Is Black Walnut Poisonous To Humans?

Black walnuts, with their distinctive flavor and numerous nutritional benefits, are becoming increasingly popular. Their benefits range from improving skin health to enhancing overall wellness.

However, are black walnuts poisonous, and are they really safe for human health? In this article, we will explore the potential toxins in black walnuts, such as juglone, and the unwanted reactions they may cause, from itching to digestive issues. Let’s find out what we might encounter if we consume black walnuts.

Is Black Walnut Poisonous To Humans?

Black walnuts can cause some uncomfortable reactions for both children and adults upon direct contact. This tree contains a natural compound called juglone, which is primarily concentrated in the roots but is also present in the leaves and bark.

Consuming a small amount of black walnuts is not likely to cause severe toxicity, but contact with the tree can lead to skin irritation [1].

If children or adults accidentally touch or play near a black walnut tree, they may experience itching, redness, or blisters due to skin irritation. People with sensitive skin, especially children, are more prone to develop contact dermatitis.

Additionally, during the pollen season, both adults and children may suffer from allergies, sneezing, or itchy eyes if standing nearby [1].

If sawdust or wood shavings from black walnuts are used as bedding for animals like horses, their reactions may be more severe, resulting in natural swelling and pain. For humans, inhaling pollen or light contact typically causes only mild allergic reactions that are not serious [1].

If someone accidentally ingests a large amount of juglone found in black walnuts, they may experience side effects such as nausea, stomach pain, or diarrhea [4].

Do you ever wonder why walnuts, despite their potential toxicity to the body, are still so widely consumed? This is because the production process removes the toxins present in the nuts, leaves.

Specifically, with walnut leaf extracts, the extraction process is carefully controlled to the content of compounds like juglone while preserving the beneficial nutrients. As a result, products derived from walnut leaves can still be used safely and offer various health benefits.

Moreover, studies have shown that walnut leaves, particularly those of the black walnut tree, contain high levels of phenols, flavonoids, and quercetin, which are known for their excellent antioxidant properties. In fact, young walnut leaves are rich in bioactive compounds that can provide therapeutic benefits [2].

Research also indicates that the green husk of the walnut tree contains the highest concentration of juglone, with an average level of 31.308 mg/100g. The juglone content in the green husk ranges from 20.56 to 42.78 mg/100g, while the leaves have a lower concentration, ranging from 5.42 to 22.82 mg/100g. Therefore, opting for products derived from the leaves can help reduce potential risks [3].

The Source Of Black Walnut Toxicity

The toxicity of the black walnut tree comes from a natural substance called juglone, which is most concentrated in the roots, husks, and buds. Juglone is also present in the leaves and trunk of the tree but in lower amounts.

When these parts fall to the ground and decompose, they leach into the soil, creating an area with the highest concentration of toxins directly beneath the tree's canopy [1].

This hazardous area can extend far from the base of the tree, and some sensitive plants may wilt, yellow, or even die when planted near a black walnut tree. The toxicity can persist in the soil for many years after the black walnut tree has been cut down, as the roots continue to release juglone during decomposition.

Some relatives of black walnuts, such as butternut and pecan trees, also produce juglone but at lower concentrations and with less impact on other plants.

While it is common knowledge among gardeners that black walnut trees hinder the growth of surrounding plants, this phenomenon has not been thoroughly researched, and much of the information is based on personal experience.

Black Walnut Toxicity To Humans Symptoms

Some toxicity symptoms of black walnuts for humans include the following:

• Skin Irritation: If you touch the leaves or husk, your skin may become itchy, red, or even develop a rash, similar to reactions from poison ivy.
• Breathing Difficulties: Inhaling dust from the black walnut tree or husk can cause wheezing, coughing, or a sore throat, especially if you are sensitive to allergens.
• Digestive Disorders: If you swallow a significant amount of juglone, you may experience nausea, abdominal pain, or diarrhea.
• Long-term Exposure: Those who frequently work with this type of tree may be at risk of developing chronic health issues.

Therefore, if you work with black walnut trees, it’s best to wear gloves and a mask for your protection [4]!

The ideal dosage for walnuts is about 30–60 grams per day, which is approximately 6 to 12 shelled nuts. This amount has been shown in studies to provide health benefits, particularly for blood pressure [5].

