If you're one to nosh on nuts, good for you. On top of being an excellent source of plant-based protein, these little bites pack a big punch when it comes to healthy vitamins, minerals, and nutrients. But you may be wondering—are there any added benefits to swapping out your cooking oil for a nut-based oil like walnut oil?
Here's a look into the research and science behind walnut oil, and if incorporating it into your diet is a good idea or downright nutty (pun intended).
What is walnut oil?
Walnut oil is made from the inedible meat of the walnut that gets left over after shelling (it typically contains about 60% oil1). Light in color, walnut oil has a smooth, nutty, slightly bitter taste to it. Walnut oil is largely produced in California and France (specifically, the Périgord and Burgundy regions).
It's mostly used as a finishing oil for dishes such as salad, grains, or roasted vegetables—for good reason. While you technically can heat up walnut oil, you have to be careful since it has a very low smoke point of only 320 degrees Fahrenheit. If burned, walnut oil not only loses some of its nutritional value, but it can start to emit pro-inflammatory compounds2.
The nutritional value of walnut oil.
- Calories: 120
- Fat: 14 grams
- Choline: 0.05 milligram
- Vitamin E: 0.05 milligram
- Vitamin K: 2.04 micrograms
- Saturated fats: 1.24 grams
- Monounsaturated fatty acids: 3.1 grams
- Polyunsaturated fatty acids: 8.61 grams
Walnut oil has an especially high polyunsaturated fat (PUFA) content compared to other oils. "Most oils have a higher monounsaturated fat (MUFA) content than PUFA, but with walnut oil, the PUFA content outweighs its MUFA content," says Shapiro.
There are two major classes of PUFAs: omega-3 and omega-6. A majority of the fat content found in walnut oil is omega-3, specifically the fatty acid alpha-linolenic acid (ALA). One tablespoon of walnut oil contains 1.41 grams of ALA, an essential fatty acid that can only be obtained through diet.
Different types of walnut oil.
Walnut oil types differ mainly by methods of extraction, says Shapiro. Here are the three different types you can find at the store:
- Cold-pressed: Also referred to as unrefined walnut oil, there is no heat used in the oil extraction process to make this type of oil. Instead, walnut kernels are fed into a press that grinds and squeezes the oil out of each one. "This helps the oil retain more nutrient properties and original flavor," says Shapiro, making this a very healthy version of walnut oil.
- Refined: "With refined walnut oil, a solvent is applied on the kernels to help extract the oil, and then heat is applied to remove the solvent," says Shapiro. You can use refined walnut oil for the same purposes you would cold-pressed, but the taste may be slightly more bitter and it will be less nutrient-dense.
- Blended walnut oil: Rather than blend walnut oil with another type of vegetable oil, some retailers may blend together cold-pressed and refined walnut oil. That's because pure, cold-pressed walnut oil can be more expensive. This can be a middle-of-the-road option in terms of flavor, price point, and health benefits.
The health benefits of walnut oil:
It may keep your heart in tiptop shape.
As we already touched on, the unique PUFAs in walnuts make it a heart-healthy oil. "PUFAs are beneficial for lowering LDL cholesterol and enhancing HDL cholesterol level, which could help to reduce the risk of cardiovascular diseases," says Shapiro.
Walnuts in their whole form have been closely studied for their link to heart health. Adults who ate 37 grams of walnuts and 15 grams of walnut oil per day for six weeks were found to have lower LDL cholesterol and triglycerides5—contributing risk factors for cardiovascular disease.
It has anti-inflammatory properties.
There's a lot of focus on the healthy fatty acid content in walnut oil, but it also has a plethora of bioactive compounds beneficial to our health. One of those is the polyphenol pedunculagin.
Pedunculagin is an ellagitannin, a specific type of polyphenol that's found in berries and nuts. When consumed, ellagitannins release ellagic acid, which has antioxidant and anti-inflammatory capabilities7. This can help protect against diseases like certain cancers8, neurodegenerative diseases9, and cardiovascular diseases6.
"The fatty acids and plant bio-actives in walnuts might promote healthier immune responses in the body, but this is difficult to study in people," adds Ann Skulas-Ray, Ph.D., assistant professor of the School of Nutritional Sciences and Wellness at The University of Arizona.
It may protect against oxidative stress and free radical damage.
