Nettle Leaf Extract

• Anti-inflammatory
• Antioxidant
• Immune modulation
• Metabolic support

• Allergy relief
• Prostate health
• Joint health
• Urinary tract health
• Hair and skin health
• Blood sugar regulation

Nettle leaf extract (Urtica dioica) exerts its biological effects through multiple mechanisms involving a complex array of bioactive compounds including flavonoids, phenolic acids, carotenoids, fatty acids, minerals, and various amines. One of its primary mechanisms is anti-inflammatory activity, which occurs through inhibition of key inflammatory pathways. Nettle extract inhibits nuclear factor-kappa B (NF-κB) activation, a master regulator of inflammation, thereby reducing the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). It also inhibits cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) enzymes, which are responsible for producing inflammatory mediators like prostaglandins and leukotrienes.

This multi-pathway inhibition contributes to nettle’s effectiveness in conditions like arthritis and allergic rhinitis. Nettle’s antihistamine properties are particularly relevant for allergy relief. The plant contains compounds that antagonize histamine H1 receptors and inhibit mast cell degranulation, reducing histamine release. Additionally, nettle extract inhibits tryptase, an enzyme involved in allergic responses.

For prostate health, nettle leaf extract works through several mechanisms. It inhibits 5α-reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT), which is implicated in benign prostatic hyperplasia (BPH). It also inhibits aromatase, which converts testosterone to estradiol, helping maintain hormonal balance. Furthermore, nettle extract interferes with the binding of sex hormone-binding globulin (SHBG) to prostate cell membranes, potentially reducing prostate cell proliferation.

Nettle’s antioxidant properties stem from its rich content of polyphenols, flavonoids, and carotenoids, which directly scavenge free radicals and reactive oxygen species. It also enhances endogenous antioxidant defenses by increasing the activity of superoxide dismutase (SOD), catalase, and glutathione peroxidase enzymes. This antioxidant activity protects cellular components from oxidative damage and may contribute to nettle’s anti-aging potential. In terms of metabolic effects, nettle extract demonstrates hypoglycemic properties through multiple mechanisms.

It enhances insulin sensitivity in peripheral tissues, stimulates glucose uptake, and inhibits intestinal α-glucosidase and pancreatic α-amylase enzymes, which slows carbohydrate digestion and absorption. Nettle also contains compounds that mimic insulin action and stimulate insulin secretion from pancreatic β-cells. For urinary tract health, nettle has mild diuretic properties, increasing urine output without depleting electrolytes. It also has antimicrobial effects against common urinary tract pathogens and anti-inflammatory effects on the urinary epithelium.

Regarding immune modulation, nettle extract stimulates T-lymphocyte proliferation and enhances natural killer (NK) cell activity while modulating cytokine production to balance immune responses. It also contains lectins that may have immunomodulatory effects. For skin and hair health, nettle inhibits 5α-reductase activity in hair follicles, potentially reducing hair loss. Its anti-inflammatory and antimicrobial properties benefit skin conditions, while its high silicon and zinc content supports collagen synthesis and tissue repair.

Nettle’s cardiovascular effects include mild hypotensive activity through vasodilation, mediated by nitric oxide production and calcium channel modulation. It also has modest effects on lipid metabolism, reducing total cholesterol and low-density lipoprotein (LDL) levels while increasing high-density lipoprotein (HDL). These diverse mechanisms of action explain nettle leaf extract’s wide range of traditional and modern therapeutic applications.

The typical dosage range for nettle leaf extract supplements is 300-1200 mg per day of dried extract, divided into 2-3 doses. For standardized extracts, dosages are typically lower, ranging from 100-500 mg daily, depending on the concentration of active compounds.

The bioavailability of nettle leaf extract varies significantly depending on the specific compounds and preparation methods. Water-soluble components like flavonoids and phenolic acids have moderate bioavailability (estimated at 15-30%),

while fat-soluble compounds like carotenoids have lower bioavailability (5-15%) unless consumed with dietary fats. Minerals in nettle extract, particularly iron, calcium, and magnesium, have variable absorption rates influenced by the presence of oxalates, which can form insoluble complexes.