However, to ensure safety, leaf extracts are used as dietary supplements, with a typical dosage of around 200 mg per serving per day. However, due to the lack of studies on the safety of leaf extracts, it's advisable to consult with a healthcare professional for more personalized advice to ensure your safety.

Black Walnut Poisoning In Humans

Irritant Contact Dermatitis

Black walnuts can cause irritant dermatitis (contact allergy) when someone touches the husk, especially the immature green husk. This is a rare type of reaction that can cause itching, redness, or rashes.

Research has shown that juglone can irritate the skin and alter pigmentation. It is considered a naphthoquinone compound, found in high concentrations in the green parts of black walnuts and other members of the Juglandaceae family [6].

However, although juglone is the main irritant, recent studies also indicate that the green husk contains many other phenolic compounds that may contribute to this dermatitis condition [6].

Staining

Contact with the husk of black walnuts can lead to skin staining, particularly when touching the immature green husk. The compound juglone not only irritates but also darkens the skin, similar to henna. This color can last a long time and may take weeks or even months to fade completely [7].

If your skin becomes stained from black walnuts, the best approach is to wash it with soap and water immediately after contact. However, if you don’t wear protective gloves, this black stain may linger for a long time, and there are no effective measures to remove this color from the skin quickly.

Blisters

Black walnuts can also cause skin reactions upon direct contact. Sensitive individuals may experience blistering or rashes after exposure to sawdust, wood dust, or even the leaves of the black walnut tree. This substance can severely irritate the skin, especially if it is scratched or damaged, allowing juglone to penetrate the skin and cause itching, rashes, or even mild burns [8].

Burning And Itching

When you come into contact with the green husk or sawdust from black walnut wood, you may feel a burning and itching sensation on your skin. The juglone in black walnuts is responsible for this reaction.

Some people may have a stronger reaction, leading to redness or even rashes. This can be not only uncomfortable but may also disrupt your daily activities. So, when working with black walnut trees, don’t forget to wear gloves to protect your hands [1]!

Black Walnut Toxicity To Human Health

If you or someone else has unfortunately come into contact with black walnuts and shows signs of toxicity, remember a few simple steps you can take to feel more comfortable:

• Clean the Affected Area: Immediately wash the itchy or rash-affected skin with soap and warm water. This will help remove some of the toxins.
• Use Anti-Itch Cream: Apply an anti-itch cream or hydrocortisone ointment to the affected skin area. This can help reduce itching and natural swelling.
• Drink Plenty of Water: Staying hydrated will support your body in the recovery process and help flush out toxins.
• Cold Compress: Place a cold cloth on the affected skin area to alleviate discomfort and natural swelling.
• Avoid Further Contact: To reduce future issues, limit exposure to black walnuts and products derived from them.
• If symptoms do not improve or worsen, seek medical help to avoid serious complications.

What To Do If You Eat Black Walnuts?

Black walnuts are not only delicious but also very beneficial for health. They are rich in antioxidants and omega-3 fatty acids, which help improve heart health and brain function. Additionally, black walnuts provide fiber, aiding digestion. However, to maximize these benefits, consume them in moderation and store them properly.

If you accidentally eat black walnuts and feel unwell, stop eating them immediately. Then, monitor for possible symptoms such as nausea, vomiting, abdominal pain, or any other unusual signs [9].

Drink plenty of water to help your body detoxify. This can ease the discomfort caused by the adverse reactions from black walnuts.

Pay special attention if you experience symptoms like prolonged vomiting, severe abdominal pain, or any signs of an allergy; contact a doctor or go to the emergency room immediately.

To ensure safety, store black walnuts in a high place or locked away, and closely supervise your yard to avoid contact. If you suspect someone has eaten black walnuts, rinse the mouth immediately and seek medical help if severe symptoms appear.

Conclusion

Black walnuts not only offer a distinctive flavor but also pose some health risks. The juglone toxin can cause skin irritation reactions and uncomfortable symptoms with direct contact.

Additionally, due to their difficult digestibility, consuming too many black walnuts at night can lead to bloating and indigestion, especially in pregnant women. To enjoy the benefits of black walnuts, consider consuming them in moderation and always pay attention to your body's reactions.