What exactly is testosterone anyway? When most people hear the word, they envision an aggressive-acting man lifting tons of weight at the gym and/or strutting around with a hard-to-miss swagger.
Yes, there is some truth to the above two situations: studies have shown there is a link between aggressive behavior and the need to appear "manly," at least in competitive situations, such as with a peer or for a sexual partner.
However, there appears to be a subtler interplay between testosterone and behavior in other types of situations - in men, and surprisingly, women as well.
Here are some interesting facts about that "man-hormone."
You May Also Like
What exactly is testosterone?
Testosterone is the main male sex hormone. It supports normal male traits such as muscle growth, facial hair, and deep voice. In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate, as well as promoting secondary sexual characteristics such as increased bone mass. In addition, testosterone is essential for health and well-being, as well as the prevention of osteoporosis.
Women (especially women in love) have testosterone, too.
You May Also Like
On average, an adult human male body produces about ten times more testosterone than an adult human female body, but females are more sensitive to the hormone.
According to studies, women in love have higher testosterone for the few months after a relationship starts than women who are single or in long-term relationships.
The opposite is true for men; those newly in love have lower testosterone than men flying solo or with a long-term partner.
Testosterone may help blast that gut.
Men whose levels of testosterone are below normal may lose their spare tire when treated with testosterone.
"Most of the studies show there's a reduction of abdominal obesity in men who are given testosterone," says...
...Adrian Dobs, MD, a professor of medicine and oncology at Johns Hopkins University School of Medicine, in Baltimore.
Because the long-term effects of testosterone therapy have not been well studied, however, it is generally only recommended in men with below-normal testosterone levels and symptoms such as fatigue, muscle or bone-mass loss, or sexual dysfunction.
Money affects testosterone.
Young men who are futures traders get a testosterone spike on days when they make an above-average profit, British researchers found.
And on the mornings when men's testosterone levels were higher than average, their average afternoon profits were higher than on their low-testosterone days, suggesting a possible cause-and-effect relationship.
More experienced traders showed an even stronger tie between testosterone and profits.
Too much testosterone isn't great for the testicles.
In men, taking steroid hormones such as testosterone as performance boosters can cause testicles to shrink and breasts to grow. For women, it can cause a deeper voice, an enlarged clitoris, hair loss from the head, and hair growth on the body and face.
In both genders, steroid abuse can cause acne, mood swings, aggression, and other problems.
Men working with an experienced doctor to treat low testosterone or women taking small amounts of testosterone under medical supervision are unlikely to have testosterone-overdose symptoms.
Sports can influence testosterone levels.
A man's testosterone levels rise when they're competing, studies have shown.
For example, after a game, the winner's testosterone will increase even more. And fans' hormone levels seem to mirror those of their athletic idols. In a group of 21 men watching a Brazil vs. Italy World Cup match, the Brazil fans' testosterone levels increased after their team won, but the Italy fans' testosterone fell.
Fat can lower testosterone.
Obese men tend to have lower testosterone than thinner men, Dr. Dobs says. It's not clear why, she adds, although one possible reason is that obesity promotes a state of widespread inflammation in the body.
"When there's fat cells, there's a lot of inflammatory factors," she says. "These inflammatory factors have been associated with suppression of testosterone synthesis."
Testosterone is not the fountain of youth.
It would be great if an aging man's vigor, muscle power, and sex drive could be restored with testosterone.
But it is not clear whether therapy will do anything for the 75% to 80% of men over 65 who have normal levels of testosterone.
Men with below-normal levels, however, may get a boost in libido, sexual function, and bone mass from supplemental testosterone. And it may help diabetic men with low testosterone build lean muscle mass.
Taking testosterone doesn't cause prostate cancer.
It has long been thought that taking testosterone increases the risk of prostate cancer. Testosterone treatment can boost levels of prostate-specific antigen, or PSA, a nonspecific marker for prostate cancer, which may lead to more prostate biopsies and more prostate-cancer diagnoses, Dr. Goodman says.
There are now, however, major questions about whether it's worthwhile to treat—or even diagnose—prostate cancers in older men, given that they're common and often slow-growing.
Low levels are linked to sleep apnea.
Men with sleep apnea are more likely to have low testosterone, and treating sleep apnea can help return it to normal.
But if a man with sleep apnea is diagnosed with low testosterone alone, taking the supplemental hormone can worsen sleep apnea. That's why it's crucial for men with low testosterone to get a thorough workup by an endocrinologist so underlying conditions that can cause low testosterone, such as sleep apnea or pituitary-gland tumors, don't go undiagnosed, Dr. Goodman says.
Testosterone may hurt men's hearts.
In 2010, researchers halted a study of testosterone therapy in older men because of a higher rate of cardiovascular problems such as heart attack in the group taking testosterone instead of placebo.
The reason isn't clear, but caution should be used in prescribing testosterone to older men in poor health, Dr. Goodman says. Declining testosterone in men is associated with health problems, but this doesn't mean giving older men testosterone will extend lifespans, he says.
Too much may kill brain cells.
It's only known to happen in a petri dish, but Yale researchers showed that nerve cells exposed to high levels of testosterone were more likely to self-destruct. The hormone boosted a "cell suicide" mechanism known as apoptosis, which, under normal circumstances, is supposed to help the body wipe out cancerous or otherwise abnormal cells.
And the higher the testosterone level in the dish, the shorter lived the cells were. Exposure to low levels of testosterone, however, had no effect on the cells.
