Trans-fats come under fire

Nutrition experts call for ban on hidden food villain.
19 May 2004

HELEN PEARSON

Now there is a new reason to avoid a side of fries. The latest food culprits are called trans-fatty acids, or "trans-fats", and a campaign is being launched today to purge these molecules from the United States' cakes, snacks and fast foods.

Never heard of them? You undoubtedly eat them. Small quantities of trans-fats occur naturally in meats and dairy products, but most arrive in our stomachs through processed foods. They are manufactured by pumping hydrogen into vegetable oils to create partially hydrogenated oils and soild margarines.

Such fats are preferred by industry because they are versatile and last longer. But nutrition experts say trans-fats are disastrous for your health. Whereas saturated fats raise both 'bad' low density lipoprotein cholesterol (LDL) and 'good' high density lipoproteins (HDL), trans-fats boost LDL without affecting HDL, increasing the risk of heart disease.

Nutritional guidelines have long advocated cutting back on the saturated fatty acids found in meat and dairy products, and boosting unsaturated fats abundant in nuts, seeds and vegetable oils.

But trans-fats have taken longer to attract attention because their effects on health were less clear. "There wasn't a strong enough science base to make a case," says Elaine Turner who studies human nutrition at the University of Florida, Gainesville.

TransFreeAmerica

Evidence for the harmful effects of trans-fats has mounted, however. In 2002, a US expert committee charged with making nutritional recommendations concluded that there was no level of trans-fats in the diet that could be deemed safe.

A US nutritional group called the Center for Science in the Public Interest, based in Washington DC, now hopes that its TransFreeAmerica campaign will raise awareness of the health concerns. It is urging food manufacturers to eliminate trans-fats and advising consumers to boycott foods containing them. It is also calling on the US Food and Drug Administration to outlaw partially hydrogenated vegetable oils.

The plan is likely to meet resistance from some food industry members reluctant to change existing supply and production processes, predicts Turner. "It's difficult to think we would ever get completely trans-fat free," she says.

Some countries and companies have already made moves to cut trans-fats. In 2003, the Danish government issued regulations slashing the amount allowed in foods.

In the United States, some food manufacturers such as Kraft Foods and McCain are scaling back the amount of trans-fats in their products. And from 2006, food companies will be required to list the amount of trans-fat on nutrition labels, so that consumers can choose what to buy.

The new campaign, "may accelerate the rate at which the industry moves," says nutrition expert Alice Lichtenstein of Tufts University in Boston. But it is important that trans-fats are replaced with healthy alternatives, she points out, such as plant oils rather than butter.

Food for thought

Fatty acids are the building blocks of fats, and the different types are distinguished based on their chemical structure. All are made up of strings of carbon atoms with hydrogen atoms attached to them. In saturated fats, each carbon atom is bonded to as many hydrogen atoms as it can hold.

Unsaturated fats contain fewer hydrogen atoms, and one or more pairs of carbon atoms are linked by double chemical bonds. A fatty acid with one double bond is called monounsaturated, those with more than one are called polyunsaturated.

Manufacturers create trans-fats by adding hydrogen to unsaturated fats. The process rearranges the hydrogen atoms around the double bonds so they are on opposite sides of the carbon chain.


© Nature News Service / Macmillan Magazines Ltd 2004


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