Measuring trans fats in foods: We're still catching up

Q. The listing for roasted chicken thighs on ND shows no quantity for trans fat.  Is it safe to assume that there is no significant source of trans fat from this item?

A. It's true that there is no value for trans fat on the Nutrition Facts label for this food, but that doesn't necessarily mean that it contains no trans fats. It just means that we don't know how much there might be. (And when you do see 0g of trans fat on the Nutrition Facts label for other foods, keep in mind that quantities less than 0.5 are rounded down to 0.)

If you scroll a little farther down the page to the detailed analysis of roasted chicken thighs, you'll see a tilde (~) after "total trans fatty acids." That means that data for this nutrient is either unavailable or incomplete.  Although the USDA has begun to measure trans fats as part of its analysis, the majority of foods in the database still do not yet have a value for this nutrient. Manufacturers have been required to include this information on their Nutrition Facts labels since 2006, so you may find trans fat information on packaged foods that is not yet included in the USDA database. Although the USDA has not measured the trans fats in roasted chicken thighs, it has measured the amount in raw chicken. If you check the listing for raw chicken thighs, you'll see a value of 0 grams for trans fats in the Nutrition Facts label, and 0.0 of trans fatty acids in the detailed analysis.

So the chicken itself is not a source of trans fats. But are trans fats created in the cooking process? Although frying at high temperatures (and in hydrogenated oils) would add a significant amount of trans fats to the finished product, roasting at 350 degrees should not.