Hydroxytyrosol is an antioxidant chemical that can be found in the water byproduct of the olive industry. Rinsing green olives with water is an integral part of olive oil processing. The remaining polyphenolic compound is defined as hydroxytyrosol, a substance that protects cells from oxidative stress. Olive oil producers can filter the chemical and use it in medicine and food preservatives.

       The researchers believe hydroxytyrosol activates specific genes at the cellular level that protect against toxin (free radical) damage. The chemical also releases dopamine into the brain, a neurotransmitter that acts as a messenger in the nervous system. Dopamine controls blood pressure and heart rate, but some synthetic dopamine does not cross the blood-brain barrier.

      Studies of natural hydroxytyrosol have found that it has the ability to penetrate the blood-brain barrier and can be absorbed in the gut and stomach. Its antioxidant properties are similar to those of green tea and grape seed extracts. The chemical was also found to be second only to garlic in protecting cell health. It has been shown to treat colon and breast cancer, lower cholesterol levels and treat degenerative diseases such as Alzheimer's.

       Hydroxytyrosol and oleopicrin are resistant to different types of bacteria, and these two chemicals work with other plant compounds to inhibit yeast spores. However, the chemicals in olives are less effective than food preservatives such as grape seed extract.