Health Benefits Of Walnuts

Medically Reviewed by Zilpah Sheikh, MD on September 01, 2023
Written by Angela Nelson
7 min read

Walnuts are seeds that come from the shell of a fruit that grows on a walnut tree.

English walnuts are the type most commonly sold in stores. Also known as Persian walnuts, they're originally from Persia and later spread throughout Asia and Europe.

Walnuts have been a beloved snack for thousands of years. The Romans thought the nut could counteract poison and treat skin conditions.

 In traditional Chinese medicine, walnuts are used to:

  • Detox the kidneys
  • Nourish the blood
  • Promote digestive health

Modern scientists have found evidence to support many of these claims. 

The American Heart Association, which has identified walnuts as a “heart-healthy” food, says that replacing saturated fats with walnut oil could lower blood pressure and total cholesterol levels when included in a healthy diet.

Today, most of the walnuts in the U.S. are grown in California, but some come from the Midwest. They are bumpy and golden brown and have a mild, earthy, and slightly tangy flavor. You can easily find them in the baking aisle of any grocery store.

Black walnuts

Black walnuts have a flavor that's bolder, richer, and earthier than that of English walnuts. Black walnut trees aren’t grown in orchards like most nuts. Instead, they grow wild across North America.

Black walnuts have the highest protein content among tree nuts and also have good amounts of vitamin A, iron, minerals, and fiber. They have higher levels of antioxidants, polyunsaturated fatty acids, and other health-promoting compounds than English walnuts. These ingredients make them useful in reducing the risk of cancer, heart disease, and diabetes.

 

One serving of English walnuts, which comprises 1 ounce or about seven walnuts, has:

  • 185 calories
  • 2.5 grams of monounsaturated fat
  • 1.7 grams of saturated fat
  • 4.3 grams of protein
  • 3.9 grams of carbohydrates
  • 1.9 grams of fiber
  • 0.7 grams of sugar

This small serving size can have a big nutritional benefit. Here are the vitamins and minerals you'll get in an ounce of walnuts:

  • Up to 2% of your daily recommended amount of calcium
  • Up to 4% of your daily iron recommendation
  • Up to 2% of your daily potassium needs
  • Up to 14% of your daily magnesium needs
  • 7% of your daily folate recommendation

They're also an excellent source of:

  • Iron
  • Zinc
  • Copper
  • Selenium
  • Vitamin C
  • Niacin

While studies have traditionally focused on the benefits of the whole nut, newer research suggests that pressing it into walnut oil retains many of its health-boosting effects.

Walnut oil is a good source of:

  • Vitamin K
  • Vitamin E
  • Choline
  • Phosphorus
  • Zinc

Walnut oil is also high in selenium. This antioxidant supports healthy thyroid function and may reduce your risk of cognitive decline, heart disease, and cancer.

Walnuts are rich in polyunsaturated fats, which are better for you than saturated fats. They're also high in healthy omega-3 fatty acids.

Studies show that eating walnuts can help lower your overall cholesterol levels as well as LDL “bad” cholesterol. Cholesterol can form plaque inside your arteries, but regularly eating walnuts can help keep your artery walls healthy.

Walnuts may help ease the type of inflammation that leads to heart disease . They may also help lower your chances of a blood clot that could cause a heart attack.

Early studies show that walnuts could decrease your odds of developing some types of cancer. They contain a substance called ellagic acid, which is also found in pecans. Bacteria in your stomach and intestines change this acid into compounds with antioxidant power, which may help ward off cancer. But we need more research to know for sure.

Heart health

Most of the fats in walnuts and walnut oil contain an omega-3 fatty acid called alpha-linolenic acid. This “good fat” can reduce your risk of heart disease by 10% when consumed as part of your daily diet. Scientists think this is because the omega-3s can lower cholesterol levels, helping keep your arteries clear and working correctly.

Eating walnuts regularly also reduces levels of triglycerides, a type of fat linked to a higher risk of heart disease, heart attacks, and stroke.

Lower risk of diabetes

Walnuts and walnut oil are high in antioxidants that can lower blood sugar levels, which can reduce your risk of diabetes. 

