Medical research on olive leaf extract is still in its early stages, but preliminary studies suggest it may benefit various health conditions. Olive leaf extract may help manage type 2 diabetes, support heart health, and protect against viral infections. However, more research is needed.

Olive leaf extract comes from the leaves of the olive tree (Olea europaea), the same tree that produces olive oil. It contains the active compound oleuropein, which is thought to contain antioxidant and anti-inflammatory properties.

Oleuropein is also found in extra-virgin olive oil and may account for some of the benefits of a Mediterranean diet. However, olive oil and olive leaf extract are distinct from one another.

This article reviews the potential olive leaf extract benefits. It also looks at the side effects of taking olive leaf extract, as well as precautions and dosage information.

Benefits of Olive Leaf Extract

Olive leaf extract has long been part of traditional medicine. Most of the potential benefits of olive leaf extract are said to come from one of its components, oleuropein. In addition to antioxidant and anti-inflammatory effects, oleuropein is said to have anti-cancer, antibacterial, and antiviral effects.

Below is a look at some of the stronger research surrounding olive leaf extract and its uses.

Before taking olive leaf extract or any other supplement, always consult a healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Helps Manage Type 2 Diabetes

Olive leaf extract may offer a potential benefit for managing type 2 diabetes. In one study, 79 adults with type 2 diabetes took either olive leaf extract or a placebo every day for 14 weeks. At the end of the study, those who took olive leaf extract had improved blood sugar control, possibly due to reduced starch absorption.

Although this study was small, it supports other animal and test tube research findings.

A lab study published in 2019 aimed to find out how olive leaf extract may work to help control diabetes. Researchers from this study suggested that oleuropein and other antioxidants in olive leaf extract may be the reason for any benefits. They concluded that olive leaf extract may enhance insulin secretion and increase glucose (sugar) uptake by cells so that it does not remain in the blood and alter blood sugar levels.

That said, olive leaf extract does not substitute standard medical treatment for diabetes. Always follow your healthcare provider’s guidance on how to properly manage and treat any health condition.

Supports Heart Health

Research has shown that olive leaf extract may offer benefits for heart health in those at risk for heart disease.

One recent systematic review and meta-analysis looked at the effects of olive leaf extract in adults with prehypertension and hypertension (high blood pressure). The review examined five clinical trials including 325 people 18–80 years old. The results suggested olive leaf extract may help reduce systolic blood pressure, low-density lipoprotein, and inflammatory biomarkers. However, the study involved a limited number of participants.

Another small human study that compared olive leaf extract to a placebo found that those who took olive leaf extract had lowered levels of blood pressure, total cholesterol, LDL (“bad”) cholesterol, and inflammation.

Despite these results, the subject requires more large-scale human trials.

Helps Protect Against Viral Infections

Olive leaf extract is also thought to have antiviral properties.

Lab tests show olive leaf extract may be used to help fight viruses like herpes, mononucleosis, hepatitis, HIV, influenza, and rotavirus. Oleuropein is suspected to be responsible for the antiviral properties of olive leaf extract.

However, this research has been limited to cell cultures and only small human trials.

In one such human trial, 32 high school athletes were randomized to receive either a daily placebo or olive leaf extract. Young athletes are especially susceptible to upper respiratory infections. At the end of nine weeks, the athletes who took olive leaf extract had shorter bouts of upper respiratory illness compared to those who took the placebo.

In light of the COVID-19 pandemic, researchers have looked at olive leaf extract’s potential role in fighting the virus.

A mini-review of lab data found that the oleuropein in olive leaf extract, along with other active substances and antioxidants, exhibited antiviral activities against SARS-CoV-2, or the coronavirus. However, human studies are needed to confirm whether it will actually be useful for this purpose.

Verywell / Anastasia Tretiak

What Are the Side Effects of Olive Leaf Extract?

Although rare, it is possible to experience side effects from taking olive leaf extract. These side effects may be common or severe.

Common Side Effects

Side effects associated with olive leaf extract are not well documented. But there is some concern that olive leaf extract may trigger reactions.

According to one review on olive leaf extract, the following side effects may occur:

If you experience side effects when taking olive leaf extract, stop using it and consult with your healthcare provider.

Severe Side Effects

Some people may develop an allergy to olive leaf extract.

The pollen from the olive leaf can trigger severe respiratory allergic reactions in people allergic to other plants in the Oleaceae family.

These plants include:

  • Ash trees
  • Forsythia
  • Jasmine
  • Lilacs
  • Olive trees
  • Rivets

Your healthcare provider can help you navigate any present or potential allergies. Be sure to stop using olive leaf extract if you experience an allergic reaction to it.


Olive leaf extract may interact with certain medications.

Talk with your healthcare provider about taking olive leaf extract if you are taking any of the following medications:

The use of antioxidants during chemotherapy is controversial. Some oncologists (cancer specialists) believe it could prevent drugs from killing cancer cells. But some research suggests it may be beneficial while also curbing some of the side effects of cancer therapy. More research is needed.

It is vital that you carefully read the ingredient list and nutrition facts panel of any supplement to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

We do not know if olive leaf extract is safe to take during pregnancy or lactation. Because of this, it is recommended to limit or avoid using olive leaf extract during these life stages.

Talk with your child’s healthcare provider about using olive leaf extract in children because research remains limited.

How to Incorporate Olive Leaf Extract Into Your Diet

Olive leaf extract supplements come in various forms, some of which you can add to food.


There is no standardized dose for olive leaf extract. This is due to a lack of research as well as the fact that olive leaf extract is not an essential nutrient that is required daily.

However, olive leaf extract dosage tends to range between 500 milligrams and 1,000 milligrams per day in studies. Although, sometimes dosage can be as low as 100 milligrams per kilogram a day.

You should follow the dosage directions of your healthcare provider or as listed on the olive leaf extract supplement packaging. Olive leaf extract may or may not need to be taken with food.

Can Olive Leaf Extract Be Taken Long Term?

Little is known about the long-term use of olive leaf extract. This is because long-term human studies of olive leaf extract do not exist. Talk with your healthcare provider about proper dosage as well as how long you should take it.

Food Sources

Olive leaf extract is not naturally found in foods. However, you may choose to use the supplement in tincture or powder form when cooking, baking, or making smoothies.

Whenever possible, a food-first approach to getting the nutrients your body needs is recommended. This is because your body can typically absorb nutrients found in foods better than those found in supplements.

A Mediterranean diet is rich in extra-virgin olive oil, vegetables, nuts, legumes, fruits, and whole grains. You can get oleuropein from extra-virgin olive oil as well as a range of other beneficial compounds and antioxidants by following this way of eating.


Olive leaf extract supplements come in capsules, soft gels, powders, and tinctures. The dosage of these supplements varies, so pay attention to how much olive leaf extract is in the one you choose.

Many olive leaf extract supplements are naturally vegan, but some capsules may be made from gelatin. Gelatin comes from cows or pigs and is not vegan.

Supplements aren’t tested and regulated the same way drugs are. When buying supplements, look for products tested and certified by ConsumerLabs, NSF International, U.S. Pharmacopeia, or other third-party agencies.


Olive leaf extract comes from the leaves of the olive tree (Olea europaea). Its active compound oleuropein is thought to contain antioxidant and anti-inflammatory properties. Although research is somewhat limited, olive leaf extract has been studied for its uses in diabetes, heart health, and viral infections.

Side effects associated with olive leaf extract are rare and mild, but allergies are possible. Always talk with your healthcare provider before taking any new supplement.


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