The role of nutrition and micronutrition in fertility

The role of nutrition and micronutrition in fertility is often underestimated.

Before starting the article, I invite you to read the latest press release from the WHO report dated April 2023. You can find it here.

According to this report, 17.5% of the global adult population (1 in 6 people) is affected by infertility (better saying subfertility) (World Health Organization, 2023).

Infertility is defined as the inability to achieve pregnancy after 12 months of regular unprotected sexual intercourse (World Health Organization, 2023), or the failure to conceive after 12 months of regular unprotected sexual intercourse. The duration decreases to 6 months for women ≤ 35 years old.

Infertility goes beyond a difficulty for the couple to have a child. It can lead to major distress, stigmatisation, and financial difficulties, affecting the mental and psycho social well-being of those involved (World Health Organization, 2023).

According to INSERM, “between one-third and half of pregnancies occur after 6 months of attempts. This low ‘reproductive yield’ compared to other animal species would be partly explained by a high rate of early spontaneous miscarriages, most of which are not even detected.”

The causes of infertility affect both sexes. It is estimated that 40-50% of infertility cases are linked to male disorders (Kumar & Singh, 2015). Ladies, you don’t bear all the responsibility!

Causes of infertility in men and women

In women, the major causes of infertility include:

• Polycystic Ovary Syndrome (PCOS), affecting 10% of women. It is a major cause of infertility in young women.

• Ovarian insufficiency related to age (the average age of mothers at the time of childbirth increased from 26.5 years in 1977 to 30.6 years in 2018) or premature ovarian insufficiency. While ovarian insufficiency is the leading cause of infertility after 35 years, premature ovarian insufficiency, associated with the absence of menstrual cycles, secondary to chemotherapy, for example, affects 2 to 4% of women of childbearing age. A partially genetic origin is not excluded.

• Bilateral tubal stenosis (reduction in the permeability of the Fallopian tubes, blocking the passage of sperm to the egg), mostly linked to a sexually transmitted infection (especially Chlamydia bacteria).

• Uterine abnormalities (malformation, fibroid).

• Endometriosis, a disease that affects ~10% of women (De Ziegler et al., 2010).

In men, the causes of infertility include:

• Testicular insufficiency (abnormality of spermatogenesis affecting the quantity or quality of sperm).
• Sexual dysfunctions (erectile and ejaculatory disorders).

Causes of infertility common to both sexes include:

• Hypothalamic-pituitary pathology: impairment of hormone production that can lead to the absence of ovulation or sperm production deficiency.

• Autoimmune diseases, particularly hypothyroidism or coeliac disease (Khizroeva et al., 2019).

• Certain treatments and medications (chemotherapy, certain antibiotics, proton-pump inhibitor). Consult the list here (Sharma et al., 2013).

• Environmental factors: tobacco, significant heat source at the testicle level, pesticides, heavy metals (lead), endocrine-disrupting chemicals.

• Stress that can alter the production of neurohormones and/or sex hormones. Moreover, the chances of fertilisation would be reduced by nearly 40% in women with high stress levels at the time of fertilisation.

• Overweight, but also underweight in women.

• Nutritional deficiencies (zinc, iodine…) (Seungdamrong et al., 2017).

Purely mechanical causes (obstruction of male or female ducts, for example) that only Western medicine can treat, and other causes, such as ovarian insufficiency related to age, will be factors not modifiable by lifestyle.

Other infertility factors can be improved through nutritional management (Sharma et al., 2013)

Roles of nutrition & micronutrition in promoting fertility

Nutrition and micro nutrition play a major role in the fertility of both women and men.

Firstly, it is necessary to identify:

1. What are the essential elements for fertility, and
2. What are the modifiable and non-modifiable factors affecting fertility in men and women.

Essential elements for fertility:

1. A couple wanting to make love/libido

Before talking about fertility, the couple must already want to make love!

Libido is a key element for both men and women. Low libido (lack of desire) can have multiple causes:

• Hormonal disorders such as hypothyroidism (Atis et al., 2010)
• The use of contraceptive pills, patches, or implants
• Chronic stress, fatigue
• Dyspareunia (pain during intercourse), explained by a lack of estrogen causing vaginal dryness, or endometriosis
• Certain medications
• Alcohol and drug consumption
• Psychological factors: depression, body image, negative experiences, problems in the couple
• Diseases such as diabetes (Kizilay et al., 2017)
• Zinc deficiency (Mazaheri Nia et al., 2021)

Lifestyle plays an undeniable role in libido (Mollaioli et al., 2020). A Mediterranean-based diet and regular physical activity are associated with better libido in both men and women (Mollaioli et al., 2020).

2. High-quality sperm

The health of sperm is defined by three criteria

• Concentration: the quantity of sperm in the ejaculate should be at least 15 million/ml
• Mobility: about 40% of sperm should have good motility (swimming in the female reproductive system to fertilize the egg)
• Morphology: sperm should have an oval head with a robust neck and a mobile tail for the majority of them.

Nutrition has a role to play in the health of sperm, particularly in limiting oxidative stress (see below).

3. Ovulation, fertilisation & implantation of the egg

If sperm reaches the uterus, there must be an egg (or several) to fertilize!

Ovulation occurs halfway through the woman’s cycle, around the 14th day for women with a 28-day cycle (which is an average, not the perfect number).

