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R S Gibson

Publications and source records attributed to R S Gibson.

At least 37 records · Page 2Linked to original sources
PubMed2000

The relative validity of a computerized food frequency questionnaire for estimating intake of dietary iron and its absorption modifiers.

OBJECTIVE: To determine the relative validity of an iron food frequency questionnaire (iron FFQ) designed to assess intakes of dietary iron and its absorption modifiers. DESIGN: A computer-administered food frequency questionnaire was designed to estimate intake of total, non-haem, haem and meat iron as well as dietary components which influence iron absorption (vitamin C, phytate, calcium, grammes of meat/fish/poultry, tea and coffee) in women consuming a Western diet. The relative validity of the iron FFQ was assessed by comparing its results with those from weighed diet records collected over 11 days. SETTING: Dunedin, New Zealand. PARTICIPANTS: Forty-nine women aged 19-31 y attending the University of Otago. RESULTS: There was good agreement between the iron FFQ and the weighed diet records for median intakes of total iron, non-haem iron, calcium, tea and coffee. For dietary component intakes, correlations between the two methods ranged from 0.39 (for vitamin C) to 0.87 (for coffee) with 0.52 for total iron, and 0.61 for haem iron. In cross-classification with the weighed diet record, the iron FFQ correctly classified between 22% (for vitamin C) and 51% (for phytate) of participants into the same quartile. Actual values for surrogate categories indicated that the questionnaire can clearly differentiate between low and high intakes of all the dietary components assessed. The questionnaire also showed an acceptable level of agreement between repeat administrations (eg a correlation for total iron of 0.65). CONCLUSIONS: The iron FFQ is appropriate for assessing group intakes of total iron, and iron absorption modifiers, in population studies to assess the aetiology and treatment of iron deficiency states in adult women consuming a Western diet. SPONSORSHIP: This research was supported (in part) by a grant from the Health Research Council of New Zealand.

Adult↗
PubMed2000

Dietary phytate reduction improves zinc absorption in Malawian children recovering from tuberculosis but not in well children.

High dietary phytate content that compromises zinc nutriture is thought to be a major problem among children of the developing world. Zinc stable isotope techniques permit the quantitative assessment of the effect of phytate reduction on zinc homeostasis. We tested the hypothesis that zinc absorption would be increased in Malawian children fed a reduced-phytate corn-plus-soy diet compared with a standard high phytate diet. Twenty-three children hospitalized in Blantyre, Malawi, were enrolled. Children were selected from those recovering from tuberculosis and from well children (those with minor injuries, those awaiting elective surgery or healthy siblings). Children received a diet of corn-plus-soy porridge (either low phytate or high phytate) for a period of 3-7 d and then participated in a zinc stable isotope study. The study included the administration of oral and intravenous zinc stable isotopes and 7-d collections of urine and stool. The diet was maintained throughout the duration of specimen collection. Zinc isotopic enrichments in urine and stool were measured, and zinc fractional absorption, total zinc absorption, endogenous fecal zinc, net zinc retention and size of the exchangeable zinc pool were calculated. Among the 14 children recovering from tuberculosis, dietary phytate reduction resulted in higher fractional absorption (0.41 +/- 0.14 versus 0.24 +/- 0.09, mean +/- SD, P: < 0.05) and total zinc absorption (169 +/- 55 versus 100 +/- 46 microg/(kg. d), P: < 0.05). No effect of phytate reduction was seen in the well children (n = 9). Phytate reduction did not decrease the absolute endogenous fecal zinc, but it did decrease it relative to total absorbed zinc. These preliminary results indicate that phytate reduction may be beneficial in improving zinc nutriture in groups with increased zinc requirements who consume a cereal-based diet.

Adolescent↗
PubMed2000

Interrelationship of indices of body composition and zinc status in 11-yr-old New Zealand children.

