Almonds Provide Fewer Calories Than Previously Thought
16 Dec 2016 --- New data from the US Department of Agriculture (USDA) has shown that both roasted and unroasted almonds provide fewer calories than previously thought. The research shows that the number of calories is largely dependent on form, and how our bodies break down the fat contained in them.
The study, conducted by scientists from USDA’s Agricultural Research Service (ARS) and jointly funded by USDA ARS and Almond Board of California, shows that compared to the number of calories listed on nutrition labels, participants actually absorbed 25% fewer calories from whole unroasted almonds and 19% fewer calories from whole roasted almonds.
David Baer, PhD, and his team from USDA's Agricultural Research Service (ARS) conducted a controlled human clinical trial using a new method to measure the calories absorbed from almonds, taking bioavailability into account.
The new method allowed the researchers to determine the number of calories actually digested and absorbed from almonds.
Speaking with NutritionInsight about the study, Dariela Roffe-Rackind, Director for Europe for the Almond Board of California said, “What we found was that with natural almonds there is 25% less calorie reduction, which is great news.”
“There is something about the self-structure of the almonds, that means that the fat is not totally broken down in our bodies and we are actually absorbing less calories but we are still absorbing the nutrients as well.”
Traditionally, calories are determined using what are known as the Atwater factors, which was developed over 100 years ago, and assigns an estimated number of calories per gram of fat, protein and carbohydrate in a food.
“We expanded upon the Atwater method in our study, so we could tease out the caloric value of a single target food,” explains Janet Novotny, PhD, a physiologist and mathematician with the research team.
“Then using the study participants’ energy intake and energy output, we were able to measure the number of calories actually digested and absorbed from a single food – in this case, almonds.
In 2012, the researchers conducted their first study using whole roasted almonds, which showed that the almonds provided fewer calories than once thought.
This time, the research team broadened their investigation to examine the calorie availability of almond forms, and also replicated the measurement of calories absorbed from whole roasted almonds.
The researchers found that whole unroasted almonds provided 25% fewer calories than expected, while whole roasted almonds provided 19% fewer calories. Chopped roasted almonds provided 17% fewer calories, though the difference between the calories absorbed from chopped and whole roasted almonds was not statistically different.
Measured calories in almond butter did not differ from calories estimated using Atwater factors.
The Atwater method of calculating calories may overstate the calories from almonds because it simply doesn’t account for the fact that not all calories from almonds are available to the body. The chewing process does not completely break down almond cell walls, and almonds are therefore not completely absorbed during digestion.
But this doesn’t explain why there is a calorie difference between almond forms. Much of this finding has to do with particle size after chewing and digestion.
The larger the particle size, after chewing for example, the less the almond is able to be broken down by digestive enzymes and more of the almond is excreted, so fewer calories are absorbed. The reverse is also true: the smaller the particle size, the more almond cells are exposed to digestive enzymes and the more calories are absorbed.
In addition to chewing and digestion, mechanical processes, such as chopping, grinding and roasting almonds can also impact particle size.
Back in November, FoodIngredientsFirst reported that almonds are now the number 1 nut in new product introductions across Europe.
