INFLUENCE OF DIETARY FATS UPON SYSTOLIC BLOOD-PRESSURE IN THE RAT

Studies were performed to determine whether feeding diets with differi ng fatty acid content and composition had an influence on systolic blo od pressure in the rat. Weanling male rats were fed standard laborator y chow (2.9% fat in total), or synthetic diets (10% fat in total) cont aining fish oil, butter, coconut oil or corn oil, for 5 weeks. Coconut oil and butter diets were rich in saturated fatty acids, whilst fish oil and corn oil were rich in the n-3 and n-6 unsaturated fatty acids respectively. Systolic blood pressure was measured using an indirect t ail-cuff method at the end of the feeding period, and compared to a gr oup of weanling rats. Feeding the different diets did not alter the gr owth of the rats, so all animals were of similar weights at the time o f blood pressure determination. Control (chow fed) animals, at nine we eks of age, had higher systolic blood pressures than the weanling, bas eline control group. Fish oil fed rats had similar pressures to the ch ow fed rats. Corn oil fed rats had significantly lower systolic pressu res than the controls. The rats fed the diets rich in saturated fatty acids (butter and coconut oil) had significantly higher blood pressure s than all other groups. Systolic blood pressure was found to be signi ficantly related to the dietary intakes of saturated and unsaturated f atty acids. The dietary intake of linoleic acid was significantly high er in corn-oil fed rats than in other groups. Systolic blood pressure was inversely related to linoleic acid intake. Feeding a diet rich in saturated fatty acids significantly increases blood pressure in the ra t. A high intake of n-6 fatty acids, and in particular linoleic acid, appears to have a hypotensive effect. Prenatal exposure of the rats to a maternal low protein diet, abolished the hypertensive effects of th e coconut oil diet and the hypotensive effect of the corn oil diet upo n young adult females. The intrauterine environment may, therefore, be an important determinant of the effects of these fatty acids on blood pressure in later life.