addition, polymorphisms of the apoB, apoC, apoA-IV and lipoprotein lipase LPL genes have been related to
the extent of cholesterol response [14 – 18], though fewer data are available and the findings are less consistent
than those relating to the apoE genotypes. We report here on predictors of plasma total cholesterol change in
a group of 55 individuals during four dietary periods of high or low saturated fat intake. More extensive geno-
typing than had been undertaken previously in a single study has enabled analysis of the extent to which a
range of polymorphisms contribute to variation in cholesterol response to alterations in the nature of
dietary fat in free-living individuals. Particular attention was paid to effects of variation in the cholesterol ester
transfer protein CETP and LPL genes as plasma CET activity and the LPL HindIII polymorphisms were as-
sociated with response of plasma cholesterol to changes in the type of dietary fat in our earlier study [4,18]. It
was also possible to estimate the effect of compliance to dietary advice on variation in response among free
living individuals.
2. Methods
2
.
1
. Participants Sixty two people aged 26 – 64 years, with plasma
cholesterol concentration 5.5 – 7.9 mmoll and triglyce- ride concentration below 3 mmoll, were recruited from
a group of 300 volunteers who responded to advertise- ments in the widely read local daily newspaper. None
were suffering from chronic medical conditions or tak- ing drugs known to influence lipid metabolism. Fifty-
five individuals 23 men and 32 women completed the 20-week study. Four males and three females withdrew
from the study. Their age, baseline total and low-den- sity lipoprotein LDL cholesterol were not significantly
different from those individuals who completed the study. Participants continued their usual activities
throughout the experimental period. Ethical approval was obtained from Southern Regional Health Author-
ity and informed consent gained from each participant.
2
.
2
. Experimental design The study involved a randomised double crossover
trial of two dietary interventions: one high in saturated fatty acids SAFA, the other high in polyunsaturated
fatty acids PUFA. After recruitment, participants recorded their usual diet for a 4-day period. This infor-
mation was used to plan the experimental diets. They were then asked to follow a standard lipid-lowering diet
total and saturated fatty acids providing around 30 and 10 of total energy respectively for 3 weeks
baseline diet. Thereafter they were randomised to one of two groups following the dietary sequences, SAFA –
PUFA – SAFA – PUFA or
PUFA – SAFA – PUFA – SAFA, each dietary phase continuing for 4 weeks
without washout periods. Weight was recorded and a fasting blood sample collected on two occasions, 1 day
apart, during the final week of the baseline and each experimental diet. Participants were also asked to com-
plete a 3-day estimated diet record of all food and drink consumed on the Thursday, Friday and Saturday pre-
ceding the week during which blood samples were taken. The diet records were analysed using the ‘Diet
Cruncher’ programme [19].
3. Experimental diets
