The olive tree (Olea europea) has been cultivated in the Mediterranean region for thousands of years. While the positive properties of the olive fruit and the oil extracted from it are known to most people, the therapeutic effect of its leaves has almost been forgotten.

The fact alone that olive trees can live for well over 1000 years, even in regions with little rain and long dry periods, shows the power that lies within the trees. The fruits can be enjoyed as olives or olive oil. The olive leaves, on the other hand, are drunk in the form of an (unfortunately very bitter) olive leaf tea or the concentrated olive leaf extract is taken in capsule form.

Olive leaves have a completely different effect on our health than olive oilThe latter works in particular through the properties of the monounsaturated fatty acids, while the olive leaf extract consists of highly concentrated polyphenols and other plant substances, especially oleuropein, but also hydroxytyrosol, flavonoids, phytosterols, glycosides and terpenes.

Oleuropein is a powerful antioxidant that is found in all parts of the olive tree, but the highest concentration is found in the olive leaves. While olives contain between 4 and 350 mg of oleuropein per 100 g of olives, liquid olive leaf extracts can contain between 800 and 950 mg per 100 ml (cf. https://www.internetchemie.info/substanz/Oleuropein.php).

The overall health effects of olive leaf extract are probably based on the interaction of its numerous healing ingredients. They work synergistically and thus increase their effectiveness. The strong antioxidant power of olive leaf extract (cf. https://onlinelibrary.wiley.com/doi/10.1002/9781119135340.ch19 and https://www.cell.com/heliyon/fulltext/S2405-8440(18)31888-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2405844018318887%3Fshowall%3Dtrue), its high chlorophyll content and the large number of secondary plant substances it contains explain the following individual effects of olive leaf extract, which have mostly been proven by initial scientific studies (especially in vitro, but there are also a few human studies):

Olive leaf extract works

• Antioxidant: Olive leaf extract shows 2.5 times higher antioxidant activity than the antioxidants vitamin C and E.
• antibacterial (cf. https://ann-clinmicrob.biomedcentral.com/articles/10.1186/1476-0711-13-24, https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00113/full and https://www.researchgate.net/publication/320876772_The_antimicrobial_activities_of_olive_leaf_extract_against_some_pathogenic_bacteria)
• antiviral (against herpes simplex)
• antimycotic (against fungi, e.g. Candida albicans) (cf. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490280/ and https://www.mdpi.com/1420-3049/21/12/1631)
• antiparasitic
• anti-inflammatory
• immune-boosting

Olive leaf extracts are characterized by exceptionally good digestibility and high bioavailability. They have no side effects and can be safely taken for longer periods as a dietary supplement.

Biochemical mechanisms of action of olive leaf extracts

• Olive leaf extracts reduce the expression of genes that promote fat accumulation: PPARy, lipoprotein lipase, fatty acid binding protein 4 (cf. https://pubmed.ncbi.nlm.nih.gov/20495905/).
• Olive leaf extracts increase the differentiation of osteoblasts (increased production of osteoblast genesis markers RUNXII, Osterix, collagen type 1, osteocalcin and alkaline phosphatase) (cf. https://pubmed.ncbi.nlm.nih.gov/20495905/).
• Olive leaf extracts stimulate the development of blood vessels and VEGF production (cf. https://pubmed.ncbi.nlm.nih.gov/24518972/).
• Olive leaf extracts normalize MDA and blood sugar levels (cf. https://www.sciencedirect.com/science/article/abs/pii/S0024320505009641).
• Olive leaf extracts reduce left ventricular and systolic blood pressure and improve stroke volume, ejection fraction and cardiac output, as well as the levels of superoxide dismutase and glutathione reductase (cf. https://pubmed.ncbi.nlm.nih.gov/25119867/).
• Olive leaf extracts prevent an increase in serum levels of malondialdehyde, interleukin-1β, TNF-α, creatine kinase-MB, troponin I and lactate dehydrogenase (cf. https://pubmed.ncbi.nlm.nih.gov/25119867/).
• Olive leaf extracts increase the production of proteins that prevent cell death (Bcl-2, Bcl-XL, Bim and p53) (cf. https://pubmed.ncbi.nlm.nih.gov/20568104/).

Therapeutic applications

Cardiovascular system

At the University of Reading (cf. https://link.springer.com/article/10.1007/s00394-016-1188-y) in Great Britain conducted a double-blind study in 2017 with 60 male subjects who suffered from pre-hypertension. They were given an olive leaf extract or a placebo for 6 weeks. Taking the olive leaf extract led to significantly improved blood pressure values ​​compared to the placebo. The systolic value fell by an average of almost 4 mmHg, the diastolic value by around 3 mmHg. Total cholesterol, LDL cholesterol and triglycerides were also reduced in the subjects thanks to the olive leaf extract, as were the values ​​of the inflammatory marker interleukin-8.

In another study with 232 patients with high blood pressure, 500 mg of oleuropein twice daily for 8 weeks was as effective as the diuretic captopril at a dosage of 12.5 to 25 mg twice daily in reducing systolic and diastolic blood pressure (see Table 1). https://pubmed.ncbi.nlm.nih.gov/21036583/).

