SACRAMENTO — Federal scientists have found that walnuts aren’t quite as high in calories as they were thought to be.
The USDA study published this winter in the Journal of Nutrition found that an ounce of walnuts is about 146 calories, or 39 less than is listed in the agency’s Nutrition Database.
A team led by David Baer, a supervisory research physiologist for the Agricultural Research Service, used newer technologies and methods than the conventional Atwater method of measuring calories that dates back to the late 1800s.
“These results could help explain the observations that consumers of nuts do not gain excessive weight and could improve the accuracy of food labeling,” Baer and the other scientists concluded.
The research, which was funded by the USDA and California Walnut Commission, could further cement walnuts’ image as a healthful food, as research in recent years has credited the nuts for improving everything from heart health and cognitive function to male fertility.
Industry insiders have said the nutrition research has helped to increase demand for walnuts and boost prices paid to growers. Prices for walnuts rose from an average of 64 cents a pound in 2008 to as much as $2.05 in 2013, although a slowing economy in China is among factors that have softened prices in the last two seasons. Walnuts from the most recent harvest were expected to average about $1.20 per pound.
Dennis Balint, the walnut commission’s chief executive officer, said the latest study came after research in various other studies observed that test subjects following a balanced diet experienced some weight loss with walnuts.
“The fact that you’re only metabolizing 79 percent of the calories (that were originally thought) is good news for people who are counting calories,” Balint said.
For this research, Baer’s team used a bomb calorimeter to measure calories rather than the conventional system named for Wilbur Olin Atwater, a researcher at Wesleyan University in Connecticut at the turn of the last century.
Baer’s team studied 18 healthy adults who took part in three-week diets either with or without walnuts, and the researchers used walnuts and the other foods as well as fecal and urine samples from the test subjects to calculate calorie levels with the newer technology.
While Baer may have discovered a more accurate way to measure calories in foods, Balint doesn’t expect food labels to change overnight “because government moves slowly,” he said.
“You don’t get rewarded for doing cutting-edge research,” he said. “We know consumers will be happy about the news, but whether or not it will start a new trend, we’re not sure.”