No Trans Fats in Peanut Butter--Contrary to Current Rumor

Recurring rumors that commercial peanut butters contain trans fats--which appear to increase risk of cardiovascular disease--have no basis in fact, according to an Agricultural Research Service study.

The rumors no doubt started because small amounts of hydrogenated vegetable oils are added to commercial peanut butters--at 1 to 2 percent of total weight--to prevent the peanut oil from separating out. And the hydrogenation process can generate the formation of trans fatty acids in oils, according to Timothy H. Sanders, who leads research at ARS’ Market Quality and Handling Research Unit at Raleigh, N.C.

To see if the rumors had any validity, Sanders prepared 11 brands of peanut butter, including major store brands and “natural” brands, for analysis by a commercial laboratory. He also sent paste freshly prepared from roasted peanuts for comparison. The laboratory found no detectable trans fats in any of the samples, with a detection limit of 0.01 percent of the sample weight.

That means that a 32-gram serving of any of the 11 brands could contain from zero to a little over three-thousandths (0.0032) of a gram of trans fats without being detected. While current regulations don’t require food labels to disclose trans fat levels, they do require disclosure of saturated fat levels at or above five-tenths (0.5) of a gram. For comparison, that’s 156 times higher than this study’s detection limit for trans fats.

By contrast, peanut butter has plenty of unsaturated fatty acids. The most abundant is oleic acid, the monounsaturated fat believed to be good for the cardiovascular system. In this analysis, oleic acid levels ranged from 19 percent of total weight in one private-label brand to 27 percent in one “natural” type. Palmitic acid, the most abundant saturated fatty acid, weighed in at about 5 percent among all brands.

Scientific contact: Timothy H. Sanders, ARS Market Quality and Handling Research Unit, Raleigh, N.C., phone (919) 515-6312, fax (919) 515-7124, mqhru@ncsu.edu.