The research, published in the Journal of Nutrition and backed by funding from the Almond Board of California, builds on previous studies that have suggested almonds could play a role in cholesterol management.
"There's a lot of research out there that shows a diet that includes almonds lowers low-density lipoprotein, or LDL cholesterol, which is a major risk factor for heart disease," said senior author Professor Penny Kris-Etherton from Penn State. "But not as much was known about how almonds affect HDL cholesterol, which is considered good cholesterol and helps lower your risk of heart disease."
Kris-Etherton and her team compared the levels and function of high-density lipoprotein (HDL cholesterol) in people who ate almonds every day, to the HDL levels and function of the same group of people when they ate a muffin with the same calorific value instead.
They found that consumption almonds resulted in not just increased HDL levels, but also improved function of HDL cholesterol – which works by gathering cholesterol from tissues, like the arteries, and helping to transport it out of the body.
"HDL is very small when it gets released into circulation," said Kris-Etherton. "It's like a garbage bag that slowly gets bigger and more spherical as it gathers cholesterol from cells and tissues before depositing them in the liver to be broken down."
"We were able to show that there were more larger particles in response to consuming the almonds compared to not consuming almonds," she explained. "That would translate to the smaller particles doing what they're supposed to be doing. They're going to tissues and pulling out cholesterol, getting bigger, and taking that cholesterol to the liver for removal from the body."
The Penn State team performed a controlled-feeding study involving two separate six-week diet periods in 48 men and women with elevated LDL cholesterol.
In both studies, their diets were identical except for the daily snack. On the almond diet, participants received 43 grams (approximately a handful) of almonds a day, while during the control period they were given an isocaloric a banana muffin.
At the end of each diet period, the researchers measured the levels and function of each participant's HDL cholesterol – finding that not only did almonds result in a higher level of HDL cholesterol, but also increased HDL functioning, as signalled by an increase in larger alpha-1 HDL cholesterol particles.
Indeed, compared to the control diet, the almond diet increased mature alpha-1 HDL particles by 19%.
Kris-Etherton noted that the increase the larger and mature alpha-1 HDL cholesterol subpopulations is meaningful because they have been linked to a lower overall risk of cardiovascular disease.
Additionally, the almond diet improved HDL function by 6.4% in participants of normal weight, said the team.
"They're not a cure-ll, but when eaten in moderation - and especially when eaten instead of a food of lower nutritional value - they're a great addition to an already healthy diet,” said the researcher.
Source: Journal of Nutrition
Volume 147, Number 8, Pages 1517-1523, doi: 10.3945/jn.116.245126
“Inclusion of Almonds in a Cholesterol-Lowering Diet Improves Plasma HDL Subspecies and Cholesterol Efflux to Serum in Normal-Weight Individuals with Elevated LDL Cholesterol”
Authors: Claire E Berryman, et al