What Is Olive Leaf Extract?

Olive leaf extract has long been used in traditional medicine. It comes from the leaves of the olive tree (Olea europaea), the same tree that produces olive oil. However, olive oil is distinct from olive leaf extract and the two should not be confused with one another.

Olive leaf extract contains the active compound oleuropein, which is thought to contain antioxidant and anti-inflammatory properties.

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

Dietary supplements are not regulated like drugs in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLabs, or NSF. 

However, even if supplements are third-party tested, that doesn’t mean they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and to check in about any potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Phenolic compounds (e.g., verbascoside, apigenin-7-glucoside, luteolin-7-glucoside, hydroxytyrosol (HT), tyrosol, and oleuropein)
  • Alternate name(s): Olea europaea
  • Legal status: Legal and sold over-the-counter in the U.S.
  • Suggested dose: No standard dose exists for olive leaf extract
  • Safety considerations: Some people have experienced allergic reactions from taking olive leaf extract

Purported Uses of Olive Leaf Extract

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

Medical research on olive leaf extract is still in its early stages. However, some preliminary studies suggest it may help treat various health conditions.

Most of the potential benefits of olive leaf extract are said to be due to one of its components, oleuropein, an antioxidant. In addition to antioxidant effects, oleuropein is said to have anti-inflammatory, anti-cancer, antibacterial, and antiviral effects.

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

Diabetes

Olive leaf extract has been shown to be potentially beneficial for managing type 2 diabetes in humans and animals. 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 recent lab study looked 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 being said, olive leaf extract does not substitute standard medical treatment for diabetes. Always follow your healthcare provider's guidance for how to properly manage and treat any health condition.

Heart Disease

Research has shown that olive leaf extract may help in improving 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 to 80 years old. The results suggested olive leaf extract may help reduce systolic blood pressure, low-density lipoprotein, and inflammatory biomarkers. However, there was a limited number of participants involved.

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, more large-scale human trials are needed on the subject.

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.

Olive leaf extract capsules
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 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.

Precautions

Because research is limited on the use of olive leaf extract, little is known about any necessary precautions.

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.

Olive leaf extract may be safe for children to use. But talk with your child's healthcare provider about using olive leaf extract, as research remains limited.

Dosage: How Much Olive Leaf Extract Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

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 (mg) and 1,000 mg 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.

Always follow the instructions on the label when taking supplements. Or talk to your healthcare provider about the dosage that's right for you.

What Happens If I Take Too Much Olive Leaf Extract?

There is no evidence to suggest that olive leaf extract is toxic when taken at high doses. However, this does not mean toxicity is not possible.

There are also no documented cases of overdose for olive leaf extract.

To best avoid the chance of toxicity, take olive leaf extract exactly as instructed. Your chance of experiencing side effects is higher if you take more olive leaf extract than you should.

Interactions

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. 

How to Store Olive Leaf Extract

Olive leaf extract supplements should be stored in a cool, dry place. Keep them in an area of your home that is not in direct sunlight.

Typically, olive leaf extract does not require refrigeration, but some products might. Follow the directions on the supplement packaging. Keep all supplements out of reach of any children or pets in the home.

Be sure to throw away any remaining olive leaf extract supplements once the expiration date listed on the label passes.

Similar Supplements

Other supplements may work similarly to olive leaf extract. Check with your healthcare provider before choosing which supplement is right for you. It may be recommended that you only take one supplement for a health condition at a time.

Supplements that are similar to olive leaf extract include:

  • Magnesium: It is believed that a magnesium deficiency may cause insulin resistance in people with diabetes. A small study found that supplementing with 250 milligrams of magnesium a day for three months resulted in reduced insulin resistance and improved blood sugar control in people with type 2 diabetes.
  • Garlic: For many years, garlic supplements have been used for heart disease. Although research is somewhat mixed, it is believed that garlic can help alleviate high blood pressure, reduce cholesterol, and decrease inflammation.
  • Selenium: Selenium, an antioxidant and essential trace mineral, may be useful for immunity and viral infections, like COVID-19. A recent review found that selenium reduces viral infections, oxidative stress, and inflammation. Researchers also found that a selenium deficiency may be linked to more severe illness from COVID-19.

It should be emphasized that supplements are not meant to treat or cure diseases on their own. Supplements like olive leaf extract should only be considered for complementary uses.

Frequently Asked Questions

  • 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 on olive leaf extract do not exist.

    Talk with your healthcare provider about proper dosage as well as how long you should take olive leaf extract.

  • How should olive leaf extract be stored?

    Olive leaf extract should be stored according to the directions listed on the label or packaging.

    Typically, olive leaf extract supplements should be stored in a cool, dark place, like a cabinet. They should also be kept out of direct sunlight.

    Some olive leaf extract supplements may require refrigeration.

  • Does olive leaf extract lower blood sugar?

    According to some research, olive leaf extract may be able to lower blood sugar. However, much of the research has been performed on animal models.

    One small human trial did find that the daily intake of 500 milligrams of olive leaf extract for 14 weeks helped to lower and manage blood sugar in adults with type 2 diabetes. Another review of clinical trials also indicated that olive leaf extract may help reduce blood pressure in humans.

Sources of Olive Leaf Extract & What to Look For

Olive leaf extract supplements come in various forms, some of which you may be able to use in food.

Food Sources of Olive Leaf Extract

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.

You can find antioxidants similar to the ones found in olive leaf extract in various foods.

Olive Leaf Extract Supplements

Olive leaf extract supplements come in capsules, soft gels, powders, and tinctures. The dosage of these supplements varies, making it important to 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 like drugs. When buying supplements, look for products tested and certified by ConsumerLabs, NSF International, U.S. Pharmacopeia, or other third-party agencies.

Summary

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 disease, 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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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Brittany Lubeck, RD
Brittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition.