After over 20 years of controversy, trans fats in food are now being either labelled (USA), banned (Denmark) or evaluated as to their current level of concentration in food and subsequent risk.
An in-depth explanation of their structure, their derivation and their effect on cardiovascular health is fairly complicated but in simple terms the following may suffice:
Spreads, margarines, biscuits, cake and pastry shortenings rely on a certain significant proportion of solid fats in their composition. The original solid fats were butter and edible tallow and then in later years – palm oil. All of these fats are approximately 50% saturated which is why they are solid and so over 30 years ago nutritionists advised consumers and the edible oil industry to reduce saturated fats in the diet as saturated fats raise serum cholesterol.
In the USA and Canada the main oils were soybean, cottonseed, canola and sunflower oils. Whilst polyunsaturated oils are a key component of “soft” polyunsaturated spreads they still need a solid fat component to give them structure. The Industry achieved this by hydrogenating “liquid unsaturated oils and producing not solid saturated fats but solid trans monounsaturated fats – these latter fats were not thought at the time to affect serum cholesterol nor cardiovascular health.
Over the years nutritional science has carried out a great deal of research into dietary lipids and cholesterol. The importance of HDL – cholesterol (beneficial) and LDL cholesterol (detrimental) have now been determined with the findings that trans fats are even more detrimental than saturated fats. In the USA, Canada and Europe liquid vegetable oils were also hydrogenated in order to make them more stable towards oxidation. In USA the oil was mainly Soybean. In Canada this was Canola (rapeseed) and in Europe was fish oil. This is unlike the situation in Australasia where dairy fats and edible tallow/palm oil were used in baking and frying. Traditionally the intake of trans fats overseas has always been higher in other countries than in Australasia. Spreads in NZ and Australia are now virtually trans free but utilise more saturated fats as a replacement. Products with pick the tick, contain less than 2% trans fat and less than 28% total trans and saturated.
A new study has published some of the levels of trans fats found in fast foods and shows a wide variation across the world. Details of the study by the former head of the Danish Nutritional Council were published in April 13 issue of the New England Journal of Medicine (345 : 1650 – 1652, 2006).
New Zealand estimate average total fat intake 75-110g per day.
Heart Foundation Recommendation (Trans) < 8% Energy ~ 5-6g)
Estimated NZ + Aus trans fat intake overall < 5g per day <8% of total energy intake.
New York Fast Food Outlet 10.2 trans fat/serving
Denmark Fast Food Outlet 0.3g
Danish Legislation < 1.0%
Average Canadian Intake 8.4g (~10% Energy)
Denmark has taken a very tough stance on trans fats (< 2% in food products), Canada is following, USA has mandatory labelling (from January 2006) and Australasia intake is quite low(<5g per day) so the issue is currently not seen as being of high priority from a dietary health point of view. In Australasia we still consume too much saturated fat – almost as bad as trans fats. There are still issues left to be resolved, namely are the trans fats in animal fats such as butter cheese and tallow as harmful as those in hydrogenated oils and what is a safe level?
Please note there will be a practical talk at the seminar on November by Danisco on how to effectively remove trans acids from the food supply.
The Heart foundation have just released a media pack of information celebrating ten years of the pick the tick programme. Figures just released show that margarine and spread manufacturers reduced trans fat by 92 percent , removing 266 tonne of trans from the food supply in New Zealand.
In parallel the Foundation wish to see a removal of saturated fat from our diet and in the past year or two manufacturers have shed 49 tone of saturated fat to earn the tick.
Butterfat and serum lipids
A recent review in Inform by Arnis Kuksis suggests different results for the effect on serum lipids on feeding milkfat. It makes interesting reading and suggests that the hypercholesterolemic effect of butterfat is due to the cholesterol. I must confess to developing a headache when you read these reports as we have been confused for decades about this topic.
Currently plant sterols are only allowed in yellow fat spreads in Australasia.
There are valid reasons to allow them in a wider variety of low fat foods.
Application A433, A434 and A508 to FSANZ for permission to utilise plant strerols in breakfast cereals, low fat milk and yoghurt are being currently reviewed prior to submission to the Ministerial council.