A walnut-rich diet can help reduce low-density lipoprotein, or “poor” cholesterol levels and boost overall heart health. Eating walnuts can also bring many other health benefits.
Most of the nuts contain monounsaturated fatty acids ( MUFAs), but the walnuts consist mainly of polyunsaturated fatty acids ( PUFAs). They also contain significant amounts of alpha-linolenic acid (ALA), the plant-based source of omega-3 fatty acid.
Walnuts also abound in other nutrients, such as folate and vitamin E. Folate helps to reduce the risk of unborn babies having central nervous system deficiencies. Vitamin E helps to form hemoglobin, the oxygen-carrying protein in the blood.
Walnuts, however, are also a high-calorie food and consuming too many will result in weight gain.
In this article we look at some of the research that supports the inclusion of walnuts in diet , particularly for people who want to control their cholesterol levels.
Walnuts, cholesterol, and heart health
Nearly 1 in 3 people in the United States have high overall cholesterol levels in their blood, according to the Centers for Disease Control and Prevention ( CDC).
High levels of cholesterol, particularly high levels of low-density cholesterol lipoprotein (LDL), increase the risk of heart disease , stroke and other health conditions.
Scientists speaking at the 2016 meeting of Experimental Biology in San Diego , CA, reported in 2016 that eating walnuts every day can have a beneficial impact on cholesterol levels without rising body weight.
The researchers analyzed data for 514 older adults, averaging 69 years of age, who took part in the Walnuts and Healthy Aging (WAHA) survey.
Around half of the participants added a handful of walnuts to their daily diet, accounting for 15 percent of their daily calorie intake. The other half consumed their usual daily diet without nuts.
The researchers found after 1 year that those on the walnut diet had significantly lower LDL cholesterol levels when compared to those who ate their usual diet.
There were no significant differences in body weight changes and high density lipoprotein ( HDL) or “good” cholesterol levels between the groups.
In 2018, the WAHA researchers concluded after further investigation that “walnuts can be incorporated into the daily diet of healthy elders without concern for adverse effects on body weight or body composition.”
Better lipid profiles
Scientists tend to find data supporting walnut’s cardiovascular benefits.
A review of 26 studies in 2018, using data for over 1,000 individuals, concluded that those who ate a walnut-rich diet had lower levels of:
- total cholesterol
- LDL cholesterol
- triglycerides, a type of fat in the blood
- apoprotein B, a protein science has linked to cardiovascular disease
The investigators did not find, in this study, that walnuts led to an increase in body weight.
They suggested one reason the improved levels with the above-mentioned compounds may be because walnuts are rich in plant sterols. These naturally occurring compounds may help stop cholesterol from being absorbed by the body.
Walnuts also contain polyphenols and tocopherol which can promote antioxidant and anti-inflammatory activity in the body. It takes more studies to confirm that.
“Incorporating walnuts into the diet increased the blood lipid profile without adversely affecting body weight or blood pressure,” the researchers concluded.
Benefits for people with diabetes
A number of other studies have also shown that daily walnut assistance may benefit cardiovascular health, including those with or at risk of diabetes.
In 2015, a study that appeared in BMJ Open Diabetes Research Care looked at people aged 25 to 75 with a high risk of diabetes. One group of participants in their daily diet contained 56 grams ( g) of walnuts, while the second group consumed no walnuts.
The team observed a major improvement in the functioning of the wall (endothelium) of the blood vessels in those who ate the walnuts after 6 months. In this category too, the LDL cholesterol levels were lower.
The team, however, found no significant impact in the group that ate the walnuts on blood pressure , blood glucose or HDL cholesterol levels.
There have also been significant increases in body fat among those Walnut-eating group members who have not received dietary advice on how to adjust their calorie intake.
Lipid profile and diabetes
In a study involving 100 people with type 2 diabetes published by researchers in 2017, participants consumed either 15 centigrams of Persian walnut oil or a placebo for 90 days each day.
