Dietary fats a quantitative and qualitative approach to reducing risk of cardiovascular disease in the fasting and fed state /

by Griel, Amy E.

Two research studies were conducted in normo- and hypertriglyceridemic individuals to determine the quantitative and qualitative effects of dietary fatty acids in the fasting and fed states, respectively. A randomized controlled feeding study was conducted to evaluate the effects of the chronic consumption of a low-fat versus a moderate-fat diet. The results of the studies conducted demonstrate that chronic intake of dietary patterns at either end of the recommended range of total dietary fat intake (20- 35% total kcal) improves levels of serum lipids and lipoproteins. Despite a reduction in fasting triglycerides following the low-fat diet, hypertriglyceridemic individuals had higher levels of atherogenic apolipoproteins following the low-fat diet, compared to the moderate-fat diet. Based on this study, the recommendation to consume a more moderate fat diet must also include a focus on the quality of the fat being consumed. The results of the second study, a randomized crossover design postprandial study indicate that the consumption of different kinds of fatty acids have very different affects on postprandial risk factors for CVD. In particular, the simple heating of a PUFA increased levels of individual trans fatty acid isomers and lipid hydroperoxides, resulting in diverse physiological responses, compared to the same un-heated PUFA. In summary, whereas the implementation of a very healthy low-fat diet may have adverse affects on the apolipoprotein profile of individuals with elevated baseline triglyceride levels, the inclusion of unsaturated fatty acids in a moderate-fat diet, has a significant hypotriglyceridemic effect in individuals, regardless of baseline triglyceride status. In making the recommendation to consume a moderate-fat diet it is important to recognize the effects of individual fatty acids on postprandial risk factors for cardiovascular disease. In particular, the heating of highly unsaturated fatty acids leads to the production of trans fatty acids and lipid oxidation end products. The diverse physiological responses observed thus indicate that a diet rich in mono- and polyunsaturated fatty acids is optimal, when compared to a diet rich in saturated and/or trans fatty acids. iii