Fertility Supplements: What the Evidence Actually Says

How to Read This Guide

Every supplement below is graded on a simple evidence scale:

Supplements with Strong Evidence

Folate / Methylfolate

Evidence: Strong. Folate (vitamin B9) is the one supplement virtually every fertility specialist agrees on. The CDC recommends 400–800mcg daily for all women of reproductive age, not just those actively trying. Folate is essential for DNA synthesis and prevents neural tube defects. Some women carry MTHFR variants that reduce their ability to convert folic acid to its active form — for them, methylfolate (5-MTHF) may be preferable, though standard folic acid works for most people.

Inositol (Myo-Inositol + D-Chiro Inositol)

Evidence: Strong for PCOS. A 40:1 ratio of myo-inositol to D-chiro inositol (typically 4,000mg myo + 100mg DCI daily) has robust evidence for improving insulin sensitivity, ovulation rates, and egg quality in women with PCOS. Multiple meta-analyses confirm benefit. For non-PCOS patients, evidence is less clear.

Supplements with Moderate Evidence

CoQ10 (Coenzyme Q10)

Evidence: Moderate. CoQ10 is an antioxidant involved in mitochondrial energy production — and egg maturation is one of the most energy-intensive cellular processes in the body. Studies suggest 400–600mg daily may improve egg quality, particularly in women over 35 whose mitochondrial function naturally declines. Several IVF studies show improved embryo quality and marginally higher clinical pregnancy rates with CoQ10 supplementation. The ubiquinol form is better absorbed than ubiquinone.

DHEA (Dehydroepiandrosterone)

Evidence: Moderate for diminished ovarian reserve. DHEA is a precursor hormone that may support follicle development. Typical dosing: 25mg three times daily for 6–12 weeks before an IVF cycle. Research from the Center for Human Reproduction suggests improved egg yield and pregnancy rates in poor responders. However, study quality is mixed, and DHEA should only be taken under medical supervision — it's a hormone, not a benign supplement.

Vitamin D

Evidence: Moderate. Vitamin D deficiency is common (40–50% of reproductive-age women) and has been associated with lower IVF success rates in observational studies. The mechanism isn't fully understood, but vitamin D receptors are present in the ovary, uterus, and placenta. Aim for serum levels of 40–60 ng/mL. Supplementation of 2,000–4,000 IU daily is generally safe and reasonable while trying to conceive.

Omega-3 Fatty Acids

Evidence: Moderate. EPA and DHA support hormonal balance and may reduce inflammation. Some studies link higher omega-3 intake with improved embryo morphology and IVF outcomes. 1,000–2,000mg combined EPA/DHA daily from a quality fish oil is a reasonable addition.

Supplements with Emerging Evidence

NAC (N-Acetyl Cysteine)

Evidence: Emerging. NAC is a powerful antioxidant that may improve ovulation rates in PCOS when combined with clomid. Some studies show benefit for endometriosis-related fertility challenges. Typical dose: 600mg twice daily.

Melatonin

Evidence: Emerging for IVF. Low-dose melatonin (3mg nightly) has been studied as an antioxidant specifically for the follicular environment. Some IVF studies show improved egg quality. Research is promising but limited — discuss with your RE before adding, especially during stimulation.

What to Skip

Royal jelly, maca root, vitex (chasteberry), and most "fertility blend" products have insufficient evidence to recommend. They're not necessarily harmful, but they're expensive for unproven benefit. Money is better spent on the supplements with stronger evidence profiles.