Serum zinc and hair zinc concentrations of some New Zealand children aged 11 yr, were examined in relation to selected anthropometric indices. Serum zinc concentrations (n = 453) in boys and girls were similar and were unrelated to anthropometric indices and hair zinc concentrations. Mean hair zinc concentration (n = 620) of the girls was higher than that for the boys (2.95+/-0.49 vs 2.46+/-0.47 micromol/g; p < 0.001). Correlation analysis demonstrated that, for the boys, all the studied anthropometric indices, with the exception of height, were significantly related to hair zinc concentration and that the confounding effects of mid-parent height and the timing of the adolescent growth spurt was small. Results for the girls were similar but less significant. Dichotomizing the hair zinc results divided both the boys and girls into two groups: those with hair zinc < 2.44 micromol/g were heavier (girls, 39.0 vs 35.2 kg; boys, 36.6 vs 34.7 kg) and fatter (mid-upper-arm fat area: girls, 15.2 vs 12.0 cm2; boys, 11.1 vs 9.5 cm2) compared to their counterparts with hair zinc > 2.44 micromol/g. The results demonstrate that in these healthy New Zealand children, those with lower hair zinc concentrations are fatter and heavier than their high-hair-zinc counterparts.

Algorithms↗
PubMed1999

Validation of a questionnaire method for estimating extent of menstrual blood loss in young adult women.

The objective of this study was to validate two indirect methods for estimating the extent of menstrual blood loss against a reference method to determine which method would be most appropriate for use in a population of young adult women. Thirty-two women aged 18 to 29 years (mean +/- SD; 22.4 +/- 2.8) were recruited by poster in Dunedin (New Zealand). Data are presented for 29 women. A recall method and a record method for estimating extent of menstrual loss were validated against a weighed reference method. Spearman rank correlation coefficients between blood loss assessed by Weighed Menstrual Loss and Menstrual Record was rs = 0.47 (p = 0.012), and between Weighed Menstrual Loss and Menstrual Recall, was rs = 0.61 (p = 0.001). The Record method correctly classified 66% of participants into the same tertile, grossly misclassifying 14%. The Recall method correctly classified 59% of participants, grossly misclassifying 7%. Reference method menstrual loss calculated for surrogate categories demonstrated a significant difference between the second and third tertiles for the Record method, and between the first and third tertiles for the Recall method. The Menstrual Recall method can differentiate between low and high levels of menstrual blood loss in young adult women, is quick to complete and analyse, and has a low participant burden.

Adolescent↗
PubMed1999

The impact of malarial infection and diet on the anaemia status of rural pregnant Malawian women.

OBJECTIVE: To investigate haematological and biochemical iron indices in relation to malaria, gravida, and dietary iron status in rural pregnant Malawian women. DESIGN: In this self-selected sample, haemoglobin, haematocrit, red cell indices, serum ferritin, serum iron, serum transferrin, and serum transferrin receptor (TfR) were measured. Infection was assessed by a malaria slide, serum C-reactive protein, and white blood cell count. Dietary iron variables were measured by three 24-h interactive recalls. SETTING AND SUBJECTS: 152 rural pregnant women recruited at 24 weeks gestation while attending a rural antenatal clinic in Southern Malawi; 36% were primagravid; 43% were gravida 2-4; 26% were gravida >5. RESULTS: Of the women, 69% (n=105) were anaemic (haemoglobin <110 g/l); 37% (n=39) had anaemia and malarial parasitaemia on the test day; 17% (n=26) with malaria were also classified with iron deficiency (ID) anaemia (based on serum ferritin < or = 50 microg/l and Hb <110 g/l) while an additional seven with malaria were classified with ID without anaemia. In malarial-free subjects, 32% were classified with IDA (serum ferritin <12 microg/l and Hb <110 g/l) and 17% with ID (serum ferritin <12 microg/l; Hb > or = 110 g/l). Serum TfR concentrations were elevated in anaemic women (P<0.01). In non-malarial parasitaemic subjects, serum TfR correlated negatively with haemoglobin (r=-0.313; P<0.001) but not serum ferritin. Of the women, 49% were at risk for inadequate iron intakes. Most dietary iron was non-haem; plant foods provided 89%; flesh foods (mainly fish) only 9%. Malarial parasitaemia and intakes of available iron impacted significantly on iron status. CONCLUSION: Anaemia prevalence from all causes was high (that is, 69%); three factors were implicated: malaria, and deficiencies of iron and possibly folate, induced partly by an inadequate dietary supply and/or secondary to malarial parasitaemia. SPONSORSHIP: International Development Research Centre (IDRC) of Canada. Opportunities for Micronutrient Interventions (OMNI) Project. Natural Sciences and Engineering Research Council of Canada.

