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Olive leaf

Supplement botanical immuneheart & metabolic
Aka: oleuropein, Olea europaea
Brands seen in Singapore: California Gold Nutrition, NOW Foods, Swanson Vitamins, Nutricost, Nature's Answer
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Meta-analysis: small falls in systolic bp and triglycerides
Pros & cons
Pros
  • 12 RCTS, 819 adults pooled in a 2022 meta-analysis
  • Systolic bp fell 3.86 mmhg; triglycerides 9.51 mg/dl
  • 2024 review: 12 more RCTS, 683 adults, mixed results
Cons
  • No change in glucose, liver, kidney or inflammation
  • Evidence for those outcomes graded low-to-very low
  • Doses ranged from 5 mg to a 990 ml daily infusion
Sources
  1. Razmpoosh et al., The effects of olive leaf extract on cardiovascular risk factors in the general adult population: a systematic review and meta-analysis of RCTs (Diabetol Metab Syndr 2022, PMID 36271405) — pooled results · read 2026-08-27
    what it says
    “Twelve studies (n = 819 participants) … OLE supplementation significantly decreased triglyceride (TG) levels (WMD = - 9.51 mg/dl) … and systolic blood pressure (SBP) (WMD = - 3.86 mmHg)”
  2. Razmpoosh et al. 2022 (PMID 36271405) — null outcomes, subgroups and evidence quality · read 2026-08-27
    what it says
    “no meaningful changes were seen in glucose hemostasis, liver and kidney, or inflammatory markers … the quality of evidence for glucose hemostasis variables, liver, kidney, and inflammatory markers, were low-to-very low”
  3. Frumuzachi et al., Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of RCTs (Antioxidants 2024, PMID 39334699) — scope and dose range · read 2026-08-27
    what it says
    “systematic review analyzed 12 human randomized controlled trials (RCTs), involving 683 participants … The studies described different dosages and forms of supplementation, ranging from 5 mg/d HT to 990 mL/d olive leaf infusion”
  4. Frumuzachi et al. 2024 (PMID 39334699) — authors' conclusion · read 2026-08-27
    what it says
    “Despite the mixed outcomes, OLE and HT supplementation show potential for improving some of the cardiometabolic health outcomes and bone, joint, and cognitive health. However, further studies are necessary to understand their benefits better and address existing limitations.”
  5. HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev. No. 001 (October 2025), Annex A (118 rows) and Annex B (4 rows) — Olea europaea / olive leaf / oleuropein NOT LISTED in either (Annex A neighbours: 58. Juniperus sabina, 73. Nerium indicum (oleander)) · read 2026-08-27
    what it says
    “The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list.”
  6. HSA Singapore — Health Supplements Guidelines GL-CHPB-3-001 Rev. No. 020 (January 2026), clause 4.8 with Tables 4–5 (vitamins and minerals only — no botanical or bee-product rows) · read 2026-08-27
    what it says
    “4.8 HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5.”
  7. iHerb Singapore — Olive Leaf category page, default listing order · read 2026-08-27
    what it says
    “1 - 48 of 57 results … California Gold Nutrition, EuroHerbs™ Olive Leaf Extract … NOW Foods, Olive Leaf Extract, 500 mg … Swanson Vitamins, Extra Virgin Olive Oil … Nutricost, Olive Leaf Extract, 750 mg … Nature's Answer, Olive Leaf Extract Standardized”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.