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Important foods to eat and avoid

Watch Michelle talk about the foods men and women should eat, and avoid to promote reproductive health.
MICHELLE BLUMFIELD: While it is well known that eating a healthy and varied diet, in line with our country’s dietary guidelines, is a key part to maintaining good overall health, exciting new research is indicating that there may be certain vitamins and food groups that could have a greater impact on our reproductive health than others. Firstly, let’s look at men. There is some evidence from two case control studies to suggest that eating a diet rich in carbohydrates and lots of fruits and vegetables to provide fibre, folate, and lycopene, correlates with improved semen quality. Benefits to male fertility may also be provided by antioxidants, which are also most abundant in plant foods like fruits and vegetables.
A recent scientific review revealed that antioxidants cause significant improvements in DNA damage and oxidative stressors, in men with reduced sperm motility. Oxidative stress can result in sperm protein, lipid, and DNA damage and sperm dysfunction. In 2015, a Cochrane Systematic Review, including 34 studies, determined that men who take antioxidant supplements had a significant increase in live birth rate and pregnancy rate when compared to the control groups. Overall, what this research tells us is that a balanced diet that includes lots of whole grain carbohydrates, fruits, and vegetables rich in fibre, antioxidants, and other key new nutrients like folate may boost the chances of paternity. Now let’s look at women. A woman’s diet might ultimately affect her fertility, particularly ovulation.
Researchers from the Harvard School of Public Health in Boston have followed more than 18,000 women participating in the Nurses’ Health Study. Each of these women reported trying to become pregnant and most actually did fall pregnant over the eight years of follow up. However, one in six of these women experienced difficulty falling pregnant with hundreds experiencing ovulatory infertility. When researchers compared their diets with the women who got pregnant easily, several key differences emerged and authors have translated them into a potential fertility diet. According to this preliminary research, foods that may help boost ovulatory fertility are lots of slow digested carbohydrates or low GI carbohydrates that are rich in fibre, such as whole grains, beans, vegetables and fruits.
So this means avoiding highly refined carbohydrates such as white bread and potatoes, or those with added sugars such as confectionery and sugar sweetened beverages. Findings from the Nurses’ Health Study indicate that the amount of carbohydrate in the diet doesn’t affect fertility. It’s actually the quality of those carbohydrates that are important. The scientific research also shows that pre-pregnancy diets that contain lots of these low GI carbohydrates and fibre can also reduce the risk of gestational diabetes during pregnancy. Fertility may also be increased by avoiding trans fats. Trans fats are commonly found in fast food, baked goods, and other commercially prepared products. Instead, recommend that women choose foods that contain monounsaturated fats, such as olive oil, canola oil, nuts, and avocados.
Because did you know that choosing foods high in trans fat instead of monounsaturated fats have been shown to more than double the risk of ovulatory infertility. Eating more plant sources of protein and less animal protein may also help boost ovulatory fertility. Plant sources of protein include lentils, quinoa, nuts and seeds, beans, and even soy containing foods like tempeh, tofu, and edamame. Research shows that when 25 grams of animal protein was replaced with 25 grams of vegetable protein, it actually reduced the risk of ovulatory infertility by 50%. What’s more is that protein from animal sources, primarily meat products, even during pregnancy, has been linked to an increased risk of overweight and obesity in children at 20 years of age.
Lastly, choose full fat dairy products over reduced fat varieties if you’re choosing to consume dairy. Results from the Nurses’ Health Study indicate that a daily serving of whole milk, and foods made with whole milk, such as full fat yogurts and cheeses, offer some protection against ovulatory infertility, while, unfortunately, skim milk and low fat milk were shown to do the opposite. These findings contradict current standard nutritional advice, particularly when weight management is concerned. A team approach involving collaboration with a dietitian, who are the experts in food and nutrition, is recommended. This will make sure that any dietary changes to promote fertility can be made while also balancing energy intake to avoid unnecessary weight gain.
Overall, there is still only limited evidence in this area. And large, well-designed, randomized control trials are needed before we can make firm recommendations to couples seeking dietary strategies to improve fertility. In the mean time, health professionals can be really confident that by promoting a well-balanced diet that includes lots of whole grain carbohydrates, plant protein, fruits and vegetables, and monounsaturated fats, they are improving the health of childbearing age women and their partners and may even encourage fertility. The summary points from this session include foods that may promote fertility in men are lots of whole grain carbohydrates and fruits and vegetables rich in fibre, antioxidants, and key nutrients like folate.
Foods that may promote ovulatory fertility in women are low GI carbohydrates, monounsaturated fats, vegetable protein, and high fat dairy sources, while limiting trans fats and animal protein.

Watch Michelle talk about the foods men and women should eat and avoid to promote reproductive health.

About Harvard Medical School’s ‘Fertility Diet’

Harvard Medical School’s ‘Fertility Diet’ was first published in 2008 and is based on data from the Nurse’s Health Study. It has not been tested further in more rigorous study designs such as randomised controlled trials as this would be difficult to do.

As healthcare professionals, we cannot say that following the ‘Fertility Diet’ will guarantee pregnancy.

On the other hand, aspects of the Fertility Diet may be applied in practice as they are in accord with nutritional recommendations of national healthy eating guidelines.

Do these key messages sound familiar?

  • Avoid trans fats

  • Replace saturated fats with unsaturated fats

  • Consume plant-based protein and non-haeme iron

  • Choose low-GI carbohydrates

  • Prenatal supplements are important

  • Maintain hydration by consuming plenty of water

  • Achieve a healthy weight

  • Be physically active

The ‘Fertility Diet’ found that full-fat dairy was associated with improved fertility outcomes. This may sound controversial compared to current recommendation.

Current Australian dietary guidelines recommend low-fat dairy for adults (and those aged > 2 years). Low-fat dairy may assist with weight control in men and women who aim to decrease their overall energy intake and it is still recommended to decrease overall intake of saturated fat.

However, there may be a place for full-fat dairy in an individual’s diet and so assessing dietary intake and lifestyle, medical history, current health goals and current biochemistry, will help you to decide whether this is an appropriate recommendation to make.

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Food as Medicine: Fertility and Pregnancy

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