A Very High Intake of Conjugated Linoleic Acid, a Trans Fat from Milk and Meat, Does Not Affect Blood Pressure in Normotensive Humans

Background: Trans fatty acids in the diet are produced either by industrial hydrogenation or by biohydrogenation in the rumens of cows and sheep. Industrial trans fatty acids increase the risk of coronary heart disease. The effects of trans fatty acids from milk and meat of ruminants are less clear. Cis-9, trans-11 conjugated linoleic acid (CLA) is a trans fatty acid unique to ruminants. Our objective was to study the effect of diets high in CLA and industrial trans fatty
acids on blood pressure. Methods: Sixty-one healthy men (n25) and women (n36) were sequentially fed each of 3 diets for 3 weeks, in random order, for a total of 9 weeks. Diets were identical except for 7% of energy (18.9 g in a diet of 10 MJ/day) which was provided either by oleic acid, by industrial trans fatty acids, or by CLA. We measured blood pressure and heart rate on days 19 and 21 (period 1), days 40 and 42 (period 2) and days 61 and 63 (period 3).
Results: Systolic blood pressure changed on average by 0.1 mmHg (95% confidence interval 1.49; 1.27, P0.87), and diastolic blood pressure by 0.5 mmHg (0.73; 1.62, P0.45) on CLA relative to oleic acid. Systolic blood pressure changed by 1.1 mmHg (2.51; 0.25, P0.11), and diastolic blood pressure by 0.5 mmHg (0.73; 1.63, P0.56) on Industrial trans fatty acids relative to oleic acid. Conclusion: High intakes of industrial trans fatty acids and cis-9, trans-11 CLA, mainly found in ruminant fat, do not affect blood pressure in normotensive healthy subjects. Supported by nhf grant 2006B176.