Couple infertility affects approximately 15-20% of couples trying to conceive. The causes are numerous and often non-nutritional (tubal factors, endometriosis, sperm problems, anovulation). However, preconception nutrition has a documented impact on gamete quality and the endocrine and metabolic environment in which conception occurs. The optimal preconception period for dietary interventions is 3-6 months: spermatogenesis lasts about 74 days, follicle maturation about 90 days. Today's dietary changes influence gamete quality from three months ago.

For her: nutrients for egg quality

Folic acid (or 5-MTHF): the most critical. 400-800 mcg daily starting at least 4-8 weeks before planned conception. Prevents neural tube defects in the baby. For women with MTHFR mutation (about 10-15% of the population): prefer the active form 5-methyltetrahydrofolate instead of synthetic folic acid. Vitamin D: vitamin D receptors are present in ovarian cells and the endometrium. Adequate levels (40-60 ng/ml) are associated with better pregnancy rates both naturally and with assisted reproductive techniques. Check your levels and supplement if needed (2,000-4,000 IU daily). Omega-3 DHA: structural component of egg cell membranes. Egg quality is correlated with DHA content in membranes. 2-3 servings of fatty fish per week or 200-300 mg of DHA from algae. Iron and ferritin: correct any deficiencies before conception. Anemia at the start of pregnancy is associated with worse outcomes. Coenzyme Q10 (CoQ10): mitochondrial antioxidant with evidence of improving egg quality especially in women over 35. 200-600 mg daily in the months before conception.

For him: nutrients for sperm quality

Spermatogenesis lasts 74 days: dietary changes today improve sperm in 2.5 months. Zinc: essential for sperm maturation and protection of sperm DNA. Deficiency reduces motility and increases morphological abnormalities. Sources: oysters, meat, pumpkin seeds, legumes. Selenium: selenoprotein P (selenium-dependent) protects sperm from oxidation. Deficiency associated with reduced motility. Two Brazil nuts daily cover your needs. Coenzyme Q10: improves sperm motility and concentration in numerous clinical studies on men with reduced seminal parameters. 200-300 mg daily. Vitamin C and vitamin E: antioxidants that protect sperm DNA from oxidative stress. Lycopene: reduces oxidative damage to sperm DNA. Cooked tomatoes with extra virgin olive oil are the most efficient source.

The Mediterranean diet and couple fertility

An analysis of 244 couples undergoing in vitro fertilization (Chavarro et al., Human Reproduction, 2018) showed that women in the highest tertile of Mediterranean diet adherence had 66% higher odds of pregnancy and 68% higher odds of live birth compared to those in the lowest tertile. The Mediterranean diet simultaneously provides all critical nutrients for fertility: folates from vegetables, omega-3 from fish, antioxidants from fruits and vegetables, zinc and selenium from fish and legumes, vitamin D from fatty fish.

What to avoid during the preconception period

Alcohol for both: reduces sperm quality, interferes with ovulation, increases miscarriage risk in the earliest weeks. There is no safe threshold: it's better to eliminate it during the preconception period. Smoking for both: accelerates follicle loss in women (premature ovarian aging), reduces sperm motility in men. Excess caffeine: above 200 mg daily (2 coffees) associated with reduced female fertility. Pesticides and xenoestrogens: choose organic for the most consumed fruits and vegetables during the preconception period. Reduce plastic for food (use glass or stainless steel for water and storage). Large amounts of soy for him: very high doses of soy isoflavones in some studies reduce sperm quality: moderation during the preconception period.

The couple's preconception plan: the 90 days before

For her: start folic acid 400 mcg immediately (or 5-MTHF), check vitamin D and supplement if low, fatty fish 3 times a week, CoQ10 200 mg daily, normal iron and ferritin (discuss with your doctor), no alcohol, reduce caffeine to max 1 coffee daily. For him: daily zinc (pumpkin seeds, oysters weekly), two Brazil nuts daily (selenium), CoQ10 200 mg daily, omega-3 from fatty fish 3 times a week, vitamin C and lycopene (cooked tomatoes + citrus), no alcohol, no smoking, no laptop on your lap or very tight pants (heat reduces spermatogenesis).

When to see a gynecologist or andrologist: the right timing

After 12 months of trying without pregnancy (or 6 months if the woman is over 35): consult a gynecologist to evaluate ovarian reserve (AMH, follicle ultrasound). The male partner: semen analysis from an andrologist or urologist. Don't wait 2 years: ovarian reserve decreases with age and time has a biological cost. The 3-month nutritional preparation period is ideal to do simultaneously with medical evaluation, not sequentially.

PCOS and fertility: the key role of nutrition

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility in women. Insulin resistance is central to PCOS: a low glycemic load diet (whole grains, legumes, reduced refined sugars) improves insulin sensitivity and can restore ovulation. Inositol (myo-inositol 2-4g + D-chiro-inositol in a 40:1 ratio) has clinical evidence of improving ovulation in PCOS. Consult a gynecologist specialized in reproductive endocrinology: the integrated approach (diet + inositol + possible metformin or letrozole) gives the best results.