Nutrition
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Walnuts: Facts, Nutrition, Benefits, & More

Written by Ashlee Mikles, MS, RDN, CD, CLS

January 10th, 2024

Walnuts are a type of nut that has a rich, crunchy texture with a mildly sweet but earthy flavor. They are enjoyed worldwide year round.

They are not only full of flavor, they are most known for the nutrients they contain and the several health benefits they provide.

Walnuts can be added to nearly any type of food or dish or be simply eaten on their own.

Keep reading to find out all you need to know about walnuts.

Fun Fact:The husks of walnuts have been used for years to make ink and even hair dye during medieval times.

History & Facts

Walnuts (Juglans regia) are a tree nut belonging to the walnut family Juglandaceae (1). It is technically the edible seed of the tree. They ripen between September and November in the northern hemisphere. The brown, wrinkly walnut shell is enclosed in a husk. Beneath the husk of the walnut fruit is a wrinkly, globe-shaped nut. The walnut is split into two flat segments to be sold commercially.

Walnuts originated in the Mediterranean region and Central Asia and have been part of the human diet for thousands of years. During Roman times walnuts were also known as the “royal nut”. Three species of walnuts are most popular, the Persian or English walnut (from Iran), the black walnut (from North America), and the Japanese walnut. This article will include information about the English or Persian walnut which is grown worldwide.

The world production of walnuts is around 3.5 million tons yearly, with the largest producer of them being China, the United States, and Iran.

Summary:Walnuts are a tree nut that is the edible seed of the tree and has been part of the human diet for thousands of years.

Nutrition Facts

If you didn’t know already, walnuts are full of tons of nutrients.

Macronutrients

In a 1-ounce serving of walnuts (around 14 halves), there are the following macronutrients (2):

  • Calories: 185 calories (kcal)
  • Protein: 4.3 grams (g)
  • Total Fat: 18.5 grams (g)
    • Saturated fat: 1.74 grams (g)
    • Monounsaturated fat: 2.53 grams (g)
    • Polyunsaturated fat: 13.4 grams (g)
  • Carbohydrates: 3.8 grams (g)
  • Fiber: 1.9 grams (g)

As you can see, walnuts are high in monounsaturated and polyunsaturated fats and omega-3 fatty acids (3). They are also a great source of protein (4).

Nuts have a reputation for being a high-calorie and high-fat food. This may be true, however, they are dense in nutrients and provide heart-healthy fats.

Walnuts are a great combination of healthy fats, protein, and fiber which can help to increase satisfaction and fullness (5). This makes them a great option for a healthy snack compared to refined or processed snacks like chips, crackers, and other simple carbohydrate foods.

Summary:Although walnuts are high in calories and fats, they are very dense in nutrients and provide heart-healthy fats that are more beneficial than they may appear.

Vitamins and Minerals

In a 1-ounce serving of walnuts (around 14 halves), there are the following vitamins and minerals (6):

  • Calcium: 27.8 milligrams (mg)
  • Magnesium: 44.8 milligrams (mg)
  • Phosphorus: 98.1 milligrams (mg)
  • Selenium: 1.39 micrograms (mcg)
  • Copper: 0.45 milligrams (mg)
  • Folate: 27.8 micrograms (mcg)
  • Choline: 11.1 milligrams (mg)
  • Vitamin E: 0.2 milligrams (mg)
  • Lutein + Zeaxanthin: 2.55 micrograms (mcg)

Walnuts are an excellent source of several vitamins and minerals, including copper, phosphorus, folate, and choline (7). These are great for maintaining bone and nerve health, maintaining the immune system, and preventing birth defects.

Walnuts also contain antioxidants which are most present in the brown skin of the walnut (8). Antioxidants are great for reducing free radicals, which can lead to oxidative stress and other negative health effects like heart disease and cancer (9).

Summary:Walnuts contain a variety of vitamins and minerals that are important for several different aspects of health in the body and also contain antioxidants.

Health Benefits

In addition to the high abundance of nutrients they contain, walnuts are linked to several health benefits.

May Improve Cognitive Function

Several studies indicate that consuming nuts, especially walnuts may improve brain health and overall brain function. Walnuts are jam-packed with nutrients and essential vitamins to help the body and mind thrive (10).

Walnuts provide a healthy dose of omega-3 fatty acids (11). Omega-3 fatty acids are necessary to prevent cognitive decline. Walnuts also help to lower inflammation and decrease oxidative stress (12). The antioxidant content in walnuts also provides benefits to boost brain health.
Eating more walnuts may even improve memory, coordination, and learning skills. It may even reduce the risk of Alzheimer’s disease, an ever-growing chronic disease (13).

Summary:Walnuts have been found to improve brain health by improving memory, and learning, and reducing the risks of certain diseases, mostly due to the high amount of omega-3 fatty acids they contain.

May Promote Heart Health

Cardiovascular disease or heart disease is the number one cause of death among men and women in the United States, killing one person every 36 seconds (14). A healthy diet and lifestyle are a few crucial elements necessary to prevent heart disease, such as eating nuts. Walnuts provide a wide variety of nutrition that is necessary to maintain a healthy heart.
Issues associated with heart disease also include hypertension or high blood pressure, high cholesterol, and obesity.

The monounsaturated and polyunsaturated fatty acids found in walnuts have been shown to decrease LDL (harmful) cholesterol and triglyceride levels. This means that a diet high in walnuts can reduce the risk of stabilizing cardio-metabolic risk factors (15). They can even level out cholesterol and even reduce plaque formation (16, 17, 18). For those who consume nuts more than four times per week, the risk of heart disease decreased by 37% compared to those who rarely or never consumed nuts.

