Effect of an Increased Intake of Alpha-Linolenic Acid and Group Nutritional Education on Cardiovascular Risk Factors: The Mediterranean Alpha-Linolenic Enriched Groningen Dietary Intervention (MARGIN) Study.
Effect of an Increased Intake of Alpha-Linolenic Acid and Group Nutritional Education on Cardiovascular Risk Factors: The Mediterranean Alpha-Linolenic Enriched Groningen Dietary Intervention (MARGIN) Study.
Year: 2002
Authors: W J E Bemelmans, J Broer, E J M Feskens, A J Smit, F A J Muskiet, J D Lefrandt, V J J Bom et al.
Publication Name: Am. J.Clin. Nutr.
Publication Details: Volume 75; Page 221.
Abstract:
In 1995, the Lyon Diet Heart Study (LDHS) demonstrated that when compared to a typical western diet, consuming a Mediterranean diet rich in alpha-linolenic acid (ALA) protected against recurrent cardiovascular events in the secondary prevention of ischemic heart disease (IHD). As part of the LDHS study, nutritional education was offered to the intervention group in addition to an increased dietary ALA consumption. Thus, the effect of nutritional education on recurrent cardiac events was never investigated separately from an increased dietary intake of ALA. In addition, the long-term effects of an increased dietary ALA intake on IHD risk factors has never been established. The objective of this current study, which was inspired by the LDHS, is to investigate separately the effects of high ALA diet on IHD risk factors after 2 years, as well as the effect of group nutritional education on dietary habits, in subjects with multiple CVD risk factors. Two hundred and eighty two subjects (124 men ad 158 women) participated in this prospective prevention study. All subjects were 30-70y old, had serum total cholesterol values of 6-8 mmol/L, and had two or more of the following CV risk factors: high blood pressure or use of anti-hypertensive medication, BMI =27, smoking, history of CVD, or family history of early onset of CVD. Subjects were assigned to either the nutritional education intervention group (NEI; n=110), or the nutritional education control group (NEC; n=172). The NEI group received education about a Mediterranean type diet, where as the NEC group received a posted leaflet containing the standard Dutch dietary guidelines. In addition, subjects in each group were randomly assigned in a double blind fashion to one of two subgroups designated to consume either an ALA-rich margarine (NEI + ALA and NEC + ALA subgroups), or an LA-rich margarine (NEI + LA and NEC + LA subgroups). The ALA rich margarine contained 46% LA and 15% ALA, while the LA rich margarine contained 58% LA and 0.3% ALA. The coordination center allocated the margarines and organized the masked distribution during the study. The amount of margarine consumed by subjects was based on participant’s usual consumption of added fat. A baseline examination for a number of parameters was performed at the beginning of the study, and follow-up examinations were conducted after 16, 52, and 104 weeks. In addition, a 10y estimated risk of developing IHD was calculated with the use of the Framingham risk function. Results from this study demonstrated that after adjustment for sex and baseline intake, the NEI group had a lower intake of total fat, energy, and SFA after 2y in comparison to the NEC group. In addition, average ALA intakes in the ALA groups were 6.3 g/d versus 1.0 g/d in the LA groups. After 2y, there was a higher ratio of total to HDL cholesterol, lower HDL cholesterol, higher serum triacylglycerol, and lower plasma fibrinogen values in the ALA group when compared to the LA group. Finally, no significant difference existed between any of the groups in 10 y estimated IHD risk. Overall, this secondary prevention trial showed a 70% reduction in cardiac events in the NEI group participants who received nutritional education and consumed the ALA rich margarine. Free provision of ALA rich margarine increased ALA intake substantially, whereas nutritional education was found to successfully increased the consumption of fish during a 2y period. Both of these dietary practices are believed by researchers to be important factors in IHD prevention.
