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5 Best Olive Leaf Extracts That Pack 2x the Antioxidants of Green Tea
Written By Supplement Institute Review Team
Olive oil gets all the attention—but it’s the leaf that holds the secret compound: a bitter plant substance called oleuropein. It’s up to 2x stronger than green tea extract. And it’s what gives the olive tree its resistance to disease. When concentrated into an extract, it delivers those protective benefits to you. Island Nutrition olive leaf extract best overall due to its high oleuropein content and authentic sourcing from family-run farms in Spain.
Detailing the Best Olive Leaf Extracts of 2025
Island Nutrition Olive Leaf Extract
Best Overall
The Island Nutrition olive leaf extract contains 25% oleuropein, 40% total polyphenols, and a 20% hydroxytyrosol complex—but what does that actually mean? It means each capsule contains a concentrated dose of the most researched compounds found in olive leaves and olive oil. Oleuropein may support immune function and blood sugar levels, while hydroxytyrosol is known for its antioxidant power, and together they help protect the body at a cellular level. They’re the reason olive leaf has been studied so extensively.
That said, our review team voted Island Nutrition best overall because it doesn’t just meet the standard—it raises it. The brand’s extract comes from olive trees grown on family-run farms in Spain and is processed using a chemical-free, traditional method that protects the full spectrum of polyphenols. It’s instructive for the immune system, targeted in its benefits, and surprisingly affordable for the quality. It’s also one of the highest-rated olive leaf extracts online—with more than 1,000 five-star reviews and a loyal customer base that keeps coming back.
Carlyle Olive Leaf Extract
Runner-Up
The Carlyle olive leaf extract offers a different kind of value—high potency, big count, and a much lower price. Each capsule contains the equivalent of 9,000mg of olive leaf and 150mg of standardized oleuropein. What makes this brand the runner-up instead of the winner? While it delivers a strong oleuropein punch, it doesn’t include hydroxytyrosol or the full-spectrum polyphenol profile found in Island Nutrition’s extract. And its sourcing isn’t as transparent—there’s no specific mention of where the olive leaves come from or how they’re processed. That said, it’s still laboratory-tested, non-GMO, and made by a trusted U.S. brand with decades of experience. If you’re looking for an affordable way to get the benefits of olive leaf extract, this is the one to pick.
Now Foods Olive Leaf Extract
Best Value
The Now Foods olive leaf extract holds a 4.6-star rating from over 5,000 customers, with more than 2,000 bottles sold in the past month. It’s not the most concentrated formula on this list, but it remains a top choice for those who want a lower-dose olive leaf supplement from a long-established, GMP-certified brand. Each capsule contains 500mg of olive leaf extract standardized to 6% oleuropein, with 120 capsules per bottle—making it the most affordable by count.
While it doesn’t match the potency of the best overall from Island Nutrition (25% oleuropein with added hydroxytyrosol) or the runner-up from Carlyle (150mg standardized oleuropein), it offers a formula made by a brand trusted since 1968. For those seeking a lower-intensity extract backed by decades of manufacturing experience, this is a reliable pick.
Pure Encapsulations Olive Leaf Extract
Hypoallergenic Pick
If you’re looking for a supplement that’s hypoallergenic and ultra-clean, Pure Encapsulations olive leaf extract stands out. It’s made by one of the most respected names in practitioner-grade supplements and is free from common allergens, artificial fillers, and unnecessary additives. While the label doesn’t list the oleuropein percentage, the focus here is on purity and formulation—developed with input from medical professionals and tested for quality at every stage.
That said, it’s more expensive than both the best overall and runner-up. A 60-capsule bottle is priced around $40 (as of this writing), which means you’re paying more for premium sourcing and hypoallergenic assurance rather than high-dose potency. Unlike Island Nutrition’s best overall formula (with 25% oleuropein and hydroxytyrosol) or Carlyle’s 150mg standardized extract, this one doesn’t highlight concentration. But for those with dietary sensitivities or looking for the most strictly vetted brand, this is the supplement most often recommended by professionals.
Best Naturals Olive Leaf Extract
Best Range
All the supplements on our list have a 4.5 or 4.6-star rating—and the Best Naturals olive leaf extract is no exception. Each capsule contains 700mg of olive leaf extract, and the 90-count bottle is typically priced under $10. It’s third-party lab tested, made in a GMP-compliant, FDA-registered facility, and free from gluten, artificial additives, preservatives, and common allergens.
Unlike the best overall from Island Nutrition, this one doesn’t list its oleuropein content or include hydroxytyrosol. And while Carlyle’s runner-up offers a standardized 150mg dose of oleuropein, Best Naturals leaves the active compound level unspecified. Even so, for shoppers focused on clean ingredients and general antioxidant support—without paying a premium—this is a solid and affordable choice.
