SUBSTITUTION OF DIETARY MONOUNSATURATED FATTY-ACIDS FOR SATURATED FATTY-ACIDS IN A FREE-LIVING POPULATION - A FEASIBILITY STUDY

The fatty acid composition of the diet of seven free-living subjects ( five men and two women) aged 41-56 years was altered for 1 month. The aim was to increase the intake of monounsaturated fatty acids (MUFAs) from subjects current habitual levels of 12% dietary energy to a targe t intake of 18% dietary energy, and to decrease saturated fatty acid ( SFA) from habitual levels of 16% dietary energy to target levels of 10 % dietary energy The change in fatty acid intake was achieved by suppl ying volunteers with foods prepared using MUFA-containing spreads or o live oil (ready meals, sweet biscuits and cakes) and also by supplying spreads, cooking oil and MUFA-enriched milk for domestic use. Body we ight and plasma total cholesterol measurements were made at baseline a nd at 2 and 4 weeks on the diet as an aid to maintaining subject compl iance. MUFA consumption was significantly increased from 12% dietary e nergy to 16% dietary energy (P < 0.01), and SFA intake was reduced fro m 16% dietary energy to 6% dietary energy (P < 0.01) during the 4-week intervention. The diet failed to achieve the target increase in MUFA but exceeded the target reduction in SFA. This was due to the fact tha t subjects reduced their total fat intake from a mean habitual level o f 38% dietary energy to a mean level of 30% dietary energy. During the dietary period, mean plasma cholesterol levels were lower at 2 weeks (P < 0.01) and at 4 weeks (P < 0.01) than the baseline, with a mean re duction of 20% over the dietary period. This study demonstrates the di fficulty of achieving increased MUFA intakes (by SFA substitution) in free-living populations when only a limited range of fatty-acid modifi ed food products are provided to volunteers.