Hydroxytyrosol is one of the most potent natural antioxidants; it even surpasses the antioxidant capacity of vitamins E and C.
Hydroxytyrosol is found in the olive trees and is concentrated mainly in the leaves, where it acts as an antibiotic and an immunostimulant. It can also be found in extra virgin olive oil—both in its free form and in the form of oleuropein (which gives the oil its bitter taste)—but not in other oils as it is eliminated during the refining process.
As hydroxytyrosol is found in extra virgin olive oil, it is commonly consumed in countries with a predominantly Mediterranean diet. Several studies have shown the relationship between the consumption of a Mediterranean diet and the low incidence of cardiovascular disease, and hydroxytyrosol is one of the compounds responsible for this effect. The antioxidant activity of hydroxytyrosol is one of the highest of all the polyphenols, even higher than that of vitamin E.
Multiple scientific studies have confirmed the beneficial effects of hydroxytyrosol. In 2015, the Universitat Oberta de Catalunya (Open University of Catalonia, UOC) published the following paper: “Hidroxitirosol, el mejor antioxidante natural y el más desconocido: Estudio comparativo con otros antioxidantes.” (“Hydroxytyrosol, the best and least-known natural antioxidant: A comparative study of different antioxidants.”) This research is based on the assumption that hydroxytyrosol may be the best natural antioxidant, the benefits of which are still not fully known. To that end, it presents a series of conclusions that are listed below.
The antioxidant capacity of hydroxytyrosol
In various in vitro tests, hydroxytyrosol was found to offer greater protection than oleuropein and vitamin E against a variety of free radicals, such as linoleic acid micelles, and it is more effective in eliminating superoxide anions. Its antioxidant efficacy was also proven for hypochlorite-induced damage. In short, many in vitro studies have shown that the antioxidant capacity of hydroxytyrosol is superior to that of vitamins C and E.
Hydroxytyrosol is naturally present in the human body; therefore, the phenols from olive trees can circulate freely (as they are naturally recognised by the body) without the adaptation problems that other types of foreign polyphenols encounter. Likewise, there are no problems related to polyphenol accumulation in the body, as they are hydrosoluble and are excreted by the renal and digestive system.
The anti-atherosclerotic activity of hydroxytyrosol
Various studies suggest that lipid peroxidation is responsible for the pathogenesis of atherosclerosis. Perioxidation modifies LDL, causing the formation of fat deposits that produce atheromas. In vitro studies have shown that rats whose diet is rich in olive oil have greater resistance to lipid peroxidation than rats receiving other diets.
In other animal and human studies, it has been observed that polymorphonuclear leukocytes are involved in the development of coronary heart disease, angina and other consequences of atherosclerosis. Measuring instruments have confirmed that the enzyme responsible for this is 5-lipoxygenase, which is effectively inhibited by the phenolic compounds present in olive oil.
The antimicrobial capacity of hydroxytyrosol
Hydroxytyrosol has proven to be a good antimicrobial agent against pathogenic bacteria in humans (in clinically isolated strains), and it is more effective than erythromycin and ampicillin. Some of these pathogens are: Haemophilus influenzae, Salmonella spp. and Vibrio parahaemolyticus.
The ability of hydroxytyrosol to induce apoptosis
Chemoprevention is currently one of the main cancer treatments. Antioxidants have a promising future in this field. Epidemiological studies have shown that extra virgin olive oil is effective in preventing both breast and colon cancer.
The health benefits of hydroxytyrosol:
Protection of the cardiovascular system
Various in vitro and in vivo studies conclude that hydroxytyrosol protects LDL against oxidation by free radicals. It also reduces the production of endothelial cell adhesion molecules. Consuming hydroxytyrosol in large quantities can regulate glutathione and provide antioxidant enzymes to adipose tissue. In 2012, the EFSA (European Food and Safety Authority) confirmed that hydroxytyrosol protects LDL against oxidation by free radicals, and that it prevents vascular deterioration caused by atherosclerosis.
Protection against neurodegenerative processes
Several studies indicate that the consumption of polyphenols reduces the risk of neurodegeneration and age-related cognitive decline. Brain activity expends a great amount of energy given that it consumes a high level of oxygen. The reactions involved in oxidation produce large amounts of free radicals that can damage cells. Hydroxytyrosol is able to protect brain cells against lipid peroxidation because it can cross the blood-brain barrier.
Protection against cancer
Studies carried out on the consumption of extra virgin olive oil and breast cancer reflect a lower prevalence of this disease in the population. Hydroxytyrosol protects against the proliferation of cancer cells and induces apoptosis in mammary epithelial cells and cancer cells.
Hydroxytyrosol protects against oxidative DNA damage:
Inflammation creates free radicals and depletes antioxidants. Hydroxytyrosol has the ability to inhibit the COX and LOX enzymes of arachidonic acid (AA), which thereby reduces the oxidative deterioration caused by inflammation.
