- High cholesterol levels (LDL level) increase the risks of heart disease and stroke.
- Walnuts are a rich source of alpha-linolenic acid (ALA).
- The study finds walnuts can lower bad cholesterol.
In 2008, 39% of the global population had high cholesterol. 
High cholesterol levels increase the risks of heart disease and stroke.
But nutrition researchers found good news for us. 😃
A new study found that eating about 1/2 cup of walnuts every day for two years can lower low-density lipoprotein (LDL) levels, known as bad cholesterol. 
Interesting right? 😄
Let’s dig deep into it. 🧐
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Table of Contents
- Key Highlights
- In a hurry? Watch the Video Instead
- The Study Process
- Quick overview of High Cholesterol
- The Result of this Study
- Researchers Note
- The Limitation of this Study
- How Walnuts can Lower Bad Cholesterol
- My Opinion
- The Final Word
The Study Process
This study was conducted from May 2012 to May 2016 and involved 708 participants between the ages of 63 and 79 (68% women).
All participants were healthy, independent-living adults residing in Barcelona, Spain, and Loma Linda, California.
Participants were randomly divided into two groups: active intervention and control.
Researchers added half cups of walnuts to the intervention group, while no walnuts were given to the control group.
All participants were allowed to eat their usual diet. 🥗
After two years, participants’ cholesterol levels were tested.
The concentration and the concentration, and the size of lipoproteins were analyzed by nuclear magnetic resonance spectroscopy.
The nuclear magnetic resonance spectroscopy test is an advanced test that enables physicians to more accurately identify lipoprotein features known to relate to the risk of cardiovascular disease.
This study had a 90% retention rate. 😇
Meaning out of 708 participants, 632 had completed the study.
Out of 632 participants, 628 had completed lipoprotein analysis.
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Quick overview of High Cholesterol
Cholesterol is a type of fat or waxy substance.
Our body needs it to build cells and make vitamins and other hormones. 
Our liver produces enough cholesterol required by our body.
But excess cholesterol, which comes from food, is dangerous. ☠️
High cholesterol doesn’t have any symptoms.
So many people don’t know whether their cholesterol is normal or high.
A simple blood test can tell you your cholesterol level (total cholesterol, HDL or good cholesterol, LDL or bad cholesterol, and triglycerides.)
The Result of this Study
The study was published in the American Heart Association’s flagship journal Circulation. 
After analyzing the participants’ data, researchers find some key points.
- After two years, the intervention group (walnut group) had lower LDL cholesterol levels — by an average of 4.3 mg/dL, and total cholesterol was lowered by an average of 8.5 mg/dL.
- Daily walnut consumption reduced the total LDL particles by 4.3 percent and small LDL particles by 6.1 percent. These changes in LDL particle concentration and composition are associated with a lower risk of cardiovascular disease.
- Intermediate Density Lipoprotein (IDL), a precursor to LDL, also decreased. In the last decade, IDL cholesterol has emerged as a relevant lipid cardiovascular risk factor independent of LDL cholesterol.
- LDL cholesterol changes among the walnut group differed by sex; in men, LDL cholesterol fell by 7.9% and in women by 2.6%.
“Prior studies have shown that nuts in general, and walnuts in particular, are associated with lower rates of heart disease and stroke. One of the reasons is that they lower LDL-cholesterol levels, and now we have another reason: they improve the quality of LDL particles,” said study co-author Emilio Ros, MD, PhD, director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Hospital Clinic of Barcelona in Spain.
“LDL particles come in various sizes. Research has shown that small, dense LDL particles are more often associated with atherosclerosis, the plaque or fatty deposits that build up in the arteries,” Ros explained.
“Our study goes beyond LDL cholesterol levels to get a complete picture of all of the lipoproteins and the impact of eating walnuts daily on their potential to improve cardiovascular risk,” Ros added.
“While this is not a tremendous decrease in LDL cholesterol, it’s important to note that at the start of the study all our participants were quite healthy, free of major non-communicable diseases,” Ros said.
“However, as expected in an elderly population, close to 50 per cent of participants were being treated for both high blood pressure and hypercholesterolemia. Thanks in part to statin treatment at 32 percent, the average cholesterol levels of all the people in our study were normal,” Ros explained.
“For individuals with high blood cholesterol levels, the LDL cholesterol reduction after a nut-enriched diet may be much greater. Eating a handful of walnuts every day is a simple way to promote cardiovascular health,” Ros added.
“Many people are worried about unwanted weight gain when they include nuts in their diet. Our study found that the healthy fats in walnuts did not cause participants to gain weight,” Ros continued.
The Limitation of this Study
The major limitation of this investigation is that both participants and researchers knew who was and was not eating walnuts.
However, the study did involve two very different populations with special diets.
“The outcomes were similar in both groups, so we can safely apply the results of this study to other populations,” Ros said.
More research is also needed to clarify the different LDL results in men and women. 🧐
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How Walnuts can Lower Bad Cholesterol
Walnuts are a rich source of alpha-linolenic acid (ALA) which is the plant-based omega-3 fatty acid.
It has been shown to decrease low-density lipoprotein cholesterol (by ∼9-16%) and blood pressure (diastolic blood pressure by ∼2-3 mm Hg), two major risk factors for CVD. 
Now, what does this finding mean to you?
The current daily recommended intake of ALA for adults over age 19 is 1,100 mg for women and 1,600 mg for men. 
So, add walnuts to your diet. 🥗
One ounce (28 grams) of walnuts provides 2.5 grams of ALA. 
According to the American Heart Association, walnuts are exceptionally high in omega-3 fatty acids, the same heart-healthy fat found in oily fish. 
The Final Word
High LDL levels are dangerous. 😲
This study finds walnuts can lower the LDL level.
But if you want to be healthy, you also need to increase your HDL level.
And the most effective way to increase HDL is to be physically active and lose extra weight.
So, eat a balanced diet, if you’re not and exercise at least 30 minutes daily. 🤾♀️
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This article is written by a certified nutritionist and verified by scientific evidence. ☑️
We rely on reputed and specialized media sites, academic research institutions, peer-reviewed studies, government agencies, and medical associations to source information. 📰
We avoid using tertiary references. Know more about how we ensure our content is accurate and current by reading our editorial policy. 🧐
Following are the references of this article.
- World Health Organization (WHO): Raised cholesterol. Accessed 4 december 2021.
- American Heart Association (Circulation): Effects of Walnut Consumption for 2 Years on Lipoprotein Subclasses Among Healthy Elders: Findings From the WAHA Randomized Controlled Trial. Accessed 4 december 2021.
- American Heart Association: What is Cholesterol? Accessed 4 december 2021.
- PubMed: Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms. Accessed 4 december 2021.
- National Institutes of Health (NIH): Omega-3 Fatty Acids. Accessed 4 december 2021.
- California Walnuts: Omega-3 ALA. Accessed 4 december 2021.
- American Heart Association: Go Nuts (But just a little!). Accessed 4 december 2021.