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Impact of nutrition on fertility: interview with Dr Marta Zermiani and our nutrition expert
With the arrival of December and the festive season, many of our patients tell us that this is one of the most difficult times of the year to maintain healthy habits.
At Vida Fertility, we have always advocated that fertility should be approached from a holistic perspective, where medicine and nutrition go hand in hand. That is why, in this article, we wanted to take a closer look at the real impact of nutrition on female and male fertility, a subject that raises many questions but is also surrounded by a lot of misinformation.
On this occasion, Dr Marta Zermiani, gynaecologist expert in assisted reproduction at Vida Fertility Madrid, talks to Sue Bedford, our partner nutritionist therapist (MSc), to offer a joint medical and nutritional perspective on how diet is a powerful tool for improving ovulation, egg and sperm quality, endometrial health, hormonal balance and implantation.
- 1. Marta, how does diet influence our fertility?
- 2. Can you give us some examples of fertility problems related to poor nutrition?
- 3. How can you tell if a patient needs help with nutrition to improve her/his fertility?
- 4. Does this also affect male fertility?
- 5. Sue, as a nutritionist, how do you work with or proceed with patients who have fertility problems?
- 6. What kind of nutritional changes are usually necessary for patients?
- 7. How long does it usually take to see improvements in a patient’s fertility?
- 8. Can intestinal dysbiosis have an impact on fertility?
- 9. Our fertility treatments
- 10. Where can I find Vida Fertility centres in Spain?
Marta, how does diet influence our fertility?
Diet influences fertility by modulating weight, metabolism, inflammation, and micronutritional status. If these mechanisms are out of balance, reproductive function is also affected.
Being underweight or overweight can disrupt cycle regularity and egg quality. A diet high in sugar and ultra-processed foods promotes insulin resistance and inflammation, conditions that can hinder ovulation. Conversely, a balanced diet provides the vitamins and antioxidants necessary for ovarian maturation and a favourable uterine environment.
Diet also influences the quality of the endometrium, as it modulates inflammation, metabolism and the availability of micronutrients useful for implantation. An excess of sugars and saturated fats increases inflammation and insulin resistance, conditions that can make the endometrium less receptive. Conversely, a diet rich in fruits, vegetables, whole grains, fish, and unsaturated fats promotes better perfusion and a more stable environment for implantation. Deficiencies in folate, vitamin D, iron, and antioxidants can compromise endometrial growth and luteal phase quality. Therefore, a balanced diet promotes endometrial thickness and functionality that are more conducive to implantation processes.
Another very important aspect is the endometrial microbiota. The endometrial microbiota is the set of microorganisms present in the uterine cavity. When ‘beneficial’ species prevail, particularly lactobacilli, the endometrium maintains a stable environment that is less inflammatory and more receptive to implantation. Alterations in its composition (dysbiosis) can increase local inflammation, reduce the quality of the immune response and decrease the chances of spontaneous implantation or implantation following ART. The endometrial microbiota is directly dependent on the intestinal microbiota. Therefore, the state of the intestine and the endometrium are closely related: a balanced intestinal microbiota also promotes stability at the uterine level, while an altered intestine can contribute to a less receptive endometrium.
Can you give us some examples of fertility problems related to poor nutrition?
Some specific examples are:
- Anovulation due to low weight or overly restrictive diets, with irregular or absent cycles.
- Polycystic ovary syndrome (PCOS) aggravated by obesity or diets high in sugar, which alters ovulation and egg quality.
- Reduced egg quality due to deficiencies in folate, vitamin D, iron or antioxidants.
- Reduced endometrial receptivity, often related to chronic inflammation, diet-related metabolic imbalances or alterations in the endometrial microbiota.
How can you tell if a patient needs help with nutrition to improve her/his fertility?
You can tell that a patient needs nutritional support by observing various clinical signs. For example, significant weight fluctuations, a very low or very high body mass index, or irregular or absent cycles may indicate that nutrition is interfering with fertility. The presence of insulin resistance, eating disorders, or documented vitamin and mineral deficiencies are also important indicators. In cases of reproductive failure or assisted reproductive treatments, evaluating nutrition becomes even more important, as correcting unhealthy habits can improve ovulation, egg quality, and the uterine environment.
Does this also affect male fertility?
