Abstract
PURPOSE OF REVIEW: Do dietary fats lower blood pressure? This review covers total fats, individual fatty acids and foods that provide specific fats. RECENT FINDINGS: Evidence for blood pressure lowering is stronger for supplements providing individual marine fatty acids than for fish intake since data on fish consumption are scarce. Such effects are more readily apparent in hypertensive than normal subjects. Biological mechanisms to support linkage between dietary fish oils and blood pressure are plausible. Information on other dietary fatty acids (saturates, linoleic acid, alpha-linolenic acid) is mostly less robust and therefore inconclusive. However, findings with respect to consumption of dairy foods especially of the low-fat variety do suggest association with lower blood pressures. Apart from marine fatty acids which have mostly been significantly associated with clinically modest blood pressure-lowering, the effects of other dietary fatty acids are inconsistent or clinically minor. Consumption of dairy especially of yoghurt has been linked with lower blood pressure despite the relatively high saturated fat content but the mechanism is unclear.
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Key Points
The best evidence from randomised controlled trials or case-control studies for an inverse association between a group of fatty acids or of individual fatty acids and raised blood pressure or existing hypertension is with fish oil fatty acids, specifically DHA and EPA. Increasing consumption of these fatty acids as the oil or as supplements leads to lower blood pressure and amelioration of hypertension. This paper showed that reduced fat diets, in observational studies and in several randomised controlled trials show beneficial lowering of blood pressure that may, however, not be sustainable. There is an insufficient evidence to determine whether any of the following fatty acids influence blood pressure: the group of saturated fatty acids, the omega-6 fatty acid linoleic acid, the plant omega-3 fatty acid alpha-linolenic acid or the most commonly consumed trans-fatty acid elaidic acid (trans-oleic). Whereas evidence from observational studies or intervention studies with total diets or with groups of foods aremore difficult to evaluate than randomised controlled trials information derived from some such studies indicates a probable association with blood pressure. The most informative of these relates to dairy consumption especially of the low-fat varieties that has shown inverse associations with blood pressure in several large observational studies. The authors note that uncertainty around the importance of dietary fatty acids contrasts with the robust evidence pertaining to other dietary measures such as reducing sodium intake.