When you note on a medical history that you've smoked a pack a day for three years, how does your doctor use this knowledge to help him reach a diagnosis?
Though doctors routinely ask us about our diet and exercise habits because of their connection with conditions like heart attacks and lung cancer, it's sometimes unclear how these activities affect our bodies' biochemistry.
Researchers at the Bloomberg School of Public Health recently investigated the effects of smoking, alcohol consumption and physical activity on men's sex steroid hormone concentrations. Abnormal levels of sex hormones have been linked to conditions like prostate cancer and diabetes.
Using information from the Third National Health and Nutrition Examination Survey, the researchers reviewed the reported diet and exercise habits and sex steroid hormone serum samples of 1,275 men.
The researchers found a correlation between the testosterone, estradiol and sex-hormone binding globulin (SHBG) levels of men and their reported diet and exercise habits. For example, men who consumed one or more alcoholic drinks per day had lower SHBG levels than men who drank less frequently.
"Our work," explained researcher Elizabeth Platz, "was done in the context of understanding which classic chronic disease risk factors are correlated with hormones and should be taken into account in trying to understand the links between hormones and chronic diseases."
After additional research further confirms these researchers' findings, doctors may be able to consider men's diets and exercise habits as possible upstream variables in prostate cancer risk.
Though factors such as age and race are well-established predictors of male sex steroid hormone levels, less is known about how modifiable habits like diet contribute to abnormal hormone levels.
In some ways, knowing information about modifiable habits is more valuable, as it gives patients the power to control their disease risk; by putting down their Heineken and pack of Marlboros, patients could balance their hormone levels and perhaps lower their risk of disease.
Current smokers, for example, had higher testosterone levels than both non-smokers and previous smokers. In fact, former smokers exhibited normal testosterone levels - suggesting that abnormal hormone levels are reversible if patients quit cigarettes.
But though the researchers found direct correlations between sex hormone levels and the men's personal habits, it's unclear exactly how this will translate into the doctor's office. "Although smoking is clearly bad for your health, we cannot say whether their higher testosterone levels are bad or good for chronic disease risk," Platz said.
More work must be done before these findings can have widespread applications. Until then, when doctors ask for your approximate daily cigarette consumption, it's not a good idea to round down.
