Researchers at the universities of Manchester and Sheffield found that smoking cannabis can have a severe effect on male fertility, yet other lifestyle choices such as drinking alcohol and wearing tight briefs were not considered to cause problems, despite earlier reports suggesting otherwise.
Sperm quality has been in decline for decades, and scientists seem unable to make up their minds as to the exact causes, citing everything from smoking to an increased exposure to oestrogen.
The latest evidence is good news for jockstrap-wearers and bad news for dope smokers, but how else can you improve your sperm count? Here we round up five of the most intriguing recommedations from recent years.
Eat red food
A report published by Ohio’s Cleveland Clinic, following analysis of 12 studies conducted by different groups around the world, found that consumption of lycopene improved the quality, mobility and volume of sperm dramatically, increasing sperm count by up to 70 per cent. Lycopene is an essential nutrient found commonly in red fruit and vegetables such as tomatoes, strawberries, cherries and peppers.
Lay off the laptop
A 2011 study published in the journal Fertility and Sterility suggested there could be a link between using a laptop with a Wi-Fi connection and a reduction in sperm quality. Sperm samples from 29 men were stored normally and under a laptop connected to WiFi. The sperm stored under the laptop became more sluggish and showed signs of DNA damage.
Get off your bike
Cycling has myriad health benefits, but not when it comes to your sperm. A 2009 Spanish study by the Andalusian Center of Sports Medicine and the University of Las Palmas found that a prolonged spell on your bike can severely affect the shape and quality of your spermatozoids. After monitoring 15 Spanish triathletes with an average age of 33 the study found that “those that systematically cycled 300 kilometers a week– had less than 4pc, which is considered a fertility problem”.
Keep your cool
The optimum temperature for sperm production is 34.5 degrees celsius, which is slightly below body temperature. A three-year University of California study in 2007 found that five out of 11 men who stopped taking hot baths experienced a sperm count rise of almost 500 per cent.
Drink coffee – but not too much
In 2003, researchers from Sao Paolo University in Brazil studied 750 men and concluded that drinking coffee can improve the swimming speed of human sperm, although whether this means pregnancy rates are higher among coffee drinkers is unclear. Other studies have suggested that drinking just three cups of coffee a day can cause genetic mutations in sperm, making it harder for them to successfully fertilise an egg.