Hedonists beware: stress can actually be good for the body. Studies on the restriction of food, exposure to low levels of radiation, alcohol, antibiotics, metals, herbicides, insecticides, and fungicides have found that low levels of these stressors can increase longevity, growth, reproductive and energetic responses.

Hormesis, defined as the beneficial effect of an otherwise harmful agent when administered in small quantities, has been documented in a diverse number of organisms, including microbes, fungi, plants and animals. However, a mechanism for the process “remains uncertain because few laboratories have studied the pathology or physiology of mammals exposed throughout life to dose rates below those causing detrimental effects. [We attempt to] provide a potential mechanism to explain these beneficial effects,” said Dr. Roody Boonstra of the Centre for the Neurobiology of Stress and the Department of Zoology at UTSC.

In a recent study conducted by Boonstra, and published in the January issue of Environmental Toxicology and Chemistry, meadow voles at the Zoological Environment Under Stress facility in Manitoba were exposed to one of three levels of radiation (low, medium, and high) over a four-year period. The researchers found that low levels of radiation resulted in a hormetic response, and was beneficial for the animals.

Radiation acts as a stressor, and causes the release of hormones called glucocorticoids. These chemicals protect against the damaging effects of over-stimulating the immune and inflammatory responses. Although traditionally thought of as the body’s primary defense system, excessive and prolonged activation of the inflammatory response (in a wound for example) can cause damage and lead to debilitating diseases such as arthritis. Glucocorticoids act to prevent this.

“Our findings suggest that a moderate increase in glucocorticoid levels, associated with low-level radiation, could be an important factor underlying the increase in longevity that has been observed in other shorter studies on small mammals exposed to low-level radiation,” said Boonstra.

Although it is certain that low levels of stressors have beneficial effects on the body, what remains unclear is how activation of the stress hormones, glucocorticoids, leads to increases in health and longevity.

So, should you pack up your bags and head for Pickering’s nuclear power plant to reap the benefits of chronic low level stressors on your body?

“The implications [of this study’s results] for humans are not direct. Our study was conducted on a short-lived mammal, the meadow vole (with a life span less than one year) and humans are a long-lived mammal (up to 100 years). So, life span and the possibility of different cumulative effects [of radiation] could prevent a direct one-to-one extrapolation. We can’t do controlled, chronic experiments on humans using low radiation doses,” said Boonstra.

So don’t head for Pickering just yet.