Medical Author: Melissa Conrad Stoppler, MD

Medical Editor: William C. Shiel, Jr, MD, FACP, FACR

Endorphins are among the brain chemicals known as neurotransmitters, which function to transmit electrical signals within the nervous system. At least 20 types of endorphins have been demonstrated in humans. Endorphins can be found in the pituitary gland, in other parts of the brain, or distributed throughout the nervous system.

Stress and pain are the two most common factors leading to the release of endorphins. Endorphins interact with the opiate receptors in the brain to reduce our perception of pain and act similarly to drugs such as morphine and codeine. In contrast to the opiate drugs, however, activation of the opiate receptors by the body's endorphins does not lead to addiction or dependence.

In addition to decreased feelings of pain, secretion of endorphins leads to feelings of euphoria, modulation of appetite, release of sex hormones, and enhancement of the immune response. With high endorphin levels, we feel less pain and fewer negative effects of stress. Endorphins have been suggested as modulators of the so-called "runner's high" that athletes achieve with prolonged exercise. While the role of endorphins and other compounds as potential triggers of this euphoric response has been debated extensively by doctors and scientists, it is at least known that the body does produce endorphins in response to prolonged, continuous exercise.

Endorphin release varies among individuals. This means that two people who exercise at the same level or suffer the same degree of pain will not necessarily produce similar levels of endorphins. Certain foods, such as chocolate or chili peppers, can also lead to enhanced secretion of endorphins. In the case of chili peppers, the spicier the pepper, the more endorphins are secreted. The release of endorphins upon ingestion of chocolate likely explains the comforting feelings that many people associate with this food and the craving for chocolate in times of stress.