There is emerging evidence that polymorphisms in the gene encoding for apoE impact on the LDL-cholesterol (LDL-C) response to dietary fat intake. It has been reported that carriers of the apoE4 allele have higher plasma LDL-C concentrations after ingestion of saturated fat (SFA)(1) and docosahexanaeoic acid (DHA) (>2g/d)(2) compared with the apoE3 wild-type. The aim of the SATgen study was to investigate the impact of a combination of SFA and DHA intake on plasma lipids according to apoE genotype.
Eighty-eight subjects were prospectively recruited according to apoE genotype (n 44 E3/E3 and n 44 E3/E4) who were matched for age, gender and BMI. A flexible dietary exchange strategy, based on models previously developed by our group(3, 4) was employed to implement three iso-caloric diets with different fatty acid profiles sequentially: Participants consumed a low fat (LF) diet (28%E fat, 8%E SFA, 55%E carbohydrate (CHO)); High SFA (HSF) diet (38%E fat, 18%E SFA, 45%E CHO) and HSF-DHA diet (HSF diet+3g/d DHA) each for an 8-week period. Commercially available spreads (LF spread (LF), butter (HSF)), oils and snacks (cereal bars, pretzels and rice cakes (LF) and chocolate bars, crisps and cakes (HSF)) were supplied to subjects to be consumed in exchange for habitual foods in order to replace the exchangeable fat in their diet. Subjects were also advised to adjust the quantity of carbohydrate and dairy products accordingly. Four 3-d weighed diet diaries were completed by the subjects (one at baseline and one during each of the dietary periods) and analysed using Dietplan 6.60 (Forestfield Software, UK).
SATgen dietary compositional targets were broadly met (see table). Total dietary fat (42.8%E and 41.0%E respectively v. 25.1%E) and SFA (19.3%E and 18.6%E, respectively v. 8.3%E) intakes were higher during the HSF compared with the LF diet (P=0.000). In addition, the DHA intake was significantly higher in the HSA-DHA diet group (P=0.000) relative to the two earlier dietary periods. Therefore the SATgen food exchange model was effective at implementation of the three experimental diets, which were well tolerated by the subjects.
The SATgen study was funded by Wellcome Trust Fund (WT085045MA).