News

The Trans-Fat Background

The growing demand for High Oleic, Low Linolenic (HO,LL) rapeseed stems from major health concerns over the levels of both saturated and so-called trans fats in the human diet across the developed world.

While high intakes of saturated fats have long been recognised as presenting particular dangers of coronary heart disease, trans fats – produced from the partial hydrogenation of polyunsaturated vegetable oils to make them more suitable for baking and deep fat frying – have only relatively recently been shown to present even greater health risks. Indeed, a New England study revealed a 2% increase in energy intake from trans fatty acids was associated with a 23% increase in the incidence of coronary heart disease.

Partial hydrogenation has been widely used in food processing since its commercialisation in the early part of the 20th Century. Vegetable oils like rapeseed and soya are very valuable for their high content of unsaturated fatty acids and omega-6/omega-3 profiles. However, they have a low melting point and are unstable at high temperatures as a result of relatively high levels of linolenic acid in particular. The problems this causes for the food industry are overcome by partial-hydrogenation, which converts a proportion of these fatty acids into their more stable ‘trans’ rather than usual ‘cis’ configuration.

The public furore that has erupted over trans fats has been considerable. Denmark introduced legislation in 2004 to limit the content of industrially produced trans fats in its food oils to 2%. In 2006 the US Food and Drug Administration forced all manufacturers to declare the trans fat content of all their foods on the labels, and the New York health department moved to ban artificial trans fats entirely from every one of the city’s restaurants.

With similar pressures growing in Europe, major food manufacturers and retailers on both sides of the Atlantic have moved swiftly to commit themselves to reducing or eliminating trans-fats in their products.

The increased availability of palm oil – with a high melting point as a result of the relative saturation of its fatty acids – has provided a convenient way for many European food manufacturers to move away from partially hydrogenated rapeseed oil in recent years. In particular, it has been used to blend with ordinary rapeseed oil to all but eliminate trans fats from vegetable shortenings.

The value of palm oil in this respect is, however, being limited by renewed impetus to reduce dietary saturated fat levels in many countries as well as increasing environmental concerns over rainforest destruction and growing biodiesel demand. The shorter frying life of palm oil and the fact that gives a less desirable, deeper yellow colour to fried foods also limits its use.

High oleic sunflower oil, which is naturally low in linolenic acid, is also being employed to overcome trans fat problems in some snack foods. But it is only produced in very limited amounts in Europe.

This leaves considerable opportunity for new varieties of oilseed rape naturally high in oleic and low in linolenic acids that are now emerging from plant breeding programmes. Providing, that is, they can be produced in sufficient quantity to meet the needs of the major food companies seeking sustainable alternatives to partially-hydrogenated, palm or sunflower oils.

Experience in the USA, with its reliance on soyabeans as a vegetable oil staple, further shows there is a good market for low linolenic soyabean varieties as an alternative to more costly total hydrogenation and blending with conventional vegetable oil.

While saturated fats have to be a greater concern from the public health perspective given their far higher levels of consumption, there is no doubt that the furore over trans fats has led to a rapid and significant change in food industry practice that should contribute to the continued efforts to drive down the major killer of cardiovascular disease.