14 DAY TRIAL // Are you an exclusive meat-eater? Bad news, 'cause your veggies could revigorate your sex life.
A team including Kevin McGraw an assistant professor at Arizona State University and Daniel Ardia, of Franklin and Marshall College in Pennsylvania has showed that carotenoids - the pigments that give carrots the orange and corn yellow color - eliminate the negative health effects induced by testosterone.
Testosterone is known to lie behind the sex drive in both males and females, besides boosting male sexual traits that are necessary to "get" a female.
Their research was made on zebra finches, a common pet bird coming from Australia.
Carotenoids induce in vertebrates (like many birds and fish species) a bright coloration, that has the role of sexual signal, attracting potential mates, but their antioxidant effect also boosts the immune system. "Researchers in animal behavior often study what keeps sexual signals like bright colors or elaborate songs 'honest,' or why all individuals cannot produce them ad nausea and try to get mates," said McGraw.
"The reason typically is that long Tails and fancy dances incur costs. Testosterone, for example, has been thought of as a double-edged sword as it relates to sexual signals, because it enhances trait production but comes at a health price to the animal. 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," explained McGraw. "In the case of the zebra finch, the cost is in the pigments -- having enough of them to develop a red beak and enough to combat testosterone, which you also need to be red."
The team tested the link between testosterone, carotenoids and the immune activity in 35 male and female zebra finches. To the surprise of the researchers, testosterone implants in zebra finches induced a stimulation of the immune system. They found that blood carotenoids, extracted from food, changed their levels in connection to testosterone levels.
When supplementary testosterone was administered, the blood carotenoid levels dropped, while the immune activity increased. "These findings show that there are nutrient specific mechanisms by which animals can avoid the immune costs of testosterone elevation and still keep their attractive and bright colors. If testosterone is having immunosuppressive effects in human men, perhaps they too could benefit from increased carotenoid intake, say, by eating more corn. This study certainly opens the door for future work on nutritional/antioxidant therapy for the hormonally immunocompromised. But we need a much better understanding of their interactions, as with testosterone, at the molecular level." said McGraw.