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Evidence Based

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6 Black Walnut Benefits—From Snacking to Supplementation

Written by Dr. Michael Ruscio, DC on November 20, 2025

Written by Dr. Michael Ruscio, DC on November 20, 2025 — Reviewed by Hannah Wright

• Background|
• 6 Black Walnut Health Benefits|
• How to Use Safely|

Most of us think of walnuts as a simple snack food, but the black walnut deserves more attention. Native to the American Midwest and East Coast, this deeply flavored nut has long been valued for its nutritional benefits and the green outer husk, which traditional herbalists use to calm infections and support gut health 1.

Modern research is beginning to confirm those uses. Both the nut and the husk contain unique plant compounds that may support cardiovascular function, reduce inflammation, and help maintain a healthy microbiome.

It’s a food with benefits that reach far beyond the pantry, and a reminder that some of nature’s most powerful medicines grow in our own backyards.

What Makes Black Walnuts Different

The black walnut (Juglans nigra) is a nutritional heavyweight. Compared with the common English walnut, it provides 1:

• More protein and vitamin E
• Higher levels of healthy fats and antioxidants
• A richer, bolder flavor

These nutrients make black walnuts an obvious choice for heart and brain health, but the real intrigue lies in the green husk. This outer layer is packed with bioactive compounds like polyphenols, tannins, and juglone, which may have antimicrobial, antifungal, and antiparasitic effects 2.

Those natural defenses protect the tree from pests in the wild and are the same compounds that herbal medicine has learned to harness in carefully measured amounts.

6 Black Walnut Health Benefits

Most research focuses on English walnuts, but their nutritional similarity suggests black walnuts may offer comparable (and possibly greater) benefits for heart and gut health.

As Food

1. Cardiovascular Support

A meta-analysis (a high-quality study of studies) found that regular walnut intake significantly lowered total cholesterol, LDL (“bad”) cholesterol, and triglycerides 3. Another meta-analysis also found walnuts may slightly improve endothelial function—how well blood vessels expand and contract—an important marker of cardiovascular health 4.

Interestingly, walnuts don’t appear to strongly influence blood-sugar control. A recent review and meta-analysis found no consistent improvement in blood-glucose markers, such as fasting glucose or HbA1c 5.

In everyday terms, replacing a processed snack with a handful of walnuts may help keep arteries healthy and resilient over time.

2. Gut Microbiome Support

Walnuts may help maintain a balanced gut ecosystem.

A systematic (methodical) review found that eating walnuts may promote beneficial, butyrate-producing gut bacteria such as Roseburia 6. Another systematic review confirmed these findings, noting modest improvements in gut bacterial diversity and short-chain fatty acid production 7.

These findings suggest that a daily serving of walnuts may help foster a healthier, more balanced gut microbiome.

The Husk

The black walnut husk, or hull, has a long history in herbal medicine. Modern lab studies are beginning to validate some of these traditional uses, though current evidence comes from cell and animal research, not human trials.

3. Antimicrobial Effects

Black walnut husks have long been used in herbal medicine for their ability to keep microbes in check, and lab studies support that tradition. Extracts from the husk inhibit the growth of several bacteria and fungi, including Staphylococcus aureus, E. coli, and Candida albicans 8.

One interesting finding is that black walnut tincture seems to prevent Candida albicans from shifting into its invasive form—the stage when it’s most likely to cause infection 9. This suggests that black walnut has the potential to help the body maintain a healthier microbial balance rather than simply trying to “kill” everything off.

4. Antioxidant and Anti-Inflammatory Activity

The husk is also rich in polyphenols and naphthoquinones, plant compounds known for their strong antioxidant effects. In lab tests, these compounds help neutralize free radicals and protect DNA from oxidative damage 2 10.

That cellular protection could be one reason the black walnut is traditionally used for skin and immune support. While we don’t yet have human trials confirming these effects, the early evidence points to a plant with meaningful anti-inflammatory potential.

5. Anticancer Potential

The following compounds in black walnut husks have shown activity against cancer cells in lab studies 10:

• Juglone slowed the growth of breast and skin cancer cells and may be able to cross the blood–brain barrier.
• Gallic acid inhibited colon-cancer cell growth.
• Ellagic acid selectively slowed the growth of colon cancer cells while leaving other cells alone.

These are promising cellular findings, but they’re still early-stage. For now, it’s best to view black walnut as a food and herbal ally that supports overall cellular health, not as a cancer treatment.

6. Neuroprotective Potential

Animal studies suggest that juglone and other walnut compounds may help protect brain tissue after reduced blood flow (ischemia), which hints at possible neuroprotective effects 10.

This area of research is still developing, but it adds to the picture of black walnut as a complex plant with broad antioxidant and protective potential.

How to Use Black Walnuts and Their Husks (Wisely)

Black walnuts are one of the most nutrient-dense nuts you can eat—and their bold flavor pairs beautifully with oats, salads, yogurt, and baked goods.

A few practical notes:

• If picking walnuts from a tree, handle with care. The green husks contain juglone, which can stain the skin and cause irritation 11 12 13. Wear gloves when processing freshly fallen nuts 14.
• Allergies. Walnuts are responsible for up to 48% of tree-nut allergies 15. If you have any nut sensitivities, stick with other nutrient-dense foods.

For most people, a small handful of black walnuts a few times a week is a simple way to add protein, healthy fats, and antioxidants to your diet.

Supplemental Use

Black walnut hull extract is a common ingredient in many natural antimicrobial and gut-support formulas. It’s often combined with other botanicals, such as berberine, oregano oil, or wormwood, to help rebalance the gut microbiome and reduce microbial overgrowth.

At the clinic, we use antimicrobial supplements containing black walnut to help:

• Support microbial balance in the gut and small intestine
• Calm inflammation related to overgrowth or imbalance
• Promote digestive comfort and regularity

Our Biota-Clear line—a line-up of natural antimicrobial blends (Biota-Clear 1b, 2a, and 2b)—pairs black walnut with complementary herbs to address different patterns of gut imbalance. Each formula is used in a stepwise gut-repair approach and is adjusted to the individual.

Whether you use Biota-Clear or another reputable product, I recommend:

• Choosing formulas that specify standardized extracts and provide clear dosing guidance
• Working with a practitioner who is experienced with herbal antimicrobials
• Starting with a lower dose and increasing gradually
• Cycling formulas rather than taking one continuously
• Monitoring your body’s response, especially digestion and energy

When used carefully, early evidence suggests black walnut husks might play a supportive role in gut health. In the clinic, we view this ingredient as one possible aid—not a standalone solution—for promoting microbial balance.

Potential Side Effects

Most people tolerate black walnuts and their husks well when used appropriately, but concentrated extracts may occasionally cause 16 17:

• Mild skin irritation or blistering from direct contact
• Digestive upset or nausea at high doses 
• Liver or kidney stress with long-term or excessive use
• Reduced absorption of oral medications due to tannins

Avoid if You Are:

• Allergic to nuts
• Pregnant or breastfeeding
• Taking prescription medications
• Living with liver or kidney disease

The Bottom Line

Black walnuts are a powerhouse food—rich in protein, healthy fats, and antioxidants that can help support heart and gut health. 

The green husks are even more potent on paper, showing impressive antimicrobial and anti-inflammatory effects in lab studies. That hasn’t been proven in humans yet, and the husks contain juglone, a natural toxin that can irritate skin or cause harm if used incorrectly. 

So, crack open the nuts and enjoy them freely, but treat husk-based products as experimental and best used with professional guidance.

The Ruscio Institute has developed a range of high-quality formulations to help our clients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you. The information on DrRuscio.com is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.