Diet and Fertility

Around one in seven couples may have difficulty conceiving and infertility tends to be diagnosed if a couple has been trying to conceive for over a year without success. For couples who have been trying to conceive for three years or more, there is only a 25% chance of a pregnancy within the following year.

In one quarter of cases, there is no explanation for the infertility, but certain factors can increase the risk. Known factors are weight and stress and those trying to conceive may feel as though they are caught in a vicious cycle as the whole process of trying to conceive is stressful in itself, let alone bringing clinical treatment into the equation. It is therefore critical to understand how to manage depression and other mental health disorders in men and women trying to conceive. This should always be done under the supervision of a medical expert, but in addition some non-medical techniques may include mindfulness (there are several apps that can be downloaded onto phones/tablets), yoga, meditation or having a relaxing massage.

So what about the role of nutrition? The British Dietetic Association have created a Food and Mood fact sheet that can be accessed by the general public on the BDA website ( www.bda.uk.com ) and several vitamins and minerals are highlighted which, in lesser amounts than needed, are linked to changes in mood. These include iron, B vitamins, folate and selenium and all of these will be discussed later as they are all linked to pregnancy and pre-conception.

An article summarising current evidence on nutritional factors related to infertility was published in America last year (Panth et al, 2018) and the authors suggest that nutrition counselling should be integrated into clinical guidelines for infertility as diet and body mass index (BMI) influence outcomes during clinical treatment, ie intrauterine insemination (IUI) and in vitro fertilisation (IVF). The authors state that there is strong evidence that healthy pre-conception dietary patterns among both men and women have beneficial outcomes on fertility and cite a large cohort study in 2007 (Chavarro et al) which found that women whose diets consisted of plan proteins, full fat dairy, iron sources and monounsaturated fats (olive based oils and spreads, rapeseed oil, avocadoes, almonds, brazils, peanuts) during the pre-conception period had a 66% lower risk of infertility related to problems with ovulation and a 27% lower risk due to other causes of infertility compared to women with lower intake of these foods. Factors controlled for in the study included age, BMI, alcohol and caffeine intake and smoking.

Preliminary data suggests that red meat intake may have an adverse effect on fertility, however more research is needed. If red meat is reduced or cut from the diet, it is important to replace the iron with non haem (plant based) sources such as lentils, chickpeas, beans, seeds, fortified breakfast cereal, dried fruit and baked beans and to ensure a source of vitamin C is taken alongside to increase absorption. The data suggests that if iron is taken in the form of foods such as these or via supplements, the risk of ovulatory (but not other causes of) infertility may be reduced.

A healthy diet can lead to a healthy pregnancy

There is no evidence that alcohol and caffeine intakes affect fertility, however they can affect pregnancy therefore if you are trying to conceive it is sensible to stop drinking alcohol and to reduce caffeine.

The recommended safe limit of caffeine during pregnancy is 200mg/day, which is easily reached if you are a coffee/tea drinker. There are roughly 40mg in a cup of tea and 105mg in a cup of home brewed coffee, but it is important to be aware that high street coffees often contain a lot more. Some chains add up to five shots of caffeine in their largest drinks and on average, in regular and large cups of filter coffee there are approximately 157mg and 387mg of caffeine contained therein respectively. That is twice to almost five times the caffeine content of one can of red bull!

It is also important to be aware of other sources of caffeine. It is found naturally in the cocoa bean, so chocolate and cocoa powder will both contain caffeine, as well as coffee/chocolate flavoured ice cream and chocolate based breakfast cereal. Although it would be assumed that decaffeinated coffee does not contain caffeine, surprisingly it does actually contain a small amount of between 2-12mg per cup, depending on the brand.

BMI and fertility

It is really important to keep your weight within the healthy BMI range of 18.5-20 as weights outside of this range have been shown to have an increased risk of problems conceiving and also maintaining healthy pregnancies. If a women is underweight, she is more likely to have nutritional deficiencies is a risk of her menstrual cycle being disrupted, therefore making it harder to conceive. Similarly being overweight can reduce the chances of conceiving and increase the risk of complications during pregnancy. A weight loss of 5-10% has been shown to dramatically improve ovulation and pregnancy rates. For example, if a women is 5 foot 6 inches tall (1.68m) and weighs 80kg, she will have a BMI of 28.4, which is outside the healthy range. Losing 5% (4kg) will bring her BMI down to 27 and 10% (8kg) 25.5. It is not just female obesity that can impact on fertility; male obesity is also linked with a higher risk of infertility. Gradual, sensible weight loss can be achieved with the support of a dietitian to ensure that major food groups are not eliminated from the diet which can cause nutritional deficiencies and worsen the chances of conception.

