Dr. Grey AI

Limonene

D-Limonene is a monoterpene found in citrus peel (especially lemons and oranges). Has preclinical anti-cancer and hepatoprotective effects. Metabolized to perillyl alcohol which has more potent anti-cancer activity. Sometimes marketed as fat burner but NO evidence supports this claim. May help with heartburn/GERD (coats esophagus). Can be obtained from fresh-squeezed citrus juice with pulp. Limited human evidence for most claims.

Quick Answer

What it is

D-Limonene is a monoterpene found in citrus peel (especially lemons and oranges). Has preclinical anti-cancer and hepatoprotective effects.

Key findings

  • Grade C: Anti-Cancer Activity
  • Grade C: Heartburn/GERD Relief
  • Grade D: Antioxidant Activity

Safety

  • In rodent models, D-limonene reduces diet-induced hepatic fat accumulation and shows antifibrotic effects against CCl4-induced liver toxicity in Wistar rats.
  • In rodent models, D-limonene diminished CCl4-induced cardiac toxicity by alleviating oxidative stress and inflammatory markers.
ℹ️ Quick Facts: Limonene

Quick Facts: Limonene

  • Best Evidence:Grade D
  • Conditions Studied:2
  • Research Outcomes:8
  • Key Effect:Antioxidant Status
Outcomes by grade:
A0
B0
C2
D6
2 conditions · 8 outcomes

Detailed Outcomes

|
C
Anti-Cancer Activity
D-Limonene and its metabolite perillyl alcohol demonstrate anti-cancer effects in multiple animal models (breast, colon, liver, pancreatic cancer) via inhibition of isoprenylation of growth-related proteins. Early-phase human clinical trials have been conducted with perillyl alcohol, though direct human evidence for D-limonene itself remains limited.
moderate↓Worsens
C
Heartburn/GERD Relief
Small human studies suggest D-limonene (typically 1000 mg every other day) may relieve heartburn symptoms, possibly by coating the esophageal mucosa or modulating gastric motility. Has been used as an alternative therapy for GERD symptoms.
3 studies
moderate↓Worsens
D
Antimicrobial Activity
In vitro studies demonstrate D-limonene has antibacterial activity against MRSA (synergistic with gentamicin), E. coli O157:H7, and antifungal properties against spoilage yeasts. Also inhibits quorum sensing in Pseudomonas aeruginosa. No human clinical evidence.
small↑Improves
D
Liver Protection
In rodent models, D-limonene reduces diet-induced hepatic fat accumulation and shows antifibrotic effects against CCl4-induced liver toxicity in Wistar rats. Hepatoprotective mechanisms may involve enzyme induction and reduction of oxidative stress markers.
moderate↓Worsens
D
Neuroprotection
A 2021 review summarized neuroprotective potential of limonene from preclinical studies. In animal models, limonene inhibits methamphetamine-induced locomotor activity via regulation of 5-HT neuronal function and dopamine release. No human clinical data exists.
small↑Improves
D
Blood Glucose Regulation
In streptozotocin-induced diabetic rats, D-limonene ameliorated hyperglycemia and diabetes-related complications. In vitro studies of Citrus medica extracts containing limonene show activities relevant to diabetes. No human clinical trials available.
moderate↓Improves
D
Antioxidant Activity
Multiple in vitro studies demonstrate antioxidant activity of D-limonene and limonene-rich citrus peel essential oils, including DPPH radical scavenging. No human clinical trials have specifically evaluated D-limonene's antioxidant effects in vivo.
small↑Improves
D
Cardioprotection
In rodent models, D-limonene diminished CCl4-induced cardiac toxicity by alleviating oxidative stress and inflammatory markers. One small human study found that olfactory stimulation with grapefruit essential oil (rich in limonene) affected autonomic neurotransmission and blood pressure.
small↓Worsens

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