Walnut Benefits for Heart Health, Brain Health, and More
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At first glance, walnuts might seem pretty strange. They’re wrinkly, oddly shaped, and resemble mini-brains. (You’ll never unsee it!) But if you can get past their peculiar appearance, walnuts are worth a try. Highly nutritious, the crunchy as they’re highly nutritious. They’re rich in good-for-you fats and antioxidants, plus vitamins and minerals to boot. Ahead, learn about walnut health benefits, plus ways enjoy to walnuts at home.
Walnuts are the seeds of the walnut tree, according to a scientific review in the International Journal of Molecular Sciences (IJMS). The tree sprouts fleshy fruits with a green, leathery outer layer known as the hull or husk. When the fruit is ripe, the hull breaks open to reveal a hard brown shell that houses the kernel (aka seed) — this is the part you eat. The other parts are typically discarded or used for industrial purposes, such as energy production, according to the aforementioned review. While there are many types of walnuts, in the U.S., the most common variety is the English walnut (aka common walnut or Persian walnut). And get this: Botanically speaking, walnuts are not actually nuts, but rather the seed of a drupe, a type of fruit that contains a seed. The more you know!
If the walnut were to win a superlative, it would likely be for its sky-high content of polyunsaturated fatty acids (PUFA), which are often referred to as “good” fats. In fact, it’s one of the top plant sources of alpha-linolenic acid (ALA), a type of PUFA that’s an anti-inflammatory superstar, according to a 2019 study. The nuts also offer fiber, folate, vitamin E, potassium, magnesium, and antioxidants, such as polyphenols, according to a review in The American Journal of Clinical Nutrition. (Related: Simple Ways to Use Walnuts In Your Healthy Cooking)
FYI, roasted walnuts or other processed forms of walnuts (e.g. walnut milk or flour) may have a different nutritional profile. For instance, in general, nuts that are raw, dry-roasted, or unsalted contain less added fat and sodium than salt or oil-roasted versions, according to the Cleveland Clinic.
Research has linked free radicals to myriad chronic diseases, but the antioxidants in walnuts can keep ’em in check. This includes compounds such as polyphenols, vitamin E, and catechin (which is also found in green tea), according to Tracey Frimpong, R.D., registered dietitian and founder of That Black RD. See, free radicals are unstable molecules that, in excess, can trigger cell damage or oxidative stress, which, over time, can snowball into chronic conditions such as heart disease and cancer. Enter: antioxidants, such as those in walnuts. These powerful disease-fighters help reduce and remove free radicals by changing their molecular makeup, according to the Harvard T.H. Chan School of Public Health. This protects cells from damage, ultimately keeping chronic disease at bay. (Related: Why You Need More Polyphenols In Your Diet)
Walnuts contain soluble fiber, one of the best nutrients for controlling blood sugar, according to a review in Annals of Medicine. As its name implies, soluble fiber is, well, soluble; it dissolves in water in the gut, creating a gel-like substance that slows down the body’s absorption of glucose, causing a steadier rise in blood sugar, explains Jonathan Purtell, R.D., a registered dietitian at Lenox Hill Hospital. This helps control blood sugar and, in turn, prevent blood sugar spikes, which, if frequent, can increase the risk of type 2 diabetes.
But soluble fiber isn’t the only nutrient responsible for this health benefit of walnuts. Magnesium and ALA — both of which, ICYMI above, are found in walnuts — help promote insulin sensitivity, adds Purtell. Insulin sensitivity refers to how well your body responds to insulin (the hormone that moves glucose into cells), which controls blood sugar and staves off type 2 diabetes, according to National Center for Biotechnology Information.
Thanks to its impressive ALA content, walnuts are your heart’s BFF. ALA (which, reminder, is a beneficial fatty acid) can lower LDL (“bad”) cholesterol, according to a study in the Journal of American Heart Association. Research also suggests that ALA has antioxidant effects that may protect against LDL oxidation — a process that’s thought to occur when LDL cholesterol reacts with free radicals in the body. LDL oxidation seems to play a role in plaque formation, which can contribute to heart disease. What’s more, according to Purtell, ALA can also promote the creation of compounds that cause vasodilation or widening of blood vessels, thereby reducing high blood pressure and with it, the risk for heart disease. Similarly, potassium adds to the health value of walnuts by relaxing blood vessels, further controlling high blood pressure and preventing heart issues, he explains.
In addition to resembling tiny brains, walnuts can actually benefit the brain. This is partially due to their impressive heart benefits; brain health, after all, relies on proper blood flow, which is controlled by the heart. Specifically, factors such as high blood pressure and cholesterol can impair blood flow to the brain, leading to cognitive impairment, according to an article in the journal Stroke. But as the heart-friendly nutrients in walnuts (think: ALA and potassium) target these factors, they can also protect the noggin. ALA also helps the body produce anti-inflammatory molecules that ward off inflammation and blood vessel damage — both of which can increase the risk of neurological disorders such as Alzheimer’s disease, says Frimpong.
