With a history just as rich as its taste, the walnut has existed for centuries—but do you know all the ways it can benefit your body? Snack on them raw, or try adding these nuts to your salads, smoothies, and baked goods to experience a healthy boost from heart to brain.
Dating back to 7000 BC, the walnut—which comes from any tree in the Juglandaceae family of trees—is one of the oldest known tree foods. Thought to have originated in Persia, early cultivation of walnuts spanned from southeastern Europe to Asia Minor to the Himalayas. In the ancient Mediterranean world, the walnut was considered one of the most important nuts—both from a health standpoint and as a status symbol.
Ancient Romans called walnuts Juglans regia, or “Jupiter’s royal acorn.” Because early history indicates that the nut originated in Persia, it’s often referred to as the “Persian Walnut”—and at that time, walnuts were reserved for royalty. Later, after trade along the Silk Road facilitated the spread of the nut, walnuts became beloved in England as “English Walnuts,” although they were never grown there commercially. For centuries, too, the oil of the nut has been used in the preparation of fine paints for artists.
In the late 1700s, Franciscan priests brought the walnut to California, where it flourished in the Mediterranean-like climate. Today, California walnuts account for 99 percent of the commercial US supply and more than two-thirds of world trade. Other countries that grow commercial walnuts include India, Turkey, China, Russia, Greece, Italy, and France.
A Snapshot of Studies
Need a reason to take a crack at this nut? Take your pick—walnuts are loaded with heart-helping, disease-fighting, body-boosting elements that all work synergistically to benefit our health. Here’s a look at what walnuts can do for you.
Walnuts contain a high amount of the omega-3 fat alphalinolenic acid, or ALA. This omega-3 is plant based, unlike its marine-based counterparts, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). When you take a fish oil supplement, you are aiming to increase your intake of DHA and EPA—which is important because although the body is able to convert ALA into DHA and EPA, it does so quite inefficiently.
That said, research has shown that those who eat a diet rich in ALA are less likely to suffer from heart-related ailments. A study published in the Journal of Medicinal Food indicated that eating just one ounce of walnuts per day can decrease the risk for cardiovascular disease; other research published in Nutrition, Metabolism, and Cardiovascular Diseases demonstrated that eating just four walnuts a day could raise blood levels of ALA. While ALA is an anti-inflammatory, it may also prevent the formation of blood clots.
The American Journal of Clinical Nutrition published a study detailing a significantly greater decrease in total cholesterol and LDL (“bad”) cholesterol in those participants who supplemented their diets with walnuts, compared with those who did not supplement. Test results published in the Journal of Nutrition indicated that just a one-time consumption of walnut oil boosted blood vessel functioning, which is often compromised in those with heart disease. Indeed, the research abounds—and it’s clear that eating ALA-rich foods like walnuts is a big part of a heart-healthy diet.
It’s no secret that heart disease and diabetes are closely related—and evidence shows that eating walnuts may reduce the risk for type 2 diabetes. For a 10-year period, researchers followed nearly 138,000 women and monitored their walnut intake; as reported in the Journal of Nutrition, they found that those who ate two or more 1-ounce servings of walnuts per week were 24 percent less likely to develop diabetes than those who ate fewer or no walnuts.
Another study appearing in the European Journal of Clinical Nutrition found that overweight adults with type 2 diabetes who ate one-quarter cup of walnuts daily showed significant reductions in fasting insulin levels, compared with those who did not eat walnuts—and that benefit was achieved within the first three months.
Many compounds found within walnuts—including vitamin E, folate, melatonin, omega-3s, and antioxidants—support brain health. Omega-3 deficiency, in particular, has been linked to cognitive problems. The brain needs these fats to function properly, yet many Americans fail to get enough in their diets. One study at Purdue University demonstrated that children with a lower concentration of omega-3 fatty acids displayed a higher risk of hyperactivity, learning disorders, and behavioral problems.
A study in the Journal of Alzheimer’s Disease reported that increased consumption of walnuts (but not other nuts) was associated with better working memory scores; the researchers attributed this to the nut’s high polyphenol content, thinking that these antioxidants may be the key factor to preserving memory. A separate study published in Neurochemical Research found that walnut extract could counteract the oxidative stress and cell death caused by amyloid beta-protein, a major culprit in the brains of those with Alzheimer’s disease; thus, they concluded walnuts may protect brain cells.
Some people steer clear of walnuts (and nuts in general) because of their fat content, fearing that eating them might make them gain weight. However, the Journal of Lipid Research published a study that found that regular walnut intake did not lead to weight gain; the study included male participants with high cholesterol and actually found that in a six-week period, the men who were eating walnuts showed a 6 percent decrease in LDL cholesterol.
When enjoyed at the proper portion size, walnuts can actually help manage your weight. They contain fiber, which helps you feel full so you ultimately eat less (or mindlessly snack less on unhealthy foods). They are quite high in calories, so to reap the best benefits and maintain your weight, substitute the nuts for other calories in your daily diet.
Gamma-tocopherol, a form of vitamin E found in walnuts, has been found to help fight prostate, lung, and breast cancers. Walnuts also reduce the levels of endothelin, a compound that increases blood vessel inflammation; men with prostate cancer are known to have higher levels of endothelin. In a study at the University of California-Davis Cancer Center, researchers looked at the effect of walnuts on prostate cancer in mice; they showed that mice who consumed the human equivalent of 2.4 ounces of walnuts a day had smaller tumors and reduced cancer growth by 40 percent.
A similar study at the Marshall University School of Medicine in West Virginia showed that mice that were fed the human equivalent of 2 ounces of walnuts daily had significantly decreased breast tumor incidence and a slower rate of tumor growth, compared with mice on a control diet. Researchers concluded that eating about 28 walnut halves a day provides enough antioxidants and phytosterols (plantderived compounds) that may help reduce the risk of breast cancer.
Nutty for Nuts
Walnuts aren’t the only nuts with health benefits. Try incorporating a variety of these nuts into your diet for a vast array of benefits, taste, and texture.
>>Almonds may reduce the risk for heart disease and lower cholesterol.
>>Pecans contain many antioxidants that help lower blood pressure and prevent breast and prostate cancer.
>>Hazelnuts contain an abundance of vitamin E, which helps the body form red blood cells, muscles, and other tissues.
>>Pistachios are associated with eye health and may reduce the risk for developing age-related macular degeneration.
By Erica Tasto