Research suggests that consumption of artificial trans fatty acids (TFAs) in hydrogenated vegetable products and deodorised supermarket oils is associated with an increased risk of cardiovascular disease. Further, although intakes of TFAs are dropping, no safe lower limit is know for their consumption from artificial sources. Dietary advice is currently therefore to avoid all artificial TFAs. However, natural sources of TFAs, such as vaccenic acid, can be found in ruminant milk and ruminant milk products. Data suggests that differences exist between the health consequences of consuming natural TFAs and those from an artificial source. Because of this, researchers1 have investigated the effects of natural TFA enriched butter on plasma lipid levels in 61 healthy women aged between 19 and 70 years. Isoenergenic diets were fed for 4 weeks and contained either 3.7 g/d (1.5% energy) or 0.9 g/d (0.3%) energy TFAs.
The results showed that the high ruminant TFA diet had no effects on plasma low density lipoprotein (LDL), apolipoprotein B, apolipoprotein A-1 or triglyceride concentration compared to the control diet. However, there was a significant but small reduction in plasma high density lipoprotein (HDL) in women with a body mass index of over 25kg/m2. This suggest that high intakes of ruminant derived TFAs such as vaccenic acid may detrimentally alter the LDL to HDL ratio of plasma, and may therefore alter the risk of cardiovascular disease in overweight women. However, no effect was seen in normal weight women. Data shows a reduction in artificial TFA consumption amongst Canadian women from 8.4g/d (3.7% of energy) in 1995 to 4.8g/d (2.0 % of energy) in 2004 to 3.4 g/d (1.4% energy) in 2008. In 2006 the estimated intake of TFAs from ruminant sources, mainly vaccenic acid, was only 1.0 g/d.
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