Diet has a huge impact on health and fertility is no exception. Men who eat the most vegetables and fruits (and therefore more vitamins, folic acid and fibre) have a better sperm count than those eating lots of protein and fat found in meat, full-fat dairy foods, French fries and snacks. Infertility in women is also linked to diet with higher rates being found in women who eat the most animal protein. Replacing just five per cent of energy intake of animal protein (meat and dairy) with vegetable protein (pulses or nuts for example) could reduce infertility risk by 50 per cent. Given that there is no harm in recommending a healthy diet and lifestyle, couples seeking assisted reproduction treatments should be advised about the drastic effect of both the male and female diet and lifestyle on treatment success.       

The Mediterranean diet has been related to lower risk of multiple chronic diseases, but it has also been found to have a positive impact on male reproductive potential. A Spanish study looking at 209 male university students found that those consuming a Mediterranean diet with high intakes of vegetables and fruits had a better sperm count than those eating a Western diet characterised by high intakes of processed meats, French fries and snacks (Cutillas-Tolín et al., 2015). The authors concluded that traditional Mediterranean diets may have a positive impact on male reproductive potential.

It was previously shown that meat and dairy foods may be linked to fertility problems. An earlier study found that men who ate the most meat and full-fat dairy products had fewer and slower sperm, while those who ate the most fruit and vegetables had higher quality sperm that swam faster (Mendiola et al., 2009). Lead researcher Professor Jaime Mendiola said “…among the couples with fertility problems coming to the clinics, men with good semen quality ate more vegetables and fruit, which means more vitamins, folic acid and fibre and fewer proteins and fats, than those with poor sperm quality”.

Replacing animal protein with plant-based protein can reduce infertility risk in women too according to a study that looked at the diets of 18,555 women who were followed up as they attempted a pregnancy or became pregnant during an eight year period (Chavarro et al., 2008). Results found that the risk of ovulatory infertility was 39 per cent higher in women eating the most animal protein. Consuming just five per cent of total energy intake as vegetable protein rather than animal protein was associated with a more than 50 per cent lower risk of infertility. The authors concluded that replacing animal sources of protein, in particular chicken and red meats, with vegetable sources of protein may reduce the risk of infertility.

Another study investigated the influence of diet on sperm quality and intracytoplasmic sperm injection (ICSI), a form of treatment for men who are infertile used in nearly half of all IVF treatments requiring just one sperm, which is injected directly into the egg (Braga et al., 2012). Two hundred and fifty men undergoing ICSI cycles were followed. Factors positively influencing sperm included fruit and cereal consumption. Factors negatively affecting sperm included BMI, alcohol consumption, smoking and the consumption of red meat which had a negative impact on the implantation rate.