The impact of diet on IVF and more: How to eat to boost your fertility 

“I lost three or four stone in a short amount of time, it crept up again, I lost it before getting married and again it crept back. My approach to food was definitely restrict-and-binge. But I’d been pulling back a little, trying to be accepting of my body. That’s why the BMI mention knocked me a bit.”

Áine contacted Willow Nutrition, an online nutrition clinic run by Dubliner Jess Willow, a registered dietician who has worked with the NHS and HSE and who trained in fertility nutrition. Willow’s approach is not just to support her client nutritionally but also to help her relationship with food.

“I work in a weight-inclusive manner. I don’t focus on weight or BMI as an indicator of health or ability to get pregnant. Crash diets, restricting [food], often lead to cutting out critical nutrients. Instead I support clients with optimising nutrition and incorporating fertility-promoting lifestyle factors.”

A fertility journey can be very emotional, she says: “Food can well be used as a coping mechanism. I work to support people around their relationship with food.”

Áine expected Willow to tell her the foods she should cut out: “It never happened. Instead it was what I could add into my diet rather than taking anything away.

“I’d always have had porridge for breakfast. Now I add Greek yoghurt, fruit, nuts, seeds. With a lunch sandwich, I’ll also have a side-salad. And in the evening — even if I’m only having pizza — I add, along with peppers and tomatoes, some leafy greens: Spinach, broccoli, kale. On diets before, I wouldn’t have considered bread of any benefit, now I eat wholemeal bread.

“I find it so refreshing — eating to make myself feel good, move well, eating for wellness rather than to lose weight and look a certain way.”

Áine hasn’t yet fallen pregnant but she’s feeling much better. Changing her relationship with food, and how she sees it, has helped her feel not so powerless around fertility.

“It definitely has given me some control over a situation where I have little control,” she says, adding that she is planning an IVF cycle soon.

The impact of nutrition on fertility

Willow’s clients vary, from couples preparing for IVF and women in their 30s planning to freeze their eggs, to couples with secondary subfertility (I prefer ‘subfertility’ to ‘infertility’, it’s less final) and women who aren’t trying for pregnancy but need support managing polycystic ovary syndrome (PCOS) or endometriosis symptoms.

She finds a big dietary-related mistake people make is not considering sooner the influence nutrition has on their fertility: “Sometimes clients have had ovulation induction and IVF and been on this journey three to four years. And this is their last cycle, their last ditch attempt, they’re pulling out all the stops. And it’s great they’re looking at nutrition but it’s disheartening because we know how much nutrition can impact on IVF.”

She points to a 2017 Greek study showing how the Mediterranean diet enhances IVF outcomes for men and women, improving sperm quality, as well as increasing likelihood of successful embryo transfers.

“This approach is rich in plant-based foods, has lots of colour from fruit, veg, salads, beans, pulses, legumes, herbs and spices, wholegrain carbohydrates, moderate amounts of fish, poultry, eggs, olive oil, nuts and seeds, some red meat and dairy. It limits processed foods and saturated fats.”

In her practice, Willow often returns to three key messages around eating for fertility:

• Eat regularly: “Occasionally I see clients skipping meals, or leaving long gaps between meals. But for optimal hormone support we want to be eating regularly.”
• Acknowledge hunger and fullness: “I use the evidence-based intuitive eating hunger and fullness scale to support clients to think about this, often for the first time in their lives.”
• Eat sufficient amounts of protein particularly in the morning: “I don’t mean whacking in protein powders but getting a portion to promote satiety, support hormonal balance and to set you up sufficiently for the day.”

Willow calls out one big myth she often encounters: “That cutting out gluten or lactose will improve fertility. Unless someone has been diagnosed with lactose intolerance or coeliac disease there’s no robust evidence to support cutting these out. It can lead to people cutting out fertility-promoting foods like dairy and wholegrains.”

She also warns against over-supplementation and not getting nutrition-status bloodwork done: “Specifically, your vitamin D, iron, folate, ferritin and vitamin B12 should be checked. They’re not routinely checked when investigating fertility, yet we know deficiencies can negatively impact fertility health.”

Willow has seen people spend hundreds of euros monthly on supplements that aren’t benefiting them: “In some cases they’re actually harming them, or interacting adversely with other supplements or medications.”

She highlights specific micro-nutrients that research finds greatly enhance fertility:

• Vitamin D: “For women undergoing IVF, adequate levels result in good quality egg-production and successful embryo-implantation. Ovarian reserve is significantly lower in vitamin D-deficient women. Insufficient levels are linked to changes in sperm count, sperm quality, and testosterone levels.”
• Folate: All women of childbearing age should take folic acid to reduce likelihood of neural tube defects in the baby. In addition, “studies confirm higher intake of folate is associated with lower risk of anovulation and ovulatory infertility, shorter time to pregnancy and greater success with fertility treatment”.

When Sophie, a Dublin-based IT worker in her 30s, spoke to me last week, she was nine and a half weeks pregnant. On the pill for years to help with troublesome hormonal issues, she was diagnosed with PCOS last year after starting trying to conceive. She says her positive pregnancy test is due to a combination of progesterone to bring on menstruation, ovulation induction and lifestyle change — including nutritional support.

“I’ve more balanced meals now. I’d never eat just carbohydrates on their own, like I used to. Previously dinner might have been just pasta, no chicken. I now have protein and fats along with the carbs. And if I’m snacking, having a piece of fruit, I pair it with nuts, or pair Greek yogurt with berries.

“I like the mindful eating approach rather than strict dieting. I definitely feel better and have more energy.”

The breakdown of what to eat

Kathryn Stewart, registered dietician at Dublin Nutrition Centre, specialises in fertility and hormonal health. She says infertility affects 10-15% of people worldwide — 35% relates to females, 30% to males, 20% to men and women, while 15% is unexplained.

Stewart encourages men to boost fertility by:

• Eating oily fish: Twice weekly, or taking high-strength omega-3 supplement. “It improves sperm motility and quality. And taking 75g of walnuts daily over 12 weeks, in addition to oily fish, is associated with improved sperm motility and morphology [sperm shape].”
• Eating diet high in unsaturated fats: Avocado, hummus, olive oil, nuts and seeds. “A low-fat diet can decrease testosterone levels.”
• With fruit/veg, having a rainbow of different colours: “Don’t just have red apples, red peppers and tomatoes. Different colours have different antioxidants to protect sperm health.”

On female fertility, Stewart points to research that found making five dietary changes can reduce risk of ovulatory infertility by 69%.

She recommends:

• Full-fat dairy as more beneficial than low-fat: “Whole milk isn’t full of fat. It has medium amounts. Watch portion-size, but eat regular yoghurt, regular cheese.”
• Swapping animal protein for plant proteins: Chickpeas, lentils, nuts, seeds. “This doesn’t apply to eggs, milk and fish.”
• Choosing low-glycaemic index carbohydrates: high-fibre oats, wholemeal bread.
• Swapping saturated fats: For hummus, peanut butter, seeds, avocado. “Swap butter in cooking for olive oil.”
• Prenatal supplements: Including vitamin D and folic acid.

For both dieticians, eating for fertility should be evidence-based and practical. Willow says: “While the focus is achieving a pregnancy, it’s also about supporting people’s relationship with food, something they can keep for the whole of their life.”