- Title
- Phytosterols and omega-3 polyunsaturated fatty acids for cardiovascular health in hyperlipidemia
- Creator
- Micallef, Michelle
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2010
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Atherosclerosis is a major factor influencing morbidity and mortality worldwide. The pathogenesis of atherosclerosis has been extensively investigated however treatment modalities have not changed much over the past decade. Prevention of atherosclerosis and its complications, both primary and secondary, are based mainly on controlling the various cardiovascular risk factors. Treating combined hyperlipidemia, and in particular reducing LDL-cholesterol and triglyceride levels, is established as a highly efficacious means of reducing both morbidity and mortality from cardiovascular disease. With the increased emphasis on various lipoprotein sub fractions, many patients need to consider combining treatments to achieve recommendations. Although statins can be an effective treatment for hyperlipidemia, they may not be sufficient to achieve the recommended LDL-cholesterol and triglyceride goals as set out by national governing bodies. This thesis examines the lipid, inflammatory and cardiovascular esponse to concomitant supplementation with phytosterols and omega-3 fatty acids in combined hyperlipidemia. Phytosterols and omega-3 fatty acids are functional ingredients with potential cardiovascular benefits. Phytosterols inhibit cholesterol absorption, thereby reducing total-cholesterol and LDL-cholesterol. The consumption of 1.5-2.0g/day of phytosterols can result in a 10-15% reduction in LDL-cholesterol within a three week period, in hyperlipidemic populations. The added benefit of phytosterol supplementation has been demonstrated in individuals already taking statin medications. Omega-3 fatty acid supplementation has strong hypotriglyceridemic properties, and provides benefits in other risk factors associated with cardiovascular disease, such as anti-thrombotic and antiinflammatory function. Given the propensity of hyperlipidemia to manifest in high risk individuals and populations alike, there is a plausible role for combining phytosterols and omega-3 fatty acids supplementation. A series of clinical trials were undertaken to explore the plasma lipid, inflammatory and overall cardiovascular response to combined supplementation with phytosterols and omega-3 fatty acids rich in either EPA or DHA. This particular dietary combination of functional ingredients was designed to optimise improvements in plasma lipid profile in individuals with combined hyperlipidemia. Findings from this thesis show that the combined supplementation of phytosterols and various omega-3 fatty acids reduces total-cholesterol, LDL-cholesterol, triglycerides and increases HDL-cholesterol, greater than the supplementation of either function ingredient alone. Furthermore, a number of circulating inflammatory mediators were analysed showing significant reductions in response to the combined dietary treatment. Overall cardiovascular risk was reduced by an average of 20%. Interestingly, the combination of phytosterols and DHA was most effective in reducing triglyceride levels and inflammatory mediators, compared to the EPA combination. The phytosterol and DHA combination showed synergistic total-cholesterol and LDL-cholesterol lowering effects. The apolipoprotein E genotype represents one of the most widely investigated genotypes with respect to lipid concentration. In this thesis, we examine the genotype within our cohort of combined hyperlipidemic individuals, who represent a population with an atherogenic lipoprotein phenotype. Whilst this genotype represents an obvious potential genetic modulator of lipid response to dietary therapies, it is yet to be explored in a case of concomitant supplementation with phytosterols and omega-3 fatty acids. In conclusion, while this study has highlighted the potential of phytosterols and omega-3 fatty acids as a preventative strategy in combined hyperlipidemia, the data prompts further examination of the relative importance of individual fatty acids and fatty acid combinations with phytosterols.
- Subject
- hyperlipidemia; phytosterols; omega-3 fatty acids; inflammation; cardiovascular disease
- Identifier
- http://hdl.handle.net/1959.13/934708
- Identifier
- uon:11887
- Rights
- Copyright 2010 Michelle Micallef
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Abstract | 291 KB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Thesis | 11 MB | Adobe Acrobat PDF | View Details Download |