Silica shows up in a lot of hair, skin, and nail supplements, often as orthosilicic acid or from plants like horsetail and bamboo. The pitch is stronger hair and nails and firmer skin. We looked at what the research actually shows, and this is one where the marketing has run well ahead of the science.
The short answer
There are a couple of small studies suggesting silica may make hair and nails less brittle and improve skin over several months. But they are small, run in narrow groups, and tied to the companies that sell the ingredient. On top of that, silicon is not even confirmed to be an essential nutrient for humans. So silica is not a scam, but the evidence is thin, and the confident claims on the label are not backed by much.
What silica is supposed to do
Silicon is a mineral found in small amounts throughout the body, including in skin, hair, and nails. In lab and animal studies, it seems to play a part in forming connective tissue and supporting collagen. That is the logic behind the supplement: hair and nails contain silicon, so more of it should make them stronger. The most studied supplement form is choline-stabilized orthosilicic acid, a version the body can absorb reasonably well.
Silica for hair and nails: what the studies found
The evidence comes down to a small number of trials. In one 20-week study, 50 women with sun-damaged skin took 10 milligrams of silicon a day and reported less brittle hair and nails, along with some skin improvements. In another, 48 women with fine hair took the same dose for 9 months and had measurably thicker, stronger hair strands than the placebo group.
Those results sound encouraging, and they are the reason silica has a beauty reputation. But look closer and the limits are clear. Both studies were small, both were done only in women with a specific concern, and both were connected to the maker of the ingredient. Independent confirmation in larger groups is missing.
The other thing worth noticing is how long they ran. The hair study took 9 months to measure a difference. Nails and hair grow slowly, so anyone trying silica needs to think in months, not weeks.
Not all silica supplements are the same
This matters if you are about to buy one, because the form on the label is not a detail. The studies above used choline-stabilized orthosilicic acid, a form designed to be absorbed. Most silica supplements on the shelf use something else, usually horsetail extract or bamboo extract, because they are cheaper.
Plant sources do contain silicon, but much of it is in a form your body absorbs poorly, and the trials that showed a benefit were not run on horsetail or bamboo. So a horsetail supplement is not the thing that was tested, even though it gets sold on the back of those results.
Horsetail has one more issue. It contains an enzyme that breaks down thiamine, or vitamin B1, which is why long-term use is generally discouraged. If you want the version with actual trial evidence behind it, look for orthosilicic acid on the label.
The bigger gap
There is a more basic problem underneath. Scientists have not established that silicon is an essential nutrient for people at all. There is no recommended daily intake, because no one has shown that humans need a set amount. Animal studies hint at a role in connective tissue, but the case in humans is unsettled. That is a shaky foundation for a supplement sold as a hair and nail essential.
You also already get silicon from food. Whole grains, some vegetables, and even beer and water contain it, so most people are not running low in the first place.
The bottom line
Silica is a case where a plausible idea and a couple of small, industry-linked studies have turned into confident marketing. The trials that exist did show less brittle hair and nails over several months, so it is not nothing. But the evidence is thin, unconfirmed by independent research, and built on a mineral that is not even proven to be essential for humans. If you want to try it, look for orthosilicic acid rather than horsetail, keep your expectations low and your spending lower, and give it months rather than weeks. For how silica compares to the other ingredients in these products, our guide on hair, skin and nails supplements walks through the whole label, and our guide on collagen covers the connective tissue silica is meant to support.
Questions people ask
Is silica good for hair and nails?
Possibly, but the evidence is limited. Two small studies found less brittle hair and nails over several months, and both were tied to the company selling the ingredient. Nobody has confirmed it independently.
Does silica make hair and nails stronger?
A couple of small studies found less brittle hair and nails over several months. The evidence is limited and comes from research tied to the sellers, so it is far from settled.
Does silica help hair growth?
The hair study measured strength and thickness of the strands rather than growth speed. So there is some evidence for sturdier hair, and none for growing it faster.
How long does silica take to work?
The studies ran 20 weeks and 9 months. Hair and nails grow slowly, so anything you notice will take months, and a few weeks tells you nothing.
Which form of silica is best for hair and nails?
Choline-stabilized orthosilicic acid is the form used in the studies. Horsetail and bamboo extracts are more common on shelves and cheaper, but they were not what the trials tested, and horsetail is not ideal for long-term use.
How much silica should I take?
The studies that showed a benefit used about 10 milligrams of silicon a day. There is no official recommended intake, because silicon is not confirmed as an essential nutrient.
Is silica the same as collagen?
No. Silica is a mineral thought to support connective tissue, while collagen is the protein itself. They are sometimes sold together.
Do I need a silica supplement?
Probably not. You get silicon from foods like whole grains and vegetables, and there is no proof that people need extra.
References
Barel A, Calomme M, Timchenko A, et al. Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin. Archives of Dermatological Research. 2005;297:147-153. https://doi.org/10.1007/s00403-005-0584-6
Wickett RR, Kossmann E, Barel A, et al. Effect of oral intake of choline-stabilized orthosilicic acid on hair tensile strength and morphology in women with fine hair. Archives of Dermatological Research. 2007;299(10):499-505. https://doi.org/10.1007/s00403-007-0796-z
Jurkić LM, Cepanec I, Pavelić SK, Pavelić K. Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds. Nutrition & Metabolism. 2013;10:2. https://pmc.ncbi.nlm.nih.gov/articles/PMC3546016/
This article is for information only and is not medical advice. Supplements are not meant to diagnose, treat, cure, or prevent any illness. Talk to your doctor before starting anything new, especially if you are pregnant, breastfeeding, or taking medication.
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