Nutrition for fertility

This article was written by one of our contributors; registered dietitian – Rania Salman.

It is estimated that infertility impacts between 8-12% of couples worldwide, with approximately 30% being attributed to male complications, 30% attributed to female complications, 30% attributed to both, and 10% are unknown (1). Infertility is defined as having unprotected sex for at least 12 months and not being able to conceive (1). There is also such a thing as secondary infertility whereby a couple struggles to conceive despite not having had fertility issues with previous children that they have had (2). In recent years, studies have begun to show that the 6 months prior to conception can have huge roles in affecting the health outcomes of a baby, in addition to optimising the chance of conception, primarily through the health and lifestyle of the parents.

When it comes to conception, it is so much more than just having sex, and for someone to be able to conceive, the following needs to happen:

1. The man needs to have healthy sperm
2. The woman needs to have a healthy egg
3. Ovulation needs to occur
4. The sperm needs to meet the egg and fertilise it in order to make an embryo
5. Implantation of the embryo into the uterus needs to occur

So it’s clear from above, fertility is definitely not just a woman’s problem and optimising the man’s nutrition and lifestyle is just as important to optimise the chances of conceiving. However, if infertility has arisen as a cause of biological or physical issues, then in this case nutrition would not be able to help. This article will discuss how nutrition can help improve male and female fertility for non-physical causes of infertility.

Male fertility

For several years, research has focused on maternal health pre-conception and how this may influence chance of conceiving, in addition to affecting the offspring’s future health outcomes.

In couples that are struggling to conceive, infertility arising secondary to male factors account for 20-30% of all cases (1, 3). There are a range of causes of male infertility, including; immunological causes, endocrine disorders and malignancy. However, in 30% of cases, no cause is found and this is known as idiopathic infertility. In these cases, lifestyle factors may be contributing (4,5). So, what are the key nutritional factors men need to consider to improve their sperm quality and quantity?

Trans and saturated fats
These are fats commonly found in foods such as fried foods, confectionary and fatty cuts of red and processed meat. Research has consistently shown that they can negatively affect the total sperm count and the quality of the semen. Some studies have also shown that these fats can negatively impact the motility of sperm (6,7). It is therefore advised that men reduce their intake of foods high in trans fats as much as possible- the closer to zero, the better- although it is acknowledged that this can be difficult if often relying on commercial foods. When it comes to saturated fat, men should be encouraged to have less than 10% total energy intake per day, in keeping with general healthy eating guidelines.   Saturated fat is found in: butter, coconut oil, lard, pastries, the visible fat on meat and fried foods. Trans fat is found in fried foods, and some types of cakes, biscuits and margarine – however trans-fat levels in food products have significantly reduced in many countries, including the UK, in recent years.

Dairy
Findings of studies looking at dairy and links of male infertility have been inconclusive and conflicting. One study showed that men who frequently consumed full-fat dairy had a higher frequency of abnormal sperm size and shape, in addition to negatively impacting sperm motility (8). On the other hand, other studies did not find any relation between sperm characteristics and full-fat dairy consumption. It is important to note that this same study did find that having low-fat dairy did positively impact the concentration of the sperm and their ability to move (8,9). Although it is difficult to discern a strong association, when results are combined, it does appear that any negative impact that dairy may have on sperm may in fact be related to the saturated fat content of dairy rather than the dairy itself. It may be prudent for men who are having difficulty conceiving to switch to low-fat dairy in the mean-time.

Oily Fish
Studies have found that oily fish consumption of at least twice per week have positive impacts on the quality of the sperm (10). This is likely due to the omega 3 fats present in fish, specifically since as sperm cells mature, the amount of omega 3 in the sperm cell membrane significantly increases. It is not exactly clear what function the omega 3 fatty acids service in sperm membranes, however, it is believed that it has functions involved in processes linked to fertilisation (10, 11). Sources of oily fish include herring, salmon, fresh tuna, pilchards, sardines, sprats, trout and mackerel.

Supplements
There has been considerable interest in supplements and infertility and they can definitely play a role in improving men’s reproductive health. Some supplements that do have an evidence-base behind them include selenium, COQ10, folate, zinc, vitamin C and vitamin E (12, 13, 14,15). Before taking any supplements, it is
recommended that you speak with a healthcare-professional, such as your GP or local pharmacist, to ensure that it is the best and safest option for you.

Female Fertility

One of the main ways nutrition and lifestyle can play a positive role in improving a female’s fertility is by optimising the quality of her eggs (16). Unfortunately, as women age, the quality of eggs start to decline leading to increased amounts of genetic abnormalities in a lot of the eggs (16). The good news is that nutrition can really help with minimising the damage to egg health as women age and therefore increase the chances of fertilisation, the development of a normal embryo and optimising the success of the pregnancy. The following points are some key areas to focus on for optimising egg quality health.

Oily Fish
As is the case with male fertility, the omega 3 fatty acids also play an important role in female fertility. Research has shown that a diet high in omega 3 can increase the lifespan of a woman’s eggs in addition to improving the quality (17). It is thought that the omega 3 fatty acids support how the cell is able to function and also support healthy DNA within the egg (17).

Antioxidant rich food
Eggs in older women have more oxidative damage in them due to a reduction in antioxidant enzymes in the eggs themselves, in addition to older women producing more oxidising compounds (18). Fortunately, research has shown that this oxidative stress can be halted or reversed by consuming a diet rich in antioxidants (18). Fruits and vegetables are very high in antioxidants so aiming to get a minimum of 5 portions per day is a good place to start, in particular aiming for a variety throughout the week in order to fully benefit from the diverse range of antioxidants present in the different types of fruit and vegetables. Additional sources of antioxidants include olive oil, nuts and seeds, spices and herbs.

Maintaining a healthy weight
Some research indicates that having a high BMI can reduce egg quality due to increased systemic inflammation and the presence of a higher amount of reactive oxygen species, both of which can negatively impact how an egg matures. Research suggests that it can take longer for women with a BMI of over 30 to conceive (19, 20). Furthermore, for women that are going through IVF, it has been reported that those with a BMI of over 30 have eggs which are smaller and so have a reduced chance of getting fertilised (19, 20). Ultimately, weight management is one part of a jigsaw when it comes to optimising fertility and it should be stressed that if attempting to lose weight, it is important to not follow an overly restrictive diet as over-restricting, crash diets and FAD diets will likely result in missing out key nutrients, which will further decrease the chances of conceiving.

Supplements
Some studies have suggested that there are certain supplements that can help specifically with preserving egg quality. Zinc is important for an egg to be able to develop and mature optimally [it’s also important for sperm quality too!] and so if you are deficient in this nutrient or you are not getting enough through your diet, then this can have a significant impact on your fertility (21). If you wish to try a food first approach, some good dietary sources of zinc include lean red meat, whole grain carbohydrates, beans, nuts and seeds (in particular sesame seeds). Studies have shown that supplementation of Coenzyme Q10 can help to reduce the age-related egg quality decline (22). A food-first approach can also be tried initially by increasing your consumption of organ meats, oily fish and whole grain carbohydrates. Again, if you are considering a supplement to help improve your egg health, it is important to discuss with a healthcare professional to ascertain whether this is the best option for you.

Summary

Nutrition can play an important role to help improve a couple’s fertility, through targeting both the woman’s and the man’s dietary habits. In order for changes to be effective, it is important for the couple to be consistent and ideally, to start making changes 3 months before trying to conceive.

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References

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