Biotin is everywhere in the hair-care aisle. Arnold Schwarzenegger’s newsletter says the science behind it is a lot weaker than the marketing suggests.

It’s in gummies, “hair, skin and nails” pills, even shampoos promising thicker strands. But according to Arnold’s Pump Club, unless someone is actually deficient in biotin, taking more of it isn’t likely to do anything for hair growth. And true deficiency is extremely rare.

“When you accounted for healthy people with normal diets, there was almost no evidence that taking biotin led to increased hair growth,” as per a scientific review and published by Arnold’s Pump Club. 

The scientific review searched the medical literature for documented cases where biotin actually improved someone’s hair or nails. It found only 18 reported cases total, an already small number, as publsihed by Arnold’s Pump Club.

Digging deeper into those cases made the picture worse, not better. Every single person had an underlying reason for their deficiency, whether a genetic disorder, medication use, or a diet severely restricting biotin intake. Once healthy people with normal diets were factored in, there was almost no evidence that supplementing with biotin increased hair growth at all.

That’s largely because most people already get enough biotin through food. Eggs, nuts, seeds, salmon and sweet potatoes all contain it, and the body’s actual requirement is small.

Beyond simply not working for most people, biotin supplements come with a real downside. In a study of healthy adults, taking 10 milligrams a day, an amount found in many hair supplements, interfered with several thyroid and hormone lab tests.

More concerning, biotin can cause troponin to appear falsely low. Troponin is the marker doctors rely on to help diagnose a heart attack, and the FDA has specifically warned that this interference can lead to missed diagnoses in emergency settings.

Top 10 foods rich in biotin

Supplementation with Biotin is so not necessary, as evidenced by the Arnold’s Pump Club newsletter.  So, skip the supplement aisle because Biotin is easy to get through everyday food, both plant- and animal-based.

As per Healthline, chicken liver tops the list by a wide margin, packing 138 mcg per 3-ounce serving, 460% of the daily value. Beef liver isn’t far behind, delivering 103% of the DV in the same portion size.

Egg yolks are another strong source, with a whole cooked egg providing about 33% of the DV. Cooking eggs fully matters here, since raw egg whites contain a protein that can block biotin absorption.

Legumes make a solid showing too. A serving of whole soybeans delivers 64% of the DV, while roasted peanuts offer 17%.

Nutritional yeast stands out among plant sources, providing 28% of the DV per serving, while brewer’s yeast offers a smaller 5%.

Rounding out the list, sweet potatoes, mushrooms, salmon, broccoli, avocados, and nuts and seeds all contribute smaller but meaningful amounts, making it easy to hit daily biotin needs through a varied diet.

Since biotin is water-soluble and not stored in the body, regular intake matters more than one large dose. For most people, these foods alone are more than enough, no supplement required.

Do you think supplement marketing oversells biotin’s benefits for hair growth?