Many of the items made with it are also bad for you without it

Junk-food lovers rejoice, for government officials are on the job protecting your health. Or are they?

Philadelphia recently became the first city to pass legislation to ban artificial trans fat — that artery-clogging, industry-created substance used in frying oil and many baked goods. Following the lead of New York City's Board of Health, which enacted regulations in December, more than a dozen states are now considering similar laws.

As an advocate for good nutrition, I'm pleased to see major cities take action on one of the most pressing public health problems of our time — the way we eat. Given that the food industry continues to lobby hard against common-sense nutrition policies at federal and state level, we need more local governments protecting the public's health. Moreover, removing trans fat from the food supply could help reduce the risk of heart disease.

Yet the effort threatens to overshadow the bigger dietary picture. Focusing on this single ingredient misses the fact that most of the items prepared with trans fat are junk foods to begin with. Fried chicken, french fries, chips, cookies and cakes are unhealthy no matter what type of fat is used. What good is a trans-fat-free doughnut?

This reductionist approach to nutrition has encouraged such absurd marketing hype as "zero trans fat" Cheetos. Replacing one ingredient does not magically create health food. Even without trans fat, these highly processed products remain devoid of nutrition, high in calories and fat, and chock full of chemical additives.

Ironically, some restaurants are substituting saturated fat, which highlights the most important limitation of trans-fat bans. Does anybody remember that we discovered the numerous cardiovascular risks caused by saturated fat (found mainly in meat and dairy products) long before food manufacturers invented trans fat?

But we never did deal adequately with the problem of excess saturated fat in the food supply. That's understandable when you realize that doing so requires taking on the extremely powerful meat and dairy industries, which have worked hard to condition Americans to make animal products the centerpiece of every meal.

And the problem isn't limited to steaks and hamburgers. Collectively, we now eat about 1 million chickens an hour (even the leanest chicken has far more fat and cholesterol than most people realize), and the average American consumes more than 30 pounds of cheese a year. The high levels of saturated fat in these foods help explain why cardiovascular disease still kills hundreds of thousands of Americans every year, despite widespread use of cholesterol-lowering drugs.

In a 2005 lecture about the role of local health departments in addressing the obesity epidemic, New York City Health Commissioner Thomas Frieden acknowledged that saturated fat was also a public health menace. But, he lamented, "People aren't about to become vegetarians." Imagine the same policy approach to cigarettes. Would Frieden ever consider saying, "We can't regulate tobacco because people won't stop smoking." Of course not. True leadership means speaking the truth, even if it's not what some people are ready to hear.

What Frieden meant is that trans fat is a politically safe target. To ban it doesn't rock anyone's world. Food manufactures and restaurants can find substitutes and keep on churning out slightly less unhealthy new versions of the same old junk food. KFC, Frito-Lay and Kraft can conduct business as usual. And the public won't change its eating habits, so all remains well in junk-food sales.

But what if health departments and legislatures began educating the public about the dangers of meat and dairy products, or processed food more generally? Then we would have to confront the sad truth that most of the 24,000 eateries in New York City and thousands more in Philly are still clogging their patrons' arteries with king-size steaks, buckets of chicken, and tubs of ice cream. The politics would be much more challenging, of course. But if health officials and politicians are serious about reducing our nation's epidemic of obesity and diet-related diseases, they won't stop with trans fat.

Michele Simon is a member of the Physicians Committee for Responsible Medicine. She wrote this commentary for McClatchy-Tribune News Service.