Consuming nettle extract with a small amount of dietary fat enhances the absorption of fat-soluble components, Liquid extracts (tinctures) generally have higher bioavailability than solid forms due to pre-solubilization of active compounds, Standardized extracts with higher flavonoid content may offer improved bioavailability of these specific compounds, Fermentation of nettle preparations may enhance bioavailability by breaking down complex plant structures, Combining with black pepper extract (piperine) may enhance absorption of certain compounds through inhibition of first-pass metabolism, Liposomal delivery systems can significantly improve bioavailability by protecting compounds from degradation and enhancing cellular uptake

For allergic conditions, nettle extract is most effective when taken 15-30 minutes before potential allergen exposure. For anti-inflammatory effects, dividing the daily dose into 2-3 administrations provides more consistent blood levels. For prostate health, consistent daily dosing is more important than specific timing. When used for its mild diuretic effects, morning administration is preferable to avoid nighttime urination.

Taking nettle extract with meals may reduce potential mild gastrointestinal effects and enhance absorption of fat-soluble components, though it may slightly delay peak absorption times.

Metabolism: Flavonoids in nettle extract undergo extensive phase II metabolism in the liver, primarily through glucuronidation, sulfation, and methylation. Some compounds are metabolized by intestinal microbiota before absorption. Phenolic acids are primarily conjugated with glucuronic acid and sulfate in the liver.

Excretion: Metabolites are primarily excreted through urine, with a smaller portion eliminated via biliary excretion into feces. The elimination half-life of most active compounds ranges from 3-8 hours, though some minerals may have longer retention times in the body.

Age: Older adults may have reduced absorption due to decreased gastrointestinal function, Gastrointestinal pH: Altered stomach acidity can affect the solubility and stability of certain compounds, Intestinal transit time: Faster transit reduces contact time for absorption, Gut microbiome composition: Influences metabolism of certain compounds before absorption, Concurrent medications: May compete for absorption or metabolic pathways, Food interactions: High-fiber meals may reduce absorption of some compounds, Processing methods: Heat treatment during manufacturing can alter compound stability and bioavailability, Extraction solvents: Water, alcohol, or mixed solvents extract different profiles of compounds with varying bioavailability

• Mild gastrointestinal discomfort (occasional)
• Allergic reactions (rare, more common in individuals with existing allergies to plants in the Urticaceae family)
• Mild diuretic effect (expected pharmacological action, not adverse)
• Temporary burning or tingling sensation (with fresh plant contact, not typically with processed extracts)
• Mild hypoglycemia (rare, primarily in individuals taking anti-diabetic medications)
• Mild hypotension (rare, primarily in individuals taking anti-hypertensive medications)

• Known hypersensitivity to nettle or plants in the Urticaceae family
• Pregnancy and lactation (due to insufficient safety data and potential hormonal effects)
• Severe kidney disease (due to mineral content and diuretic effects)
• Severe liver disease (precautionary, due to limited data)
• Children under 6 years (due to insufficient safety data)

No established upper limit. Clinical studies have used doses up to 1500 mg daily of dried extract without significant adverse effects. Traditional use suggests safety at typical recommended doses, but long-term safety data for high doses is limited.

Medical Conditions: Individuals with diabetes, hypertension, kidney disorders, or bleeding disorders should use with caution and under medical supervision. Those with a history of kidney stones should be aware of the oxalate content in nettle.

Surgery: Discontinue at least 2 weeks before scheduled surgery due to potential effects on blood glucose, blood pressure, and mild anticoagulant effects.

Allergies: Individuals with allergies to related plants (hemp, hops) may have cross-reactivity to nettle.

Monitoring: Those using nettle for blood sugar or blood pressure management should regularly monitor these parameters.

Acute: Very low acute toxicity. Animal studies show LD50 values far exceeding therapeutic doses.

Chronic: Limited long-term toxicity studies, but traditional long-term use suggests safety at recommended doses.

Genotoxicity: No evidence of genotoxicity in available studies.

Carcinogenicity: No evidence of carcinogenic potential; some studies suggest potential anti-cancer properties.

Pediatric: Limited data available for children under 12 years; use with caution and only under healthcare provider supervision. Generally considered safe for children over 12 at adjusted doses.

Geriatric: Generally well-tolerated; monitor for potential interactions with medications commonly used in this population. May need dose adjustment due to potential changes in kidney or liver function.

Renal Impairment: Use with caution due to mineral content and diuretic effects. Not recommended in severe renal impairment.

