Olive Oil

Olive oil (Olea europaea L.) is a natural oil obtained from the fruit of the olive tree. It is one of the cornerstones of the Mediterranean diet and has been used for thousands of years as both a food and a source of healing. In addition to its unique flavor, it offers numerous benefits to the body thanks to its rich biochemical composition. This comprehensive review details the definition of olive oil, its biochemical composition, its effects on general health (especially immune system, inflammation, cardiovascular health, physical performance and reproductive health), uses, side effects, dosage information and storage conditions based on scientific sources.

Description and Production

Olive oil is a vegetable oil obtained by pressing ripe olives by mechanical methods (pressing or centrifugation). No heat or chemical solvents are used in the production process, allowing olive oil to retain its nutritional value and bioactive components. It is divided into different classes according to its quality:

• Extra Virgin Olive Oil (EVOO): It is olive oil of the highest quality. It has a free fatty acidity of less than %0.8, no sensory defects and a characteristic fruity taste and aroma. It is the richest in nutritional value and bioactive components.
• Riviera Olive Oil: It is a mixture of refined olive oil and extra virgin olive oil. Although the refining process improves the taste and color of olive oil, it causes it to lose some of its beneficial components.
• Olive Pomace Oil It is an oil obtained from olive pulp (pomace) by chemical solvents. It is generally not used for cooking and has low nutritional value.

Biochemical Composition

The benefits of olive oil to the body stem from its complex and rich biochemical composition. This composition may vary depending on the olive variety, the geography, climate, harvest time and production method.

• Main Components (Triglycerides): Zeytinyağının yaklaşık %98-99’u trigliseritlerden oluşur. Bu trigliseritler, esas olarak aşağıdaki yağ asitlerinden oluşur:
  • Monounsaturated Fatty Acids (MUFAs): It is the most distinctive feature of olive oil. Especially oleik asit (%55-83) is extremely rich in oleic acid. Oleic acid is critical for heart health.
  • Polyunsaturated Fatty Acids (PUFAs): It contains essential fatty acids such as linoleic acid (omega-6) and alpha-linolenic acid (omega-3), but in low ratios (%3-21).
  • Saturated Fatty Acids (SFAs): It contains small proportions (%8-18) of saturated fatty acids such as palmitic acid and stearic acid.
• Minor Components (Non-Saponified Fraction): They are the bioactive components responsible for a large part of olive oil's benefits to the body. Although they make up only %1-2 of the total composition of olive oil, they have powerful antioxidant, anti-inflammatory and other biological effects.
  • Polyphenols They are the most important bioactive components of olive oil. It contains phenolic compounds such as oleuropein, hydroxytyrosol, tyrosol, ligstroside and apigenin. These compounds give olive oil its bitter and pungent flavor and have strong antioxidant and anti-inflammatory properties.
  • Tocopherols (Vitamin E): It is found especially in the form of α-tocopherol and is a powerful antioxidant. It protects cells against oxidative damage.
  • Carotenoids Carotenoids such as beta-carotene and lutein give olive oil its slightly yellowish color and have antioxidant properties.
  • Phytosterols It contains ingredients such as β-sitosterol, which helps reduce cholesterol absorption.
  • Squalene: It is a triterpenoid that is beneficial for skin health.
  • Phenolic Alcohols Compounds such as hydroxytyrosol and tyrosol are found in high concentrations, especially in extra virgin olive oil, and have heart-protective effects.

Effects on bodily functions

The positive effects of olive oil, especially extra virgin olive oil, on human health are supported by numerous scientific studies.

