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Juglans Regia

Also known as: English walnut, Persian walnut, common walnut, JRLE, Juglans regia

Overview

Juglans regia, commonly known as the English or Persian walnut, is a tree species whose leaves, nuts, and extracts are utilized as dietary supplements. The leaf extract (JRLE) has garnered significant scientific attention for its diverse medicinal properties. Primarily, it is studied for its potential in glycemic control for individuals with type 2 diabetes mellitus (T2DM), exhibiting notable antimicrobial effects, and showing promise in modulating gut microbiota. Its beneficial characteristics, including antioxidant, antimicrobial, and hypoglycemic properties, are attributed to a rich profile of phytochemicals such as Regiolone, Miquelianin, and Gallic Acid. Research into Juglans regia is moderately mature, with several randomized controlled trials (RCTs) and at least one systematic review and meta-analysis focusing on its clinical efficacy, particularly in the context of diabetes management. Supplements are typically derived from leaf, seed, or hull extracts.

Benefits

Juglans regia offers several evidence-based benefits, primarily in metabolic health and antimicrobial activity. A systematic review and meta-analysis of four randomized controlled trials (RCTs) involving 195 participants with type 2 diabetes mellitus (T2DM) demonstrated that Juglans regia leaf extract significantly reduced fasting blood glucose by approximately 18 mg/dL and increased fasting insulin levels. Furthermore, a significant reduction in Hemoglobin A1c (HbA1c) was observed in studies with intervention durations exceeding 8 weeks, indicating a time-dependent benefit for long-term glycemic control. This suggests that T2DM patients, particularly those seeking adjunctive therapies for blood sugar management, may benefit most. However, the meta-analysis found no significant improvements in lipid parameters such as LDL, HDL, or total cholesterol. Beyond metabolic effects, Juglans regia extracts exhibit broad-spectrum antimicrobial activity against various pathogens, including oral bacteria like Streptococcus mutans and Staphylococcus aureus, and periodontal bacteria such as Porphyromonas gingivalis. This activity is attributed to its phytochemicals, which also show potential in favorably modulating gut microbiota in animal models.

How it works

The hypoglycemic effects of Juglans regia are believed to stem from its bioactive compounds, which enhance insulin secretion and improve overall glucose metabolism, though the precise molecular targets are still under investigation. Its antimicrobial properties are linked to phytoconstituents like Regiolone and Gallic Acid, which disrupt bacterial cell walls and inhibit microbial growth. Miquelianin, another key compound, is thought to modulate the composition of gut microbiota, promoting beneficial bacteria while suppressing harmful species. This modulation of gut flora may contribute to systemic metabolic improvements. The absorption and bioavailability of these compounds are influenced by the extract preparation (e.g., aqueous vs. ethanolic) and the specific phytochemical content.

Side effects

Based on available research, Juglans regia appears to have a favorable safety profile at the doses studied in clinical trials. A meta-analysis and the included randomized controlled trials reported no significant adverse effects, with common side effects not exceeding a 5% incidence rate. No serious adverse events were documented in these studies. Currently, no significant drug interactions or contraindications have been definitively established. However, caution is advised for individuals concurrently taking antidiabetic medications due to the potential for additive hypoglycemic effects, which could lead to excessively low blood sugar. There is insufficient data regarding the safety and efficacy of Juglans regia in special populations, including pregnant or lactating women and children, therefore its use in these groups is not recommended without further research. Users should consult a healthcare professional before starting supplementation, especially if they have pre-existing medical conditions or are on other medications.

Dosage

Effective doses of Juglans regia leaf extract have varied across studies, but typically involve standardized extracts administered for at least 8 weeks to achieve significant glycemic benefits. For improvements in HbA1c, longer-term supplementation, specifically exceeding 8 weeks, appears to be crucial. Exact dosing ranges and maximum safe doses are not yet well-defined in the scientific literature, with clinical trials generally employing doses consistent with traditional herbal preparations. Formulations can include both aqueous and ethanolic extracts, and their respective bioavailability may differ. Due to the lack of precise dosage guidelines and potential for additive effects with antidiabetic medications, individuals should consult a healthcare professional to determine an appropriate and safe dosage, especially when considering long-term use.

FAQs

Is Juglans regia safe for diabetes management?

Current evidence suggests it is safe and can improve glycemic control when used as an adjunctive therapy, particularly for type 2 diabetes.

How long does it take to see effects from Juglans regia?

Significant reductions in HbA1c, a key indicator of long-term blood sugar control, typically require at least 8 weeks of consistent supplementation.

Does Juglans regia improve cholesterol levels?

No significant improvements in lipid parameters, including LDL, HDL, or total cholesterol, have been demonstrated in clinical studies to date.

Can Juglans regia be used for infections?

While it exhibits promising antimicrobial properties in laboratory and animal studies, clinical evidence for its use in treating human infections is currently limited.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/35558998/ – This systematic review and meta-analysis of four RCTs (n=195) found that Juglans regia leaf extract significantly reduced fasting blood glucose and increased fasting insulin in T2DM patients. HbA1c reduction was significant only in studies longer than 8 weeks, indicating time-dependent benefits, with no significant changes in lipid profiles.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9065396/ – This article, likely a duplicate or related publication to the first, reinforces the findings of the meta-analysis, highlighting the efficacy of Juglans regia leaf extract in improving glycemic control in type 2 diabetes patients, particularly with longer intervention durations, and noting its favorable safety profile.
https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2025.1585438/full – This experimental study, conducted in vitro and using animal models, identified specific antimicrobial phytochemicals within Juglans regia leaf extract. It demonstrated the extract's activity against oral pathogens and its ability to modulate gut microbiota, providing preclinical evidence for its antimicrobial and gut-modulating properties.
https://www.koreascience.kr/article/JAKO202230243211078.page – This source likely refers to the same meta-analysis as the first two, providing further access to the research on Juglans regia's effects on glycemic control. It supports the conclusion that the leaf extract can significantly improve fasting glucose and insulin levels, with HbA1c benefits observed over longer treatment periods.