Diet directly influences male fertility because it acts on several fundamental mechanisms of sperm production and quality. Excess calories, especially from refined sugars and saturated fats, promote overweight and obesity, conditions that alter hormonal balance, reduce testosterone levels and increase circulating oestrogens, compromising spermatogenesis.
Nutritional deficiencies in vitamins (C, D, E), folates, zinc, selenium and antioxidants increase oxidative stress in the testicles, damaging sperm DNA and reducing sperm motility and morphology. Many studies show that excessive consumption of coffee or caffeine may be associated with increased oxidative stress and greater sperm DNA fragmentation. Caffeine can increase the production of free radicals and reduce the effectiveness of antioxidant systems in the testicles, damaging sperm DNA. However, moderate consumption (1-2 cups of coffee per day) does not usually have a significant effect on sperm quality.
Intestinal dysbiosis can also have an indirect influence through systemic inflammation and metabolic alterations that affect testicular function.
Conversely, a balanced diet rich in fruit, vegetables, whole grains, legumes, fish and unsaturated fats promotes a stable hormonal profile, reduces oxidative stress and promotes the production of high-quality sperm, which increases the chances of natural conception or conception through assisted reproduction techniques.
Sue, as a nutritionist, how do you work with or proceed with patients who have fertility problems?
I work mostly online, by combining evidence-based smart nutrition, lifestyle interventions, and targeted testing to support natural conception, assisted fertility treatment (IVF/IUI), or preconception optimization. Before their 60-minute first consultation, the patients typically submit: their fertility and reproductive history, cycle details (length, ovulation, PMS, symptoms), medical details/lab results, a food diary, a lifestyle questionnaire (sleep, stress, exercise, exposure to toxins), any supplements/medications they are already taken. Then, during the consultation, I will go through the completed questionnaire and will give the patient an initial personalised nutritional therapy and lifestyle recommendations – including Dietary strategy, Key nutrients, Lifestyle adjustments, Supplement recommendations, Optional testing strategy – if required.
What kind of nutritional changes are usually necessary for patients?
Fertility nutrition in general aims to improve egg quality, sperm quality, hormone balance, cycle regularity, implantation, and inflammation levels. The key areas that I look at specifically to help achieve the above are Diet, specific nutrients, supplements and lifestyle patterns.
How long does it usually take to see improvements in a patient’s fertility?
This depends on the patient’s situation, but common patterns are for a Standard Patient Care: a follow-up session every 3-4 weeks for 3 months; and for an intensive Patient Care (IVF preparation or complex cases): a follow-up session every 2–3 weeks. This typical follow-up session includes reviewing symptoms and progress, adjusting personalised nutrition plan, updating supplement protocol, reviewing any lab results, discussing stress, sleep, energy and coordinating with medical fertility treatment timeline (IVF cycles, stimulation phase, etc.).
Can intestinal dysbiosis have an impact on fertility?
Yes absolutely — intestinal dysbiosis CAN influence fertility, and this is a growing area of research within reproductive medicine and nutritional therapy. Gut dysbiosis can negatively affect both female and male fertility via inflammation, hormones, nutrient absorption, immune function, and metabolic pathways.
After reviewing both the medical and nutritional perspectives, it is clear that diet is much more than a supplement: it is a fundamental pillar in many processes that have a direct impact on fertility.
During these Christmas weeks, our message is one of calm. It is not about giving up on enjoying the festivities, but about finding a balance that respects your body and your family plans.
At Vida Fertility, both our medical team and the external collaborators like Sue we work with, are here to accompany you every step of the way. If you have questions about your diet, are starting treatment, or are looking to improve your fertility overall, we would be delighted to assess your situation with you.
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Where can I find Vida Fertility centres in Spain?
📍 C/ Palermo 15, Hortaleza, 28043 Madrid
📞 Phone number: +34 919 29 83 23
🕒 Opening hours: Monday to Friday from 8am to 7pm
📍 Av. Óscar Esplá 1, Bajo, 03008 Alicante
📞 Phone number: +34 919 29 83 23
🕒 Opening hours: Monday to Friday from 8am to 7pm
ℹ️ The information published on Vida Fertility is reviewed by our fertility specialists and medical team, following up-to-date scientific criteria and evidence-based medicine. Our team is a member at scientific societies such as SEF, ESHRE and SEGO.
