Part of healthy aging, as well as gut
health, hunger and satiety, and metabolic health
Edelman Seattle
The WAHA study is a dual site two-year
clinical trial conducted by researchers from the Hospital Clinic of Barcelona
and Loma Linda University and is aimed at determining the effect of walnuts on
age-related health issues.
"Given walnuts are a high-energy food, a prevailing concern
has been that their long term consumption might be associated with weight
gain," said Dr. Emilio Ros, director of the Lipid Clinic, Endocrinology
& Nutrition Service at the Hospital Clinic of Barcelona.
"The
preliminary results of the WAHA study demonstrate that daily consumption of
walnuts for one year by a sizable cohort of aging free-living persons has no
adverse effects on body weight. They also show that the well-known
cholesterol-lowering effect of walnut diets works equally well in the elderly
and is maintained in the long term.
"Acquiring the good fats and other nutrients
from walnuts while keeping adiposity at bay and reducing blood cholesterol
levels are important to overall nutritional well-being of aging adults. It's
encouraging to see that eating walnuts may benefit this particular
population."
After one
year, the study found that both diets had minimal effect on body weight,
triglycerides, and HDL cholesterol. However, the walnut-diet resulted in
significant LDL cholesterol reductions compared to the control, nut-free diet.
"As we continue the WAHA study, we will assess how walnut
consumption may affect, among other outcomes, cognitive decline and age-related
macular degeneration, conditions that were major public health concerns,"
said Dr. Ros.
Taking place April 2-6 in San Diego, the annual EB meeting
attracts an international audience of over 14,000 leading research scientists
and exhibitors. Additional new research abstracts presented at EB suggest
walnuts may have the potential to positively affect several important health
factors, including gut health, hunger and satiety, and metabolic health. The
following summaries share these findings:
Gut Health: Food choices and the gut microbiome play an
important role in human health. A recent study conducted by researchers at the
Agricultural Research Service, United States Department of Agriculture (USDA)
examined how the heart health benefits of walnuts may be linked to gut health
among 18 healthy adults.2
Study results show that daily consumption of 1.5
ounces of walnuts significantly affects the bacteria in the human gut in a way
that is favorable to decreasing inflammation and cholesterol, which are two
known indicators of heart health.
These results help further the understanding
of the heart health benefits of consuming nuts, including walnuts.
Hunger and Satiety: For the first time, researchers from the
University of Georgia have shown that the types of fat eaten on a daily basis
can alter long-term appetite responses, such as hunger and satiety.3
After
consuming high-fat meals rich in saturated fat, 18 sedentary adults of normal
weight were randomly assigned to consume either a diet high in polyunsaturated
fat or a control diet for the next seven days.
Researchers found that consuming
a diet high in polyunsaturated fat after meals rich in saturated fat favorably
alters hunger and satiety markers. Walnuts are a great option for getting more
polyunsaturated fat, with 13 grams per ounce.
Metabolic Health: A recent animal study conducted by researchers
at Oregon State University looked at the addition of walnuts and
polyphenol-rich foods to a typical high-fat Western diet to understand the
impact on metabolic health in male mice.4
Results showed that a walnut-diet
supplemented with polyphenol-rich foods such as raspberries, cherries or green
tea may help reduce inflammation.
Mice that consumed walnuts on their own or in
combination with polyphenol-rich foods also demonstrated significant effects on
factors related to metabolic syndrome, in addition to changes in both liver
gene expression and metabolite levels consistent with an improved metabolic
state. As this study was performed on animals, findings cannot yet be applied to
humans.
Bioactive components or synergistic effects of walnuts may be
contributing factors in providing these health benefits.
Walnuts are unique
among nuts in that they are primarily composed of polyunsaturated fat (13 grams
per ounce), which includes alpha-linolenic acid (ALA), the plant-based omega-3
fatty acid. They are the only nut to contain a significant amount of ALA with
2.5 grams per one ounce serving.
Scientific conclusions cannot yet be drawn from abstracts
presented at EB 2016, but these findings help advance the understanding of
potential benefits of eating walnuts as part of a healthy diet.
All studies were supported in part by the California Walnut
Commission (CWC) and abstracts can be found in The Federation of American
Societies for Experimental Biology Journal. The CWC has supported
health-related research on walnuts for over 25 years. While the CWC does
provide funds and/or walnuts for various projects, the actual studies are
conducted independently by researchers who design the experiments, interpret
the results and write the manuscripts.
Resources:
1. Ros E, Rajaram S, Sala-Vila A, et al. Effect of a 1-Year
Walnut Supplementation on Blood Lipids among Older Individuals: Findings from
the Walnuts and Healthy Aging (WAHA) study [abstract]. FASEB J.
2016;30(Supp 1)293.4. Available at: http://www.fasebj.org/content/30/1_Supplement/293.4.abstract
2. Guetterman HM, Swanson KS, Novotny JA, et al. Walnut
Consumption Influences the Human Gut Microbiome [abstract]. FASEB J.
2016;30(Supp 1)406.2. Available at: http://www.fasebj.org/content/30/1_Supplement/406.2.abstract
3. Cooper JA, Stevenson JL, Paton CM. Hunger and satiety
responses to saturated fat-rich meals before and after a high PUFA diet
[abstract]. FASEB J. 2016;30(Supp 1)405.7. Available at: http://www.fasebj.org/content/30/1_Supplement/405.7.abstract
4. Shay NF, Luo T, Miranda O, et al. Mice Fed High-fat
Obesigenic Diets with Walnut Plus Other Whole Foods Demonstrate Metabolic
Improvement and Changes in Gene Expression and Metabolomic Patterns [abstract]. FASEB
J. 2016;30(Supp 1)428.3. Available at: http://www.fasebj.org/content/30/1_Supplement/428.3.abstract