Vegetables oils are a rich source of polyunsaturated fatty acids, and this makes them liquid at room temperature. However, vegetable oils can undergo a process called hydrogenation, whereby under the presence of a catalyst, the fatty acid molecules can be saturated with hydrogen, converting a polyunsaturated fatty acid into a saturated fatty acid. This process is useful because saturated fatty acids are solid at room temperature and can therefore be used in a range of products not suited to liquid polyunsaturated fatty acids. The preference to use hydrogenated polyunsaturated fatty acids rather than saturated fatty acid is based on the lower price of vegetable oils compared to animal fats. The main problem with the hydrogenation process is that as a by-product of the process a group of fatty acids called the trans fats are produced. These result from the partial hydrogenation of polyunsaturated fatty acids, and evidence suggests that have particularly deleterious health effects in humans.
Awareness of the dangers of trans fats in foods has been slow to reach the consumer. This has been for a number of reason, not least the desire by the food industry to hide from public view the data showing damaging effects from trans fat consumption. However, as with all things, eventually the truth will out, and in the case of trans fats there is now a growing awareness of the dangers. In response, the food industry has in many cases removed trans fats from their products, not because of any concerns over the health of its customers, but more because of the damaging effects to profits that surround bad publicity. Some countries have stipulated mandatory labelling of trans fats in products, while other, notable the United Kingdom, have not. The main problems associated with trans fat consumption involve inhibition of normal fatty acid regulatory pathways, including the essential fatty acids. As these fatty acids are particularly important to infants the accumulation of trans fats in breast milk is particularly worrying,.
Evidence suggests however that where trans fat labeling is implemented and where trans fats are removed from products through reformulation, the trans fat concentrations of breast milk falls. For example, researchers1 have analysed the effects of mandatory labelling and reformulation of trans fats in Canada by measuring the trans fat content of breast milk. The results of this study showed that the trans fat content of breast milk fell from 2.7 to 2.2 to 1.9 % of total milk fat from 2009 to 2010 to 2011. In comparison, the trans fat content of milk as a percentage of total fat was 7.2 % in 1992 prior to the acceptance of the dangers of trans fats by the authorities. The researcher calculated that the trans fat intakes of the breast feeding mothers is now below the minimum stipulated levels recommended by the World Health Organisation. However as no lower limit of safety is associated with trans fat ingestion, it is pertinent to ask how the World Health Organisation arrived at the recommended levels to begin with.
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