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Surely hard fats were declared unhealthy?
‘Until about 20 years ago fats and oils were hardened in a way which led to the formation of trans fatty acids. These trans fats raise levels of LDL cholesterol. But nowadays the hardening process has been improved and hard fats can be made without any trans fats. There is hardly any trans fat in margarines and spreads for on bread either.’
Hard fat contains more saturated fat and that is not good for you either, is it?
‘I’ve done some quick sums. If people eat a portion of fries twice a week, they consume about 14 grams more saturated fat if they fry them in hard fat than in oil. The maximum recommended amount of saturated fat for a man is 196 grams a week. So if you eat fries in moderation, the increase in your intake of saturated fat won’t be too bad.’
Why is it better to deep-fry in hard fat?
‘There is a controversy in the scientific world as to whether frying in oils with a lot of unsaturated fatty acids leads to strong chemical reactions. In that case, undesirable substances are formed such as hydroperoxides, aldehydes and ketones. These substances can react with the fries themselves and possibly in the body as well. It is not yet known what the consequences could be. Hard fat is more stable; it undergoes fewer chemical reactions. If I have to choose between the negative health effects of saturated fatty acids and the potential damaging effects of the reactive substances formed when deep-frying in oil, I am more worried about the latter.’
The health council advises otherwise.
‘In general I agree with its advice, but in this case I want to introduce some nuances. Oils are not bad for your health in themselves, but deep-frying might be a special case. Imagine that this was be damaging. I think it’s important that research is done on this. Until then I think it’s better to use hard fats.’
Your colleague Sander Kersten responded critically on Foodlog. He is afraid consumers will get confused if Wageningen experts don’t agree.
‘I don’t think it is at all strange that there are different points of view in Wageningen. Nutrition is a complex science. A university benefits from debate, and that helps science progress.’