Adolescent↗
PubMed1999

Factors associated with failure of medical therapy in patients with unstable angina and non-Q wave myocardial infarction. A TIMI-IIIB database study.

CONTEXT: Current management of patients with unstable angina and non-Q wave myocardial infarction generally consists of intensive medical therapy, with angiography and revascularization sometimes limited to those who fail such therapy. AIM: To determine if certain baseline characteristics are predictive of patients who fail medical therapy, since such patients could then be expeditiously directed to a more invasive strategy in a cost-effective manner. METHODS: The study cohort consisted of the 733 patients in the Thrombolysis in Myocardial Ischemia (TIMI) IIIB study who were randomized to conservative strategy. Patients were to be treated with bedrest, anti-ischaemic medications, aspirin, and heparin, and were to undergo risk-stratifying tests, consisting of an exercise test with ECG and thallium scintigraphy, scheduled to be performed within 3 days prior to, or 5 days after, hospital discharge and 24 h Holter monitoring scheduled to begin 2-5 days after randomization. Baseline clinical and ECG characteristics were compared between patients who 'failed' medical therapy and those who did not 'fail'. Failure was defined using clinical end-points (death, myocardial infarction, or spontaneous ischaemia by 6 weeks after randomization) or a strongly positive risk-stratifying test. For each test an ordered failure profile of results was calculated and consisted of death, myocardial infarction, or rest ischaemia occurring prior to performance of the test, a markedly abnormal test result, and no abnormality. RESULTS: Clinical end-points occurred in 241 (33%) patients and were more likely to occur in patients who at presentation were older, had ST-segment depression on the qualifying ECG, or were being treated with heparin or aspirin. Characteristics independently predictive of developing a clinical event or an abnormal exercise treadmill test included: ST-segment depression on the qualifying ECG, history of prior angina, family history of premature coronary disease (i.e. onset <55 years of age), prior use of heparin or aspirin, and increasing age. By combining these baseline risk characteristics for each outcome the incidence of developing a clinical event ranged from 8% if none was present to 63% if all six were present, and of developing a markedly abnormal risk stratifying test from 8-21% if none were present to approximately 90% if all six were present. CONCLUSIONS: Baseline characteristics associated with developing a clinical event or a markedly abnormal risk stratifying test were similar: rest anginal episode accompanied by ST-segment depression and occurring despite treatment with aspirin and heparin, a history of angina, older age, and family history of coronary disease. Patients with these characteristics are appropriate candidates for expeditious cardiac catheterization and consideration for revascularization, while patients without them may be suitable for medical management alone.

Aged↗
PubMed1998

Oral contraceptives did not affect biochemical folate indexes and homocysteine concentrations in adolescent females.

