Sugar-sweetened drinks such as soda can lower semen quality, a new study has found.
Researchers have found that high consumption of sugary drinks is associated with low sperm motility, or sperm movement - but this was true only for healthy, lean men.
The researchers found no relationship between sugary drink consumption and sperm motility in overweight or obese men.
The study analysed the semen of 189 men between the ages of 18 and 22 from Rochester, New York. Each participant got a physical exam, answered a questionnaire about his health habits and diet, and provided a semen sample.
The men self-reported how often they consumed sugar-sweetened drinks over the past year, from zero to six drinks per day.
Sugary drinks included more than just sodas, said study author Jorge Chavarro, professor of nutrition and epidemiology at Harvard.
For example, sports drinks alone accounted for about 40 per cent of the sugar-sweetened beverages the men reported drinking.
The top 25 per cent of study participants who drank the most sugary drinks consumed an average of 2.7 sugar-sweetened beverages per day, 'Live Science' reported.
Consuming this many sugary drinks didn't seem to affect sperm concentration, shape or ejaculation volume, the study found.
But the lean men in this high-intake category had 6.3 per cent lower sperm motility than their counterparts who consumed, on average, less than one sugary drink per day.
Higher sugary drink intake was also associated with lower levels of a reproductive hormone called the follicle stimulating hormone, or FSH.
This hormone helps control sperm production, and the men in the study, both lean and obese, who consumed the most sugary drinks had slightly lower FSH levels.
The study was published in the journal Human Reproduction.