Hydroxytyrosol represents an antioxidant chemical discovered in the water byproduct of the olive industry. Green olives are rinsed with water as part of the process to make olive oil. The polyphenol chemical left behind, defined as hydroxytyrosol, is considered a scavenger substance that protects cells from oxidative stress. Manufacturers of olive oil can filter and preserve the chemical for use in drugs and as a food preservative.
Researchers believe hydroxytyrosol activates certain genes at the cellular level that guard against damage from toxins, commonly called free radicals. This chemical might also release dopamine in the brain, a neurotransmitter that serves as a messenger within the nervous system. Dopamine controls blood pressure and heart rate, but some synthetic forms of dopamine cannot cross the blood-brain barrier.
Studies with natural hydroxytyrosol show its ability to cross this barrier and be absorbed in the stomach and intestines. Its antioxidant properties are similar to those of green tea and grape seed extract. Researchers discovered this chemical ranks second only to garlic in its ability to protect cell health. It shows promise in treating colon and breast cancer, for lowering unhealthy cholesterol levels, and treating degenerative diseases, such as Alzheimer’s.
One animal study revealed hydroxytyrosol counteracted the effects of oxidative stress on cells. Scientists tested the brains of mice after exposure to irons and nitric oxide, substances known to harm healthy cells. Antioxidant effects were seen even at very low doses of the chemical. Another study concluded this substance might reduce the harmful effects of second-hand smoke.
Small amounts of the chemical exist in virgin olive oil, but most remains in the water during processing. The leaves of olive trees contain another chemical called oleuropein, which represents a weaker antioxidant not readily absorbed by the digestive system. Antibiotic properties also exist in oleuropein, which is added to some skin products.
Waste water from grape processing can be saved and converted into a powder supplement or food additive. It might preserve freshness of processed food better than some commonly used preservatives. Both hydroxytyrosol and oleuropein were tested against different types of bacteria, and both chemicals suppressed yeast spores when used along with other plant compounds. When compared to grape seed extract as a food preservative, chemicals from olives proved less effective.