OBJECTIVE: The study was designed to determine the impact of currently available oral contraceptive agents (OCAs), smoking, and alcohol on biochemical indexes of folate and vitamin B-12 in adolescent females. DESIGN: Subjects completed a 3-day weighed food record along with a detailed lifestyle questionnaire that included questions on OCA, cigarette, and alcohol use. After subjects had fasted overnight, blood samples were collected and analyzed for levels of serum and red blood cell (RBC) folate and serum B-12 and homocysteine. SUBJECTS/SETTINGS: Two hundred twenty-nine adolescent females (aged 14 to 20 years) were recruited from southern Ontario, Canada, by advertisements in newspapers, high schools, universities, shopping malls, adolescent drop-in centers, and community groups. STATISTICAL ANALYSES PERFORMED: Multiple regression models were used to determine the effect of lifestyle factors and covariates (e.g., dietary folate intake, supplemental folate intake, and age) on biochemical indexes. RESULTS: OCA use, alcohol use, and smoking were not significantly associated with lower serum or RBC folate levels, after controlling for folate intake. Serum homocysteine levels were not associated with smoking or OCA use; however, we estimated a 13% higher concentration among alcohol users than nonusers. Smoking and alcohol use were not associated with serum B-12 levels, but OCA use was associated with an estimated 33% lower serum B-12 level than nonuse. APPLICATIONS: Our findings provide no evidence to suggest that currently available OCAs have a negative impact on the folate status of adolescent females; thus, dietary advice designed to specifically encourage an increase in folate intake among adolescents who use OCAs is not supported. In contrast, serum B-12 levels were lower among OCA users than nonusers, which suggests that an interaction between OCA and some vitamins may persist. The suboptimal biochemical folate indexes of smokers may have more to do with the dietary quality of smokers than previously appreciated. Thus, efforts to improve dietary folate intakes of adolescents who smoke may be an important strategy for improving the folate status of young women.

Adolescent↗
PubMed1998

Complementary foods for infant feeding in developing countries: their nutrient adequacy and improvement.

OBJECTIVE: To assess the energy and nutrient adequacy of a variety of complementary foods used in parts of Africa, India, Papua New Guinea, the Philippines and Thailand. METHOD: The energy, nutrient and anti-nutrient (dietary fibre and phytic acid) content (per 100 g as eaten, per 100 kcal, and per day) of twenty-three plant-based complementary foods consumed in developing countries was calculated from food composition values based on chemical analysis for the trace minerals, non-starch polysaccharide and phytic acid, and the literature. Results were compared with the estimated nutrient needs (per day; per 100 kcal) from complementary foods for infants 9-11 months, assuming a breast milk intake of average volume and composition and three complementary feedings per day, each of 250 g. RESULTS: Complementary foods should provide approximately 25-50% of total daily requirements for protein, riboflavin and copper; 50-75% for thiamin, calcium and manganese; and 75-100% for phosphorus, zinc and iron. Most or all appear to meet the estimated daily nutrient needs (per day; per 100 kcal) from complementary foods for protein, thiamin and copper (per day), but not for calcium, iron, and in some cases zinc, even if moderate bioavailability for iron and zinc is assumed. Some of those based on rice are also inadequate in riboflavin (per day; per 100 kcal). CONCLUSIONS: Even if strategies to improve the bioavailability of iron and zinc are employed, they are probably insufficient to overcome the deficits in calcium, iron and zinc. Therefore, research on the feasibility of fortifying plant-based complementary foods in developing countries with calcium, iron and zinc is urgently required.

Africa↗
PubMed1998

Is zinc a limiting nutrient in the diets of rural pregnant Malawian women?

Pregnant women consuming plant-based diets are at risk of Zn deficiency; Zn requirements for fetal growth and maternal tissue accretion are high. Therefore we have studied, at 24 and 33 weeks gestation, the Zn status of eighty-seven pregnant rural Malawian women (mean age 22.7 years) who consume maize-based diets, using anthropometry, dietary intake data, plasma and hair Zn concentrations, and infection status via serum C-reactive protein, leucocyte count, and malaria blood smear. Of the women, 12% were stunted (height-for-age Z score < -2 SD) and 20% lost weight over the 9-week period; weight gain averaged 0.13 kg/week. Mean plasma Zn concentration declined significantly from 24 to 33 weeks (7.9 (SD 2.2) v. 6.6 (SD 2.0) mumol/l; P < 0.0003). Both plasma and hair Zn values were very low; nearly 50% of the women had both plasma and hair Zn values below acceptable cut-off values. No significant differences in biochemical Zn indices existed between those who tested positive and negative for infection. Cereals (mainly maize) provided more than two-thirds of mean energy intake compared with less than 5% from flesh foods. As a result about 60% of the subjects had dietary phytate:Zn molar ratios greater than 15, and more than 35% had inadequate Zn intakes based on probability estimates and WHO basal requirements. Biochemical evidence of Zn deficiency was attributed in part to low intakes of poorly available Zn. The anthropometric, biochemical, and dietary data together indicate that Zn deficiency may be a factor limiting pregnancy outcome in rural Malawian women.