Hepatic Impairment: Limited data; use with caution in those with liver disease.

Pregnancy: Traditionally used to reduce postpartum hemorrhage, but insufficient safety data for use during pregnancy. May have hormonal effects that could affect pregnancy. Generally not recommended.

Lactation: Insufficient safety data; traditionally believed to increase milk production, but scientific evidence is limited. Use with caution.

Moderate. Fresh nettle plants contain histamine, formic acid, and other compounds that cause the characteristic stinging sensation upon contact. However, processed nettle leaf extracts typically have these compounds deactivated. Allergic reactions to oral nettle supplements are uncommon but possible, particularly in individuals with existing allergies to plants in the Urticaceae family.

In the United States, nettle leaf extract is regulated as a dietary supplement under the Dietary Supplement Health and Education Act (DSHEA) of 1994. This classification means it is not subject to pre-market approval for safety and efficacy, but manufacturers are responsible for ensuring their products are safe before marketing and that any claims made are not false or misleading. The FDA has not approved any specific health claims for nettle leaf extract. Manufacturers can make structure/function claims (e.g., ‘supports joint health’ or ‘helps maintain healthy histamine levels’) but cannot make disease claims (e.g., ‘treats arthritis’ or ‘cures allergies’) without going through the drug approval process.

Nettle is generally recognized as safe (GRAS) for use in foods when used in normal culinary amounts.

Eu: In the European Union, nettle leaf has been evaluated by the European Medicines Agency (EMA) Committee on Herbal Medicinal Products (HMPC). The EMA has established a Community herbal monograph for nettle leaf, recognizing its traditional use for minor joint pain, mild allergic rhinitis, and as a diuretic to increase urinary output for flushing of the urinary tract. Products containing nettle leaf can be registered as Traditional Herbal Medicinal Products (THMPs) if they meet quality standards and have been in medicinal use for at least 30 years (including at least 15 years within the EU). Nettle is also approved for use in food supplements under the Food Supplements Directive 2002/46/EC.

Canada: Health Canada has included nettle leaf in the Natural Health Products Ingredients Database with a medicinal ingredient monograph. It is approved for use in Natural Health Products (NHPs) with several permitted claims, including as a nutritive tonic, for allergic rhinitis, and for joint pain. Products must meet the quality requirements outlined in the Natural Health Products Regulations and obtain a Natural Product Number (NPN) before being marketed.

Australia: The Australian Therapeutic Goods Administration (TGA) lists nettle leaf as an approved ingredient for listed complementary medicines. It is included in the Therapeutic Goods (Permissible Ingredients) Determination with specific requirements and restrictions. Products containing nettle must be listed on the Australian Register of Therapeutic Goods (ARTG) before they can be marketed.

Uk: Post-Brexit, the UK continues to recognize nettle products registered as THMPs under the previous EU system. The Medicines and Healthcare products Regulatory Agency (MHRA) maintains similar standards to the EMA for herbal products.

Germany: In Germany, nettle leaf has been evaluated by Commission E (the German regulatory authority for herbs) and is approved for use in supportive treatment of rheumatic ailments and for irrigation therapy in inflammatory conditions of the lower urinary tract. It has a positive monograph, indicating official recognition of its medicinal uses.

Us: In the US, nettle leaf supplements must be labeled as dietary supplements and include a Supplement Facts panel listing the amount of nettle leaf or extract per serving. They must include the standard FDA disclaimer: ‘These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.’ Any structure/function claims must be accompanied by this disclaimer.

Eu: In the EU, products registered as THMPs must include specific approved indications based on traditional use, recommended dosage, and appropriate warnings. Food supplements must comply with the Food Supplements Directive labeling requirements, including recommended daily dose and warning statements.

Warnings: Common required warnings across jurisdictions include: not for use during pregnancy and lactation; keep out of reach of children; consult healthcare practitioner before use if taking medications or have medical conditions, particularly diabetes, blood pressure disorders, or hormone-sensitive conditions.

Standardization: One of the primary regulatory challenges for nettle leaf products is the lack of universally accepted standardization parameters. Different manufacturers may standardize to different compounds (e.g., flavonoids, silicic acid, or total phenolics) or may not standardize at all, leading to product variability.

Claim Limitations: The restriction on disease claims limits manufacturers’ ability to communicate some of the better-researched benefits of nettle, particularly for allergic rhinitis and joint pain, where clinical evidence exists but cannot be explicitly stated on product labels in many jurisdictions.

