[Truncated abstract] This thesis examines the potential role of dietary intake in the development of two common conditions affecting the prostate gland; prostate cancer and benign prostatic hyperplasia (BPH). Diet is of interest as a potential risk factor for prostate cancer because of geographical variations in prostate cancer incidence and increased prostate cancer risks associated with migration from Asian to western countries. Some geographical variation has been suggested for BPH, but this is less certain. However, both prostate cancer and BPH have potential links with diet through their positive associations with sex hormone levels, metabolic syndrome, increased insulin levels and chronic inflammation. In addition, zinc is an essential dietary micronutrient required for semen production in the prostate gland. The original work for this thesis is presented in six manuscripts of which, four have been published in peer-reviewed journals (at the time of thesis completion). BPH investigated in this thesis is defined as surgically-treated BPH. The following hypotheses were investigated. Regarding foods, nutrients and the risk of prostate cancer and BPH: 1. Increasing intakes of fruits, vegetables and zinc are inversely associated with the risk of prostate cancer and BPH 2. Increasing intakes of total fat and calcium are positively associated with the risk of prostate cancer and BPH. 3. Dietary patterns characterised by high meat, processed meat, calcium and fat content are positively associated with the risk of prostate cancer and BPH. 4. Dietary patterns characterised by high fruit and vegetable and low meat content are inversely associated with the risk of prostate cancer and BPH. v Regarding methodological issues related to the study of diet-disease relationships: 5. Dietary patterns (overall diet) elicited from principal components analysis yield stronger diet-disease associations than when studying isolated nutrients. 6. Remotely recalled dietary intake is reliable enough to be used in studies of chronic disease with long latency periods, such as prostate cancer and BPH. Methods: Data from two studies was used to address the hypotheses above. ... Based on the literature reviewed and the original work for this thesis, the most important dietary risk factors for prostate cancer and BPH appear to be those common to western style diets, i.e. diets high in red meat, processed meat, refined grains, dairy products, and low in fruit and vegetables. This type of diet is likely to result in marginal intakes of antioxidants and fibre, excess intakes of fat and possibly, moderate intakes of carcinogens associated with processed meat and meat cooked at high temperatures. These dietary factors have been linked with biomarkers of inflammation, and they support the hypotheses that chronic inflammation is involved in the development of both prostate cancer and BPH. In addition, this work builds on evidence that zinc is an important factor in prostate health. There is scope for more investigation into the reliability of dietary patterns and the use of nutrient patterns as an alternative to focussing on single food components. Further studies on the reliability of remote dietary intake would also be useful. Because of the latency of chronic disease, it can be theorised that remote dietary recall may uncover more robust diet-disease relationships.
|Qualification||Doctor of Philosophy|
|Award date||9 May 2008|
|Publication status||Unpublished - 2007|