By the end of the study period, those who consumed the walnut oil had improved lipid profiles when researchers compared them with those who took placebo.
The scientists noted that the following compounds could help to achieve their health benefits in walnuts and walnut oil:
- l-arginine, the amino acid the body needs to make the vasodilator nitric oxide
- dietary fibers
- folic acid
The researchers indicated that “walnut oil may be a valuable natural treatment for patients with type 2 diabetes who suffer from hyperlipidemia.”
The cardiovascular system isn’t the only part of the body that might benefit from walnut and walnut oil intake.
A study that appears in Reproduction Biology linked the eating of walnuts to an improvement in several sperm health indicators.
The study involved 117 healthy men aged 21 to 35 years who had eaten a Western-style diet. The researchers split them up into two groups.
For 12 weeks the first group ate 75 g walnuts a day and the second group avoided walnuts.
Compared to the nut-free group the men who had eaten walnuts had significantly higher rates by the end of the study period:
- sperm vitality
- sperm motility, or ability to move
- sperm morphology
The researchers, however, couldn’t tell whether consuming walnuts would help young men with fertility problems.
Research at the British Journal of Cancer in the United States Nurses ‘ Health Study has taken data from more than 75,000 women.
The findings suggested a link between consuming at least twice a week a 28-g serving of nuts and a significantly lower risk of pancreatic cancer; In this analysis the nuts included almonds, nuts from Brazil and walnuts.
The authors said the risk reduction was due to any risk factors the participants may have had for pancreatic cancer, such as smoking and diabetes.
A 2015 study of the mouse, published in The Journal of Nutritional Biochemistry, suggested that a diet containing walnuts could slow the growth of colon cancer by causing beneficial changes in cancer genes.
Scientists published findings in The Journal of Nutrition , Health & Aging in 2014 which indicate that eating walnuts may improve mental ability.
The team used data from U.S. adults, aged 20 to 90, from several years of the National Health and Nutrition Examination Survey ( NHANES).
Those with a higher daily intake of walnuts showed better results on six mental ability tests including speed in memory , concentration, and processing information.
A study on mice in 2014 suggested eating walnuts could benefit brain function.
The mice bred to model Alzheimer’s disease progress ate either a walnut-rich diet, or a walnut-free diet.
Many who ate walnuts showed significant improvements in learning skills, memory, levels of anxiety and other brain function tests when the scientists compared them with those who did not.
An earlier study by the same team suggested that walnut extract could protect against the harmful effects of amyloid-beta protein. This protein is the main constituent of amyloid plaques formed by people who develop Alzheimer’s disease in their brains.
The authors suggested that walnuts could help to reduce the risk, delay the development or slow Alzheimer’s disease progression.
Walnuts are a food rich in nutrition but they are also high in calories and can result in weight gain if people eat too many of them. Therefore, walnuts should be eaten in moderation, and as part of a balanced lifestyle.
For a person with a nut allergy, walnuts can also cause severe or even fatal allergic reactions. Anyone suffering from a nut allergy should not eat walnuts and other nut types.
See our dedicated article here for more on allergies, and how to tell the difference between an allergy and intolerance.
Walnuts in the diet
Walnuts can be a healthy and savory complement to the diet.
Below are several guidelines for using walnuts:
- eat them alone as a snack
- serve them alongside dates, dried fruit, or low-fat cheese
- sprinkle them on muesli
- make walnut bread
- add them to a salad for extra crunch
As for walnut oil, for a nutty flavor, you can add it to the salads or pour some on cooked vegetables.
However cooking the oil can give it a bitter taste, so after cooking it is safer to add it.
A growing research body indicates eating a moderate amount of walnuts will support cholesterol levels, cardiovascular system, and other health aspects.
It is worth noting that interested groups, such as the California Walnut Commission, endorse such research on the benefits of walnuts.
Further research is needed to confirm the walnut’s potential health benefits.