Yes, there is a vitamin H, though you won’t find it labeled that way on most supplement bottles today. Vitamin H is an older name for biotin, a B vitamin now more commonly called vitamin B7. The name stuck around long enough to cause confusion, but the nutrient itself is well established and plays several important roles in the body.
Why It Was Called Vitamin H
The Hungarian biochemist Paul György first identified the nutrient between 1932 and 1934, during a productive stretch in which he also helped discover vitamins B2 and B6. He named his new find “vitamin H” because it appeared essential for healthy hair and skin. The “H” comes from the German words “Haar” (hair) and “Haut” (skin). Over time, scientists realized it belonged to the B vitamin family and reclassified it as B7, but the vitamin H label still appears occasionally on supplements and in older references.
What Biotin Does in Your Body
Biotin is a water-soluble vitamin that works as a helper molecule for five different enzymes in the body. These enzymes handle some of the most fundamental metabolic tasks: converting food into blood sugar, breaking down fats, and processing amino acids from protein. Without biotin, these enzymes can’t transfer the chemical groups they need to complete their reactions, and metabolism stalls.
In practical terms, biotin helps your body turn the food you eat into usable energy and build the fatty acids your cells need for their membranes. It also supports the process of making new glucose when your blood sugar drops between meals. Because it touches so many metabolic pathways, even a modest shortfall can cause wide-ranging symptoms.
How Much You Need
Adults need 30 micrograms of biotin per day. That’s a tiny amount, and most people hit it easily through a normal diet. During pregnancy, the recommendation stays at 30 micrograms; during breastfeeding, it rises slightly to 35 micrograms. Children need less, scaling from 5 micrograms for infants up to 25 micrograms for teenagers.
No tolerable upper limit has been set for biotin, meaning researchers haven’t identified a dose at which it becomes toxic. That said, the absence of a formal ceiling doesn’t mean megadoses are harmless. High-dose biotin supplements can cause a separate, serious problem with medical testing (more on that below).
Food Sources
Biotin shows up in a wide range of foods, which is one reason deficiency is rare. Eggs are one of the best-known sources, along with organ meats like liver, nuts, seeds, salmon, and sweet potatoes. Whole grains, dairy, and many vegetables also contribute smaller amounts. Eating a varied diet generally provides more than enough.
One quirk worth knowing: raw egg whites contain a protein called avidin that binds to biotin so tightly the vitamin can’t be absorbed. The biotin-avidin bond is essentially permanent, and the whole complex passes through your digestive tract unused. Cooking denatures avidin, so scrambled or hard-boiled eggs pose no problem. You’d need to consume a dozen or more raw egg whites daily to actually trigger a deficiency this way, but it’s the reason bodybuilders who drink raw egg shakes sometimes run into trouble.
What Deficiency Looks Like
Biotin deficiency is rare in the United States, but when it occurs, the symptoms are distinctive. The skin develops a scaly, red rash, often around the eyes, nose, and mouth. Hair thins and can fall out. Nails become brittle. These are the outward signs, and they’re consistent with the nutrient’s original “hair and skin” reputation.
Neurological symptoms can be more concerning. Deficiency has been linked to seizures, muscle weakness, poor coordination, and developmental delays in children. In inherited conditions where the body can’t properly use biotin, five organ systems are commonly affected: the nervous system (in roughly 67% of cases), skin (54%), eyes (34%), hearing (27%), and respiratory system (18%). These inherited forms typically appear in infancy, but milder versions can surface later in life with subtler symptoms like limb stiffness or balance problems.
Biotin for Hair and Nails
Because deficiency causes hair loss and brittle nails, biotin supplements are heavily marketed for hair growth and nail strength. The logic seems straightforward: if a lack of biotin damages hair, more biotin should help it grow. But the evidence doesn’t support that leap for people who already get enough biotin from food.
No studies have proven that biotin supplements improve the appearance of hair, skin, or nails in people without a deficiency. If you’re experiencing thinning hair or weak nails, the cause is more likely iron deficiency, a thyroid issue, or another underlying condition. Some people do report benefits from biotin supplements, but without controlled data, it’s difficult to separate a real effect from a placebo response or from simply correcting a mild, undiagnosed shortfall.
A Hidden Risk With Lab Tests
One genuinely important concern about biotin supplements is their ability to interfere with blood tests. The FDA has issued warnings that biotin can significantly skew lab results, and the agency continues to receive reports of problems. The interference is particularly dangerous with troponin tests, which measure a protein released during heart attacks. Biotin can cause falsely low troponin readings, potentially masking a cardiac emergency.
Thyroid panels are also vulnerable. Depending on the test design, biotin can make thyroid hormone levels appear falsely high or low, leading to misdiagnosis or unnecessary treatment changes. The problem isn’t limited to people taking massive doses. Many hair, skin, and nail supplements contain 5,000 to 10,000 micrograms of biotin, well over 100 times the daily adequate intake, and that’s enough to throw off results.
If you take a biotin supplement and need blood work, let your doctor or the lab know beforehand. Stopping the supplement for 48 to 72 hours before testing is usually enough to clear it from your system and avoid interference.