We've all seen those "0 trans fat" labels, particularly on baked goods, in the aisles of supermarkets. The problem is zero doesn't always mean zero, a little fact I missed when the new FDA labeling regulations took effect in 2006.

They permit any product with less than 0.5 grams of trans fats to be labeled zero. And that figure is per serving, so some companies could and did reach less than 0.5 grams simply by reducing the serving size.

That means if you ate double the serving size recommended on the box, be it Cheese Nips or a slice of Jiffy cornbread, you could be getting a full gram of trans fats. And if you ate the recommended serving size but ate both products in the same day, you'd still be getting a full gram of trans fats.

So trans fats, along with high fructose corn syrup and salt, are still very high on the list of ingredients to watch out for. Excess salt raises the risk of hypertension, and high fructose corn syrup is believed to raise the risk of diabetes.

When it comes to trans fats, here's what the American Medical Association has to say: "Trans fats raise your bad cholesterol levels and lower your good cholesterol levels. Eating trans fats increases your risk of developing heart disease and stroke. It's also associated with a higher risk of developing type 2 diabetes." 

The first trans fat-laden product, Crisco, appeared on the market in 1911 and by the latter half of the 20th century, it had found its way into thousands and thousands of products. Crisco was reformulated in 2007, but it consisted largely of partially hydrogenated cottonseed oil for nearly 100 years.

And when I was a child, I remember my grandmother making absolutely great apple pies with it. They had thin, very flaky crusts. And she would use the excess dough to make cinnamon "cookies." We hung around the kitchen until they came out of the oven. 

Back then, Crisco was thought to be healthier than butter. Today researchers claim trans fats are responsible for 20,000 to 30,000 deaths a year.

I toured the Stop & Shop aisles the other day, checking the labels on products that took up a lot of shelf space or could be called convenience foods. I found mixes for some dinner items—like sloppy joe—to be full of salt, high fructose and trans fats.

Duncan Hines cake mixes and canned frosting also had partially hydrogenated oils listed in the ingredients. And Nabisco Chips Ahoy may say zero trans fats on the label, but the ingredients list partially hydrogenated cottonseed oil. The same goes for Pop Tarts.

There are two other kinds of fats described on some labels—expeller pressed and interesterified fats. Expeller pressed just means the oil was mechanically, not chemically, extracted so I am relieved when I see that on a label.

Interesterified is a new one for me, so I checked it out online and found it to be somewhat controversial. One published study assigned 30 people to rotate diets containing natural palm oil, trans fats or the interesterified, which, like partial hydrogenation, is a chemical process. Both the trans fats and interesterified raised LDL levels and lowered HDL levels but the interesterified also suppressed insulin production. (Interesterified oil is an ingredient in Pepperidge Farm's Milano Double Chocolate Cookies.)

Websites specializing in diabetes also warn patients to stay away from interesterified oils. And I suspect that also goes for those of us who do not want to get diabetes.