Science continues to uncover the benefits of alpha-linolenic acid (ALA), the omega-3 essential fatty acid found in plant foods like soybeans, nuts and seeds. Omega-3 fats have been shown to help prevent heart disease and stroke, and they may help control lupus, eczema, and rheumatoid arthritis, as well as play protective roles against cancer and other conditions.
Walnuts are unique among tree nuts in that they contain the highest amount of ALA. An ounce of dried English walnuts supplies 2.6 grams of ALA, and an ounce of black walnuts provides 0.6 grams of ALA. Walnut oil has 1.4 grams of ALA in each tablespoon, but does not contain dietary fiber. One ounce is about a quarter of a cup, or 12 – 14 walnut halves.
There is a host of health benefits associated with ALA intake, including:
A 2009 American Journal of Clinical Nutrition meta-analysis reviews the heart health benefits of walnuts on 365 participants from several trials. When compared with control diets, diets supplemented with walnuts resulted in a significantly greater decrease (-10.3 mg/dL) in total cholesterol and LDL “bad” cholesterol (-9.2 mg/dL). Walnuts also provided significant benefits for certain antioxidant capacity and inflammatory markers and had no adverse effects on body weight.
Animal research published in the British Journal of Nutrition found a diet containing as much as 6 percent walnuts (equivalent to one ounce or 1/4 cup per day in humans) was able to reverse age-related motor and cognitive deficits in aged rats.
A study evaluating the effect of dietary alpha-linolenic acid provided by walnuts and flaxseed on bone turnover found bone health improved with ALA consumption. This clinical research study was published in the January 2007 issue of Nutrition Journal.
A Yale study published in Diabetes Care finds walnuts improve blood flow in adults with type 2 diabetes. Another study in the same publication reported a positive effect of a moderate-fat diet, inclusive of walnuts, on blood lipid profiles in patients with type 2 diabetes. The walnut group achieved a 10% reduction in LDL cholesterol and a greater increase in HDL (good) cholesterol levels than the other two treatment groups.
A Nutrition and Cancer study investigated whether consumption of walnuts could affect growth of human breast cancer tumors (MDA-MB 231) implanted into mice. After 35 days, the breast cancer tumors of the walnut-fed mice were significantly less (2.9 ± 1.1 mm3/day) – about half the size of the tumors – than in the mice that were not fed walnuts (14.6 ± 1.3 mm3/ day). Researchers concluded that the results of this pilot study demonstrate that consumption of walnuts could slow the growth of cancers possibly by slowing the growth of tumor cells; however more research is needed before understanding its application to humans.
Your one-ounce serving of walnuts provides benefits beyond the 2.5 grams of ALA, including being a top source of antioxidants (13.126 mmol), as well as providing 4 grams of protein, 2 grams of fiber and 10% of needed daily value of magnesium and phosphorus.
But most U.S. adults have yet to discover the benefits of walnuts. Only 5.5% of all adults (ages 19-50) consume tree nuts of any kind! This small percentage of people actually do a pretty good job of integrating tree nuts (including walnuts) into their diet, and average about 1.25 ounces of tree nuts per day. But the other 94.5% of us report no consumption of tree nuts whatsoever. In a recent look at the nutritional differences between tree nut eaters and non-eaters, researchers have reported some pretty notable findings: on a daily average, tree nut eaters take in 5 grams more fiber, 260 milligrams more potassium, 73 more milligrams of calcium, 95 more milligrams of magnesium, 3.7 milligrams more vitamin E, and 157 milligrams less sodium!
U.S. per capita use of all tree nuts was over 3.0 pounds (shelled basis) in recent years, up from 1.7 pounds in 1977
If you want to help your shoppers increase their intake of walnuts, look to the California Walnut Commission as a source of recipes. Here is a gorgeous summer salad that pairs walnuts with summer’s finest fruits:
Blueberry, Watermelon and Walnut Salad
- 1/4 cup lime juice
- 1/4 cup olive oil
- 2 tablespoons honey
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper, ground
- 2 cups watermelon, seedless, cubed
- 1 cup blueberries, fresh
- 1 cup California walnuts, chopped
- 1 bell pepper, yellow, large, cut in bite-size pieces
- 6 cups baby greens, mixed
- 4 chicken breast halves (about 4 ounces each), skinless, boneless, grilled or sautéed until cooked through
- Preheat oven to 350º F and spread walnuts in one layer on baking sheet. Bake until just toasted and aromatic, about 8 minutes; remove and let cool.
- To prepare vinaigrette, in a small bowl, whisk together lime juice, oil, honey, salt and pepper.
- For the salad, in a medium bowl, combine watermelon, blueberries, walnuts and bell pepper; add half of the vinaigrette; toss to coat. In a large bowl, toss greens with remaining vinaigrette. Divide greens among 4 plates; top with fruit and walnut mixture. Slice each chicken breast diagonally and serve with the salad.
Nutrition Information, Per Serving:
535 calories; 35 g fat; 4 g saturated fat; 14 g monounsaturated fat; 16 g polyunsaturated fat; 378 mg sodium; 29 g carbohydrate; 5 g fiber; 32 g protein