Can changing your diet really boost fertility?

Weight and diet have a significant impact on fertility.
Weight and diet have a significant impact on fertility. Photo: Shutterstock

If you're trying to fall pregnant, you may want to rethink that soft drink. A study of 18,000 women found that making small changes to your diet could boost your fertility by almost 70 per cent – and one of the recommended strategies is simply to cut out soft drinks.

"Weight and diet have a significant impact on fertility," says Melanie McGrice, a specialist fertility dietitian with a Master's Degree in Dietetics. "Research shows that for every additional body mass index (BMI) point over 29, a woman's fertility decreases by 4 per cent."

McGrice explains that excess weight can impact a woman's fertility in three key ways:

1. Unhealthy eggs. DNA is the genetic code that helps to create new life. Research shows that women who are overweight tend to have more 'disorganised' DNA in their eggs.

2. Overproduction of oestrogen. Oestrogen is the primary female sex hormone, and is produced in the body by the ovaries and by stored body fat. Carrying too much body fat can result in an overproduction of oestrogen, eventually leading to hormone imbalance. About 30 per cent of infertility is thought to be caused by oestrogen imbalance.

3. Implantation of the embryo. Being overweight impacts the environment of the uterus, making it more difficult for the embryo to implant and receive the nourishment it needs for survival.

When it comes to weight and fertility, men certainly aren't off the hook. "There is a lot that male partners can do, as they are half of the equation," McGrice says. Achieving a healthy weight is one of the most important steps, with research suggesting that a man who is just 10kg overweight has a 10 per cent reduction in fertility.

Diet can also help in cases of endometriosis, which is often associated with infertility. McGrice says this is currently a hot field of research, with many new dietary strategies emerging.

In particular, research shows that both a Mediterranean-style diet and a low FODMAP diet may be beneficial (FODMAPs, or Fermentable Oligo-saccharides, Disaccharides, Mono-saccharides and Polyols, are a group of carbohydrates that can be poorly absorbed in the small intestine). "Usually, I would recommend a tailored combination of the two diets for my clients with endometriosis," McGrice says.


She also recommends a prenatal multivitamin for all women trying to conceive. "One of the key reasons for taking a prenatal multi is to boost our folate intake. Folate deficiency is still the primary cause of neural tube defects in Australia. Folate, or folic acid as it's known in its synthetic form, helps to reduce the risk of these defects, like spina bifida and cleft palate."

Unfortunately, many women don't start taking folic acid or a prenatal multivitamin until they discover they're pregnant, which is often too late. That's because the neural tube is one of the first parts of a baby to develop.

"Most women don't discover they're pregnant until they've missed a period and are at least five weeks along," McGrice says. "By that time, the neural tube is usually formed already." 

Other key nutrients, such as iodine, need boosting too. However, when it comes to supplementation, everyone's requirements are different.

For example, the standard recommendation for folic acid is 400 mg per day (in addition to dietary folate), but some women – such as those who are overweight, smoke, have a family history of neural tube defects, or take certain medications – have increased requirements. Women who have genetic problems absorbing folic acid may need a folinic acid supplement instead.

When it comes to iodine, the average woman requires 150 mcg per day, but women who have thyroid issues may need to avoid prenatal multivitamins that contain iodine.

"You can see that your prenatal multi really needs to be tailored to your requirements," McGrice says. "That's why it is highly recommended for every woman to consult a fertility dietitian before they think about conceiving."

So, if you're planning a pregnancy, when is the best time to change your diet? "In an ideal world, it is recommended to start focusing on dietary changes 12 months before trying to conceive, as you need time to improve the health of your eggs and build up your nutrient stores," McGrice explains. "However, it is a case of 'better late than never' and there's a lot that we can do in just a few weeks."  

For more information on fertility and diet, visit or view Melanie McGrice's profile.