In possibly the first of its kind law ever passed in the United States, the New York City board of health administration has banned serving preparations containing most artificial trans fats from 1 July, 2007 to combat cholestrol-induced diseases and unhealthy obesity.

Trans fats are synthetically produced and added to some products to add flavour or texture, are cheaper and have a longer shelf life, but play havoc with consumers'' health.

New York''s millionaire mayor Michael Bloomberg, who banned smoking in bars and restaurants during his first term, has backed the new law saying, it could save lives

The law would apply to restaurants, delicatessens, fast food chains and local eateries. With some exceptions, they will be barred from using spreads and frying oils containing artificial trans fats commonly used for frying French fries and fried chicken.

Restaurants will be given a three-month reprieve before they start facing penalties for violating the ban.

Makers of bakery products like doughnuts, cookies and pies and other baked foods that use partially hydrogenated vegetable oil for texture, have been given until July 2008 to enable them to locate suitable substitutes before they too are made to phase out trans fats.

Even the ubiquitous ''mom and pop'' stores that serve ''home-made'' delicacies will be covered under the ban.

Grocery stores or cafes that serve prepared foods in the manufacturer''s original packaging have been exempted from the ban.

This is because packaged foods have been required to list trans fat content on their labels since January 2006, and several manufacturers are now advertising the ''fat-free and low-carbohydrate content'' as a marketing strategy.

Trans fats are produced synthetically when food processors harden fat to make it more like butter through the hydrogenation (chemical treatment of unsaturated fats with hydrogen). The process helps to extend the shelf life of products and enhance the texture of some foods.

However, trans fats play havoc with the human body by increasing the risk of heart disease and strokes by increasing low-density lipoproteins or LDL that researchers have dubbed the ''bad'' cholesterol, and reduce the levels of high-density lipoproteins or the ''good'' cholesterol.

Not all trans fats are chemically induced; some also occur naturally in certain meat and dairy products and these have been exempted from the ban as the new law is aimed at eliminating virtually all artificial trans fats that are chemically added to oils to add flavour or texture to foods like French fries and crusts on pies and doughnuts.

The restaurant industry is up in arms against the new legislation. Opposing the measure as costly, it has threatened to challenge the laws in court, a move that has left health officials unmoved. They maintain that nearly all the artificial trans fats could be easily replaced with healthier options.

Calling it a public health issue, New York City health commissioner Thomas Frieden told reporters, "We know that trans fats increase the chance of heart attack, stroke and death, and they don''t have to be there. People are dying of heart disease."

In a separate move, the board of health has also ordered restaurants to standardise how they display the number of calories in dishes on their menus in an effort to combat obesity. This law also applies to restaurants that already report calorie counts and requires them to display it on menus and menu boards.

This disclosure will apply only to restaurants that serve standardised portions and make already make nutritional information available voluntarily. Companies that don''t wish to comply can simply stop providing any nutritional data.