Biotin is found in a wide range of everyday foods, with organ meats, eggs, nuts, seeds, and certain vegetables being the richest sources. Also known as vitamin B7, biotin is a water-soluble vitamin your body uses to break down fats, carbohydrates, and proteins into usable energy. Most people get enough through a normal varied diet, and your gut bacteria actually produce some biotin on their own.
Foods Highest in Biotin
The adequate intake for adults is 30 micrograms (mcg) per day. Here’s how common foods stack up, based on data from the National Institutes of Health:
- Beef liver, cooked (3 oz): 30.8 mcg, which covers a full day’s needs in one serving
- Whole egg, cooked: 10.0 mcg
- Sunflower seeds, roasted (¼ cup): 2.6 mcg
- Sweet potato, cooked (½ cup): 2.4 mcg
- Almonds, roasted (¼ cup): 1.5 mcg
- Spinach, boiled (½ cup): 0.5 mcg
- Broccoli, fresh (½ cup): 0.4 mcg
Organ meats and eggs are by far the most concentrated sources. Beyond these, biotin is present in salmon, pork, dairy products, and whole grains, though in smaller amounts. Because it’s spread across so many foods, outright deficiency is uncommon in people eating a varied diet.
One important note about eggs: raw egg whites contain a protein called avidin that binds to biotin and blocks its absorption. Cooking deactivates avidin completely, so cooked eggs are a great source while raw egg whites can actually work against you.
Your Gut Bacteria Also Produce Biotin
Humans can’t manufacture biotin on their own, but the bacteria living in your intestines can. Research published in the journal Gut found that mice raised without gut bacteria had significantly lower circulating biotin levels than mice with a normal microbiome, even when both groups ate the same diet. Wiping out gut bacteria with antibiotics produced a similarly sharp drop in blood biotin levels.
This means your microbiome acts as a secondary supply line. The composition of your gut bacteria influences how much biotin actually reaches your bloodstream, regardless of what you eat. People with severe obesity, for example, tend to have fewer biotin-producing bacteria in their gut. Nearly 78% of people with severe obesity in one study had suboptimal or deficient biotin levels, compared to about 20% of lean individuals, despite similar biotin intake from food. Bariatric surgery, which reshapes the gut environment, was associated with recovery of biotin-producing bacteria and improved blood biotin levels.
What Biotin Does in Your Body
Biotin serves as a helper molecule for enzymes that manage three core metabolic tasks: converting fats into energy, processing glucose, and breaking down certain amino acids from protein. Without enough biotin, these pathways slow down, which is why deficiency shows up first in tissues with high turnover, like skin, hair, and nails.
This metabolic role is why biotin supplements are so heavily marketed for hair and nail health. For people who are genuinely deficient, restoring biotin levels does reverse hair loss and skin problems. For people already getting enough, though, there’s limited evidence that extra biotin provides additional benefit.
Signs of Biotin Deficiency
Deficiency develops gradually. Early signs are vague: fatigue, thinning hair, and dry or scaly skin rashes. As it progresses, a characteristic pattern emerges where a red, flaky rash appears specifically around the eyes, nose, and mouth. This is sometimes called “biotin-deficient face.”
If left untreated, deficiency can progress to neurological symptoms: numbness and tingling in the hands and feet, muscle weakness, depression, and lethargy. In severe cases, particularly in infants and young children, it can cause developmental delays, seizures, and hearing loss. These advanced symptoms are rare in adults eating a typical diet, but certain groups face higher risk. These include people on long-term anticonvulsant medications, heavy alcohol users, pregnant women (biotin needs increase during pregnancy), and people with inflammatory bowel conditions that impair absorption.
Safety and Lab Test Interference
No upper intake limit has been set for biotin because it hasn’t been shown to cause toxicity, even at high doses. Your body excretes excess biotin through urine. This doesn’t mean mega-doses are harmless, though.
The FDA has issued warnings that high-dose biotin supplements can interfere with blood tests, producing dangerously wrong results. The most concerning: biotin can cause falsely low readings on troponin tests, which are used to diagnose heart attacks. A falsely low result could lead to a missed diagnosis in an emergency. Thyroid panels and other hormone tests can also be skewed. If you take biotin supplements, especially the high-dose versions sold for hair and nails (often 5,000 to 10,000 mcg per pill, far above the 30 mcg daily recommendation), let your healthcare provider know before any lab work. Stopping the supplement for a few days before testing is typically enough to clear it from your system.