Trans Fat – An undeserved Bad Reputation?
Within the lay press trans fat has had a lot of negative publicity of late. On November the 7th 2013 the food and drug administration (FDA) in the USA stated that trans fats are not “generally recognised as safe” (1). In the US this will mean a move towards reclassification and ultimately elimination from the food supply. The world health organisation recommend that trans fats should be limited to no more than 1% of total daily intake. A review by Mozaffarian et al in 2009 (2) found that controlled trials and observational studies provide concordant evidence that the consumption of trans fatty acids from partially hydrogenated oils contributes significantly to increased risk of cardiovascular disease.
With everything we need to be quite precise and careful in our classification of what is considered ‘bad’ and what is ‘good’. Not all trans fats are equal. As we can see from the review above by Mozaffarian et al, artificial trans fat is something that we should keep to a bare minimum.
There are in fact two naturally occurring trans fats, vaccenic acid and conjulgated linoleic acid (the popular weightloss supplement CLA). Both of these trans fats are found naturally in meat and dairy. The data on ruminant (animal based) TFA’s is scarce. Stender 2008 et al (3) concluded “the lack of evidence for a harmful effect of RP-TFA intake, the fact that these fatty acids cannot be removed from ruminant fat and have been part of human food in millennia, places the burden of proving that these fats are more harmful than saturated fats.” One such study that did look into the health effect of CLA and vaccenic acid found that both had no effect on blood pressure or arterial elasticity in healthy young men (4).
As with most things we need to be careful when discussing various topics within nutrition. From the data available we can conclude that artificial trans fats should be limited or at best completely removed from our food chain. However it would be incorrect to suggest all trans fats are ‘evil’ as many of us will consume dairy and various meat products containing naturally occurring CLA and vaccenic acid.
(4) http://nutrition.highwire.org/content/136/4/992.short – no dif in BP and artierial elasticity