Journal Name:
British Journal of Nutrition
Article Title:
Long-term monounsaturated fatty acid diets reduce platelet aggregation in healthy young subjects
Date Written:
2003
Volume:
90
Number:
Page:
597
Author(s):
Smith, R.; Kelly, C.; Fielding, B.; Hauton, D.; Sliva, K.; Nydahl,, M.; Miller, G.; Williams, C.
Article:
Coronary heart disease (CHD), the most common type of cardiovascular disease, has become a major health burden worldwide. The American Heart Association reported that total direct and indirect costs of cardiovascular disease (CVD) and stroke in 2004 is estimated to be US $368.4 billion. A significant risk factor in the development of this disease is high intakes of both dietary fat (total) and saturated fat (SFA). Health organizations recommend a heart healthy diet should consist of no more than 30% of total energy as fat, and no more than 10% as saturated fat. Paradoxically, concern has also been raised over reducing total dietary fat as often it is coupled with an increase in carbohydrate (CHO) consumption - a situation that potentially may result in adverse health effects. Studies have found high CHO diets may increase plasma triacylglycerols (TAG) and decrease levels of beneficial HDL cholesterol, both situations are positive risk factors for CHD. This concern has prompted numerous experimental studies to explore alternative dietary strategies. One such strategy currently under investigation involves substituting SFA with monounsaturated fatty acids (MUFA) found in vegetable oils such as canola oil. This dietary approach, when compared to low fat, high CHO diets, has been found to reduce total and LDL-cholesterol, without reducing HDL-cholesterol or increasing fasting plasma TAG.
Although substituting MUFA for SFA has been used in numerous experimental studies with successful results, the majority of research has been conducted in middle-aged subjects, or subjects with elevated fasting lipoprotein levels. As such, little information is available regarding the effect of this type of diet in other population groups, such as in younger individuals with normal blood lipid profiles. However, a recent study6 investigated the effect of substituting two levels of dietary SFA with MUFA in younger individuals with normal lipid profiles. Results from this study favor the inclusion of MUFA rich foods, such as canola oil, in a heart healthy diet.
Fifty-one students attending the University of Reading participated in a parallel single-blind design study. All participants consumed a standard reference diet for an eight- week run period. This was immediately followed by the consumption of either a moderate or a high MUFA diet for an additional 16- week period. Twenty-five students were assigned to consume the moderate-MUFA diet that consisted of 13% of total energy as SFA, 15% as MUFA, and 6% as polyunsaturated fat (PUFA). The remaining twenty-six students consumed a high-MUFA diet that consisted of 10% of total energy, 18% MUFA, and 6% PUFA. The diets differed only in SFA and MUFA content, while PUFA and trans fatty acid content remained constant between the two diets. Either canola oil or high MUFA sunflower oil provided the source of MUFA in both diets. Blood samples were taken at baseline and at 8-week intervals throughout the study, and were subsequently analyzed to for a range of atherogenic and thrombogenic risk markers (used to determine risk of CHD), such as platelet aggregation, cholesterol values (total, LDL, and HDL), fasting factor VII, and fibrinogen concentrations.
No differences between the two experimental diets were found with regard to effects on fasting blood lipids. Significant reductions in total and LDL-cholesterol were observed for both MUFA enriched diets, and a small but significant reduction in HDL-cholesterol was also observed in both groups. However, the high-MUFA diet had favorable effects on platelet aggregation and fasting factor VII when compared to baseline, which was not observed in the moderate-MUFA diet.
Although both MUFA diets had similar effects on fasting blood lipids, only the high MUFA diet had a positive impact on additional risk markers in comparison to the moderate-MUFA diet. Regardless, these results demonstrate that replacing saturated fat in the diet with either moderate or high levels of MUFA is in fact beneficial in reducing risk markers of CHD in healthy young individuals. Furthermore, incorporating MUFA into the diet is quite easily achieved by consuming MUFA rich foods such as canola oil, which contains 55% MUFA., , , ,
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