H. pylori has been classified by World Health Organization as type I carcinogen for its association with gastric cancer. Among its suggested pathological pathways is oxidative stress, which may reduce the bioavailability of dietary antioxidants. The main objectives of this thesis were to estimate the prevalence of H. pylori infection in Ontario and to assess its effect on the bioavailability of two main dietary antioxidants, vitamins E and C.
To estimate the prevalence of H. pylori infection, a volume of 10 ul of plasma was aliquoted from stored blood of 1306 adults from Ontario. The blood samples belonged to controls of a population-based study of colorectal cancer. The overall weighted seroprevalence of H. pylori was 23.1% (95% CI: 17.7-29.5) with males having higher infection rates than females. Seroprevalence of the infection increased with age and number of siblings. Being non-white, born outside Canada and immigrating at an age greater than 20 years increased risk for H. pylori infection. An inverse association with seroprevalence was found for education and alcohol consumption.
In order to investigate whether H. pylori positive compared to H. pylori negative subjects have lower changes in plasma concentrations of ascorbic acid and alpha tocopherol when supplemented with these vitamins, H. pylori negative (n=32) and H. pylori positive (n=27) volunteers received vitamin C (500 mg) and alpha tocopherol (400 IU) supplementation daily for 28 days. H. pylori infection status was determined by 13C urea breath test. Post supplementation plasma ascorbic acid and alpha tocopherol were significantly higher than pre supplementation concentrations in both groups. The changes in plasma ascorbic acid and alpha tocopherol were not significantly different between H. pylori negative and positive groups (ascorbic acid: 13.97±16.86 vs. 20.87±27.66, p=0.76; alpha tocopherol: 15.52±9.4 vs. 14.47±15.77; p=0.39 for H. pylori negative and positive groups respectively).
The weighted seroprevalence of H. pylori infection was 23.1%. Age, sex, ethnicity, place of birth, age at immigration, education and alcohol consumption were factors associated with the infection prevalence in the population studied. In addition, we found no effect of H. pylori infection on the bioavailability of vitamins E and C.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/16810 |
| Date | 20 January 2009 |
| Creators | Naja, Farah |
| Contributors | Kreiger, Nancy |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
| Format | 1774567 bytes, application/pdf |
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