The Health Benefits of Black Walnut

Cracked black walnuts on a wooden table

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Black walnut (Juglans nigra) is a type of nut thought to offer a number of health benefits. The tree nut contains tannins, a class of substances with antioxidant and anti-inflammatory properties. Long used in certain systems of herbal medicine, a black walnut extract is available in dietary supplement form and is believed to help in the treatment of certain illnesses including infections.

Black walnuts are also commonly eaten in the United States. The tree nut is high in unsaturated fat and protein and provides certain nutritional benefits. Black walnut contains essential fatty acids, including linoleic acid, oleic acid, palmitic acid, stearic acid, and linolenic acid (an omega-3 fatty acid) as well as minerals like magnesium and potassium.

Health Benefits

There's currently a lack of research on the effects of dietary supplements containing black walnut extract. It is too soon to tell if they can provide any health advantage to humans. Additionally, there are different types of black walnuts and extracts from each may provide a different level of benefits (if any) based on their concentration of bioactive agents.

One study investigating antibacterial properties of black walnut found that there was variation between different types (cultivars). Researchers examined 22 cultivars and found that one variety (Mystry) exhibited the strongest antibacterial activity.

Regardless of variety, black walnuts, in general, may provide fewer benefits than other types of walnuts.

One small study published in the Journal of Medicinal Food in 2011 compared the cardiovascular effects of black walnuts to those of English walnuts. For the study, 36 people ate about 1.06 ounces of black walnuts or English walnuts every day for 30 days. Study results showed that participants who added English walnuts to their diets experienced greater improvements in several measures of cardiovascular health compared to participants who added black walnuts to their diets.

Lastly, researchers are still investigating how to effectively extract the active compounds from the nut. Without proper extraction methods, supplements containing the bioactive compounds may not provide benefits at all.

Despite the lack of evidence, black walnut is touted as a natural remedy for the following health problems:

  • Asthma
  • Constipation
  • Diabetes
  • Heartburn
  • High blood pressure
  • High cholesterol
  • Leukemia
  • Diphtheria
  • Syphilis
  • Intestinal worms
  • Skin wounds

In addition, some believe that black walnut can protect against heart disease, cancer, and infections caused by ​an overgrowth of yeast (such as yeast infections, candida, and thrush).

When applied topically, black walnut is said to aid in ​the treatment of conditions like canker sorespsoriasis, and warts.

There is not enough scientific evidence to support the use of black walnut or black walnut extract for these health benefits.

Possible Side Effects

Due to a lack of research, little is known about the safety of long-term use of supplements containing black walnut extract. However, there's some concern that black walnut may trigger certain side effects, including diarrhea.

Due to the high tannin content, people with liver or kidney disease or certain gastrointestinal conditions should avoid black walnut. People who are taking blood pressure medication should avoid black walnut. Pregnant or nursing women and children should avoid black walnut supplements.

People with allergies to black walnuts should not take black walnut supplements. Cross-sensitivity or contamination with other nuts is possible, so people with nut allergies should avoid black walnut.

It's important to note that self-treating a chronic health condition with black walnut and avoiding or delaying standard care may have serious consequences. If you're considering the use of black walnut in the treatment of a condition, make sure to consult your healthcare provider.

Selection, Preparation, and Storage

Often sold in liquid extract form, dietary supplements containing black walnut are available for purchase online and in natural-foods stores, drugstores, and stores specializing in dietary supplements.

While supplements containing black walnut extract may not provide health benefits, some people enjoy eating black walnuts. There is also some evidence that increasing your nut consumption may boost heart health. Black walnuts are sold in the whole form at many grocery stores and natural-foods stores.

When shopping for walnuts, you'll usually find them in bags and in bulk bins, typically in the produce section. Keep walnuts in the shell for as long as possible to preserve freshness. Once out of the shell, keep them in your refrigerator or freezer, depending on when you’re going to use them. According to some sources, if your walnuts smell like paint thinner they’re rancid and they should be thrown away.

Are Black Walnuts Toxic When Consumed by Dogs?

They may be toxic to animals, so dogs should not consume black walnuts. The nuts contain a toxin called juglone and some research has shown that the substance may be dangerous to dogs and horses.

Do Black Walnuts Taste Different Than Other Walnuts?

Some people taste a difference between English walnuts and black walnuts. Black walnuts are often described as more earthy, dark and bold than the more common English variety. Black walnuts are usually grown wild and can have a shell that is harder to crack.

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