Olive leaf extract, derived from the leaves of the olive plant (Olea europaea L.), has been used for centuries in traditional medicine in countries like Greece, Morocco, and Tunisia. Recent research suggests that this extract may offer a range of health benefits, including support for weight management, improved heart health, and enhanced immune function. This is primarily attributed to its rich content of polyphenolic compounds, such as hydroxytyrosol, oleuropein, and oleocanthal. Prof. Dr. Erdem Yeşilada, Head of Yeditepe University Pharmacognosy and Phytotherapy Department, has experimentally proven that olive has anti-inflammatory, blood sugar lowering, blood pressure lowering, atherosclerosis preventing, blood lipid level lowering, bone loss repairing, anti-microbial, antioxidant, and anticancer properties, and many other effects.
The Power of Polyphenols
What makes olive so effective is its rich polyphenolic content, including hydroxytyrosol, oleuropein, and oleocanthal. The strong antioxidant effect of green tea is often mentioned, but hydroxytyrosol has an antioxidant effect that is reportedly 10 times stronger than green tea. However, because these substances have a bitter taste, they are often lost when olive fruits are processed. The olive leaves that are pruned and discarded are actually the most important source of polyphenolic compounds.
Olive Leaf Extract and Weight Management
One of the most promising areas of research on olive leaf extract is its potential role in weight management.
Animal Studies
An animal study from 2014 researched the effect of olive leaf extract in preventing high-fat, diet-induced obesity. It’s thought that olive leaf extract prevents obesity by regulating the expression of genes that affect weight gain and can also aid in reducing food intake. In laboratory tests, oleuropein lowered body fat and weight gain in animals fed high-cholesterol and high-fat diets. It also reduced food intake, suggesting olive leaf extract can also help manage appetite and overeating.
In a 2016 study, researchers orally administered oleuropein to rats with obesity that were consuming a high-cholesterol diet. After 8 weeks, the rats had a lower body weight, less fat tissue, and an improved metabolic profile.
Read also: Lemon Olive Oil Cake (Keto)
Human Studies
A clinical study carried out in 2013 investigated the effect of olive leaf on 'insulin resistance', which is one of the main factors of obesity in humans. In the measurements, it was observed that olive leaf extract improves insulin sensitivity by 15-20 percent. This value is reportedly similar to that of some known diabetes medications.
In experiments on the mode of action, it was suggested that olive leaf extract exerts its effect by stimulating the secretion of factors that regulate insulin sensitivity (IGFBP-2) and prevent excess insulin secretion (IGFBP-1).
The present trial aims to evaluate a supplementation of the olive leaf extract (OLE) in adjunct with a weight loss diet on anthropometric indices, glycemic indices, lipid profile, as well as the level of adipokines, and free fatty acid in obese women. We carried out an 8-week randomized, placebo-controlled, double-blind, parallel-group, clinical trial. The participants were randomly stratified according to age and they were assigned to one of the two study groups: Standard weight loss diet (estimated daily energy requirements minus 500 kcal) + OLE supplementation (n = 35) in intervention group or Standard weight loss diet (estimated daily energy requirements minus 500 kcal) + placebo (n = 35) in placebo group. The study groups were homogeneous regarding the baseline age, height, weight, body mass index (BMI), waist circumferences, married status, and physical activity levels (p > 0.05). The results of analysis of covariance presented significant decreases in BMI, fat mass, and body weight in the OLE group compared to those in the placebo group (p < 0.05).
Olive Leaf Extract and Heart Health
Research suggests that olive leaf extract can have positive effects on atherosclerosis, or narrowing of the arteries, which is the highest risk factor for heart disease. High levels of LDL, or “bad” cholesterol, and total cholesterol are risk factors for developing this disease.
Cholesterol Levels
One animal study from 2015 assessed the effects of olive leaf extract on cholesterol levels. Rats who took the extract for eight weeks had significantly decreased cholesterol levels. A 2008 study compared the effects of food supplementation with olive leaf extract with lifestyle advice in 40 identical twins with high blood pressure. After 8 weeks, the team found that olive leaf extract significantly lowered LDL cholesterol levels within the twin pairs in a dose-dependent manner, meaning that larger doses had a greater effect.
