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WHO Report on Trans Fats: Effects of Industrial versus Ruminant Trans Fat

Catherine J. Field, PhD

Professor, Department of Agricultural, Food & Nutritional Science, University of Alberta 

Data from randomized, controlled trials and observational studies demonstrate unequivocally that industrial trans fatty acids (TFA) derived from partially hydrogenated oils adversely affect several cardiovascular risk factors and are highly correlated with an increased risk of coronary heart disease (CHD) events.


  1. Industrial TFA consumption is believed to increase cardiovascular risk in multiple ways.
  2. Ruminant TFA consumption in the amounts normally consumed does not appear to increase CHD risk.
  3. Consumption of ruminant-derived vaccenic acid may impart health benefits beyond those associated with conjugated linoleic acid.


The purpose of the World Health Organization (WHO) scientific review on TFA was to examine the evidence generated since the 1993 Joint FAO/WHO Expert Consultation on Fats and Oils in Human Nutrition, and to inform member countries on the health consequences of TFA consumption that have emerged since the release of the last report. The new information was deemed sufficient to recommend the need to significantly reduce or to virtually eliminate industrially produced TFA from the food supply.1

The Impact of TFA

The adverse effects consistently observed in several studies with respect to industrial TFA include:

  • increased low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a),
  • reduced high-density lipoprotein cholesterol (HDL-C)
  •  increased total/HDL-C ratio
  • increased blood markers of inflammation
  • endothelial dysfunction.1

On the other hand, according to the WHO report, the scientific evidence does not generally support an adverse effect of ruminant TFA on CHD risk, in the low amounts usually consumed.1

The predominant trans isomer in ruminant fats is vaccenic acid (VA), whereas elaidic acid is the main industrial TFA. Contrary to what has been reported for the latter, animal and human feeding trials do not demonstrate an adverse association between intake of ruminant VA and the risk of myocardial infarction or CHD.2 Studies, including those from our group, using rodents with dyslipidemia suggest that ruminant-derived VA may in fact have a beneficial impact on blood lipid levels (particularly by lowering hypertriglyceridemia)3 and inflammatory markers.4

While most studies suggest that any health benefit associated with VA may be conferred by in vivo mammalian conversion of VA to cis-9, trans-11- conjugated linoleic acid (CLA), emerging data suggest that the consumption of this trans fat may impart health benefits beyond those associated with CLA.2 More research should be encouraged to establish the health effects of consuming VA.



  1. Uauy R et al. WHO Scientific Update on trans fatty acids: summary and conclusions. Eur J Clin Nutr 2009;63:S68-S75. 
  2. Field CJ et al. Human health benefits of vaccenic acid. Appl Physio Nut Metab 2009;34:979-991.
  3. Wang Y et al. Novel hypolipidemic properties of trans-11 vaccenic acid are due to reduced hepatic lipogenesis and lower intestinal chylomicron secretion in the JCR:LA-cp rat. J Nutr 2009;139(11):2049-2054.
  4. Blewett H et al. Vaccenic acid favorably alters immune function in obese JCR:LA-cp/cp rats. Br J Nutr 2009;102: 526-536.

Keywords: ruminant trans fat , who report , blood markers of inflammation , endothelial dysfunction , vaccenic acid , elaidic acid , trans fat

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