Black walnuts are a tree nut with a strong flavor and a harder shell than English walnuts

Black walnuts grow in North America and have a distinctive earthy, slightly bitter taste that is much stronger than the milder English walnuts you find in most grocery stores. The shell is thick and dark, which is why they are harder to crack open than other nuts. Because of their intense flavor, people typically eat them in smaller amounts — sprinkled on salads, baked into breads, or mixed into ice cream — rather than as a handful of snacks.

The nut meat itself is rich in fat and protein, which is why they show up in conversations about nutrition. They also contain compounds called polyphenols, which are found in many plant foods. The kernel is oily and can go rancid if stored improperly, so they are usually kept in the refrigerator or freezer after cracking.

Key Takeaways

  • Black walnuts contain omega-3 fatty acids and protein, making them nutrient-dense like other tree nuts.
  • The flavor is much stronger than English walnuts, so most people use them as a flavoring ingredient rather than eating them by the handful.
  • Black walnuts are harder to shell than other nuts and are less commonly sold pre-shelled in stores.
  • The nut meat contains polyphenols and other compounds that researchers have studied in laboratory settings, though human research is still limited.

What nutrients black walnuts contain

Black walnuts are high in fat — about 60 percent of their weight — and most of that fat is polyunsaturated, the type found in fish and seeds. They also contain omega-3 fatty acids, specifically a plant-based form called ALA (alpha-linolenic acid). One ounce of black walnuts (about 14 halves) contains roughly 2.5 grams of protein and around 190 calories.

They are also a source of minerals including manganese, copper, and magnesium. The outer hull and shell contain tannins, which are compounds that give the nut its astringent taste and have been studied for various properties in laboratory research. However, most of what people eat is the kernel inside, not the hull.

Compared to English walnuts, black walnuts have a higher concentration of some compounds, which is one reason they have drawn research attention. That said, the total amount you would eat at one time is usually small because of the strong flavor, so the practical nutritional contribution depends on how often and how much you consume.

How black walnuts differ from other nuts

The most obvious difference is flavor: black walnuts taste earthy and assertive, while English walnuts are mild and buttery. This makes black walnuts less versatile as a snack nut and more useful as an ingredient in cooking or baking. The shell is also significantly thicker and harder to crack, which is why they are less common in stores and why many people buy them already shelled (though this costs more).

Black walnuts also contain juglone, a compound produced naturally by the tree. Juglone is what gives the nut its dark color and has been the subject of laboratory research, though most human studies remain limited. English walnuts do not contain juglone in meaningful amounts.

From a practical standpoint, English walnuts are easier to find, easier to crack, and easier to eat in quantity. Black walnuts are a specialty ingredient that works well when you want a strong nutty flavor in a specific dish. Both are nutrient-dense, but they serve different purposes in the kitchen.

What research says about black walnuts

Laboratory studies have found that black walnut compounds show activity against certain bacteria and fungi in test tubes. Some animal studies have looked at whether these compounds affect cholesterol or inflammation, with mixed results. However, human studies are sparse, and most of what researchers have published involves small groups or short time periods.

The polyphenols in black walnuts are similar to those in other nuts, berries, and plant foods, and polyphenols in general have been associated with heart health in large population studies. That does not mean black walnuts specifically will change your health — it means they contain compounds that are also found in many foods people eat as part of healthy diets.

If you see claims that black walnuts treat or prevent disease, those claims go beyond what current research supports. The evidence is strongest for basic nutrition — they are a calorie-dense food with protein, healthy fats, and minerals — rather than for any specific health outcome.

How to store and use black walnuts

Shelled black walnuts should be stored in an airtight container in the refrigerator or freezer because the high fat content means they can become rancid at room temperature. In the freezer, they will keep for a year or longer. In the refrigerator, they are best used within a few months. You can tell if they have gone rancid by smell — they will have an off or musty odor.

Unshelled black walnuts are harder to crack than other nuts and require a heavy-duty nutcracker or a vise. Many people soak them first to soften the shell slightly. If you buy them in bulk, store the unshelled nuts in a cool, dry place away from moisture.

In cooking, use black walnuts sparingly because of their strong flavor. A small handful mixed into oatmeal, salad, or baked goods is usually enough. They pair well with chocolate, cinnamon, and maple flavors. You can also make black walnut butter by grinding shelled nuts in a food processor, though it will be thicker and more intensely flavored than peanut or almond butter.

Where to find black walnuts and what they cost

Black walnuts are less widely available than English walnuts. You may find them in the bulk section of natural food stores or specialty grocery stores, but conventional supermarkets often do not stock them. Online retailers and specialty nut companies sell both shelled and unshelled black walnuts, usually at a higher price than English walnuts because they are harder to process.

Shelled black walnuts typically cost more per pound than unshelled ones, but the labor of cracking them yourself is significant. If you live in an area where black walnut trees grow wild, you can harvest and crack them yourself, though this is time-intensive and requires drying and curing the nuts properly.

Prices vary by season and supplier, but expect to pay roughly two to three times more for black walnuts than for English walnuts. Because you use them in smaller amounts, a small container can last several months if stored properly.

Potential concerns and who should be cautious

Black walnuts are high in calories and fat, so portion control matters if you are watching your intake. They are also a tree nut, so anyone with a tree nut allergy should avoid them. Cross-reactivity between different tree nuts varies by person, so someone allergic to one tree nut is not automatically allergic to all of them, but it is worth discussing with a healthcare provider.

The tannins in black walnuts can cause digestive upset in some people if eaten in large amounts. Starting with a small amount and seeing how your body responds is a reasonable approach if you are trying them for the first time.

Black walnuts contain compounds that may interact with certain medications or conditions, though research on this is limited. If you take blood thinners, have kidney disease, or are pregnant, it is worth mentioning black walnuts to your healthcare provider before making them a regular part of your diet.

Frequently Asked Questions

Are black walnuts better for you than English walnuts?

Both are nutrient-dense nuts with healthy fats and protein. Black walnuts contain higher concentrations of some compounds like juglone and polyphenols, but human research comparing the two is limited. The choice often comes down to taste preference and availability rather than one being objectively "better."

Can I eat black walnuts if I have a walnut allergy?

Black walnuts and English walnuts are different species, but both are tree nuts. If you are allergic to walnuts, you should avoid black walnuts unless a healthcare provider has tested you specifically for black walnut allergy. Cross-reactivity varies by person.

What does it mean if black walnuts taste bitter?

The bitter taste comes from tannins and other natural compounds in the nut. This is normal and expected. If the bitterness is accompanied by a musty or off smell, the nuts may have gone rancid and should not be eaten.

Can I grow black walnut trees at home?

Yes, black walnut trees grow in much of North America and can be planted in yards with space. However, they take many years to produce nuts, and the trees release juglone into the soil, which can harm some other plants nearby. Check your local growing zone before planting.

How much black walnut should I eat per day?

There is no standard recommendation. Because they are calorie-dense and strong-flavored, most people eat them in small amounts — a quarter cup or less per day as part of a mixed diet. If you are new to them, start with a small handful and see how your body responds.