To improve chances of conception, men should drink a pint of beer daily, cut down on coffee, eat more fruit and vegetables (beware a coating of sperm-harming pesticides), and avoid vegetarian or vegan diets, according to recent studies.
The various research projects, examining how nutrition corresponds to sperm quality, were presented at the annual conference of the American Society for Reproductive Medicine (ASRM), held in Hawaii.
Some preliminary results were 'definitely surprising', said Dr Jorge Chavarro, assistant professor of nutrition and epidemiology at Harvard School of Public Health, Boston.
Researchers from Massachusetts General Hospital in Boston determined that drinking just under three units of alcohol a day – around a pint of beer – boosted the success of a pregnancy following IVF to 57 percent, as opposed to a 28 percent success rate for men who drank the least. The findings were based on a study of 105 men over 214 IVF cycles. The study also found that the chances of conceiving were half as likely for men who drank more than three regular cups of coffee a day, than if it was for men drank who less than one a day.
Meanwhile, researchers from the University of Rochester Medical Center in Rochester, New York, found that infertile men who drank alcohol were less likely to report sexual or erectile problems than teetotalers. The results were based on 753 surveys conducted on men with an average age of 35.
Studies looking at the effect of tobacco produced less surprising results. Researchers at the Rochester fertility clinic in New York found that infertile men who smoke were more likely than non-smokers to experience sexual dysfunction. Researchers from Sao Paulo Federal University in Brazil also showed that smoking is more harmful to sperm than having a varicocele (a varicose vein in the scrotum).
No mechanism was proposed to account for the impacts of caffeine or alcohol, but ASRM President Dr Rebecca Sokol notes: 'The human organism is complex and substances we inhale and imbibe have systemic effects beyond the stimulation the user is seeking. These studies provide new information that can help men make healthy choices for themselves, their partners, and their future children.'
Another set of findings presented at the meeting suggested that eating fruit and vegetables coated with pesticide residues could harm sperm quality. Dr Chavarro and colleagues from the Harvard School of Public Health and the Massachusetts General Hospital found that men who consumed the highest quantity of pesticide-coated greens had 64 percent less normal shaped sperm, and these were 70 percent slower than those of men who consumed less pesticides.
While research from the Loma Linda University School of Medicine in California comparing 26 vegetarians and five vegans to 443 non-vegetarians, found that vegetarians and vegans demonstrated lower sperm concentration and motility, although not in the infertile range. Sperm function and DNA tests were similar across all groups.
Dr Paul Turek, President of the Society for Male Reproduction and Infertility, USA, commenting on the pesticides study, concluded, 'Nutrition is important to good reproductive health, but food that is good for you can contain other substances not-so-good for you.'
The studies have not yet been peer reviewed and more research is needed before the findings could be turned into recommendations for men looking to increase their fertility.