Read also: Olive oil guide for Mediterranean cooking.
Blood Pressure
Olive leaf extract may help lower systolic and diastolic blood pressure. A 2017 study found that olive leaf extract successfully lowered blood pressure. A lower blood pressure can reduce your risk of stroke and heart attack. In a 2011 study, researchers randomized people with stage 1 hypertension to take either 500 milligrams (mg) of olive leaf extract or 12.5-25 mg of captopril, a medication for high blood pressure, twice per day. After 8 weeks, blood pressure was significantly lower for both groups. The team concluded that the olive leaf extract was as effective at lowering blood pressure in people with stage 1 hypertension as captopril.
Olive Leaf Extract and Type 2 Diabetes
A review of olive leaf extract and type 2 diabetes found that olive leaf oil extract can help improve insulin secretion in cells. Animal studies have shown that olive leaf extract may reduce hyperglycemia, reduce hyperinsulinemia (too much insulin in the blood), reduce blood glucose, plasma malondialdehyde, and other signs of oxidative stress (an imbalance of free radicals that can harm the body), reduce cholesterol, and increase serum insulin.
One human study found that people who took olive leaf extract tablets lowered their average blood sugar level and fasting plasma insulin levels. However, insulin levels after eating weren’t significantly affected. In a study published in 2012, it was reported that olive leaf extract is effective in sugar metabolism in type-2 diabetics and reduces the level of glycosylated hemoglobin (HbA1c) after 14 weeks of administration.
Additional Benefits of Olive Leaf Extract
Beyond weight management, heart health, and diabetes, olive leaf extract has been associated with a variety of other potential health benefits:
- Antimicrobial Properties: Olive leaf extract’s antiviral and antimicrobial factors reduce the ability of the herpes virus to invade surrounding cells.
- Neuroprotective Effects: Oleuropein is also shown to have a protection against Alzheimer’s disease. The antioxidant effects of olive leaf extract may also help with preventing damage or loss of dopamine neurons that’s associated with Parkinson’s disease as well.
- Antioxidant Activity: The extract has strong antioxidant properties.
- Anti-inflammatory Properties: Olive has anti-inflammatory properties.
- Anticancer Potential: In one cell study, olive leaf extracts were shown to stop cancerous cell growth.
Olive leaf extract is a natural source of wellness with therapeutic properties that are gastroprotective (protects digestive system), neuroprotective (protects central nervous system), antimicrobial (inhibits microorganism growth), anticancer (reduces risk of cancer), anti-inflammatory (reduces risk of inflammation), antinociceptive (reduces pain stimuli), and antioxidant (prevents oxidation or cell damage).
Read also: Olive Oil and Weight Management
Dosage and Safety
The daily supplemental dosage is generally 500 to 1,000 milligrams. It's often recommended to divide the amount into a few doses per day. It is advisable to start with a smaller dosage when first taking the extract and gradually increase the dosage as your body allows. Carefully read and follow all of the directions that come with your chosen brand of olive leaf extract, as strength and dosages may vary between manufacturers.
No adverse changes were observed in the liver and kidney values of subjects with the administration of the extract. In this regard, the olive leaf extract is reported to be safe.
Potential Side Effects and Interactions
If you take any blood pressure medication or blood thinners or have diabetes, check with your doctor before taking olive leaf extract. It’s possible to develop severe respiratory allergic reactions. Talk to your doctor before trying olive leaf extract. Remember that some changes may be subtle and gradual over time. You may also not experience any changes at all with olive leaf extract.
Some studies report mild side effects - including coughing, vertigo, stomach pains, and headaches. Some people are allergic to the pollen produced by olive trees and may have an allergic reaction when taking olive leaf extract. Olive leaf extract may lower your blood pressure and blood sugar levels. If you have diabetes or are taking medications to manage your blood sugar or blood pressure, talk to your doctor before taking olive leaf extract. People with kidney disease should consult with their doctor before taking it, as well. Not enough data is available to suggest olive leaf extract is safe for pregnant or breastfeeding women.