Muscle and joint protection
Hydroxytyrosol stimulates the production of chondrocytes that can regenerate and repair articular cartilage. Hydroxytyrosol is also beneficial for physical exercise as it increases the production of glutathione (an endogenous antioxidant) and decreases the production of lactic acid and subsequent muscular atrophy.
Protection against AIDS
Hydroxytyrosol, together with oleuropein, are the first group of molecules capable of multiple actions against the AIDS virus. Hydroxytyrosol inhibits viral entry and integration, and it acts both inside and outside the cells. This discovery is a good starting point for the development of new HIV inhibitors.
Protection of the immune system
By suppressing the synthesis of LDL, hydroxytyrosol can prevent colon and breast cancer, premenstrual syndrome, and cardiovascular disease. It also has an antimicrobial effect and destroys colonies of microorganisms that cause infections in the respiratory, intestinal and genital tracts.
Prevention of osteoporosis
The administration of hydroxytyrosol has positive effects on the formation and growth of bones. It is therefore possible to use hydroxytyrosol to treat the symptoms of osteoporosis.
The protection of hydroxytyrosol against other diseases:
Hydroxytyrosol is beneficial for eye health, especially in regeneration strategies for retinal pigment epithelium, macular degeneration and glaucoma, all of which are caused by oxidative stress.
Dermoprotective effects in the aqueous-oil phase
It protects against UVB rays and reduces skin pigmentation. It protects against oedema and erythema caused by excessive sun exposure, and it may even be effective in treating psoriasis.
It stimulates the production of proteins that promote cell survival.
Significant increase in research to determine the health benefits of hydroxytyrosol:
There is no doubt that researchers from all over the world have made a huge effort to highlight the health benefits of this polyphenol. Some of the latest studies are listed below, along with links to learn more about them.
Recently published properties of hydroxytyrosol
- It improves mitochondrial function and reduces oxidative stress in the brain.
- Maternal administration improves neurogenesis and cognitive function in prenatally stressed babies.
- It provides a protective effect against endothelial dysfunction in human aortic endothelial cells.
- Protective effects for acute inflammation and rheumatoid arthritis.
- It provides neuroprotection and cellular antioxidant defence, suggesting its potential pharmaceutical use for the treatment of neurodegenerative disorders.
- It ameliorates disturbances in white adipose tissue and plays a relevant metabolic and inflammatory function in overweight or obesity conditions.
- It is a bioactive compound that can counteract oxidative and inflammatory processes.
- It would ensure a less oxidative impact of chemotherapeutic drugs on breast cancer patients, which could potentially improve their well-being.
- Supplementation may be advantageous in rheumatoid arthritis.
- It reduces oxidative stress in the brain.
- Maternal administration improves cognitive function in prenatally stressed children.
- It reduces colon cancer growth.
- Hydroxytyrosol-cetuximab combination yields enhanced chemotherapeutic efficacy in colon cancer cells.
- It provides a basis for developing a new dietary strategy for the prevention of rheumatoid arthritis.
- It reduces oxidative DNA damage.
- It protects against damage to plasma.
- It prevents metabolic impairment reducing hepatic inflammation.
- It improves the main oxidative-stress parameters, insulin resistance and steatosis in children with non-alcoholic fatty liver disease (NAFLD).
- It has an antioxidant effect on human sperm quality.
- A basis for the creation of new pharmacological agents for cancer prevention and therapy.
- Cardioprotective effects of hydroxytyrosol by attenuation of metabolic risk factors.
- It ameliorates brain pathology and restores cognitive functions.
- It inhibits both enzymatic and spontaneous oxidation of endogenous dopamine and mitigates the increase in spontaneous oxidation during monoamine oxidase inhibition.
- It provides a cardioprotective effect against myocardial infarction.
- It increases vitamin C levels.
- It induces cell cycle arrest and apoptosis in colon cancer cells.
- It attenuates liver oxidative stress induced by a high-fat diet.
- Supplementation offers potential pharmacological and nutritional treatments.
- A potential candidate microbicide for preventing the transmission of AIDS (HIV-1) or curtailing its replication.
- For the treatment of prostate cancer.
- It is a therapeutic agent against thyroid cancer.
- It protects against ischemic injury.
- It exerts a neuroprotective effect on diabetic retinopathy.
- It protects against oxidative stress related to the nervous system.
- Neuroprotective effect in diabetes mellitus.
- It attenuates the initial steps of atherosclerosis.
- It reduces uric acid levels.
- It attenuates acute lung injury.
- It protects from bisphenol-A effects in livers and kidneys.
- Anti-inflammatory and antitumor effects
- Modulation of the immune system.
- It inhibits cancer stem cells and the metastatic capacity of triple-negative breast cancer cell lines.
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