Eating almonds on a regular basis may help boost
levels of HDL cholesterol while simultaneously improving the way it removes
cholesterol from the body, according to researchers.
In a study, researchers 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 instead. The researchers found that while participants
were on the almond diet, their HDL levels and functionality improved.
Penny Kris-Etherton, distinguished professor of
nutrition at Penn State, said the study, published in the Journal of Nutrition,
builds on previous research on the effects of almonds on cholesterol-lowering
diets.
"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,"
Kris-Etherton said. "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."
The researchers wanted to see if almonds could not
just increase the levels but also improve the 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," Kris-Etherton said. "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."
Depending on how much cholesterol it has collected,
HDL cholesterol is categorized into five "subpopulations," which
range from the very small pre?-1 to the larger, more mature ?-1. The
researchers hoped that eating almonds would result in more ?-1 particles, which
would signal improved HDL function.
In the controlled-feeding study, 48 men and women
with elevated LDL cholesterol participated in two six-week diet periods. In
both, their diets were identical except for the daily snack. On the almond
diet, participants received 43 grams -- about a handful -- of almonds a day.
During the control period, they received a banana muffin instead.
At the end of each diet period, the researchers
measured the levels and function of each participant's HDL cholesterol. The
researchers then compared the results to the participants' baseline
measurements taken at the beginning of the study.
The researchers found that compared to the control
diet, the almond diet increased ?-1 HDL -- when the particles are at their
largest size and most mature stage -- by 19 percent. Additionally, the almond
diet improved HDL function by 6.4 percent, in participants of normal weight.
"We were able to show that there were more
larger particles in response to consuming the almonds compared to not consuming
almonds," Kris-Etherton said. "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."
An increase in this particular HDL subpopulation is
meaningful, Kris-Etherton explained, because the particles have been shown to
decrease overall risk of cardiovascular disease.
Kris-Etherton said that while almonds will not
eliminate the risk of heart disease, they may be a smart choice for a healthy
snack. She added that in addition to their heart-healthy benefits, almonds also
provide a dose of good fats, vitamin E and fiber.
"If people incorporate almonds into their diet,
they should expect multiple benefits, including ones that can improve heart
health," Kris-Etherton said. "They're not a cure-all, 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."
Claire Berryman, postdoctoral fellow at U.S. Army
Research Institute of Environmental Medicine, and Jennifer Fleming, instructor
in the College of Health and Human Development at Penn State, also worked on
the study.
The Almond Board of California supported this study