Quality Control: Ensuring consistent quality and accurate species identification remains a challenge. Adulteration with similar-looking plants or confusion between nettle leaf and root (which have different properties and uses) can occur.

Sustainable Sourcing: As demand increases, ensuring sustainable wild-harvesting practices or transitioning to cultivated sources presents regulatory and supply chain challenges.

In recent years,

there has been increased regulatory scrutiny of herbal products globally, with more emphasis on quality control, standardization, and evidence-based approaches. The European Food Safety Authority (EFSA) has been evaluating health claims for botanicals, though most evaluations have been on hold pending resolution of the broader regulatory framework for botanicals in the EU.

There is growing interest from regulatory bodies in the potential health benefits of nettle, particularly its anti-inflammatory and anti-allergic properties, though

this has not yet translated into approved health claims in most regions. Some countries are developing more specific quality standards for nettle products, including testing requirements for potential contaminants like heavy metals and pesticides.

Nettle has a dual status in many jurisdictions as both a food and a supplement ingredient. Fresh or dried nettle leaves are widely used as a food (in soups, teas, etc.) and are generally regulated as conventional foods. More concentrated extracts or formulations making health claims are typically regulated as supplements or herbal medicines.

This dual classification can create regulatory complexities, particularly for products that fall in the gray area between food and supplement, such as nettle teas that make health claims.

Low to Medium

The typical cost for nettle leaf extract supplements ranges from $0.10 to $0.50 per 300-600 mg dose, depending on brand, formulation, and quality. For a standard daily dose, this translates to approximately $3-15 per month for supplementation.

Nettle leaf extract offers good value for its cost when compared to other supplements with similar applications. For allergic rhinitis, it provides a cost-effective alternative to both over-the-counter antihistamines and other natural options like quercetin or butterbur, with fewer side effects than pharmaceutical options. For joint health, it is significantly less expensive than supplements like glucosamine/chondroitin while offering complementary anti-inflammatory benefits. As a nutritive tonic, it provides a broad spectrum of minerals and vitamins at a lower cost than many specialized mineral supplements.

The relatively low cost is due to nettle’s abundance, ease of cultivation, and minimal processing requirements for basic preparations.

Harvesting method (wild-harvested vs. cultivated), Organic certification (organic products typically cost 20-50% more), Processing method (simple drying vs. extraction processes), Standardization (standardized extracts cost more but offer more consistent potency), Brand positioning and marketing approach, Packaging (sustainable or premium packaging increases costs), Third-party testing and certifications, Geographic source (European sources often command premium prices)

Bulk Purchasing: Buying larger quantities can reduce the per-dose cost by 20-40%.

Subscription Services: Many supplement companies offer subscription discounts of 10-15% for regular deliveries.

Combination Products: For certain applications, combination products containing nettle along with synergistic compounds may offer better value than purchasing supplements separately.

Growing Your Own: Nettle is easily grown or wild-harvested in many regions, offering significant cost savings for those willing to process it themselves.

Tea Form: Nettle tea is generally less expensive per dose than capsules or extracts, though it may contain lower concentrations of certain compounds.

Properly stored dried nettle leaf typically has a shelf life of 1-2 years. Encapsulated or tableted extracts generally have a shelf life of 2-3 years. Liquid extracts (tinctures) typically have a shelf life of 3-5 years due to the preservative effect of alcohol. Freeze-dried extracts, when properly stored, can maintain potency for 2-3 years.

Store in a cool, dry place away from direct sunlight. Optimal temperature range is 15-25°C (59-77°F). Avoid exposure to high humidity. Keep container tightly closed when not in use. Dried herb and solid extract forms should be stored in airtight containers, preferably opaque or amber to protect from light. Liquid extracts should be stored in tightly sealed amber glass bottles. Refrigeration is not necessary but may extend shelf life, particularly for alcohol-free liquid preparations.

Light exposure: UV radiation can degrade flavonoids and other phenolic compounds, Heat: Temperatures above 40°C (104°F) can accelerate degradation of thermolabile compounds, Oxygen: Exposure to air promotes oxidation of phenolic compounds and other antioxidants, Moisture: High humidity can promote hydrolysis reactions and microbial growth, Microbial contamination: Improper drying or storage can lead to mold or bacterial growth, Enzymatic activity: Residual plant enzymes can degrade active compounds if not properly deactivated during processing

Dried Herb: Relatively stable when properly dried and stored, though gradual loss of volatile compounds and oxidation of phenolics occurs over time. Typical shelf life: 1-2 years.