Preclinical research has found that walnut oil can reduce oxidative stress10 because of its antioxidant makeup. When looking at both normal cells and hyperglycemic cells for 72 hours, researchers found that walnut oil increased the antioxidant capacity of cells that were otherwise damaged by hyperglycemia (high blood sugar).
Walnut oil also controlled the superoxide dismutase (SOD) activity in cells that hyperglycemia had increased. If SOD is not regulated over time, it can lead to cell damage. This means that those with hyperglycemia or a risk of developing it may benefit from starting to incorporate more walnut oil into their daily diet.
It may lower blood sugar if consumed long term.
During a randomized controlled clinical trial, 100 subjects with Type 2 diabetes were split into two groups: one consumed 15 grams (a little over a tablespoon) of walnut oil a day for three months, while the other group made no dietary changes.
The group that consumed walnut oil showed a decrease in blood glucose levels compared to the control group11. This, in part, is thanks to the antioxidants and anti-inflammatory effects found in walnut oil from ALA.
It may help your skin, too.
The downsides of walnut oil:
Those with nut allergies should steer clear.
Walnut oil can have a positive impact on your health, but only if you don't have any allergies to nuts, says Shapiro. Certain walnut oils (such as cold-pressed) have potent amounts of nuts in them and as such, could cause allergic reactions or sensitivities upon consumption.
Consuming too much could cause gastrointestinal issues.
"As with any oil, using too much walnut oil (especially on an empty stomach) may lead to an upset stomach," says Skulas-Ray. Using a dash of walnut oil to drizzle on top of a salad is one thing, but using lots of it for deep frying is going overboard with this oil—especially when you consider its low smoke point.
So, is walnut oil healthy?
When used in moderate amounts for dressing and finishing your meals, yes.
"Walnut oil has high concentrations of PUFAs that reduce bad cholesterol," Skulas-Ray summarizes. "There is also research demonstrating benefits for blood pressure and other cardiovascular risk factors. Plus, it is particularly enriched in ALA, which not many foods provide."
Walnut oil vs. other oils.
Here's how walnut oil stacks up to a few other popular cooking oils:
Walnut oil vs. olive oil:
"Walnut oil contains higher amounts of ALA than olive oil, while olive oil has more oleic acid," says Skulas-Ray. Both can be beneficial in promoting and protecting heart health.
It can be harder to find food sources with ALA in them, giving walnut oil a leg up. Olive oil has a much higher smoke point than walnut oil, though, which makes it a safer oil to cook with.
Walnut oil vs. canola oil:
Canola oil also has more oleic acid than walnut oil. Yet, walnut oil contains more PUFAs while canola oil has a high MUFA content. Canola's smoke point can be as high as 400 degrees Fahrenheit, which is why many use it for frying. Most canola oil is highly processed, so it's usually considered one of the least healthy cooking oils and it's a less nutritious pick than walnut oil overall.
Walnut oil vs. flaxseed oil:
"Flaxseed oil (or linseed oil) is the richest source of ALA, but some people don't enjoy the flavor and it can oxidize (aka, go rancid) more quickly than other oils," says Skulas-Ray. Shapiro adds that flaxseed oil has an especially low smoke point of 225 degrees Fahrenheit, which is why both are used mainly as dressings.
Walnut oil recipe substitutes
Frequently Asked Questions
How much walnut oil should I take daily?
Is walnut oil better than olive oil?
What makes walnut oil so special is its high ALA content. However, when cooking it's best to use olive oil instead of walnut oil as heating the oil can burn it and make it taste bitter.
Can you put walnut oil on your skin?
Yes, applying a small amount of walnut oil to the skin is good for hydration as long as you're not allergic. There are also many over-the-counter products that are infused with walnut oil.
If you're looking to get more heart-healthy ALAs in your diet, walnut oil is an excellent source of it. Use it as a replacement for creamy, saturated-fat-filled salad dressings or as a finishing touch to veggies and protein. Just make sure you're storing the cooking oil properly to retain its benefits!
Colleen Travers is a freelance writer and editor who specializes in health, nutrition, diet, fitness, and wellness trends for various publications and brands. Her work has appeared in Reader's Digest, SHAPE, Fit Pregnancy, Food Network, and more. She lives on Long Island with her two kids, two rescue pets, and husband.