It is entirely possible to have anovulatory cycles, meaning there is no expulsion of an egg.

Anovulatory cycles can hide PCOS, ovarian dysfunction, endometriosis, or hypothyroidism. In general, a lack of progesterone makes embryo implantation impossible.

Other causes of ovulation problems include diabetes, obesity, intense physical activity, certain medications, excessive weight loss, psychological stress.

Hormonal changes during the menstrual cycle

Once the egg is fertilised by a sperm, it needs to implant, meaning it attaches to the endometrium where it can continue to “grow.”

At this stage, everything is very fragile, and life hangs by a thread! Many factors will either favour or hinder implantation: the woman’s weight, the presence of endocrine disruptors, the use of tobacco/alcohol/drugs, etc.

In summary

Table 1: factors necessary for fertility

Woman	Man
– A sufficient number of ovarian follicles containing good-quality eggs* – Adequate hormonal secretions allowing ovulation, fertilisation, and implantation* – Permeable tubes to allow the migration of the egg and spermatozoa	– A sufficient quantity and quality of sperm* – Absence of physical anomalies

In parallel, many essential steps are involved in the development of the foetus’s first cells:

• Unprotected and regular sexual intercourse (ideally around the woman’s ovulation)
• A sufficient quantity and quality of sperm
• Ovulation (expulsion of the egg)
• Fertilisation (meeting between the egg and the sperm)
• Implantation of the fertilised egg
• Development of the egg without it being expelled (miscarriage)

Each of these steps involves countless finely orchestrated mechanisms depending on many factors, including nutrient status.

Modifiable and non-modifiable factors affecting fertility

• Non-modifiable factors: genetics, age.
• Modifiable factors related to lifestyle: physical activity, overweight, nutrition, alcohol, tobacco, stress, long-term use of contraceptive pills.

Physical abnormalities can be modifiable depending on the cases (surgery).

Environmental factors can fall into both categories. Indeed, while it is entirely possible to avoid a large part of endocrine disruptors and chemicals present in food and drinking water, it is impossible to avoid all sources of pollution.

1. Environmental factors

Several environmental factors have been correlated with fertility:

• Electromagnetic waves (Deepinder et al., 2007) (El-Hamd & Aboeldahab, 2018)
• Endocrine disruptors
• Pesticides
• Lead, mercury
• Bisphenol A (and probably others) (Li et al., 2011; Miao et al., 2014)

Some dietary choices can decrease the intake of molecules affecting fertility, such as favoring products from organic agriculture, raw/frozen (non-canned) products.

2. Oxidative stress

Oxidative stress is defined as the set of aggressions caused by molecules (reactive oxygen species; ROS) on the cells of our body.

It is linked to the imbalance between free radicals and the quantity of antioxidants available and usable by the body (Makker et al., 2009).

Oxidative stress directly affects the quality of gametes (sperm and egg) and therefore fertility (Agarwal et al., 2005).

It is entirely possible to significantly reduce oxidative stress by adopting a healthy lifestyle and a balanced diet, rich in antioxidants and micronutrients, by limiting caffeine and alcohol, avoiding tobacco, maintaining a “healthy” weight, and through regular physical activity (Anton et al., 2020).

It is essential for both women and men to consume a lot of antioxidants, especially foods rich in vitamins E, C, B9, carnitine, N-acetyl cysteine, co-enzyme Q10, zinc, selenium, and lycopene (Majzoub & Agarwal, 2018).

Diet, micro nutrition & fertility

Apart from a balanced macronutrient diet (carbohydrates, fats, proteins) based on th Mediterranean diet, many nutrients are essential for fertility, such as:

• Calcium
• Iron*
• Zinc
• Magnesium*
• Iodine*
• Selenium*
• Vitamin D*
• Vitamins B6, B9*, B12*

*Frequent deficiencies (Skoracka et al., 2021)

In my practice, I observe very frequent iron deficiencies in women with menstruation and almost systematic deficiencies in iodine, zinc, and vitamin D (even with supplementation that is not always sufficient).

Yet, dietary analysis and blood tests are required before starting supplementation.

The role of the microbiome in fertility

Studies have highlighted that the quality of the microbiome also has an impact on fertility (Skoracka et al., 2021; Vitale et al., 2022; Zamora & Vizcaíno Ledesma, 2019).

An imbalanced diet disrupts the microbiome’s equilibrium and negatively influences its composition. Therefore, taking care of the microbiome through nutrition will have an impact on fertility (not to mention the beneficial effects for the baby!)

In summary

Lifestyle has a significant impact on fertility, influencing it positively or negatively. Specifically, the role of nutrition and micronutrition in fertility is undeniable but unfortunately underestimated.

A Mediterranean-based diet (rich in fibres from fruits and vegetables, unrefined cereals, legumes, omega-3, olive oil, low-fat dairy products, plant proteins, poultry, and vitamins and minerals) compared to a Western diet (rich in trans fatty acids, refined cereals and sugar, red meat, and high glycemic index products/drinks) promotes fertility in both men and women.

Because some deficiencies are very common (e.g. zinc, iodine, vitamin D, and omega-3), and many nutrients are necessary for both fertilisation and the proper course of pregnancy, nutritional support is recommended, and tailored supplementation will be essential (such as vitamin B9 in the form of methyl folate)

If you are having difficulty conceiving a child or want to optimise your nutritional status for a baby project, feel free to contact me!

References

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