Capsules Tablets: More stable than raw herb due to reduced surface area exposure to air. Excipients may provide additional stability. Typical shelf life: 2-3 years.

Liquid Extracts: Alcohol-based extracts (tinctures) are highly stable due to the preservative effect of alcohol. Glycerites and alcohol-free extracts are less stable and may require refrigeration after opening. Typical shelf life: 3-5 years for alcohol-based, 1-2 years for alcohol-free.

Freeze Dried Extracts: Excellent stability due to very low moisture content and reduced oxidation during processing. Highly sensitive to moisture after packaging is opened. Typical shelf life: 2-3 years.

Standardized Extracts: Stability varies based on the specific compounds standardized and the extraction process. Generally stable when properly formulated with appropriate excipients. Typical shelf life: 2-3 years.

High-performance liquid chromatography (HPLC) to monitor levels of key compounds like flavonoids and phenolic acids over time, Spectrophotometric analysis to track changes in total phenolic content, Antioxidant capacity assays (DPPH, ORAC, FRAP) to monitor functional degradation, Accelerated stability testing at elevated temperatures and humidity, Microbial testing to ensure absence of pathogenic growth during storage, Organoleptic evaluation (color, odor, taste) for quality control

Antioxidants: Addition of natural antioxidants like vitamin E or rosemary extract can help prevent oxidation of phenolic compounds.

Desiccants: Silica gel packets included in packaging can reduce moisture exposure, particularly important for powdered forms.

Nitrogen Flushing: Replacing oxygen with nitrogen in the package headspace can significantly reduce oxidative degradation.

Vacuum Packaging: Removing air from packaging reduces oxidation potential.

Microencapsulation: Encapsulating sensitive compounds in protective matrices can enhance stability against environmental factors.

Proper Drying: Initial proper drying to optimal moisture content (typically <10%) is critical for long-term stability.

Dried herb and solid dosage forms remain relatively stable for 6-12 months after opening if properly resealed and stored according to recommendations. Liquid extracts maintain stability for 1-2 years after opening if properly sealed between uses. Freeze-dried extracts are particularly sensitive to moisture and should ideally be used within 3-6 months after opening, with careful attention to resealing and possibly using desiccants.

Nettle leaf extract contains natural chlorophyll which may degrade over time, causing a color change from bright green to olive or brownish-green.

This color change does not necessarily indicate loss of medicinal properties, as many of the key flavonoids and phenolic compounds remain stable even as chlorophyll degrades.

However , significant darkening or development of off-odors may indicate improper storage or degradation of active compounds. The mineral content of nettle extract (calcium, magnesium, iron, etc.) remains stable during storage, even

when organic compounds may degrade.

Natural Sources

Cultivation And Harvesting

Extraction Methods

Quality Considerations

Commercial Production

Regional Variations

Nettle (Urtica dioica) has a rich and diverse history of use spanning thousands of years across multiple civilizations. Its name derives from the Anglo-Saxon word ‘noedl’ (needle), referring to its stinging hairs, while its genus name Urtica comes from the Latin ‘urere’ meaning ‘to burn,’ again referencing its characteristic sting.

The earliest documented medicinal use of nettle dates back to Ancient Egypt, where archaeological evidence suggests it was used for arthritis and lower back pain. Ancient Greek and Roman physicians extensively documented nettle’s medicinal applications. Hippocrates (460-370 BCE), the father of modern medicine, recorded over 60 medicinal uses for nettle, including as a diuretic, for joint pain, and for wound healing. Dioscorides, in his De Materia Medica (1st century CE), recommended nettle for asthma, pleurisy, and gangrenous wounds. The Roman physician Galen prescribed nettle for numerous conditions including diuresis, arthritis, and as a warming herb.

In ancient Rome, a practice called ‘urtication’ involved deliberately stinging the skin with fresh nettle to treat arthritis and rheumatism, utilizing the counter-irritant effect and the anti-inflammatory compounds released during stinging. This practice continued well into the 19th century in various European folk medicine traditions.

