Boosting fertility by taking care of diet and health

1. Fertility: Why and how to ensure a healthy and balanced diet?

Studies on the relationship between diet and human fertility have proliferated in recent decades. The results of this research have clearly established that a balanced and healthy diet during the preconception period improves fertility in both women and men. For optimal function, the body requires macronutrients in specific proportions: carbohydrates should represent 40 to 55% of total energy intake (TEI), protein 10 to 20%, and fats 35 to 40%. Based on this scientific data, several key recommendations emerge.

A. Emphasize healthy fats

Lipids are primarily composed of fatty acids , the distribution of which must maintain a balance necessary for the proper functioning of the body. They provide us with energy, contribute to the synthesis of our hormones and cell membranes, and allow the absorption of vitamins A, D, E, and K. However, the modern diet generally contains too many saturated fatty acids and not enough monounsaturated and, especially, polyunsaturated fatty acids (including the well-known omega-3s). These latter are particularly essential for cardiovascular and brain health and for combating inflammation.

It is therefore important to consume oilseeds such as almonds, hazelnuts, walnuts, oily fish such as salmon, tuna, mackerel, sardines, as well as vegetable oils rich in unsaturated fats such as rapeseed, flaxseed, soybean.

B. Maintain stable blood glucose levels

Studies show a link between excessively high glycemic loads and ovulation disorders. Blood sugar spikes trigger an overproduction of insulin. This excessive stimulation can eventually lead to insulin resistance , a condition where cells respond less effectively to the action of this hormone. High insulin levels disrupt the hormonal axis by increasing the production of androgens (male hormones) by the ovaries. This imbalance can disrupt ovulation , or even cause anovulation (absence of ovulation).

This phenomenon is well-documented, particularly in women with polycystic ovary syndrome (PCOS) , a common ovulation disorder linked to insulin resistance in 50 to 70% of cases. Conversely, better-controlled insulin levels (through a low-glycemic-index diet and regular physical activity) can promote improved insulin sensitivity, rebalance sex hormones, and improve menstrual cycle regularity and ovulation.

To limit blood sugar spikes, it's advisable to favor foods with a low glycemic index : starchy foods, whole grains and flours, legumes (lentils, chickpeas, kidney beans), fruits (apples, pears, berries), vegetables, and oilseeds (walnuts, Brazil nuts, flax seeds, chia seeds). Conversely, sweets and products made with refined white sugar should be limited as much as possible. It's better to opt for alternatives like stevia, which has a more moderate impact on blood sugar.

C. Load up on protein

Proteins play a key role in fertility, as they are the essential building blocks for the formation of cells and reproductive hormones (estrogen, progesterone, testosterone, etc.). It is important to prioritize plant-based protein sources , which are lower in saturated fatty acids than animal proteins and rich in fiber, antioxidants, vitamins, and minerals. Nevertheless, moderate consumption of animal protein remains beneficial, particularly for its intake of vitamin B12 and heme iron, a form that is better absorbed than iron from plant sources. Fish and red meat can therefore be consumed approximately twice a week.

2. What role do micronutrients play in fertility?

Specific micronutrient supplementation has proven effective in the field of fertility. Some play an essential role in both women and men.

A. Folic acid

This is the best-known supplement recommended for women during the preconception and pregnancy periods. Folic acid (or vitamin B9) is one of the B vitamins essential for the healthy growth of the unborn baby. Numerous studies have shown that folic acid helps reduce the risk of brain malformations (neural tube defects) during pregnancy. Similarly, folic acid intake is associated with a lower incidence of infertility.

However, dietary sources alone are insufficient to provide the folate intake required to protect against these birth defects. In fact, 75% of women of childbearing age have folate intakes below the recommended daily allowance. Therefore, if you are planning a pregnancy, it is recommended to start taking the supplement at least three months before trying to conceive.

Discover our tips on folic acid supplementation

B. Myo-inositol

Myo-inositol is a molecule naturally present in cell membranes. Once released inside the cell, it acts as a secondary messenger :

• by mimicking the action of insulin , in particular by activating glucose transporters
• by promoting the action of FSH, the follicular stimulation hormone.

