When unsaturated vegetable fats are hydrogenated, the process produces yet another type of fatty acid as a side product – a trans-fatty acid. These contain double carbon-carbon bonds - and hence are unsaturated – but the configuration of the carbon chain is altered so as to make the fatty acid behave as though it were saturated.
Why are trans-fatty acids bad for you?
We know that saturated fats are harmful. They are often found in foods which also contain cholesterol and they raise the levels of LDL.
Margarines – the solid ones are the worst, the more liquid the best
Doughnuts, cakes, biscuits which are high fat (there are reduced fat biscuits on the market. Read the labels carefully)
Many processed foods, including “slap” chips, potato crisps, many corn crisps and many types of cheese crackers