Walnuts help to decrease your risk of CVD or cardiovascular disease, the number one cause of death in the United States (19). This is likely due to the beneficial fat and antioxidants that the walnuts contain. Although heart disease comes with genetic components, diet, and lifestyle can be the deciding factor. Several of these statements refer to whole or chopped nuts, and not products that contain nuts.

Summary:Consuming walnuts may decrease the LDL (bad) cholesterol and triglyceride levels in the body which can help reduce the risk of heart conditions and disease.

May Help With Weight Management

Many diets tend to preach skipping nuts in your diet. That couldn’t be further from the truth. Nuts provide so much nutrition that can help with weight loss and much more (20). Trying to lose weight with no luck plagues millions of Americans and it can be very hard to maintain weight once the weight loss happens. A change in diet is one of the number one necessary acts to keep weight off and sustain weight loss long term.

Routine nut consumption, such as walnuts, has been associated with higher levels of energy use while resting, meaning more calories were burned than when not walnuts were not consumed (21). Studies that have included nuts in weight loss studies have found greater weight loss in the diets that included nuts versus the diets that did not.

While walnuts alone cannot help with weight loss, they are a perfect addition to a healthy diet. They provide your daily healthy fat intake, along with fiber, vitamins, and minerals needed to sustain good health (22). Walnuts are the perfect snack to help out with weight loss (23).

One important factor to lose weight is to make sure to include protein, fiber, and healthy fat during meals (24). Walnuts can easily be that healthy fat and fiber for a go-to snack and eaten other ways too. You can add walnuts easily to several recipes as well.

Summary:Walnuts are high in protein, fiber, and calories in a small serving meaning they can help aid satiety and prevent overeating an abundance of extra calories which can sometimes lead to weight gain.

Ways to Consume

Walnuts are available both raw or roasted and salted or unsalted. They are most typically eaten on their own as a snack but can also be incorporated into several different kinds of foods. Walnuts are also used to make walnut oil-which is an oil frequently used in culinary cuisine. Keep in mind it is expensive and not a great choice for frying because of its low smoke point.

Here are some more ways to add in walnuts:

  • Top a handful of them on breakfast foods like oatmeal, yogurt, or even cereal.
  • Add walnuts to your favorite baked breads, muffins, cakes, or scones.
  • Grab a handful of walnuts for an easy and quick snack. Take a small bag with you to work when you need an energy boost to get through the day.
  • Add some crunch and protein to any salad.
  • Crush and sprinkle walnuts on any vegetable side.
  • Toast or blend walnuts into a paste to make the perfect nutty flavor topping.
  • Make homemade granola with a mixture of walnuts and other nuts, seeds, and dried fruit, using walnut.
  • Use walnuts to make a pesto.

Fun Fact:Walnuts can be a great snack choice right before bed. This is due to the levels of tryptophan they contain, which is known to cause sleepiness in some people.

Risks

Although walnuts are part of a balanced diet, they do pose some potential risks for some people.

  • Don’t overeat them: Some negative effects can occur when walnuts are consumed in excess. For example, walnuts are a food that is denser in calories, 185 calories for every 1 ounce of them to be exact. Because of this, they can increase the chance of weight gain. Additionally, high consumption of walnuts has been linked to diarrhea, potentially because of the high oil content they contain. Those with gastrointestinal conditions like irritable bowel syndrome (IBS) may have digestive issues when it comes to eating large servings of walnuts.
  • Allergy: People who are allergic to nuts should not eat walnuts (25). Nut allergy can cause an uncomfortable rash, hives, or difficulty breathing after eating walnuts. Medical attention may be warranted and should be sought if necessary.
  • Choking Risk: Young children should not consume pieces of nut, or they should be supervised while doing so, as this can lead to choking. To incorporate walnuts without this risk, walnuts can be finely ground and mixed into other foods or be eaten as walnut butter.

Summary:Walnuts may have negative effects when eaten in abundance, can cause allergy for some, and should not be given to young children due to the choking hazard they pose.

Frequently asked questions

What is the usual shelf life for walnuts?

Because walnuts have a high-fat content, they are at an increased risk of becoming rancid. Even though nuts that become rancid are not technically unsafe, they can cause a flavor profile change that is not pleasant (26). This is less likely to happen when they are stored properly. Keeping walnuts in their shells in a cool, dark, and dry place can improve their shelf life.

How should walnuts be stored?

To make sure walnuts stay fresh as long as possible, they should be kept in an airtight container in a cold place. They should not be exposed to warm temperatures for long periods.  Keep them stored in an airtight container or their original sealed packaging. They stay fresh for longer when they are kept in a refrigerator below 40 degrees Fahrenheit or in a freezer below 0 degrees Fahrenheit (27). They can be stored for up to a year this way. Remember to keep them away from foods with strong odors, as walnuts can absorb the flavors of other foods.

Did You Know?:Walnuts are the oldest known tree food, dating back to 7000 BC!

Conclusion

Walnuts are an excellent option for most diets, specifically for their healthy fat content, fiber, protein, and wide range of nutrients.

They offer an impressive list of health benefits like promoting heart health, improving cognition, and may even help with weight management.

Walnuts are easy to incorporate with meals and snacks and even delicious on their own.

Where can walnuts fit into your diet today?

Ashlee Mikles, MS, RDN, CD, CLS

Ashlee Mikles, RDN, CD, CLS Ashlee Mikles is a registered dietitian and certified lactation specialist working in community nutrition and public health....Read more

Evidence Based

This article is based on scientific evidence, and written, fact-checked & medically reviewed by health experts.

Throughout this article, you’ll find scientific references (highly trusted peer-reviewed scientific papers, links denoted by the numbers in the parentheses (1, 2, 3)).