Choosing the Best Olive Leaf Extract: A User’s Guide
Quick Facts About Olive Leaf Extract You’ll Want to Know
Antioxidant strength: Oleuropein is up to 2x stronger than green tea extract.
Sick less often: Reduced illness duration by 28% in athletes.
Natural blood pressure support: Lowered systolic BP by 11.5 mmHg and diastolic by 4.8 mmHg in adults with stage 1 hypertension.
As effective as medication: Matched Captopril’s effect on lowering blood pressure.
Insulin sensitivity: Improved by 15%, with a 28% boost in β-cell function.
Lowers LDL cholesterol: Reduced bad cholesterol levels in adults with mild hypertension.
Antibacterial: Inhibited growth of E. coli, Staphylococcus aureus, and Salmonella.
Anti-fungal: Active against Candida albicans.
Fights inflammation: Suppresses IL-6, TNF-α, and other pro-inflammatory markers.
Skin benefits: Protects against UV damage and collagen breakdown in cell studies.
Cognitive support: Shown to reduce oxidative stress in brain cells.
7 Things You Need to Consider When Choosing the Best Olive Leaf Extract
1. Oleuropein Content
This is the compound everyone talks about—and for good reason. Oleuropein is the primary active polyphenol in olive leaves, and it’s been linked to immune support, antioxidant activity, and healthy blood sugar levels.
Some supplements list the olive leaf dose (like 500mg), but not how much of that is standardized to oleuropein. That matters. The Island Nutrition olive leaf extract, for example, contains 25% oleuropein per capsule—a high and clearly labeled amount that helps you know exactly what you’re getting.
2. Total Polyphenols
Oleuropein is important, but it’s not the only polyphenol in olive leaves. Look for products that mention total polyphenols on the label. These compounds work together to support the body at a deeper level. Some supplements leave this off entirely. The better ones include a full spectrum. Island Nutrition olive leaf extract includes 40% total polyphenols, which makes a big difference in long-term antioxidant support.
3. Hydroxytyrosol Content
This is one of the most potent antioxidants in olive oil—often more powerful than vitamin C—and it’s sometimes included in olive leaf formulas as part of a complex. If you see it on the label, that’s a good sign. That said, 20% hydroxytyrosol complex, like what’s found in the Island Nutrition olive leaf extract, gives you stronger immune protection and cellular health.
4. Standardization and Transparency
Don’t settle for vague descriptions like “pure,” “premium,” or “high quality.” Look for numbers: standardized percentages of oleuropein or hydroxytyrosol, third-party testing, and clear sourcing. Ultimately, if a label only mentions milligrams without any active compounds, it’s hard to know what you’re actually getting.
5. Country of Origin
Where the olive leaves are grown matters. Spain, Italy, and Greece are known for high-quality olives and strict farming practices. Many trusted products will clearly state the origin. Some will only say “made in the USA”—which doesn’t always mean the ingredients were grown there.
6. Processing Method
How the extract is made affects what ends up in the capsule. Traditional water and alcohol extractions preserve the polyphenols. And harsh solvents and high heat can destroy them.
7. Allergen and Filler Warnings
Last but not least—what’s not in your supplement matters just as much. Look for options free from gluten, GMOs, artificial preservatives, and unnecessary fillers. If you have allergies or sensitivities, choose a product that’s clearly labeled as hypoallergenic or free from common triggers.
People Also Asked
What is olive leaf extract?
Olive leaf extract is made from the leaves of the olive tree and contains natural compounds like oleuropein and hydroxytyrosol—known for their antioxidant and immune-supporting properties. It's been used for centuries in traditional Mediterranean wellness practices.
Can I take olive leaf extract if I am on medication?
It depends on the medication. Olive leaf extract may affect blood pressure or blood sugar levels, so it’s best to check with your doctor before starting—especially if you're taking meds for those conditions.
How long does it take for olive leaf extract to work?
Some people notice changes in energy or immune resilience within a few days, but deeper benefits—like antioxidant protection or blood sugar support—tend to build over several weeks. A high-quality product, like Island Nutrition olive leaf extract, may deliver results more consistently thanks to its standardized active compounds.
Can I take olive leaf extract during pregnancy?
Pregnant or breastfeeding women should avoid olive leaf extract unless advised by a healthcare provider. There isn’t enough clinical research to confirm its safety during pregnancy.
Why did the Island Nutrition olive leaf extract rank best overall?
It has 25% oleuropein, 40% total polyphenols, and a 20% hydroxytyrosol complex. It’s also sourced from olive trees grown in Spain and processed using traditional, chemical-free methods. If you’re looking for a supplement with transparency, strength, and clean sourcing, Island Nutrition olive leaf extract checks every box.
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