Thesis (Ph.D.)--University of Western Australia, 2007.

No description available.

published_or_final_version / Biological Sciences / Master / Master of Philosophy

published_or_final_version / Surgery / Master / Master of Medical Sciences

Background: The role of aspirin (100 mg daily) and omega-3 fatty acids (FA) (1 g daily) for primary prevention of cardiovascular disease in diabetes is being investigated in the 2x2 factorial design ASCEND trial. To support the interpretation of the trial's efficacy findings, it is important to compare self-reported compliance by participants with measures of the biochemical effects of each intervention. The previous data on the effect of supplementation with omega-3 FA on coronary heart disease is uncertain. Methods: The ASCEND trial randomly allocated 15480 people with diabetes (94% type 2 DM) who do not already have diagnosed occlusive arterial disease to receive aspirin or placebo and to omega-3 FA or placebo. Blood and urine samples were collected by mail at baseline and after 3 years follow-up. The effectiveness of aspirin to suppress urinary thromboxane B2 (UTxB2), a marker of platelet activity, and, of omega-3 FA supplements to increase red cell membrane omega-3 index were assessed. A systematic review of previous trials of omega-3 FA was conducted to summarize the prior evidence for the effects of omega-3 FA supplements on major vascular events (MVEs). Results: Aspirin reduced UTxB2 levels by 67% (63-70%) (p < 0.0001) compared with placebo, from 3453 pg/mg (95% CI 3061-3895) at baseline to 1190 pg/mg (1100-1287) on those allocated to aspirin during the trial. During follow-up, the omega-3 index increased by 33% (95% CI 26%-39%) in those allocated omega-3 FA compared to placebo (p < 0.0001). The meta-analysis of previous studies of omega-3 FA showed no effect on MVEs (HR 0.97; [0.93-1.01]) overall or in any pre-specified sub-groups. Conclusions: Low dose aspirin and omega-3 FA are biochemically effective at reducing UTxB2 and increasing the omega-3 index, respectively. Previous trials show that supplementation with omega-3 FA had no significant effect on MVEs. The results of the ASCEND trial, assessing the effects of both aspirin and omega-3 FA on MVEs, will be available in 2018.

No description available.

Omega-3 fatty acids are increasingly recognised as playing an important role in human brain development and mental health. The polyunsaturated fatty acids (PUFAs) include omega-3 and omega-6 fats which are essential fatty acids (EFAs), consumed via the diet. Omega-3 fatty acids are particularly abundant in fish oils. The omega-3 fatty acids are being focused on for their role in depression, the main types being docosahexaenoic acid (DHA), which is abundant in neural tissue, and also eicosapentaenoic acid (EPA) which is biologically very active. There is an emerging literature in relation to omega-3 fatty acid blood levels in depression and the effects of treatment with omega-3. Strong epidemiological evidence has also been published indicating an association between a population's fish intake and depression rates. A specific research focus on omega-3 as a treatment for depression in the perinatal period is also starting to emerge. The importance of this particular area is enhanced by the knowledge that omega-3 depletion occurs during the perinatal period due to fetal diversion for neurodevelopment. In view of the lay public promotion of omega-3 and its appeal to women as a 'natural therapy', there is a need to scientifically evaluate its effectiveness to treat depression in the perinatal period. It is also important to investigate omega-3 as an alternative to antidepressants given the ongoing uncertainties regarding their safety in pregnancy. In this thesis a literature review presents current research relating to this field. This is followed by a description of the methodology and results for the two trials conducted. The results of the double-blind randomised placebo controlled trial of omega-3 as a treatment for depression in the perinatal period were essentially negative. However this result is limited by the small sample size in the study and therefore it may be unwise to interpret the result as conclusive. The case-control study confirmed the hypothesis that omega-3 levels were more depleted in depressed women compared to non-depressed women. A discussion of the results and trial limitations then follows in the thesis. It is concluded that further larger studies are warranted in this area.

The primary objective of this study was to determine if the intake of omega-3 fatty acids (O3FA), from self-selected foods and supplements, was associated with a reduction in muscle soreness in collegiate rowers. Several groups of collegiate rowers were identified as potential subjects and, using an IRB-approved protocol, 61 volunteers from this subject pool agreed to participate in the study. At the end of the first week of fall practice, subjects were asked to provide information on age, weight, height, ethnicity, rowing level, sun exposure, exercise regimen, pre- and peak-soreness and exertion levels, hydration status, and food/supplement intake. A Talag scale was used to determine the severity of muscle soreness, and a modified Borg scale was used to determine the exertion intensity level. A food frequency questionnaire using a 10-point Likert scale was used to assess food and supplement intake, with a special focus on O3FA. Subjects with a higher intake of EPA/DHA rich bottled supplemental fish oil, taken by spoon, had significantly higher soreness levels than those with lower intakes (p = 0.028). Higher soreness was also significantly associated with higher intake of EPA/DHA rich fish oil capsules (p < 0.001). Lower soreness was significantly associated with higher fruit intake (p = 0.030). These findings suggest that high intakes of O3FA from fish oils, regardless of liquid or capsule form, may be contraindicated for collegiate rowers wishing to reduce muscle soreness. Recommending fruit intake may be warranted for rowers wishing to reduce muscle soreness.

Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid (n-3 PUFA) required for fetal neurodevelopment. Increased DHA levels are associated with 17β-estradiol levels, as DHA is higher in women relative to men and in pregnant relative to non-pregnant women, suggesting a maternal adaptation to supply DHA to the fetus. DHA can be synthesized in the body from shorter n-3 PUFA through sequential elongation-desaturation, with Δ6-desaturase being the rate-limiting enzyme. The goal of the present thesis was to characterize the mechanism underlying higher DHA in situations of altered 17β-estradiol status by examining the expression of DHA synthesis enzymes in rodent models. Fatty acid composition of several lipid classes was measured by gas chromatography and enzyme expression was measured by RT-qPCR and immunoblotting. Hepatic Δ6-desaturase and phospholipid DHA was higher in female relative to male, and in pregnant relative to non-pregnant rats. Similarly, 17β-estradiol supplementation of ovariectomized rats resulted in increased hepatic Δ6-desaturase expression and DHA content, while ovariectomy itself had no effects on DHA levels despite controlling for hyperphagia. Mice deficient in the DNA binding activity of estrogen receptor α (ERα) had no differences in hepatic Δ6-desaturase or DHA levels. These results suggest that 17β-estradiol mediates the higher DHA levels in females and during pregnancy through increasing hepatic Δ6-desaturase expression, although the effects of removing 17β-estradiol signalling through ovariectomy or ERα disruption are less clear. This work helps to explain findings of altered DHA status in response to changes in 17β-estradiol concentrations, possibly resulting in more appropriately tailored dietary DHA recommendations. Also, increased understanding of the regulation of DHA synthesis may improve DHA yields in agri/aquaculture and enable increased content of DHA in the food supply.

Thesis (M. Med. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 47-49).