Where to find olive leaves

One study suggests that possible side effects may include muscle discomfort and headache. People who experience severe or concerning side effects should stop taking the extract and speak to their doctor. It is also not clear whether olive leaf extract can interact with other medications. People who are taking prescription medications should speak to a doctor before taking olive leaf extract.

Preliminary studies suggest that olive leaf extract may have several health benefits. These include lowering blood pressure, improving cholesterol levels, and reducing the risk of weight gain and type 2 diabetes. However, it is necessary for scientists to conduct more large-scale studies in humans to confirm these findings and to determine the long-term safety of taking olive leaf extract. A range of products containing olive leaf extract are available to purchase online.

Licorice root may offer potential health benefits, such as fighting infection, preventing tooth decay, and relieving stomach discomfort. Learn more…. Extra virgin olive oil is an unprocessed, tasty, and healthful alternative to olive oil. It is full of healthful fats and has health benefits with…. High blood pressure is common, affecting one in three people in the U. We discuss natural ways to reduce blood pressure, including diet, exercise…. Spirulina is blue-green algae often hailed as a superfood.

It contains many key nutrients and may have wide-ranging benefits, including for blood…. A new analysis shows that the so-called Portfolio diet — which consists of four main food components — reduces cholesterol and cardiovascular risk. Health benefits of olive leaf extract. Medically reviewed by Debra Rose Wilson, Ph. Weight gain Cholesterol Blood pressure Type 2 diabetes Dosage Side effects Summary We include products we think are useful for our readers.

Weight gain. Share on Pinterest Olive leaf extract is available as a supplement. Blood pressure. You may also not experience any changes at all with olive leaf extract.

Though mango leaves aren't as popular as the juicy, sweet fruit, they may still provide health benefits when consumed as a tea or supplement.

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Dark leaves, clear lungs? Learn more about the potential benefits of English ivy as well as some possible downsides and how to use it. TMG is a compound that's produced by your body, though it's also found in supplements and foods. Here's all you need to know about TMG supplements. Bay leaves have been used many different ways throughout history for possible health benefits.

But what does the science say? Read on to find out. While spirulina is often touted for its health benefits, there are several side effects of spirulina to be aware of. However, because of their polyphenolic composition, olive leaves have potential in numerous other applications.

In this review we analyze the chemical composition of olive leaves, and discuss current processing methods of the olive leaf waste, including thermochemical, biochemical, drying, extraction and condensation methods. We also examine current applications of the treated olive leaves in sectors relating to cattle feed, fertilizers, novel materials, energy generation, and food and pharmaceutical products.

The aim of this review is to provide a resource for producers, policy makers, innovators and industry in shaping environmentally sustainable decisions for how olive leaf waste can be utilized and optimized.

The olive tree plays an important role in the history, economy, and culture of Western civilization Rhizopoulou, Fossil evidence indicates an origin in the Oligocene, in what is now Italy and the Eastern Mediterranean Basin, 20—40 million years ago Waterman and Lockwood, It is believed that olive tree cultivation began in Mesopotamia 4, B.

C , with the first records of olive crops dating to the Minoan civilization, at around 2, B. As the cultivated olive variety did not generate significant quantities of oil, Egyptians used it primarily as a pharmaceutical and cosmetic product Zaragoza, ; Meeks, Ancient Greece had an appreciation for olive oil which is reflected in images on jars and walls such as those seen in the palace of Knossos.

In fact, a symbol still seen today is the crown of olive branches in recognition of peace and victory. The consumption of olive oil also functioned as a marker of social class distinction Foxhall, Through trade and constantly traveling Greek warriors, olive tree cultivation was introduced in Italy and the consumption of olive oil grew rapidly.

It has been estimated that Romans imbibed 20 l of olive oil per year Bownan and Gansey, The trade routes were based on wine, garum and olive oil, with olive oil being used in the skylights to illuminate the interior of houses.

The use of olive oil became so popular that there was great competition in the stalls selling oils; one example counts more than stalls selling olive oil, compared to stalls selling bread Thorndike, As can be seen throughout history, olive trees have not only been extensively cultivated for dietary purposes, but have also become a symbol of Mediterranean culture, as well as a representation of peace, victory, and life.

Today, Greece has by far the largest per-capita consumption of olive oil, followed by Spain and Italy; but the latest figures indicate that the consumption of olive oil outside its home territory has been rising steadily. This represents 4. The olive tree plantations comprise around 2. Spain is also the main exporter internationally. Smaller industries exist in Australia and in the United States California, Hawaii, Texas, Georgia, and Oregon ; although most of the olive oil consumed in these countries is usually imported from Italy, Spain and Turkey.

Per capita consumption is highest in Greece over 24 l per year , followed by Spain 14 l per year and Italy 14 l per year. However, overall, the consumption of olive oil outside its cultivation zones has been rising steadily Weber et al. The olive oil industry generates by-products that can have a negative impact on the environment when not processed correctly.

One of the by-products are the olive leaves, produced by the pruning and harvesting of olive trees. Normally, olive leaves get gathered with other objects such as twigs and branches. Avraamides and Fatta , reported that for everyone liter of olive oil produced, 6.

