Calories in Walnuts: Full Nutrition Breakdown

Walnuts are a nutrient-dense tree nut distinguished by their uniquely high content of omega-3 fatty acids, specifically alpha-linolenic acid (ALA). One ounce of English walnuts (about 14 halves) delivers roughly 18.5 grams of fat, 4.3 grams of protein, and is a notable source of manganese, copper, magnesium, and phosphorus. Their rich, slightly bitter flavor and tender texture make them a popular addition to salads, baked goods, and snack mixes.

Calories by serving size:

Walnuts are the only tree nut with a significant amount of ALA omega-3 fatty acids, providing about 2.5 grams per ounce — more than meeting the daily adequate intake for this essential fat. They also contain a diverse array of polyphenol antioxidants, including ellagitannins and pedunculagin, which are primarily concentrated in the papery skin surrounding each walnut half. Regular walnut consumption has been linked in research to improved brain function, reduced inflammation, and better cardiovascular health markers.

Frequently Asked Questions (FAQ)

How many walnut halves are in one ounce?

One ounce of walnuts contains approximately 14 walnut halves, weighing about 28 grams. This standard serving provides 185 calories and is the amount most commonly used in clinical nutrition studies investigating the health benefits of walnuts. Because walnut halves vary in size, weighing your portions on a food scale is the most accurate way to track intake, though a small handful is a reasonable visual estimate.

Are walnuts good for brain health?

Walnuts have been called a "brain food" for centuries, and modern research supports this reputation. Several observational studies have found that regular walnut consumption is associated with better cognitive function and slower age-related cognitive decline. The ALA omega-3 fatty acids in walnuts help reduce neuroinflammation, while their polyphenol antioxidants combat oxidative stress in brain tissue. A 2020 clinical trial published in the American Journal of Clinical Nutrition found that older adults who consumed about 1.5 ounces of walnuts daily for two years showed better cognitive scores compared to a control group.

Why are walnuts higher in calories than some other nuts?

Walnuts have about 185 calories per ounce, which is higher than almonds (164 kcal) and cashews (157 kcal) primarily because they contain more total fat — about 18.5 grams per ounce compared to roughly 14 grams in almonds. However, the type of fat in walnuts is predominantly polyunsaturated (including ALA omega-3s), which has been strongly associated with reduced cardiovascular disease risk. Despite the higher calorie count, studies consistently show that regular walnut consumption does not lead to weight gain when eaten as part of a balanced diet, likely due to their satiating combination of fat, protein, and fiber.

What is the omega-3 content of walnuts compared to fish?

One ounce of walnuts provides about 2.5 grams of ALA omega-3 fatty acids, making them the richest plant source of this essential fat. However, ALA is a short-chain omega-3 that must be converted to the long-chain forms EPA and DHA (found in fatty fish) by the body, and this conversion rate is relatively low — typically only 5 to 10 percent. While walnuts are an excellent omega-3 source for vegetarians and vegans, they are not a direct substitute for the EPA and DHA found in salmon, sardines, or fish oil supplements. Including both walnuts and fatty fish in the diet provides the most comprehensive omega-3 coverage.

How should walnuts be stored to maintain freshness?

Walnuts are more perishable than many other nuts due to their high polyunsaturated fat content, which makes them susceptible to rancidity when exposed to heat, light, or air. For short-term storage (up to one month), keep shelled walnuts in an airtight container in the pantry away from direct light. For longer storage, refrigerating walnuts extends their freshness to about six months, and freezing them in a sealed bag preserves quality for up to a year. Rancid walnuts will have a sharp, paint-like smell and a bitter taste, and should be discarded as rancid fats may have harmful health effects.