Adolescent↗
PubMed1998

Suboptimal zinc status in pregnant Malawian women: its association with low intakes of poorly available zinc, frequent reproductive cycling, and malaria.

A study of 152 rural Malawian women aged 23.2+/-5.5 y (x+/-SD) at 24 wk gestation included measurements of biochemical indexes of zinc (plasma and hair), protein (serum albumin), and infection (serum C-reactive protein, white blood cell count, and malaria), and dietary intakes (via three interactive 24-h dietary recalls). Data on health, demographic and socioeconomic status, family characteristics, reproductive history, and anthropometry were also collected. The study revealed a high prevalence of suboptimal zinc status: 36% of the women had low plasma and 46% had low hair zinc values. Median daily intake of zinc (9.0 mg) was low and poorly available: 61% was provided by cereals and 20% by flesh foods. Median intake of animal protein was only 5.6 g/d, and phytate intakes were high (1.4 g/d). Women consuming diets with phytate-zinc ratios > 17 (the median) had lower hair zinc concentrations (1.6 compared with 1.8 micromol/g, P < 0.03), were older (24 compared with 20 y, P < 0.02), and had a higher number of pregnancies (3 compared with 2, P < 0.02) than those consuming diets with a phytate-zinc ratio < 17. Frequent reproductive cycling was related to zinc status; hair zinc was higher for a prima- than for a multigravida (2.0 compared with 1.6 micromol/g, P < 0.01). Malaria prevalence was also associated with hair zinc (P < 0.05) but not with plasma zinc, after the number of pregnancies was controlled for. We conclude that low intakes of poorly available dietary zinc, frequent reproductive cycling, and malaria prevalence are three major factors in the etiology of suboptimal zinc status in these rural, pregnant Malawian women.

Adolescent↗
PubMed1998

Assessment of dietary zinc in a population.

Assessment of dietary zinc status in a population requires several steps, consisting of the measurement of food intake distributions in the population; the analysis of local staple foods, from which zinc intake distributions can be determined, and the comparison of zinc intakes with requirement estimates to determine the risk of inadequate intakes. In low-income countries, these steps may be complicated by the lack of preexisting food-composition data, variations in food preparation methods, inhibition of absorption by other compounds in the diet, and variations in intake among seasons, individuals, and populations. Different techniques for determining the adequacy of zinc intake are compared. Whereas the techniques described in this paper allow for the determination of probability estimates for risk of zinc inadequacy, they do not allow for the identification of actual individuals in a population who are zinc deficient, or define the severity of zinc inadequacy. This information is vital, especially in areas where zinc deficiency is but one of many health problems, and can be obtained only from more detailed biochemical and physiologic studies of zinc status.

Biological Availability↗
PubMed1998

Dietary interventions to prevent zinc deficiency.

This review describes household dietary strategies to improve the content and bioavailability of zinc in predominantly plant-based diets and the implementation of these strategies in a community-based dietary intervention study in rural southern Malawi. The strategies involve increasing intakes of foods with high bioavailable-zinc contents, absorption enhancers, or both and using germination, fermentation, and soaking to reduce intake of phytic acid, a potent inhibitor of zinc absorption. The strategies were implemented at the household level in Malawi through a participatory research process that focused on building relationships with the community and involving them in the design, implementation, and monitoring and evaluation processes. In this way, community participation and awareness of zinc deficiency might be enhanced and the dietary strategies planned will be appropriate and sustainable.

Biological Availability↗
PubMed1997

Management of unstable angina pectoris and non-Q-wave acute myocardial infarction in the United States and Canada (the TIMI III Registry).