1. Effects on Cardiovascular Health: The benefits of olive oil on heart health are one of the most researched topics. Thanks to its high oleic acid and polyphenols:
   • Cholesterol Management: It helps to increase good cholesterol (HDL) levels while lowering bad cholesterol (LDL) levels.
   • Blood Pressure Regulation: It can reduce the risk of hypertension by lowering blood pressure.
   • Endothelial Function: It protects the lining of the arteries (endothelium) and improves its function, which reduces the risk of atherosclerosis (hardening of the arteries).
   • Anti-thrombotic Effect: It may reduce the risk of heart attack and stroke by reducing platelet aggregation (blood clotting).
   • Research Example: The PREDIMED study (Estruch et al., 2018) showed that adding extra virgin olive oil or nuts to the Mediterranean diet significantly reduced the risk of major cardiovascular events. This study strongly supports the cardioprotective effects of olive oil.
2. Effects on Inflammation: Olive oil, especially extra virgin olive oil, has strong anti-inflammatory properties. The polyphenols it contains, especially oleocantal, have similar effects to non-steroidal anti-inflammatory drugs (NSAIDs).
   • Mechanism Oleocantalum reduces the production of inflammatory mediators by inhibiting the activity of COX-1 and COX-2 enzymes.
   • Research Example: A study by Beauchamp et al. (2005) showed that oleocantalum exhibits an anti-inflammatory effect like ibuprofen and has potential in the prevention or management of chronic inflammatory diseases.
3. Effects on the Immune System: The bioactive components of olive oil can support the correct functioning of the immune system. Thanks to their antioxidant properties, they reduce the damage caused by free radicals and optimize the function of immune cells.
   • Research Example: Some in vitro and animal studies suggest that polyphenols in olive oil may increase lymphocyte proliferation and modulate cytokine production (Crespo et al., 2020). However, more research is needed on their direct effects on the immune system in humans.
4. Reducing Cancer Risk: Polyphenols and other antioxidants in olive oil may help reduce the risk of some types of cancer by preventing DNA damage at the cellular level and suppressing tumor growth.
   • Research Example: Numerous epidemiological studies show that the Mediterranean diet and olive oil consumption reduce the risk of some types of cancer, particularly breast, colon and prostate cancer (Schwingshackl et al., 2017).
5. Brain Health and Neurodegenerative Diseases: By reducing oxidative stress and inflammation, olive oil may protect brain health and help reduce the risk of neurodegenerative diseases such as Alzheimer's and Parkinson's.
   • Research Example: In animal models and some limited human studies, it has been shown that polyphenols in olive oil can reduce amyloid plaque deposition and improve cognitive functions (Abuznait et al., 2013).
6. Digestive System Health: Olive oil can support the digestive system by positively influencing the gut microbiota and regulating intestinal motility. It can help relieve constipation and reduce the symptoms of some digestive disorders.
7. Physical Performance and Recovery: While olive oil is not a direct performance enhancer, it can indirectly contribute to athletes' recovery processes and overall endurance thanks to its positive effects on overall health and its anti-inflammatory properties. As part of a healthy diet, it can support muscle repair and energy metabolism.
8. Reproductive Health: Olive oil may support reproductive health by protecting sperm and egg cells from oxidative stress thanks to its antioxidant properties. It may have indirect positive effects on hormonal balance.
   • Research Example: Some studies show that fertility rates are higher in couples following a Mediterranean diet (Karayiannis et al., 2017). This effect is attributed to the antioxidants and healthy fatty acids contained in olive oil.

Areas of Use

Olive oil has a wide range of culinary uses and is also used in cosmetics and traditional medicine:

• Edible Oil It is widely used in salads, sauces, soups, vegetables, meat and fish dishes. Especially extra virgin olive oil preserves its nutritional value in the best way when consumed raw.
• Frying Although it does not have a high smoke point, it can be used for medium temperature frying and oven cooking.
• Cosmetics: Used as a skin moisturizer, hair mask and massage oil. Thanks to its antioxidant content, it can help delay skin aging.
• Traditional Medicine: It has been used traditionally for constipation, digestive problems and skin conditions.

