗
PubMed1993

Preparation effects on tortilla mineral content in Guatemala.

We have previously reported that in Guatemala, the calcium, iron, and zinc contents of tortillas from rural areas are higher that that of tortillas from urban centers. This study examines variation in the calcium, iron, zinc and copper content of tortilla according to the implements used for making tortillas and inquires as to whether preparation effects mediate rural-urban variation in tortilla mineral content. Tortilla samples and information on how the tortillas were prepared were collected from the female heads of a total of 50 households from three rural, two semi-urban and one low income urban community. Samples of lime used for making tortillas were collected from 31 households. To grind masa, a hand mill was found to be used in some rural households whereas a motorized mill predominated in the semi-urban and urban areas. Most women used grinding stones called the "mano y metate" to further refine the texture of the masa. Tortillas prepared with the combined use of the hand mill and "mano y metate" had a significantly (p < 0.05) higher iron content. Use of the "mano y metate" was also associated with a significantly (p < 0.05) higher zinc content. These results suggest that the use of certain grinding implements may mediate rural-urban variation in tortilla iron and zinc content. The cooking surface, pot used for nixtamalization, source of water, and amount of lime used did not significantly account for variation in the content of these minerals.

Female↗
PubMed1992

Studies on the application of the relative-dose-response test for assessing vitamin A status in older adults.

We investigated the time course and the reproducibility of the relative-dose-response (RDR) test for assessing vitamin A status in older adults. The maximum plasma retinol response to 480 retinol equivalents (RE) of retinyl palmitate in abnormal responses was at 6 or 7 h after dosing compared with the 5-h sampling interval recommended by others for younger adults and children. With respect to reproducibility, the diagnostic concordance of two RDR tests at 7-d intervals in 14 elders was 71%. In 29% of tests, one test was abnormal and the other normal. Linear regression of the two RDR values in these 14 subjects gave a correlation coefficient of -0.08. We conclude that the procedure for the RDR should be modified when applied to persons greater than 60 y of age, and that multiple repetitions of the test are needed to provide a stable indication of vitamin A stores in an elderly individual.

Aged↗