In a Swiss study from 2008 with identical twins (cf. https://onlinelibrary.wiley.com/doi/10.1002/ptr.2455) with slightly elevated blood pressure, the test subjects were given either 500 or 1000 mg of an olive leaf extract for eight weeks. Body weight, heart rate, blood pressure, and glucose and lipid levels were measured every 14 days. The result: Blood pressure could be reduced with the olive leaf extract in a dose-dependent manner. With the higher olive leaf extract dose, the systolic value fell by an average of 11 mmHg (from 137 to 126), and the diastolic value by an average of 4 mmHg (from 80 to 76). With the lower dose, the values ​​fell only slightly; in the control group, they remained unchanged or even rose slightly. In the olive leaf group, cholesterol levels also fell significantly and in a dose-dependent manner.

The antihypertensive effects of olive leaf extracts may be due to their ability to maintain blood vessel function, as observed in a small study of 13 subjects with slightly elevated blood pressure (see Table 1). https://pubmed.ncbi.nlm.nih.gov/25148955/). In rats with high blood pressure, an olive leaf extract reduced blood pressure, heart rate, and enlargement of the heart and kidneys, while simultaneously improving blood vessel function (cf. https://pubmed.ncbi.nlm.nih.gov/26593388/).

Chronic inflammation

In a study with 18 healthy volunteers, an olive leaf extract reduced the production of pro-inflammatory cytokines (IL-8) and improved the function of blood vessels (see Figure 1). https://pubmed.ncbi.nlm.nih.gov/26051429/).

In another clinical study with 45 women with breast cancer, a combination of hydroxytyrosol from olive leaf extract with omega-3 fatty acids and curcumin reduced inflammation (measured via sensitive CRP) after one month of intake.

Hydroxytyrosol also reduced inflammation and pain in a small study of 25 subjects with arthritis (see: https://pubmed.ncbi.nlm.nih.gov/23746949/).

In human brain cells, an olive leaf extract prevented inflammation by reducing COX-2 production (see Figure 1). https://pubmed.ncbi.nlm.nih.gov/26410343/). The phenolic components of olive leaf extracts also show significant activity against polyarthritis and soft tissue rheumatism and all types of respiratory tract inflammations.

blood sugar levels

The blood sugar-lowering effect of oleuropein is based on its ability to block the formation of free radicals by Nox2, as shown in a small study with 20 healthy subjects (see 2.1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470561/).

In a small study with 20 healthy volunteers, oleuropein from olive leaf extract reduced blood sugar levels after meals by blocking the production of free radicals by Nox2 (see Figure 1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6005585/).

In another study of 46 middle-aged, overweight men at increased risk for developing type 2 diabetes, supplementation with olive leaf extract for 12 weeks improved insulin sensitivity and the activity of pancreatic cells that produce insulin (see Table 1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3596374/).

Bone

In a clinical study with 64 women with osteoporosis, consumption of an olive leaf extract for 12 months maintained bone density and increased markers of blood levels of bone-forming cells (osteocalcin) (see Table 1). https://pubmed.ncbi.nlm.nih.gov/25560820/).

In a study with human bone marrow stem cells, it was observed that oleuropein increased bone cell production (see Figure 1). https://pubmed.ncbi.nlm.nih.gov/20495905/).

neurodegenerative diseases

Amyloid diseases such as Alzheimer's are caused at least in part by the buildup of misfolded proteins in tissue, which cause inflammation and tissue damage (see: https://pubmed.ncbi.nlm.nih.gov/26092624/). Olive leaf extracts may prevent these misfolded proteins from entering the brain. This effectively prevented toxicity and tissue damage in studies conducted on mice (see https://pubmed.ncbi.nlm.nih.gov/25293421/). Even in advanced stages of Alzheimer's disease, mice experienced an improvement in brain function after treatment with oleuropein (see https://pubmed.ncbi.nlm.nih.gov/25293421/). In rats with Parkinson's disease, an olive extract reduced cell damage and cell death (cf. https://pubmed.ncbi.nlm.nih.gov/23394606/).

Oleuropein can also restart autophagy (“cell recycling”) in the cell. Autophagy deficiency has been demonstrated in Alzheimer’s disease in particular, which can result in toxins accumulating in the cells. In a study from Spain (see https://onlinelibrary.wiley.com/doi/10.1155/2018/5010741In 2018, it was shown in brain samples from Alzheimer's patients that oleuropein is able to initiate autophagy, which could possibly trigger a healing process.

Colon

Many digestive problems are accompanied by inflammation of the intestinal mucosa.

In intestinal samples isolated from 14 subjects with ulcerative colitis, treatment with an olive leaf extract reduced the production of pro-inflammatory molecules (the enzyme COX-2 and the cytokine IL.17) and the infiltration of immune cells (CD3, CD4 and CD20), resulting in a reduction of inflammatory damage (see Figure 1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409730/).

The olive leaf extract also removes the "wrong" bacteria from the digestive system and thus enables the regeneration of a healthy intestinal flora. In addition, olive leaf extract shows promise in the fight against Candida fungi and parasites.

gout

A study by the University of Leipzig found that olive leaves contain substances that inhibit the enzyme xanthine oxidase. This enzyme promotes the development of gout. This provides the first scientific evidence for what traditional folk medicine has long known. In Mediterranean regions, olive leaves have been used to treat gout for centuries.

intake recommendation

In principle, plant extracts should always be taken with or shortly after meals. Exception: If you have a Candida infection, bacterial digestive problems or the presence of parasites, you could test your tolerance on an empty stomach because the extract will then work better. If you experience diarrhea or nausea, it is better to take the extract after a small meal.