Preliminary research suggests that its benefits may include actually reducing the risk of certain cancers and heart disease. A review of clinical research over the past 16 years, published recently in the journal Lipid Technology, stated that natural CLA trans fat "has no effect or may actually lower LDL cholesterol and has little effect on HDL cholesterol or triglycerides."
But consuming the manufactured variety of trans fat likely trumps out the good stuff for most people.
If you're like the average person in the United States, you're getting about 2 to 3 percent of your calories from manufactured trans fat. That would be about 4 to 6 grams (amounting to 36 to 54 calories) for a 2,000-calorie diet.
Another recent review in the journal Lipids concluded that one would need to eat 4 percent of your total calories as manufactured trans fat to raise your bad cholesterol, and about 6 percent to lower your good cholesterol.
That said, this level is quite possible if you regularly eat a lot of fries, baked goods and deep-fried foods. Think about it -- a nice order of fries and a few cookies for a kid, and he's over the limit. Definitely doable.
Manufacturers are quickly finding substitutes for manufactured trans fat, but we're not out of the woods yet.
The thing is, the best substitute for partially hydrogenated fat in food is either butter or some other saturated fat. Why? Two reasons.
First, with baked goods, you need a fat that will remain solid at room temperature. Make a batch of cookies with corn oil and they'll drip like a faucet when they cool off.
Second, for deep-frying, solid fats have a higher smoking point, so there's less risk of them bursting into flames at frying temperature.
The good news is that some things are already being done for you.
Whether they sell deep-fried foods or packaged baked goods, most companies are switching to trans-free fats, even if that means they're likely just trading manufactured trans fat for saturated fat.
As for the natural trans fats, like CLA, there seems to be no need to worry about them, at least not at this point, and they may even bring some benefits.
Here are some simple tips to keep your dietary "trans action" in check:
Eat deep-fried foods only occasionally (hint: occasionally is not every other day but more like once a week -- at most) and in modest portions.
Read the nutrition facts panel on packaged goods. Aim for foods that say "0 grams trans fat."
Read the ingredient label also. If it says "partially hydrogenated vegetable oil," at least make sure that the nutrition facts label says "0 grams trans fat."
Keep to single portions of baked goods; these foods are not usually overflowing with nutrition, so keep them as occasional foods either way.
As for natural trans sources, don't sweat over them. Dairy foods such as milk, yogurt and cheese are nutrient-rich, loaded with calcium and lots of other nutrients we need. They can also be high in saturated fat however, so get lower-fat choices most of the time. How much cheese? Keep it to about four ounces a week. That's livable, will keep you happy, and can still keep your diet low in saturated fat.
Keith-Thomas Ayoob is an associate professor in the department of pediatrics at the Albert Einstein College of Medicine in New York City.