As a consequence of this production magnitude, environmental effects must also be considered. Clearly, there are different practices and techniques for the agricultural production of olives and the subsequent olive oil production, and each of these have different adverse environmental effects associated with them Salomone and Ioppolo, However, the essence of these effects is that production of olive oil involves important resource consumption, such as energy and water, and considerable emission and waste generation Salomone and Ioppolo, Given the magnitude of the industry, the optimization of its life cycle is crucial to limit these adverse effects.

Various life cycle analysis have been done to identify the key elements and processes that give rise to the most significant environmental problems. These studies then report the overall consumption and emissions by production of 1 l of olive oil, with the total number being broken down by the various sub-processes including fertilization, irrigation, pruning… Table 1 Avraamides and Fatta, Table 1. Overall consumption and emissions by production of 1 l of olive oil Avraamides and Fatta, A key segment is the analysis of CO 2 emissions.

The majority of this CO 2 is generated when the pruning residues are burned, as a way to get rid of the biomass and obtain energy, creating g of CO 2 per liter of olive oil Avraamides and Fatta, Currently, there are several studies and procedures to use olive leaves in different sectors such as in the food, energy and pharmaceutical industries.

Olive leaves' composition can be broadly divided into lignocellulosic and what the literature refers to as olive leaf extract. The lignocellulosic compounds of olive leaves consist of different concentrations of cellulose, hemicellulose and lignin. The composition is leveraged for energy production through biochemical and thermochemical treatments of the whole leaf.

However, olive leaf extracts are of special interest for their therapeutic effects and are generally used for pharmaceutical and food applications. These extracts have different classes of bisphenols, discussed in section Olive Leaves Apostolakis et al. In this review we further discuss current olive leaf treatments and applications. The aim is to provide a reference for producers, policy makers, and industry in shaping environmentally sustainable decisions for how olive leaf waste can be utilized and optimized.

Olive leaves appear in two different steps of the olive oil production process Figure 1. Figure 1. Schematic designed to show the two processes where olive leaf by-products are generated. Reproduced from Manzanares et al. As formerly discussed, the pruning process is an essential process of the olive tree life cycle. Eliminating old branches gives the tree a structure, facilitating harvest and balancing out production.

Pruning is typically done in winter but, depending on the temperature of the region, it can be delayed until late in the season as the process can make the orchard less resistant to the cold. It is also possible to prune the trees during the summer if needed, for example, if the plant is infected.

This is exceptional as during the summer months the plant grows better and it is less probable for bacteria to spread International Olive Council, As mentioned before, we can broadly divide olive leaf composition into two categories, namely:.

Lignocellulosic materials. Olive leaf extract. Cellulose, hemicellulose and lignin are the building blocks that make up all leaves Table 2. In general, chemical composition and moisture content of leaves determine aspects such as the heating value of the foliage. Table 2. Lignocellulosic components of olive leaves Garcia-Maraver et al. There are also other molecules present in trace amounts specific to the olive tree, including:. Possible roles of these molecules are to defend the plant from insects and UV radiation.

Among these molecules, oleuropein Figure 2 is the most abundant of the constituents of olive leaf extract. It has important properties, including antioxidative, antimicrobial and antiviral effects. However, using the extract without isolating the components might be beneficial due to bisphenol's synergistic effects. These compounds are also found in the fruit of the olive tree. For example, oleuropein is. The amounts present of other polyphenols.

Overall, the polyphenolic profile of the olive leaf is affected by technological factors and industrial processes used for extraction, including: preparation, solvent type, solvent composition, solid-to-solvent ratio, particle size of the extracted material, temperature, pH, time and temperature of extraction.

In addition, the polyphenolic profile is also affected by agronomic factors such as the leaf age, degree of ripeness, geographical origin Table 3 , cultivation and phonological stage during sampling Sahin and Bilgin, Table 3.

Total polyphenols, flavonoids and oleuropein of olive leaf extracts Ben Salah and Abdelmelek, As the leaf ages, the amount of oleuropein decreases while the amount of hydroxytyrosol increases due to the chemical and enzymatic processes that take place Tan et al.

The antioxidant potential of oleuropein may be due to its ability to chelate metals ions, such as Cu and Fe, that catalyze free radical generation reactions Andrikopoulos et al.

Given the large quantities of leaves, there are various efforts to utilize them and extract energy or various molecules. The leaf by-products can therefore undergo various treatments before they are used for different purposes Table 4. These treatments are summarized in the five categories below:. Thermochemical treatments: Combustion, gasification, and pyrolysis.

Biochemical treatments. Drying methods. Extraction methods. Condensation of active components. Table 4. Treatments for olive leaves with corresponding description, advantages, and disadvantages. The biochemical and thermochemical treatments are quick and cheap ways of treating big quantities of olive leaves, and therefore are the most popular treatments.

However, in these treatments the leaves are used along with branches and logs that are part of the OTPB. The main purpose of thermochemical treatments is to get rid of the leaves or to obtain energy, like biofuels.

