"Eating is medicine" – this motto has been held to be true in many cultures for centuries. Today, reproductive medicine confirms: what ends up on the plate affects the quality of eggs, hormonal balance, and the chances of pregnancy. The surprise: it’s not just “more nutrients” that help. For some micronutrients, too much can even be counterproductive. Those who want high performance in life should think with precision when it comes to fertility – not in blanket rules.

Fertility begins at the cellular level. Egg cells are energy-intensive and particularly sensitive to oxidative stressimbalance between free radicals and antioxidants that can damage cells. Mitochondria – the "power plants" of the cells – determine how well maturation, fertilization, and early embryonic development function. Nutrition controls two main axes here: the glucose-insulin metabolismhow the body processes sugar and how cells respond to insulin and mitochondrial bioenergeticsconversion of nutrients into cellular energy. Additionally, micronutrients like iron influence the ovarian reservenumber and quality of remaining follicles in the ovary and markers like FSHfollicle-stimulating hormone, which increases with decreasing egg reserve. The core idea: targeted nutrition can improve cellular quality – just as training enhances performance.

Stable blood sugar is essential for ovulation: high glycemic load correlates with a higher risk of ovulatory disorders, which can prolong the path to pregnancy ^[1]. A paradox emerges with iron: while iron is important during pregnancy, a correlation has been observed between high iron supplementation and lower ovarian reserve in women undergoing fertility treatment – a hint that "more" is not automatically "better" ^[2]. On the energy side of the egg cell, coenzyme Q10 comes into focus: as a mitochondrial co-factor and antioxidant, it is associated with better egg quality, maturation, and embryo development, especially in older women or those with diminished reserve ^{[3] [4]}. Lifestyle deterrents remain relevant: excessive caffeine consumption increases the risk of miscarriage, even if natural fertility itself is not clearly impaired ^[5]. Furthermore, chronically high alcohol consumption damages reproductive functions in animal models and can reduce follicle and egg quality – effects that may partially reverse after abstinence ^{[6] [7]}.

A large prospective cohort study involving 18,555 premenopausal women linked high carbohydrate intake, particularly high glycemic load, to an increased risk of ovulatory infertility. The practical relevance is: carbohydrate quality – not just quantity – affects insulin sensitivity and ovulation ^[1]. In an observational study among women trying to conceive, high doses of iron supplements were associated with lower ovarian reserve; the effect was primarily driven by supplements rather than dietary iron. For practical purposes, this means using iron strategically and indication-based, rather than blanket high dosing ^[2]. Additionally, several review articles consolidate the evidence that coenzyme Q10 enhances mitochondrial energy production, reduces oxidative stress, and thereby improves egg maturation, fertilization, and embryo quality – particularly in the context of assisted reproduction and among older patients. These studies establish biological plausibility and report clinical improvements in egg count and embryo quality ^{[3] [4] [8]}. Finally, a meta-analysis suggests that high caffeine intake increases the risk of miscarriage in a dose-dependent manner, supporting a cautious limit in daily consumption ^[5].

- Add 1–2 servings of legumes (e.g., lentils, beans) per day. Prefer iron from food rather than high supplement doses; avoid standalone iron supplements beyond needs, as high intake has been associated with lower ovarian reserve ^[2].
- Increase the proportion of whole grains (oats, rye, quinoa, brown rice). Aim for at least half of your daily carbohydrates to come from whole grains to support insulin sensitivity and reduce ovulatory disorders ^[1].
- Integrate foods rich in coenzyme Q10 such as meat (especially heart, beef), mackerel/sardines, as well as oil seeds (sesame) and nuts. For women aged 30+, or with weak ovarian reserve, medically supervised CoQ10 supplementation may be considered, as studies show improvements in egg maturation, embryo quality, and ART success ^{[3] [4] [8]}.
- Avoid excessive alcohol consumption. Plan alcohol-free weeks or longer abstinence periods; animal models show clear losses in reproductive capacity due to chronic consumption that may improve after withdrawal ^[6], and early exposure damages ovarian functions ^[7].
- Limit caffeine. Aim for low to moderate amounts (e.g., ≤200 mg/day), as higher consumption is associated with an increased risk of miscarriage ^[5].

The coming years will clarify which dosage ranges are optimal for iron and CoQ10 across various fertility profiles, and how individualized carbohydrate patterns can stabilize ovulation. Precision nutrition – tailored to biomarkers like insulin sensitivity and ovarian reserve status – is likely to become the standard strategy to simultaneously promote egg quality, energy, and long-term fertility.