The antioxidant properties of walnuts help, too. Basically, “when the brain is under oxidative stress, it can lead to cognitive decline,” explains Frimpong. That’s because, over time, oxidative stress wreaks havoc on brain cells. But walnuts’ antioxidants can decrease this oxidative damage, ultimately delaying or slowing the progression of cognitive decline, according to a scientific review published in the journal Nutrients. (Related: Simple Strategies to Improve Brain Health)
You might be surprised to learn that walnuts contain melatonin, which can help you catch some Zzz’s. Melatonin is a hormone that regulates the body’s circadian rhythm or internal body clock, according to an article in the journal Cells. Your melatonin levels naturally drop in the a.m., causing you to wake up. Come evening, your melatonin levels increase, making you sleepy and tired. Your pineal gland (a gland located in the brain) can make melatonin on its own, says Purtell, but you can also get it from melatonin-containing foods such as, yup, walnuts. Simply put, eating walnuts may help boost your melatonin levels, and in turn, help you catch some shut-eye.
Walnuts are tree nuts, which are one of the most common food allergens, according to the American College of Allergy, Asthma, & Immunology (ACAAI). Possible symptoms of a food allergy include hives, coughing, stomach cramps, difficulty breathing, and swelling in the tongue or mouth. In severe cases, a food allergy can cause a life-threatening reaction that inhibits breathing called anaphylactic shock, adds Frimpong. That said, if you “have a history of allergies to other tree nuts, such as almonds, hazelnuts, and cashews, be cautious when consuming [walnuts],” says Frimpong — if at all. Granted, it’s possible to be allergic to some tree nuts and not others, according to the ACAAI. But if you’re new to walnuts and have a history of food allergies, be sure to visit an allergist before chomping down on ’em, suggests Frimpong.
At your supermarket, you may find loose walnuts in the bulk section or in pre-portioned packages. They also vary in preparation (raw/dry-roasted/roasted in oil), seasoning (unsalted/salted/spiced), and form (whole/halved/chopped).
Whole walnuts are available with or without shells. As you can probably guess, walnuts sans shell are super convenient. But without the protection of said shells, they can go bad pretty quickly, says Frimpong. This is due to the nuts’ high content of unsaturated fats, which are fragile and easily affected by heat, according to the Academy of Nutrition Dietetics. So, if you want to keep fresh walnuts on hand year-round, your best bet is to buy in-shell walnuts and crack ’em open just before eating, recommends the California Walnut Board. In this case, you’ll need a nutcracker, such as the Anwenk Nutcracker (Buy It, $17, amazon.com).
If de-shelling sounds like too much work, opt for shelled walnuts instead — just remember to store ’em properly to avoid premature spoilage. For starters, you’re going to want to keep them cold (think: in the fridge or freezer) since walnuts deteriorate when exposed to heat. Pre-packaged walnuts, however, can be kept at room temperature until the “best by” date as long as the container stays closed. Once opened, store in a sealed container (e.g. an air-tight glass jar) in the fridge. In general, shelled walnuts will last three to six months at room temp (again, in a cool and dry place) or one year in the refrigerator, given the temperature stays below 32°F, according to Utah State University. If you’d rather keep them in the freezer, know they should last for at least two years. (Related: The 10 Healthiest Nuts and Seeds)
And how do you know your walnuts are fresh or spoiled? Fresh ones should smell mild, nutty, and somewhat earthy while rancid ones have an “off” flavor or sour smell, much like paint thinner (yuck!), according to the California Walnut Board. Another tell-tale sign is visible mold, adds Frimpong.
Less commonly, walnuts are available in other forms, including walnut oil, milk, or flour. Also known as walnut meal or powder, walnut flour — e.g. Erbology Organic Walnut Flour (Buy It, $18, amazon.com) — can be used to make gluten-free baked goods. However, as a study in the International Journal of Food Science notes, walnut flour has a high moisture and fat content, so you may need to adjust the other ingredients in a recipe. For best results, consider following a recipe specifically designed for walnut flour, such as these no-bake walnut cookies from the food blog Paleo Grubs. Finally, walnuts are also available as an ingredient in packaged foods, including nut mixes, granola bars, and sweet treats, such as Maxine’s Heavenly Walnut Banana Bread Cookies (Buy It, $10, amazon.com). Some ready-made foods may be laden with added sugar and salt, though, so if you’re watching your intake of either ingredient, be sure to check the product label first.
Walnuts are delicious in both sweet and savory recipes, including side dishes, entrées, and desserts. Just like any other nut or seed,
And just like many other nuts or seeds, they’re also great to eat by the handful. Ultimately, you can use walnuts like you would any other nut or seed, or simply eat them by the handful. Still not sure how to enjoy this nutritious nut? Cop these ideas to enjoy walnut health benefits galore:
In pesto. No pine nuts? No problem. Use walnuts instead for a unique take on pesto and enjoy with crusty bread.
As a meat substitute. Thanks to their somewhat chewy and meaty texture, finely chopped walnuts work surprisingly well as a meat substitute. Not convinced? Check out this recipe for walnut Bolognese.