This mechanism makes it a key player in reproductive physiology, with positive effects on oocyte development. In follicular fluid, myo-inositol is recognized as a marker of good oocyte quality, promoting follicle maturation and embryonic development. In assisted reproductive technology (ART), it improves ovarian sensitivity and oocyte maturation. Furthermore, its combination with folic acid during the preconception period has shown a reduction in the risk of neural tube defects. Its beneficial effects are demonstrated at a dose of 4 g per day.

C. Iodine, selenium, and zinc: 3 essential trace elements for fertility

Iodine is essential for the synthesis of thyroid hormones , which regulate cell growth and maturation. Its role in fetal brain development, particularly during the first months of pregnancy, is crucial. Yet, 75% of women of childbearing age have insufficient iodine intake. Iodine deficiency can cause mild hypothyroidism, affecting fertility, delaying the age of first birth, and increasing the risk of miscarriage and unexplained infertility.

Selenium plays a role in the development of ovarian follicles responsible for oocyte production. It also acts as an antioxidant, protects against heavy metals, and contributes to proper thyroid function. Present in optimal concentrations in the ovaries, it promotes a cellular environment conducive to follicular development and oocyte quality. In men, it supports sperm production and motility , explaining its high concentration in the testicles.

Finally, zinc , involved in over 300 enzymatic reactions, contributes to protein synthesis and hormonal regulation. Recent studies confirm its role in reproductive health. It participates in the maturation of oocytes and the successful completion of fertilization in women, and improves sperm quality in men.

D. The other B vitamins, vitamins C, D and E

Vitamin D3 contributes to the production of sex hormones and participates in the regulation of cell growth . It also supports insulin synthesis and facilitates glucose uptake by cells. Vitamins C and E act as antioxidants and participate in the regeneration of other antioxidants such as glutathione. B vitamins , meanwhile, play an essential role as cofactors in many of the body's metabolic reactions, particularly in the folate and methylation cycles, and can contribute to supporting antioxidant defenses.

3. What lifestyle habits should be changed to promote fertility?

The lifestyle of the couple, both in the man and the woman, also has a significant influence on fertility.

A. Tobacco

Smoking by either partner reduces fertility. Cigarettes are even considered the number one enemy of fertility. In women, smoking is linked to decreased ovarian reserve, delayed conception, and a higher risk of miscarriage. In men, it significantly reduces sperm quality. Given these factors, quitting smoking or, at the very least, reducing consumption becomes essential. In this context, seeking help and support is crucial. It's also important to note that secondhand smoke is harmful as well.

B. Overweight and malnutrition

Obesity, like malnutrition, is associated with an increased risk of ovulation disorders. Obesity leads to a risk of anovulation (absence of ovulation), which compromises attempts at conception. A 5% weight loss has been shown to normalize certain factors, thereby restoring normal oocyte maturation and, in some cases, avoiding the need for assisted reproductive technologies.

Conversely, insufficient food intake or severe dietary restrictions lead to weight loss, an overall lack of nutrients, and an increased risk of infertility. It is therefore advisable to aim for a BMI (Body Mass Index) between 19.5 and 24.9.

C. Other important parameters

The psychological aspect must also be taken into consideration. Stress creates a less favorable environment for conception. Regular and appropriate physical activity offers numerous benefits, all of which contribute to optimizing the chances of pregnancy.

Another essential point, rarely discussed, is the frequency of sexual intercourse. Regular relations (2 to 3 times a week), at the opportune time in the cycle, are an important condition for increasing the chances of conception. However, it is just as important to maintain spontaneity and balance within the couple.
Fortunately, there are several simple methods to identify the ovulation period: using ovulation tests available in pharmacies, analyzing your temperature every morning, observing changes in vaginal discharge, or calculating your menstrual cycle.

This article is for informational purposes only and does not replace a consultation or advice from your doctor.

Scientific references

Public Health France: Recommendations regarding diet, physical activity and sedentary behavior for adults, 2019

World Health Organization: WHO Infertility Report, 2020

"PCOS and Insulin: Dangerous Liaisons" Thursday, September 14, 2023. Part 1: PCOS: Is Insulin to Blame? Dr. Geoffroy Robin

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