What Is Biotin and Should It Be In Your Prenatal Supplement?

Biotin is a vitamin that gets a lot of attention for supporting hair, skin, and nail health. It’s often also cited in fertility-supportive supplements. And, biotin is an essential vitamin with important functions in the body—but more isn't always better. And in some cases, taking high doses may create unexpected problems.

Here’s what biotin actually does, how it affects your fertility, and why it's worth mentioning to your healthcare provider before your next round of bloodwork.

Biotin, also known as vitamin B7, is a water-soluble B vitamin that helps your body convert carbohydrates, fats, and proteins into energy. It acts as a cofactor for enzymes involved in metabolism and helps maintain healthy skin, hair, and nails.

Unlike some nutrients, your body can't produce biotin on its own. You get it through foods like eggs, fish, meat, dairy products, nuts, seeds, and certain vegetables. Research suggests that most people eating a typical Western diet easily meet the recommended daily intake of 30 mg through food alone. 

If you've ever searched for solutions to hair thinning or brittle nails, you've probably been told to take biotin.

There's a reason for this connection: biotin contributes to keratin production, the structural protein that makes up your hair and nails. Because of this relationship, biotin has become a staple ingredient in many beauty supplements. The problem is that science doesn't fully support its widespread use, and it’s only really effective if you have a biotin deficiency.

A recent systematic review published in JAMA Dermatology found that, while biotin may help people with a true deficiency, there’s no convincing evidence that supplementing beyond normal levels improves hair growth in people who already have adequate biotin status.

In other words, if you're not deficient, more biotin doesn't necessarily mean more hair, stronger nails, or better skin.

The answer here is simple—enough to correct a deficiency. Biotin deficiency is uncommon but can occur in individuals with certain genetic conditions, chronic alcohol use, prolonged use of specific medications, or gastrointestinal conditions that impair nutrient absorption. Pregnancy can increase biotin needs, making deficiency more common during this life stage, which is why many prenatal vitamins include it.

In these cases, correcting a deficiency may improve symptoms such as hair thinning, brittle nails, skin changes, and fatigue.

But, for the average person experiencing hair loss, it's important to remember that biotin deficiency is rarely the underlying cause. Iron deficiency, thyroid dysfunction, hormonal changes, stress, postpartum shifts, nutritional deficiencies, autoimmune conditions, and genetics are often more likely contributors and should always be assessed before assuming biotin is the best solution.

The recommended intake for most adults is just 30 mcg per day, which most of us can get from diet alone. But, if you’re trying to conceive or pregnant, getting a bit more can help ensure you’re avoiding deficiency during a period when Biotin demand is higher (just make sure to talk to your doctor—more on that below.)

While biotin is generally considered safe, high-dose supplementation can interfere with laboratory testing, and this is arguably the most important thing consumers should know about biotin. And, many hair, skin, and nail supplements contain between 5,000 and 10,000 mcg of biotin daily—more than 150 times the recommended intake.

Many modern laboratory tests rely on a technology called the biotin-streptavidin system. When large amounts of supplemental biotin are circulating in the bloodstream, test results can become inaccurate.

Depending on the type of test, biotin may cause results to appear falsely high or falsely low.

Research has shown that biotin can interfere with:

• Thyroid function tests (TSH, Free T4, Free T3)

• Estrogen (Biotin can produce false positives for high estrogen, which is problematic for fertility monitoring patients)

• Cardiac markers such as high-sensitivity troponin

• NT-proBNP, a marker used in heart failure assessment

• Reproductive hormones such as FSH and beta-hCG

• Vitamin D testing

• Ferritin

• Parathyroid hormone (PTH)

• Prolactin

• PSA and certain tumour markers

Unnecessary supplementation can cause more harm then benefit and completely skew someone’s laboratory assessment and treatment plan accordingly. 

In some cases, biotin supplementation has even caused laboratory results that mimic conditions such as hyperthyroidism.

The U.S. Food and Drug Administration (FDA) has issued safety communications regarding biotin interference because inaccurate laboratory results can lead to delayed diagnoses or unnecessary investigations.

The exact timeline depends on the dose and the laboratory test being performed, but studies suggest that interference often resolves within 48 to 72 hours after stopping supplementation.

That said, some healthcare providers recommend discontinuing biotin for several days before bloodwork, particularly if thyroid testing, hormone assessments, or cardiac markers are being evaluated.

If you're taking a supplement that contains biotin, it's always worth mentioning it to your healthcare practitioner before having laboratory testing completed.

Biotin often shows up in prenatal vitamins and fertility supplements, which naturally raises the question: does it improve fertility? 

• Biotin may help developing eggs thanks to its role in mitochondrial support; egg cells require a ton of energy to mature and the mitochondria is at the heart of that energy production. 
• While human evidence is limited, some laboratory and animal studies suggest biotin may play a role in reproductive function, and one study found that adding biotin to sperm preparation media improved fertilization outcomes in a mouse model. 
• And we know that both biotin deficiency and excessive biotin intake have been associated with reproductive changes in animal studies, suggesting that balance, not excess, is likely important.

Many prenatal vitamins do contain biotin, although the amount varies considerably between brands.

Pregnancy increases biotin metabolism, and research suggests that marginal biotin deficiency may occur more frequently during pregnancy than we previously thought. Some researchers have raised concerns that tooo little Biotin during pregnancy could affect fetal development, which is one reason Biotin is commonly included in prenatal formulations alongside nutrients such as Folate, Iron, Iodine, and Choline.