During pregnancy, the baby will get all the nutrients needed for growth from its mother, therefore it is really important pre-pregnancy to make sure reserves are well stocked. Some important micronutrient requirements and considerations:

Folate and folic acid

Folate is the name of one of the B vitamins (B9), whereas folic acid is the man made form, sold as supplements. A deficiency of folate in the body is linked to neural tube defects in babies, such as spina bifida and it is recommended in pre-conception and for the first 12 weeks of pregnancy that a 400ug supplement should be taken, in addition to good dietary sources of folate. These include oranges, green leafy vegetables, kiwis, beans, almonds, cashews and fortified breakfast cereal. Some women will need higher doses of folic acid, for instance, if they are at higher risk of a pregnancy affected by neural tube defects and this should be discussed with their GP.

There are lots of healthy foods containing vitamin D

Vitamin D

All pregnant women should take a supplement containing 10ug of Vitamin D. This vitamin is needed as it regulates the amount of calcium and phosphate in the body which are both needed for healthy bones, teeth and muscles. Dietary sources should also be eaten and these include oily fish, fortified dairy products, eggs, fortified non-dairy products.

Iron

It is important to build up your iron stores before becoming pregnant as low stores pre-pregnancy are linked to developing anaemia during pregnancy. Dietary sources include red meat, fish and poultry, however there are many plant based sources also, as mentioned previously. There are certain foods that can reduce the body’s absorption of iron so it is important to be aware of these. These include foods containing calcium, such as milk and other dairy products, tea, coffee and some vegetables (such as raw spinach: cooking can help increase absorption). It is beneficial to not drink tea or coffee with meals and to leave at least one hour either side of each snack/meal.

Iodine

Iodine is essential for thyroid hormone production and these hormones are essential for adequate brain and neurological development. This is particularly important during early pregnancy, lactation and early years of life. In fact, iodine is seen as a key nutrient for the first 1000 days of life (the time between a woman’s pregnancy to just before her child’s second birthday).

The recommendations for iodine in the UK for pregnancy and lactation are 140ug but these are based on the assumption that the mother has adequate stores pre-conception. The main sources of iodine in the UK are milk and milk products. Other sources include fish, meat and meat products, eggs, bread, fruit, vegetables and potatoes. For those on plant based diets or who are unable to have dairy, the iodine concentration of milk alternatives, compared to cows milk, have a very low iodine content (around 2% of cows milk). Fortified milks have a reasonable content so it should be ensured that the milk alternative is fortified with iodine. For those following a plant based diet with the only sources being fortified milk​alternatives, it may be beneficial to take a suitable supplement but avoid excessive intake by choosing one providing no more than 150ug daily. For those planning a pregnancy it would be sensible to think about iodine as well as folic acid, iron, calcium and vitamin D.

Zinc

Insufficient zinc intake during pregnancy has been linked with pre-term delivery, low birth weight and prolonged labour. It is needed to enable cells to change from general to more specialised forms so has a key role in growth during pregnancy. It also plays a role in regulating men’s blood testosterone levels – low levels can result in decreased production of sperm. Male requirements are slightly higher as about 0.6mg of zinc is lost per ejeculation. Therefore, when trying to conceive it would be beneficial to snack on zinc rich snacks, such as pumpkin or sunflower seeds. Other dietary sources include meat, shellfish, dairy, nuts, beans, tofu, brown rice and oats.

Selenium

This is important for a healthy reproductive system and, like zinc, regulates testosterone levels. Good sources include meat, fish, brazil nuts and eggs. Only a very small amount is required daily to meet requirements and in fact, eating just one brazil nut a day is enough to meet these requirements.

Getting the right nutrition cannot guarantee conception or ensure the health of your baby, however, as long as both partners follow a healthy, balanced diet, ensuring that they are consuming enough of all the nutrients mentioned in this article and maintaining a healthy BMI, they will give themselves the best chance of conceiving, either naturally or through medical treatment. As discussed, there are many other factors involved in boosting the chances of conception, and these should all be considered together, not as separate entities.