Management of Q-wave acute myocardial infarction (AMI) has been shown to differ between the United States and Canada, with more catheterization and revascularization procedures performed in the United States, but with little or no apparent difference in clinical outcomes. No previous studies have evaluated management differences for the acute coronary syndromes of unstable angina pectoris and non-Q-wave AMI. We therefore compared treatments and outcomes between 14 United States and 4 Canadian tertiary care centers participating in an observational registry of all consecutive admissions for unstable angina or non-Q-wave AMI between 1990 and 1993. A random, stratified sample was selected for detailed assessment and follow-up. There were 1,733 patients enrolled in United States centers and 642 in Canadian ones. In United States centers patients were less likely to receive intravenous nitroglycerin, heparin, beta blockers, calcium antagonists, or > or = 2 anti-ischemic agents. Coronary arteriography during index hospitalization was equally frequent in both countries (63.4% vs 66.9%, p = 0.781), but at 6 weeks and 1 year coronary arteriography was slightly less frequent in the United States patients. Revascularization by coronary angioplasty or bypass surgery was equivalent at 6 weeks and 1 year; however, there were trends toward less angioplasty and more bypass surgery in the United States than in Canada. Patients at United States centers stayed in the hospital fewer days than patients at Canadian centers (mean 8.2 vs 12.1 days, p <0.001). Death or AMI by 6 weeks was not different (4.8% vs 4.4%, p = 0.633), nor was it different at 1 year (10.0% vs 10.2%, p = 0.836). The combined outcome of death, AMI, or recurrent ischemia was more common in United States than in Canadian patients at 6 weeks (18.4% vs 13.9%, p = 0.004). Our findings indicate that United States physicians and hospitals did not consistently utilize more resources and were not more aggressive than their Canadian counterparts when treating acute coronary syndromes during this period.

Aged↗
PubMed1997

Circadian variation in the onset of unstable angina and non-Q-wave acute myocardial infarction (the TIMI III Registry and TIMI IIIB).

Circadian variation has been demonstrated in several types of acute cardiovascular disease, including acute myocardial infarction (AMI), sudden cardiac death, silent ambulatory ischemia, and thrombotic stroke. In contrast, no diurnal variation was observed in 1 study of non-Q-wave AMI, and limited data are available for unstable angina. To assess whether circadian variation is present in unstable angina and non-Q-wave AMI, we examined the time of onset of ischemic pain in 7,731 patients who were prospectively identified in the Thrombolysis in Myocardial Ischemia (TIMI) III Registry, 3,318 of whom were enrolled in the prospective study, and in 1,473 patients enrolled in the TIMI IIIB trial. A circadian variation in the onset of pain was observed, with an increase in the number of patients experiencing the onset of pain in the morning hours between 6 A.M. and 12 noon (p <0.001). This circadian variation was observed both in patients with unstable angina and in those with evolving non-Q-wave AMI. A similar circadian pattern was observed in all subgroups tested. These findings were confirmed in the TIMI IIIB trial and complement previous studies suggesting that circadian variation exists in the onset of the full spectrum of myocardial ischemic syndromes.

Aged↗
PubMed1997

Admission prediction of expected final myocardial infarct size using weighted ST-segment, Q wave, and T wave measurements.

Formulas for predicting final acute myocardial infarction (MI) size from ST-segment deviation on an initial electrocardiogram were proposed by Aldrich et al. for anterior and inferior infarct locations. This study of 529 patients who did not receive thrombolytic therapy was performed to determine the effectiveness of the Aldrich formulas for predicting final QRS MI size; to propose new formulas for predicting final MI size using ST-segment deviation, Q wave, and T wave information in a development population of 322 patients; and to evaluate the new formulas in a randomly selected population of 207 patients. The Aldrich formulas achieved correlations with final infarct size of r = .40 for anterior and r = .43 for inferior MI locations in the present population which are weaker than those previously reported. Formulas that consider electrocardiographic parameters in addition to ST-segment deviation were proposed for both anterior and inferior final MI size. In the test set of 207 patients, these models explained 16.9% and 15.2% of the variation in final MI size for anterior and inferior locations respectively. They may prove useful in assessing the extent of myocardial salvage where interventions are to be tested.

Electrocardiography↗