With certain supplements, you have to be very careful about dosage. Taking too much can cause bothersome side effects and toxicity, but biotin isn't one of them. In fact, there's no evidence that excessive biotin vitamins directly cause negative health effects, according to the National Institutes of Health. However, it may interfere with the accuracy of some blood tests.
You can take a biotin supplement with a multivitamin each day without risk of biotin overdose.
What Is Biotin?
Biotin is one of the eight B vitamins, along with vitamins B1, B2, B3, B5, B6, B7, B12 and folic acid. Biotin is a cofactor that aids the metabolism of fatty acids, glucose and amino acids. It also plays roles in gene regulation and cell signaling.
Like all the other B vitamins, biotin is water-soluble. This means that excess amounts are excreted in your urine and not stored in fat cells like the fat-soluble vitamins A, D, E and K. Because of this, you have to replenish your stores of the B vitamins each day, through your diet and supplements. But because they don't accumulate in your body, there is little risk of getting too much of most B vitamins, including biotin.
AI and Supplement Values
When there isn't enough evidence to establish an estimated average requirement (EAR) for nutrient needs of the general population, the National Academy of Medicine determines an adequate intake (AI). The AI is the amount believed to cover the needs of healthy adults.
The AI for biotin is 30 micrograms for adults and pregnant women; for lactating women, the AI is 35 micrograms. Biotin supplements contain doses often hundreds of times the AI. For example, pills are often sold in biotin 5,000 micrograms, 10,000 micrograms and even 100,000 micrograms. These provide between 16,667 and 333,333 percent of the AI.
Biotin and Multivitamin Use
Many multivitamins contain biotin, and the amounts may vary significantly. For example, the men's formula of the One A Day brand multivitamin provides 75 micrograms biotin, but the women's formula contains 1,000 micrograms, a quite significant difference. However, even if you are a woman and taking this multivitamin in addition to a high-dose biotin supplement, you are unlikely to have any direct negative effects.
Risks of Excessive Intake
The National Academy of Medicine has not established an Upper Tolerable Intake Limit (UL) for biotin because of the low risk of toxicity. According to the NIH, research shows that there are no adverse effects to the average person taking 10,000 to 50,000 micrograms of biotin daily. Furthermore, even patients with biotin deficiency who receive up to 200 milligrams or 200,000 micrograms of oral biotin or 20 milligrams of intravenous biotin daily do not risk a biotin overdose.
However, that does not mean there is no risk. Taking biotin above the AI can cause significant false high or low results on some laboratory tests. For example, according to a 2018 case report and literature review published in Cureus, doses of 15 milligrams or 15,000 micrograms can cause statistically significant false high and low results on thyroid tests.
The danger is that these incorrect results could lead to misdiagnosis of a medical condition or incorrect patient management, both of which could have life-threatening risks. Be sure to inform your doctor if you are taking biotin and need to have laboratory tests so that she can take the proper steps to verify accuracy of your results.
Uses of Biotin Supplements
Cases of biotin deficiency are rare, according to the NIH, so most people who take biotin supplements do so because of the purported benefits of taking extra biotin. One of the most common uses of mega-dose biotin supplements is for the vitamin's purported benefits to hair, skin and nails.
Because biotin deficiency causes thinning hair, scaly skin and brittle fingernails, many consumers take biotin, even though they're not deficient, in the hopes that it will help them grow their hair, improve their skin and give them strong nails. However, MedlinePlus, a service of the U.S. National Library of Medicine, states that there is not enough evidence to support its use for this purpose.
On the other, hand, if you have a deficiency and associated side effects, taking a biotin supplement to get your levels back to normal may improve thinning hair, scaly skin rashes and brittle nails.
Other Uses of Biotin
Other uses of high-dose biotin supplements and their likelihood of effectiveness include:
- Skin rash in infants — likely ineffective
- Treatment of an inherited disorder called biotin-thiamine-responsive basal ganglia disease — insufficient evidence
- Diabetes — insufficient evidence
- Diabetic nerve pain — insufficient evidence
- Muscle cramps from dialysis — insufficient evidence
- Multiple sclerosis — insufficient evidence
Research has not conclusively proven that biotin supplementation isn't effective for treating the above conditions; however, research is nascent and more is needed. If you have a condition that you think may be helped by supplementing with biotin, talk to your doctor about it first.
Getting More Biotin
It's not necessary to take a biotin supplement, in addition to a multivitamin, to get all the biotin you need each day. In fact, even if you don't take a multivitamin, you can still get enough biotin just from eating a healthy diet.
According to NIH, foods that are typically good sources of biotin include organ meats and other meats, fish, eggs, nuts, seeds and certain vegetables, such as sweet potatoes. The good news is that these foods are also rich sources of other nutrients that are important to your health and may provide benefits that you are seeking from biotin. According to the Mayo Clinic, if you are eating enough of these healthy foods, you shouldn't need to take a supplement.
A better idea is to spend your money on eating fresh, high-quality foods such as organic fruits and vegetables, grass-fed meats and dairy, whole grains, fresh fish and healthy fats from nuts, seeds and avocado. This type of diet will boost your biotin levels naturally, help improve pre-existing health conditions and ward off disease.
- Colorado State University: Fat-Soluble Vitamins: A, D, E, and K – 9.315
- NIH: Biotin
- National Academy of Medicine: Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins
- Immunovites: High Dose d-Biotin 100mg (Equivalent to 100,000mcg) 90ct Bottle - Veggie Capsules - High Potency
- Nature's Bounty: Biotin
- One A Day: Multivitamin for Men
- One A Day: Multivitamin for Women
- National Academy of Medicine: Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels, Vitamins
- Cureus: Effect of High-Dose Biotin on Thyroid Function Tests: Case Report and Literature Review
- Mayo Clinic Health System: Get Radiant Hair, Skin and Nails Naturally
- MedlinePlus: Biotin