Ingredients
We don't hide our ingredients.
Every supplement brand says their formula is "clinically backed." Most don't tell you what's actually in it, at what dose, or why.
We do.
Below is every ingredient in Duo Him and Duo Her, what it's there for, and the research behind it. When our Certificate of Analysis is available after our first production run, we'll link it here publicly — because you should be able to verify what you're putting in your body.
DUO HIM — Key ingredients
Zinc
Why it's here: Zinc plays a central role in testosterone production and sperm development. Most men don't get enough from diet alone, particularly those who exercise regularly.
What the research says: Multiple studies support zinc's role in supporting healthy testosterone levels in men with zinc deficiency.
Vitamin D3
Why it's here: Vitamin D functions as a hormone in the body and plays a key role in testosterone production. Studies consistently find that men with higher vitamin D levels tend to have higher testosterone levels. Most people are deficient, especially in northern climates and with indoor lifestyles.
Selenium
Why it's here: Selenium is an antioxidant mineral that supports healthy sperm motility and protects sperm cells from oxidative damage. It's one of the most studied micronutrients for male reproductive health.
Lycopene
Why it's here: Lycopene is the antioxidant that gives tomatoes their red color. It has been studied for its role in supporting sperm quality, concentration, and morphology. Including it in a powder makes it significantly more bioavailable than eating raw tomatoes.
Creatine
Why it's here: Creatine supports ATP production — the cellular energy currency. We included it for energy and physical performance, not just athletic output. It's one of the most studied supplements in existence and has an excellent safety profile.
Vitamin C and Vitamin E
Why they're here: Both are antioxidants that support overall cellular health, including protection against oxidative stress that can impact sperm quality.
DUO HER — Key ingredients
Methylated Folate (5-MTHF)
Why it's here: Methylated folate is the bioavailable form your body can actually use — unlike synthetic folic acid, which requires conversion that many people can't do efficiently due to the MTHFR gene variant. It supports healthy cell division, fetal neural tube development, and is a foundational preconception nutrient.
Iron
Why it's here: Iron deficiency is one of the most common nutritional deficiencies in women of reproductive age. Iron supports energy production, oxygen transport, and healthy reproductive function. We use a highly absorbable chelated form to minimize digestive discomfort.
Vitamin D3
Why it's here: Vitamin D supports calcium absorption, hormone signaling, and healthy reproductive function. It's involved in estrogen production and ovarian function. Most women are deficient.
Omega-3 Fatty Acids
Why they're here: Omega-3s support hormone production, healthy inflammation balance, brain health, and — specifically for preconception — support healthy egg quality and uterine lining.
Iodine
Why it's here: Iodine is essential for healthy thyroid function, which directly regulates reproductive hormones. Thyroid dysfunction is one of the most underdiagnosed causes of hormonal imbalance in women. The RDA for iodine increases significantly during pregnancy.
B-Complex (B6, B12, and full spectrum)
Why they're here: B vitamins support energy production, mood regulation, and cellular health. B6 specifically supports hormone balance by helping the body process estrogen. B12 supports neurological health, energy, and cell formation. Together, the B-complex is a foundational support system for overall wellbeing.
Third-party testing
Every batch of Duo Him and Duo Her is independently tested by a third-party laboratory for potency, purity, and safety before it ships. We will publish our Certificate of Analysis here for every production run.
Our manufacturing partner is GMP-certified. This means they follow FDA Good Manufacturing Practices — a set of quality controls that governs everything from ingredient sourcing to finished product testing.
Questions about our ingredients?
DM us on Instagram @duodaily or email us at duodaily@gmail.com. We read every message and we'll answer honestly.
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The information on this page is provided for educational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any new supplement.