Study Shows Veggies Flush with Carotenoids Might Counteract Testosterone Health Risks

While testosterone lets males develop the traits that help attract a mate, the substance has also been linked to suppression of the immune system. However, according to new research from Arizona State University, males who eat the right carotenoid-packed vegetables seem able to counteract testosterone's health risks.

Carotenoids are the health-benefiting, anti-oxidant pigments that make foods like tomatoes red, sweet potatoes orange and spinach green.

In a study of zebra finches, researchers Kevin McGraw of ASU and Daniel Ardia of Franklin and Marshall College found that birds given testosterone implants responded as if their immune systems had been stimulated. Those same birds became healthier even as their carotenoid levels declined, indicating that the antioxidants were directly battling the extra testosterone in their bodies.

"This study shows that testosterone may not be as costly as previously thought, so long as animals can nutritionally offset the immune detriments of testosterone," said McGraw, who studies the functions of naturally occurring chemicals in birds and their relationship to the birds' colors and health. "They may even experience a net health benefit as a result."

McGraw said the research shows that nutrient-specific mechanisms -- in this case, carotenoids -- not only provide male zebra finches with the bright coloration they need to attract a mate, but help them avoid the downsides of testosterone.

"If testosterone is having immunosuppressive effects in human men, perhaps they, too, could benefit from increased carotenoid intake - say, by eating more corn," McGraw said. "This study certainly opens the door for future work on nutritional and antioxidant therapy for the hormonally immunocompromised. The interface between diet and health in animals is a fascinating one. But we need a much better understanding of their interactions, as with testosterone, at the molecular level."

McGraw's and Ardia's findings are published in this month's edition of Biology Letters.