Eriodictyol

Eriodictyol is a flavanone compound found in citrus fruits that demonstrates potent antioxidant activity through hydroxyl group-mediated hydrogen donation to neutralize reactive oxygen species. This bioactive compound suppresses NF-κB signaling pathways and inhibits pro-inflammatory cytokine production in preclinical studies.

Origin & History

Eriodictyol is a naturally occurring flavanone (C₁₅H₁₂O₆) primarily found in citrus fruits like lemons, oranges, and grapefruits, as well as in herbs like yerba santa (Eriodictyon californicum). It is extracted using solvent methods such as ethanol or methanol, or isolated through chromatography, featuring a characteristic structure with hydroxyl groups at positions 5, 7, 3', and 4'.

Historical & Cultural Context

Eriodictyol-rich yerba santa (Eriodictyon californicum) has been used in Native American and early Californian traditional medicine since the 19th century for respiratory issues like coughs and asthma, typically as tea or tincture. The compound lacks deep historical roots in traditional systems like Ayurveda or Traditional Chinese Medicine.

Health Benefits

• Antioxidant activity through hydrogen donation from hydroxyl groups to neutralize reactive oxygen species (preclinical evidence only)
• Anti-inflammatory effects via NF-κB suppression and pro-inflammatory cytokine inhibition (animal studies)
• Potential cardiovascular support as part of citrus flavanoid complexes, though a 2019 RCT (PMID: 30813460) found no significant lipid improvements
• Possible respiratory health benefits based on traditional use of eriodictyol-rich yerba santa (historical evidence only)
• Cellular protection through Nrf2 pathway activation for antioxidant enzyme expression (preclinical PMID: 29576462)

How It Works

Eriodictyol exerts its antioxidant effects by donating hydrogen atoms from its hydroxyl groups at positions 3', 4', 5, and 7 to scavenge reactive oxygen species including superoxide anions and hydroxyl radicals. The compound suppresses inflammatory responses by inhibiting nuclear factor-κB (NF-κB) translocation and downstream production of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6. Additionally, eriodictyol modulates nitric oxide synthase activity and cyclooxygenase-2 expression in inflammatory pathways.

Scientific Research

No large-scale human randomized controlled trials or meta-analyses specifically on isolated eriodictyol exist in major databases. A 2019 RCT (PMID: 30813460) on citrus flavanones including eriodictyol in 60 hypercholesterolemic patients found no significant lipid improvements. Most evidence remains preclinical (in vitro/animal studies), with human data limited to observational studies on flavonoid-rich foods.

Clinical Summary

Current evidence for eriodictyol comes primarily from in vitro cell culture studies and animal models, with no published human clinical trials available. Animal studies using doses of 10-50 mg/kg body weight have demonstrated significant reductions in inflammatory markers and oxidative stress parameters. Cell culture research shows IC50 values of 15-30 μM for antioxidant activity against DPPH radicals. The lack of human clinical data limits the ability to establish therapeutic efficacy and optimal dosing recommendations for health applications.

Nutritional Profile

Eriodictyol is a pure flavanone compound (C15H12O6), not a whole food ingredient, therefore it contains no macronutrients, vitamins, minerals, or fiber as standalone components. Molecular weight: 288.25 g/mol. It is a flavanone-class polyphenol characterized by a 3',4',5,7-tetrahydroxyflavone skeleton. Naturally occurring concentrations in food sources: lemon peel (~0.5–2.0 mg/100g fresh weight), yerba santa (Eriodictyon californicum) leaves (~1–5% dry weight, the richest known source), orange peel (~0.1–0.8 mg/100g), and tomato skin (trace amounts, ~0.01–0.05 mg/100g). Bioavailability: oral bioavailability is moderate and highly variable; eriodictyol undergoes extensive first-pass colonic microbial metabolism, being converted to 3,4-dihydroxyphenylpropionic acid and other phenolic acids by gut microbiota. Peak plasma concentrations following typical dietary exposure are low (estimated <1 µmol/L). Glucuronidated and sulfated conjugates are the predominant circulating forms post-absorption, detected in plasma within 1–2 hours of ingestion. Lipophilicity (logP ~1.9) limits aqueous solubility (~0.03 mg/mL at physiological pH), restricting passive absorption in the upper GI tract. No caloric contribution, no protein, no lipid, no carbohydrate content as an isolated compound.

Preparation & Dosage

No clinically studied dosages for isolated eriodictyol due to lack of human trials. Preclinical contexts suggest 50-100 mg/day in powder or extract form, often as part of citrus bioflavonoid complexes standardized to 5-20% flavanones. Commercial supplements use non-standardized forms without established therapeutic ranges. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Hesperidin, Naringenin, Vitamin C, Quercetin, Rutin

Safety & Interactions

No specific safety data exists for isolated eriodictyol supplementation in humans, though it appears naturally in citrus fruits consumed safely for centuries. Theoretical interactions may occur with anticoagulant medications due to potential effects on platelet aggregation observed in animal studies. Pregnant and breastfeeding women should avoid concentrated eriodictyol supplements due to insufficient safety data. Individuals with citrus allergies may experience cross-reactivity with eriodictyol-containing supplements.