The overall aim of the research described in this thesis was to evaluate the effect of vitamin A supplementation on respiratory health, assessed by lung function in children aged 6--9 years. It comprises three studies. / The first study determined the magnitude of vitamin A deficiency in the target population in Wukro wereda, Northern Ethiopia. Of the 1339 eligible children identified by house to house surveys, 824 had complete data for vitamin A indicators and anthropometry. Xerophthalmia was detected in 5.8% of the children, 8.4% had serum retinol levels <0.35 mumol/L and 51.1% between 0.35--0.70 mumol/L. Liver vitamin A reserve was also found to be low in 41.0% of the children using the Modified Relative Dose Response (MRDR) and in about 85% of the children, the daily vitamin A intake was below the FAO/WHO basal requirement (<250 RE/day). / The second study found that in comparison with children with adequate vitamin A reserve (MRDR < 0.06), those with low reserve (MRDR ≥ 0.06) had forced expiratory volume in one second (FEV1) 48.8 ml (p = 0.006) lower when unadjusted, 23.1 ml (p = 0.04) when partially adjusted for age, gender and height and 14.1 ml (p = 0.20) when fully adjusted for demographic, general health, lung function and household related characteristics. / The third study describes the results of a randomized controlled trial (RCT) to evaluate the impact of vitamin A supplementation on respiratory health as assessed by change in FEV1 at 4 months. The average change was 53.3 ml (n = 496) and 53.8 ml (n = 501) in the vitamin A and placebo groups respectively. After adjusting for baseline covariates, the difference between them was -3.6 ml (95%CI: -21.6, 14.4). In sub-analysis of the data, gender and vitamin A status subcategories were found to be effect modifiers. / In conclusion, high dose vitamin A supplementation did not show an effect on change in FEV1 at 4 months in children aged 6--9 years with high prevalence of vitamin A deficiency. Sub-analysis findings suggest that the benefits to vitamin A intervention in the study setting can probably be achieved if the other nutritional deficiencies such as zinc are addressed. Moreover, the results also suggest that the effects of vitamin A supplementation on respiratory health status are complex and these need to be taken into account in future studies to assess the clinical and public health implications of vitamin A supplementation in this age group.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36964 |
| Date | January 2000 |
| Creators | Kassaye, Tarik. |
| Contributors | Johns, Timothy (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (School of Dietetics and Human Nutrition.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001808122, proquestno: NQ70055, Theses scanned by UMI/ProQuest. |
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