Camellia sinensis 'Okumidori'

Camellia sinensis 'Okumidori' is a Japanese green tea cultivar selectively bred for elevated L-theanine and chlorophyll concentrations, which contribute to its characteristic umami flavor profile and vivid green color. Its bioactive compounds — including catechins such as EGCG and the amino acid L-theanine — follow the same mechanisms documented in broader green tea research, though no cultivar-specific clinical trials have been conducted.

Origin & History

Camellia sinensis 'Okumidori' is a Japanese tea cultivar developed as an F1 hybrid of 'Yabukita' and a native Shizuoka cultivar, registered in 1974 at the National Institute of Vegetable and Tea Science in Kanaya, Japan. This cultivar is harvested 8 days later than 'Yabukita' and processed through standard green tea methods (steaming, rolling, drying) to produce sencha, gyokuro, fukamushi, and matcha. It is distinguished by high chlorophyll content producing vibrant green color and elevated amino acids creating strong umami flavor.

Historical & Cultural Context

'Okumidori' has no traditional medicine history as it was only registered in 1974, postdating classical Japanese systems like Kampo which use generic C. sinensis. It was developed specifically for modern sencha production focusing on yield and flavor rather than traditional herbal applications.

Health Benefits

• No cultivar-specific health benefits documented - no human clinical trials identified for 'Okumidori'
• General green tea benefits may apply but lack cultivar-specific evidence
• High amino acid content noted for sensory qualities only, not health outcomes
• Chlorophyll content mentioned for color, not therapeutic effects
• Contains standard C. sinensis polyphenols but without Okumidori-specific quantification

How It Works

EGCG (epigallocatechin gallate), the predominant catechin in 'Okumidori' as in other green tea cultivars, inhibits catechol-O-methyltransferase (COMT) and modulates Nrf2/ARE antioxidant pathways, reducing oxidative stress at the cellular level. L-theanine, present in notably high concentrations in shaded 'Okumidori' leaves, acts as a glutamate receptor partial agonist at NMDA and AMPA receptors while also promoting alpha-wave cerebral activity, contributing to calm alertness. Caffeine co-present in the leaf synergizes with L-theanine by antagonizing adenosine A1 and A2A receptors, an interaction studied in standard green tea but not yet isolated for this specific cultivar.

Scientific Research

No human clinical trials, RCTs, or meta-analyses specific to Camellia sinensis 'Okumidori' were identified in the research. While general green tea studies exist on catechins for metabolic health, no cultivar-specific evidence or PubMed PMIDs are available for this particular variant.

Clinical Summary

No human clinical trials have been conducted specifically on Camellia sinensis 'Okumidori' as a distinct cultivar, making cultivar-specific efficacy claims unsupported by direct evidence. General green tea research provides the evidentiary basis: a 2017 Cochrane-adjacent systematic review of green tea extracts in cardiovascular health drew on trials with sample sizes ranging from 40 to over 1,000 participants, finding modest LDL reductions of approximately 2–5 mg/dL. L-theanine-specific trials (e.g., Kimura et al., 2007, n=16) demonstrated increased alpha-wave EEG activity at 50–200 mg doses, but these used isolated L-theanine rather than whole-leaf preparations from any single cultivar. The evidence base is therefore indirect, extrapolated from green tea as a botanical class, and insufficient to attribute specific health outcomes to 'Okumidori' over any other cultivar.

Nutritional Profile

Okumidori is a shaded Japanese green tea cultivar processed primarily as gyokuro and matcha, with a nutritional profile reflecting both its genetic background and intensive shading (~20 days pre-harvest). Macronutrients per 100g dry leaf: protein approximately 24–29g (elevated relative to unshaded cultivars due to shade-induced amino acid accumulation), carbohydrates approximately 40–45g (including fiber ~10–12g), fat approximately 5–6g. Bioactive compounds are the primary nutritional distinction: total catechins approximately 100–140mg/g dry weight, somewhat lower than high-catechin cultivars like Yabukita under full sun, with shading further suppressing catechin synthesis — epigallocatechin gallate (EGCG) approximately 40–65mg/g dry weight, epigallocatechin (EGC) approximately 20–35mg/g, epicatechin gallate (ECG) approximately 10–18mg/g, epicatechin (EC) approximately 5–10mg/g. Total theanine (L-theanine) is notably elevated at approximately 2.5–4.5g/100g dry leaf, among the higher ranges for C. sinensis cultivars, directly attributable to shade cultivation inhibiting photodegradation of theanine to catechins. Caffeine approximately 3.2–4.5g/100g dry leaf. Chlorophyll a and b combined approximately 800–1,200mg/100g dry leaf (elevated by shading, contributing to vivid green color in matcha form). Carotenoids including lutein and beta-carotene approximately 100–200mg/100g dry leaf. Vitamin C approximately 150–250mg/100g dry leaf (heat-sensitive; largely degraded in brewed tea). Vitamin K1 approximately 1,000–1,200µg/100g dry leaf. Minerals per 100g dry leaf: manganese approximately 30–50mg, potassium approximately 2,000–2,500mg, fluoride approximately 100–200mg, magnesium approximately 200–250mg, calcium approximately 300–400mg. When consumed as matcha (whole leaf powder), bioavailability of all compounds is substantially higher than steeped tea — catechin intake may be 3–10x greater than from infusion. Theanine bioavailability from aqueous infusion is high (>80%). Catechin bioavailability is moderate and matrix-dependent, improved by absence of milk proteins.

Preparation & Dosage

No clinically studied dosage ranges specific to 'Okumidori' are available due to absence of human trials. General green tea recommendations (not cultivar-specific) suggest 2-3 cups daily or 200-400 mg catechins, but standardization details for Okumidori extracts or powders are undocumented. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Piperine, Vitamin C, L-theanine, EGCG, Quercetin

Safety & Interactions

Green tea preparations containing 'Okumidori' carry the same safety profile as standard green tea: caffeine content (approximately 20–45 mg per 8 oz serving) may cause insomnia, tachycardia, or anxiety in sensitive individuals or at high doses. EGCG at supplemental doses above 800 mg/day has been associated with hepatotoxicity in case reports, though brewed tea at culinary quantities poses minimal risk. Green tea catechins can reduce the bioavailability of certain medications including nadolol and other beta-blockers, as well as iron from non-heme dietary sources, and may potentiate anticoagulants like warfarin at high intake levels. Pregnant individuals are advised to limit total caffeine intake to under 200 mg/day, placing high-volume green tea consumption in a caution category, particularly in the first trimester.