During the Middle Ages, nettle remained an important medicinal herb throughout Europe. The 12th-century German abbess and herbalist Hildegard von Bingen recommended nettle for stomach ailments and as a detoxifying herb. The herb was also valued for its fiber, which was used to make cloth that was comparable to linen but more durable. During World War I, Germany used nettle fiber extensively when cotton was in short supply, producing nettle uniforms and even nettle paper.

In traditional European folk medicine, nettle was considered a spring tonic and blood purifier, used to cleanse the body after winter. It was also widely used for gout, arthritis, anemia, and as a galactagogue to increase breast milk production. The 17th-century English herbalist Nicholas Culpeper wrote that nettle ‘consumes the phlegmatic superfluities in the body of man, that the coldness and moisture of winter has left behind.’

Native American tribes, including the Winnebago and Dakota, used nettle medicinally for similar purposes as Europeans, suggesting independent discovery of its properties. They applied nettle topically for muscle and joint pain and consumed it as a nutritious food and medicine for pregnancy, childbirth, and numerous other conditions. The Winnebago used nettle root tea for urinary and prostate problems, an application that has been validated by modern research.

In Traditional Chinese Medicine (TCM), a related species, Urtica thunbergiana, has been used for thousands of years, primarily for urinary issues, allergic rhinitis, and as a treatment for what TCM practitioners call ‘wind-damp’ conditions, which correlate roughly with arthritis and rheumatism in Western medicine.

In Ayurvedic medicine from India, nettle (known as Vrishchhiyaa-shaaka) has been used for thousands of years as a blood purifier, diuretic, and for treating skin disorders, allergies, and anemia. It was also valued for its high mineral content, particularly iron, making it an important remedy for anemia.

During the 18th and 19th centuries, nettle continued to be used in Western herbal medicine for rheumatism, gout, and as a diuretic. Sebastian Kneipp, a 19th-century Bavarian priest and one of the founders of the naturopathic medicine movement, was a strong proponent of nettle for purifying the blood and treating rheumatism.

The 20th century saw a decline in nettle’s medicinal use with the rise of pharmaceutical medicine, though it remained important in traditional European herbalism and experienced a revival with the growth of interest in natural medicine in the latter part of the century. Modern scientific research began to validate many of nettle’s traditional uses, particularly for allergic rhinitis, benign prostatic hyperplasia (using the root), and inflammatory conditions.

In contemporary herbal medicine, nettle leaf is valued for its anti-inflammatory, anti-allergic, and nutritive properties. It has become popular as a natural remedy for seasonal allergies, a use that has been supported by clinical trials. The root has gained recognition for supporting prostate health, while the leaf is more commonly used for allergies, inflammation, and as a nutritive tonic.

Beyond medicine, nettle has a long history as a nutritious food source, particularly in spring when fresh greens were scarce. It contains more protein than almost any other leafy green vegetable and is rich in vitamins and minerals. Traditional cuisines from Scandinavia to the Mediterranean include nettle soups, pesto, and cooked greens. Nettle beer and nettle tea have been consumed for centuries, both for their flavor and medicinal benefits.

Nettle also has a significant history in textile production. Nettle fiber has been used to make cloth since the Bronze Age, with archaeological evidence of nettle textiles dating back to 2000 BCE in Denmark. Nettle cloth was widely used throughout Europe until cotton became more readily available, and experienced a revival during both World Wars when other fibers were scarce.

Today, nettle continues to bridge traditional uses and modern applications. It is being investigated for sustainable textile production, as a nutritional supplement, in organic farming as a fertilizer and pest deterrent, and in an expanding range of medicinal applications as research continues to validate and expand upon its traditional uses.

Investigation of nettle extract for management of metabolic syndrome parameters, Evaluation of topical nettle preparations for inflammatory skin conditions, Assessment of nettle extract’s effects on immune function in healthy adults, Comparative study of different nettle species and extraction methods for allergic rhinitis

Long-term safety and efficacy studies beyond 12 weeks, Standardization of extracts and identification of optimal active compound profiles, Comparative effectiveness studies against conventional treatments, Dose-response relationships for different indications, Mechanisms of action in vivo, particularly for metabolic and immune effects, Effects on gut microbiome composition and function, Potential epigenetic mechanisms, Bioavailability and pharmacokinetics of specific bioactive compounds