Proven Health Benefits of Walnuts, How Many to Eat, and More (Science Based)

Walnuts are a nutritional powerhouse, a true superfood that's easy to add to your daily diet. These crunchy, earthy-tasting nuts are packed with antioxidants, essential fatty acids, and a rich blend of vitamins and minerals. Regularly eating just a handful of walnuts can have a profound impact on your overall health, from improving brain function to protecting your heart.

A growing body of scientific research supports the many benefits of walnuts. Studies show that consuming them can lower "bad" LDL cholesterol, decrease blood pressure, and reduce oxidative stress and inflammation throughout the body. In fact, some of these positive effects can be measured just hours after eating them. Let's delve into why these nuts are so good for you and how you can best incorporate them into your life.

What Are Walnuts?

Walnuts are the edible seeds of trees belonging to the Juglans genus, most commonly the Persian or English walnut and the black walnut. They grow inside a hard shell that must be cracked to reveal the distinctively shaped, wrinkly lobes within. A thin, brown skin covers the edible kernel, and this skin is a crucial part of the nut's nutritional value.

Like many nuts and seeds, walnuts are prone to spoilage if not stored correctly due to their high oil content. To keep them fresh, shelled walnuts should be stored in an airtight container in the refrigerator, where they can last for up to six months. You can also freeze them for up to a year. Un-shelled walnuts should be kept in a cool, dry, and dark place for up to six months.

Nutritional Profile and Key Benefits

The impressive nutritional makeup of walnuts is why they're so highly regarded. A 1-ounce serving (about 14 walnut halves) contains 185 calories, 4.3 grams of protein, and nearly 2 grams of dietary fiber. They also have a low glycemic index, making them a great snack for stable energy.

Beyond their basic macros, walnuts contain a unique combination of polyunsaturated fatty acids, specifically omega-6 (linoleate) and omega-3 (linolenate). They are one of the richest plant-based sources of omega-3s, with a single serving providing 2.57 grams of the beneficial fatty acid alpha-linolenic acid (ALA). These healthy fats are a primary reason for the nut's cardiovascular benefits.

Walnuts are also an excellent source of essential vitamins and minerals. A quarter-cup (approx. 30 grams) provides 50% of your daily manganese needs, 23% of your copper, 11% of your magnesium, and nearly 5% of your iron.

Why Walnuts Are the Champion of Nuts

Among the many types of nuts, walnuts stand out. Research by Dr. Joe Vinson, a chemistry professor at the University of Scranton, found that walnuts contain more polyphenols—powerful antioxidants—and have a higher antioxidant potency than pistachios, almonds, pecans, cashews, Brazil nuts, hazelnuts, and macadamia nuts. In fact, the antioxidants found in walnuts are thought to be 15 times more potent than vitamin E. This powerful combination of antioxidants helps to combat free radicals and protect your cells from damage.

When you compare walnuts to almonds, the difference is clear. While almonds are a healthy choice, 100 grams of almonds contain far fewer antioxidants and a significantly lower amount of omega-3s than the same amount of walnuts. This high concentration of beneficial compounds is what makes walnuts so effective at promoting health.

How to Eat and Store Walnuts for Maximum Benefit

Just a small handful of walnuts a day is enough to reap their full health benefits. Research suggests that eating just 7 walnuts a day is sufficient. They are best consumed raw, as heat can diminish some of their nutrients. You can also soak them overnight to improve their nutrient profile and digestibility.

It's highly recommended to eat the entire walnut, including the thin, brown skin. While some find the skin to be slightly bitter, it contains a high concentration of antioxidants that you would otherwise miss out on.

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In-Depth Health Benefits of Walnuts

Let's explore the specific ways that walnuts can boost your health.

Promote Healthy Brain Function

Walnuts' high levels of antioxidants and omega-3s help to reduce inflammation and oxidative stress in the brain. This can help prevent degenerative brain diseases and improve overall cognitive function. Studies have shown that a diet rich in walnuts can improve mood in healthy individuals and may have the potential to slow the progression of Alzheimer’s disease. Their high omega-3 content can also positively impact memory and learning skills.

Support Cardiovascular Health

Eating walnuts every day is a simple way to protect your heart. The unique combination of polyunsaturated acids in walnuts can help lower bad cholesterol and reduce hypertension. Studies have shown that consuming about half a cup of ground walnuts for eight weeks significantly lowers the risk of coronary heart disease. Unlike some other high-fat foods, walnuts do not cause weight gain when used as a replacement food in the diet, making them a heart-healthy choice.

Improve Gut Microbiota

Walnuts act as a prebiotic, feeding the beneficial bacteria in your gut. A trial published in the Journal of Nutrition found that consuming 42 grams of walnuts daily for two weeks led to an increase in good gut bacteria, highlighting their role in gastrointestinal health.

Aid in Weight Management

Despite being high in calories and fat, walnuts can be a great tool for weight loss. The healthy polyunsaturated and monounsaturated fats provide satiety, helping you feel full and satisfied. A study found that a weight-loss diet enriched with walnuts was more effective at lowering LDL cholesterol and blood pressure than a standard weight-loss diet.

Manage Diabetes

The nutritional content of walnuts can help manage diabetes symptoms and reduce the risk of developing the disease. A trial found that women who ate at least 28 grams of walnuts a week had a lower chance of developing type 2 diabetes. Their polyunsaturated fats and low glycemic index make them an ideal food for those with diabetes.

Enhance Male Reproductive Health

For men, walnuts can significantly improve fertility. A randomized controlled trial found that consuming 18 whole walnuts a day for 12 weeks led to marked improvements in sperm vitality, morphology, and shape.

Have Anti-Cancer Properties

While more human studies are needed, preliminary research suggests that walnuts may have cancer-fighting properties. The ellagitannins in walnuts are converted into a compound called urolithin in the gut, which some studies have shown can help kill off prostate cancer cells. The combination of antioxidants and other beneficial compounds in walnuts may help to prevent the development of certain cancers.

Boost Skin and Hair Health

The powerful antioxidants, vitamins (C, E, K, and B-group), and minerals (selenium, copper, and zinc) in walnuts are vital for healthy skin and hair. They protect skin cells from damage and can reduce the visible signs of aging. The omega-3s also help promote hair growth and scalp health, giving your hair a shiny, healthy look.

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Side Effects and Precautions

Walnuts are generally safe and highly beneficial. The only significant concern is an allergic reaction, which can be severe for those with a tree nut allergy. If you have this allergy, it is crucial to avoid walnuts.

When purchasing walnuts, choose whole ones that feel heavy for their size with no cracks or stains. For shelled walnuts, look for plump, unwrinkled kernels and smell them to ensure they aren't rancid. Proper selection and storage are key to enjoying all the health benefits these incredible nuts have to offer.