2.4 Diet and lifestyle factors for fertility

Various lifestyle-related factors such as obesity, smoking, substance abuse and heavy alcohol consumption are known to have a negative impact on both male and female fertility and the success of ART (1, 2). Other lifestyle habits may also adversely affect reproductive health, and advice on modifiable lifestyle factors should be given to couples to help them make positive changes to potentially improve their chances of a healthy pregnancy. This will enhance overall wellbeing and make the couple feel that they can do something together, which is within their control.
With timelines in mind, 3-6 months is an ideal timeframe to focus on nutrition and lifestyle changes to enhance fertile health, but of course any length of time is beneficial.

Smoking

Smoking is associated with an increased risk of infertility and lower ART success rates in women (1, 2) and with impaired semen quality (3) in men.

Weight

Weight is often related to eating and activity habits. It is a well-known fact that obesity can have a significant impact on male and female fertility, and these patients should be supported to lose weight safely and effectively without compromising their nutritional intake or over-exercising, in order to help protect their fertility.
The good news is that the negative effects of obesity on fertility are reversible. With an average weight loss of 10.2 kg, 90% of previously anovulatory, obese women began ovulating (16).
Women who are underweight and have extremely low amounts of body fat are at higher risk of ovarian dysfunction and infertility (17). Underweight women are also at increased risk of premature births (18). Underweight women should be encouraged to increase their intake of nutrient-dense foods to promote weight gain, without resorting to unhealthy foods.

Dietary advice

A healthy, varied and balanced diet is key to maintaining good overall health. A diet rich in carbohydrates, fibre, folate and lycopene (11) as well as fruit and vegetables will improve semen quality (12).
Semen parameters may be negatively affected by the consumption of alcohol and red meat, but positively influenced by fruit and cereal consumption. Red meat may also negatively impact fertilisation and implantation rates (5).
Antioxidant intake has been associated with a shorter time to pregnancy (4) while high antioxidant levels have been seen to increase semen quality, compared to low or moderate amounts (13). A Cochrane review recorded a significant increase in live birth rate for men with an oral antioxidant intake(14).
Trans fats (mostly found in packaged food) may increase the risk of infertility in women (15).

Alcohol

In men, alcohol consumption has been linked with negative side effects such as testicular atrophy, diminished libido and reduced sperm count (19, 20, 21). Links between alcohol and sperm morphology have been observed alongside an impact on morphology and motility (22).
In women, alcohol consumption has been shown to increase the length of time taken to conceive (23), decrease the conception probability rate by over 50% (24), decrease the implantation rate, increase the risk of spontaneous abortion and foetal death (25, 26), and increase the risk of ovulatory disorders and abnormal blastocyst development (27).
The amount of alcohol considered safe when trying to conceive is not known. Couples should be advised to minimise their intake or avoid alcohol altogether when trying to conceive.

Caffeine

Caffeine has been associated with an increased time to pregnancy over 9.5 months, particularly following consumption of over 500 mg per day (28). Women who consume more than 100 mg of caffeine/ day may be more likely to experience a miscarriage or spontaneous abortion (29, 30, 31). Caffeine consumption during the first trimester is linked to both miscarriage and stillbirth (32). The risk of stillbirth increased by almost 80% and 300% following the consumption of 4-7 cups and 8 cups of coffee, respectively (33).

Exercise

Physical activity may help improve ART outcome, with women exercising in the year prior to receiving infertility treatment, being more likely to have a positive outcome (6). Higher implantation and live birth rates have been documented in women who remain active during infertility treatments (7, 8).

Sleep

Adequate sleep is an important factor for human health and wellbeing (9). However, the link between sleep quality and reproductive health is largely unknown. Sleep disturbances are related to high levels of stress and anxiety, and may therefore indirectly affect reproductive health in both partners, as well as testosterone production and semen parameters in the male partner (10).

Toxic exposure

While the human body has defences to protect against the environmental toxins to which it is exposed through eating, drinking, breathing and skin contact, these chemicals may also have a negative impact on fertility. Patients should therefore be advised to minimise their exposure as much as possible.
Air pollution has been found to affect morphology and motility, and to increase DNA fragmentation (34, 35, 36). For women, exposure to air pollution can lead to preterm delivery, miscarriage, stillbirth, spontaneous abortion and foetal loss (37, 38).

Recommendations for clinics

Diet and lifestyle should be discussed sensitively and without apportioning blame. Aim to start from the couple’s current position and move them forward step by step. Everyone has a different ‘baseline’ and too much too soon can be overwhelming. Both couples should ideally be involved in the process. The best results are achieved when the patient agrees to the steps to be taken. For example, when discussing reduced alcohol consumption, discuss with the patient whether total abstinence is the best option for them or whether they would prefer to consume a set number of units on set days of the week or each month. It is important for the patient to feel involved in these discussions in order for targets to be achievable.
With the above in mind, help clients to:

• Stop smoking
• If overweight, aim for slow, steady weight loss (no fad diets);
• Do not advise patients to follow a low-fat diet, but encourage them to limit their carbohydrate intake to no more than a small portion (potatoes, pasta, rice, beans) at each meal. Healthy fats, protein and fibre should also be included in each meal to keep hunger pangs at bay (consider eggs, poultry, fish, nuts and seeds as well as all vegetables).
• (see exercise, below) If underweight, do not advise patients to eat ‘junk foods’. Instead, explore whether their digestive system requires attention and screen for coeliac disease as this may affect nutrient absorption without exhibiting any gastrointestinal symptoms. Advise patients to snack on high-calorie, nutritious foods such as nuts, seeds and avocado on crackers.
• The Mediterranean diet is mostly akin to the types of foods that promote fertility. Print out the Mediterranean diet pyramid or recommend a good Mediterranean cook book.
• Foods to include: legumes, wholegrains, fruits, vegetables, olive oil, poultry, eggs, fish (including oily fish twice a week), herbs and spices.
• Foods to limit: red meat, sweets, products made from refined flour such as white bread and pasta.
• Advise patients to cook from scratch wherever possible and to avoid heavily processed foods.
• Inquire whether patients are getting 7-9 hours of good quality sleep each night, and whether they feel refreshed on waking. Recommend some of the following for those with sleeping problems: meditation apps, gentle yoga exercises, turning phones off in the evening, installing blackout blinds and establishing a healthy bedtime routine.
• Both partners should ideally partake in gentle exercise for 30-60 minutes daily, such as walking, swimming, yoga or Pilates. Some muscle building is preferable since this helps to increase the metabolic rate. However, over-exercising may be detrimental for both partners.
• Strategies to reduce toxic exposure may include avoiding cycling in traffic, taking the scenic route in order to avoid polluted roads, using more natural hygiene products and cleaning products, purchasing an air purifier if living or working in a polluted environment, and reducing the use of plastics such as cling film, plastic food containers or water bottles.

Resources

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