Definition of "naturally occurring" [naturally occurring]

• Existing by nature and without artificial aid (adjective)

WordNet. Princeton University. 2010.

• "Glutathione is a naturally occurring antioxidant that is depleted in patients with wasting diseases such as sepsis, cancer, and AIDS."
• "“What we found was that the apple phenolics, which are naturally occurring antioxidants found in fresh apples, can protect nerve cells from neurotoxicity induced by oxidative stress,” Dr. Lee states."
• "Over the course of more than a decade, he connected mottling to the naturally occurring presence of fluoride in drinking water."