For this purpose, OTPB is processed with methods such as combustion, gasification or pyrolysis. Nowadays, combustion is the simplest way to get rid of the OTPB. Its advantages include high thermal efficiency, low operation cost and non-frequent cleaning. The gasification process involves the partial oxidation of the biomass with an amount of oxygen or steam carried out at higher temperatures. In practice, most of the OTPB is burned at the roadside after harvesting.

Only large diameter branches are collected and are used for domestic heating. The conversion into olive leaf pellets for subsequent heating is currently being considered. The advantages to thermochemical processes are that installations are less bulky, simpler and smaller while the biochemical ones must use heat and gas immediately.

However, there are some disadvantages to these practices, especially concerning the generation of waste products. Biochemical processes are another possible treatment for the OTPB and include anaerobic digestion and bioethanol production. Anaerobic digestion consists of introducing the biomass into a digester without oxygen, followed by the addition of a bacterial culture which is responsible for biogas production.

There are scarce references in the literature of methane generation from OTPB. However, the finest OTPB particles have found to achieve the highest methane yield Nonetheless, olive mil waste has a higher potential for anaerobic digestion and hence methane production.

Since around 10—12 million cubic meters of Olive Mill Wastewater are produced yearly, it is possible that researchers have focused on this issue—explaining the lack of information on methane production from OTPB Costa et al.

As the pruning biomass has a high cellulose and low lignin content, it is an ideal substrate for bioethanol production. Currently, the bioethanol production encompasses four stages, namely: pre-treatment, hydrolysis of polysaccharides into monomer sugars, fermentation of monomer sugars to ethanol, and ethanol concentration. There are several methods used to dry the whole leaves with the purpose to concentrate the bioactive compounds present in the leaves.

Various studies have measured the impact of each method. The most common procedures are solar drying, infrared drying, microwave drying and freeze drying. Solar drying consists of drying the leaves by convective heat through solar power or specialized equipment.

Studies have investigated the quality attributes of dried leaves in terms of color, total phenols and radical scavenging activity while controlling the temperature and airflow. The results found significant differences between the temperature, the total phenols and scavenging activity.

At lower temperatures, antioxidant capacity was higher but total phenols decreased. Otherwise antioxidant capacity was lower when the leaf was dried at higher temperatures and flow rates Bahloul et al. Infrared drying uses infrared radiation to reduce the moisture in the leaves. Some investigations have observed the difference between fresh and blanched leaves dried at different temperatures, studying its total phenolic content and color difference between each sample.

Microwave drying also uses radiation to reduce the water content of the leaves, while freeze drying uses pressure and low temperatures to obtain the same result. A study compared the total oleuropein and other phenols present in the leaves depending on different drying methods microwave, freeze, vacuum, oven, and ambient air. Extraction and condensation treatments are employed when the bioactive compounds present in olive leaves are used as natural additives in the food and medicine industry.

Now, more than ever, it is necessary to explore greener techniques that are respectful of the environment, present no health risks, and maintain the bioactivity of the molecules. The three most common extraction methods for the compounds in olive leaves are 1 supercritical fluid extraction, 2 ultrasound assisted extraction and 3 maceration. The main differences between these methods are the extraction yields, solvents, and cost. Supercritical fluid extraction is a versatile technique used for extraction and precipitation of bioactive molecules.

Supercritical fluids have a lower viscosity than liquids and therefore are more hydrodynamic. They have a lower surface tension which enables a high penetrability through porous surfaces Cejudo Bastante, Studies on olive leaf supercritical fluid extraction use carbon dioxide and ethanol.

Ultrasound assisted extraction is a time-efficient way of extracting bioactive compounds. When ultrasound waves are applied, intense pressure and temperature gradients within the material are created. This induces physical structural disruption due to cavitation, which enhances mass transfer and the release of the intracellular substances into the extraction medium. Studies claim that it can also get viable extraction yields without the need of using high amounts of solvents or high temperatures, making it more sustainable.

A common way of recovering phenolics is via maceration. In this process, the leaves are dried, crushed and macerated in a range of solvents including acetonitrile, ethanol or distilled water at different pH values. The extracts are then filtered, and the solvents removed from the filtrate using a rotary evaporator Ghomari et al.

The downsides to this technique include hugely variable results depending on solvent they range from In addition to the three methods discussed above, there are countless other extraction methods used to extract valuable compounds from olive leaves, employing:.

Eco-friendly deep eutectic solvents Athanasiadis et al. Low-transition temperature mixture Karageorgou et al. Solvent-free microwave-assisted extraction Sahin et al. Instant controlled pressure drops Mkaouar et al. Pressurized liquid extraction Herrero et al. The highest polyphenolic content reported amongst these is obtained by using eco-friendly deep eutectic solvents Athanasiadis et al. Once the olive leaf extract has been extracted from the olive leaves with the techniques discussed above, there are various methods for condensing it to increase the concentration of valuable compounds.

The two most popular methods for this purpose are freeze drying and spray-drying. Spray drying is a technique which converts the frozen olive leaf extract into a powder using a spray drier Ghelichkhani et al.