Studies show these antioxidants have anti-inflammatory effects as well. Inflammation is our body’s natural response to stress and infection, but it can cause insulin resistance, which blocks the body’s ability to use sugars. This raises blood sugar levels, putting you at a higher risk of obesity and diabetes.

Obesity prevention

Although nuts are high in calories, long-term studies have shown that people who eat nuts in healthy portions have lower rates of weight gain and obesity than those who don't. Scientists think that's because nuts are high in fiber and help satisfy hunger.

Better gut bacteria

Findings from a few studies suggest that people who eat walnuts have more probiotics and other good gut bacteria than those who don’t.

A healthy balance of gut bacteria is linked to reduced rates of both depression and colon cancer.

Brain health

Plant compounds in walnuts have been shown to reduce inflammation in the brain and improve thinking and memory.

Other studies have looked at how walnuts can protect the brain from oxidative stress (uneven amounts of harmful free radicals and helpful antioxidants in the body), which can lead to Alzheimer’s and other brain disorders.

Better skin

Studies show that your body converts walnut oil’s fatty acids into compounds that make up your skin. Scientists believe that getting enough omega-3s and omega-6s in your diet—like those in walnut oil—may improve skin health, heal wounds faster, and treat eczema, acne, and even some skin cancers.

You can also apply walnut oil to your skin. The oil’s anti-inflammatory and antioxidant effects may help slow signs of aging and treat conditions such as psoriasis.

Cancer prevention

While we need more research, studies show that the nutrients in walnuts may slow the growth of cancer cells. Walnut oil’s antioxidants can help fight cell damage, which scientists believe leads to cancer.

Walnuts may sound like a superfood with many valuable vitamins and nutrients, but you should stay away from them in certain situations:

If you’re allergic to nuts. If you have a tree nut allergy, walnuts are not for you. Symptoms of an allergic reaction can range from an itchy mouth (oral allergy syndrome) to severe, life-threatening conditions, such as anaphylactic shock.

If you’re on a low-calorie diet. Walnuts can be up to 65% fat (even though it’s mostly the good kind of fat) and are high in calories. One handful may have about 10% of the calories you need for a day.

Medication interaction. Walnuts can interact with some thyroid medications. Talk to your doctor to make sure walnuts and walnut oil are OK to add to your diet.

You can eat walnuts on their own as a snack or as a crunchy topping for yogurt, stir-fry, a veggie dish, or ice cream. For the biggest heart health benefits, choose unsalted walnuts that are raw or dry-roasted instead of those cooked in oil.

You can use black walnuts in any recipe that calls for English walnuts. Expect a more vibrant flavor.

Here are some ways to use walnuts in recipes:

  • Sprinkle on salads
  • Add to pasta dishes, or use them to make pesto sauce
  • Create muesli with oats, seeds, dried fruit, and chopped walnuts
  • Add walnuts to muffins and quick bread recipes
  • Make homemade granola bars
  • Mix walnuts with dried fruit, chocolate chips, and other nut varieties for trail mix

Walnuts are high in oil and can get stale and taste bitter if exposed to warm temperatures for too long. It's best to store walnuts (with or without their shells) in an airtight container in a cool, dry place. You can keep them in the refrigerator for up to 3 months or freeze them for up to a year.

Walnuts can absorb odors, so keep them away from strong-smelling foods. If your walnuts are rubbery or shriveled, that means they’re spoiled and should be thrown away.

 

Walnut oil is made from shelled walnuts that are ground, boiled, and pressed until a liquid oil is produced.

Health benefits of walnut oil

Walnut oil shares many of the same benefits as walnuts. It is a rich source of nutrients and antioxidants, some of which may even improve your memory and concentration. It's also high in selenium, an antioxidant that supports healthy thyroid function and may reduce your risk of cognitive decline, heart disease, and cancer.

It's available at most grocery stores and is mostly used as a finishing oil to add flavor to recipes, sauces, and dressings. Walnut oil can be used for pan frying, but avoid cooking it at too high a temperature. At its smoking point, around 320 F, the oil can lose some nutrients and develop a bitter taste.