Side Effects and Dosage Information

Olive oil is a foodstuff that is generally considered safe and side effects are rare. However, side effects may occur with excessive consumption or in some cases:

• Weight Gain: Like all fats, olive oil is high in calories. Excessive consumption can lead to weight gain.
• Digestive Problems: In some people, high consumption of olive oil can cause diarrhea or stomach upset.
• Allergic Reactions: Very rarely, allergic reactions to the olive tree or olive oil can occur.
• Drug Interactions: People taking blood thinners (e.g. warfarin) are advised to be careful due to the potential effect of olive oil on clotting. It may be useful for people taking diabetes medications to monitor their blood sugar levels, as olive oil may have blood sugar lowering effects.

Dosage Olive oil is a food, not a medicine. Although there is no standard "dosage", the Mediterranean diet recommends a daily consumption of 2-4 tablespoons (about 30-60 ml) of extra virgin olive oil. This amount is considered sufficient to take advantage of its potential benefits.

Storage Conditions

Proper storage conditions are vital to preserve the quality and nutritional value of olive oil:

• Dark Colored Bottles: Olive oil is prone to oxidation and spoilage when exposed to light. It should therefore be stored in dark glass bottles or metal cans.
• Cool and Dry Environment: High temperatures reduce the quality of olive oil. It should be stored in a cool (14-18°C is ideal) and dry place, away from direct sunlight and heat sources.
• Protection from Air Contact: Oxygen is an important factor that causes olive oil to spoil. The bottle should be tightly capped and it is recommended to buy it in small bottles or consume it soon after opening to minimize contact with air.
• Things to Avoid: Storing it in the refrigerator can cause the olive oil to freeze and become cloudy, but this does not affect its quality. It becomes clear again when it reaches room temperature. However, refrigerated storage can cause some flavors to be lost.

Conclusion and Future Research

Olive oil, especially extra virgin olive oil, is a unique food ingredient that offers proven benefits through its rich biochemical composition and powerful antioxidant, anti-inflammatory, cardioprotective and anti-cancer effects. As an essential part of the Mediterranean diet, it plays an important role in preventing chronic diseases and improving overall health. Future research should examine in more detail the specific mechanisms of action of the minor components of olive oil, investigate the effects of genetic factors on the benefits of olive oil, and analyze in depth how different olive varieties and production methods affect its benefits to the body. It is important for consumers to choose good quality extra virgin olive oil and consume it as part of a balanced diet to maximize its benefits to the body.

Sources

• Abuznait, A. H., Qosa, H., Busnena, B. A., El Sayed, K. A., & Kaddoumi, A. (2013). Olive-derived oleocanthal rapidly and dose-dependently modulates amyloid-β protein levels in vitro and in vivo: evidence for its anti-Alzheimer's activity. ACS Chemical Neuroscience, 4(6), 977-987.
• Beauchamp, G. K., Keast, R. S. J., Morel, D., Lin, J., Pika, L. S., Han, Q., ... & Breslin, P. A. S. (2005). Phytochemistry: Ibuprofen-like activity in extra-virgin olive oil. Nature, 437(7055), 45-46.
• Crespo, M. C., Maestre, B., Al-Ghafri, M. M., & Visioli, F. (2020). Extra virgin olive oil and the immune system: A review. Nutrients, 12(4), 939.
• Estruch, R., Ros, E., Salas-Salvadó, J., Covas, M. I., Corella, D., Arós, F., ... & Serra-Majem, L. (2018). Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra virgin olive oil or nuts. New England Journal of Medicine, 378(24), e34.
• Karayiannis, D., Kontogianni, M. D., Mourtzoukou, E., Loutradis, D., & Panagiotakos, D. B. (2017). Adherence to the Mediterranean diet and the effect on the success of in vitro fertilization in women undergoing their first IVF treatment. Human Reproduction, 32(3), 677-684.
• Schwingshackl, L., Hoffmann, G., & Schwingshackl, L. (2017). Dietary patterns and risk of cancer: a systematic review and meta-analysis of prospective studies. Annals of Oncology, 28(6), 1177-1188.