Silicon Deficiency: What the Evidence Shows

Table of Contents

1. What the Evidence Actually Says
2. The Biology: Why a Human Shortfall Isn't Seen
3. The Bone and Connective-Tissue Research, Honestly
4. Who, If Anyone, Could Run Low
5. What the Evidence Means in Daily Eating
6. Related Nutrients and Minerals
7. The Real Causes Behind Silicon Worries
8. Key Research Papers
9. Connections
10. Featured Videos

What the Evidence Actually Says

It is worth being precise about words. A deficiency, in the strict nutritional sense, means that going without a nutrient produces a recognizable disease that the nutrient then cures — the way too little vitamin C causes scurvy, or too little iodine causes goiter. By that standard, silicon has never met the bar in humans. No silicon-deficiency illness has ever been described in a person, no clinical guideline defines a "low silicon" threshold, and routine lab panels do not measure it. The U.S. Institute of Medicine has not set a Recommended Dietary Allowance (RDA) for silicon precisely because the evidence is not strong enough to prove it is essential or to define how much a person needs.

So why does silicon come up at all in discussions of bone and connective-tissue health? Because the picture is genuinely more interesting than "irrelevant." The honest summary breaks into three tiers of evidence:

• Older evidence in animals, not repeated in a later study. Experiments in the early 1970s reported that chicks and rats raised on highly purified, silicon-stripped laboratory diets grew poorly and developed abnormalities of bone, cartilage, and connective tissue. Edith Carlisle's chick experiments and Klaus Schwarz and David Milne's rat experiments, both published in 1972, are the foundation of the entire field. Those diets were artificial and do not exist in nature or in any human kitchen. Later attempts to replicate the findings, in the words of a 2008 study, "found mild alterations in bone metabolism without any adverse health effects." That study, by researchers from several laboratories, fed rats a specially made low-silicon diet for 26 weeks: they showed no outward illness, and their bodies and bones grew slightly longer rather than stunted. Their kidneys passed less silicon into urine, which the authors read as the body holding on to silicon when intake is low. The authors wrote that they were "unable to reproduce the profound deficiency state reported in rats and chicks in the early 1970s."
• Moderate evidence — population associations in people. Large dietary surveys have repeatedly found that people who happen to eat more silicon tend to have higher bone mineral density. The most cited is the Framingham Offspring study (over 2,800 people), where higher silicon intake tracked with denser hip bone in men and premenopausal women, but not in postmenopausal women. This is a real signal, but it is observational: people who eat more silicon also tend to eat more whole grains, fruits, vegetables, and beer, and to differ in many other ways, so the silicon itself may not be the cause.
• Weak / preliminary evidence — human supplement trials. Only a handful of small trials have given people a silicon supplement (usually a form called choline-stabilized orthosilicic acid) and measured bone. They are promising at the level of laboratory markers but are too small and too few to prove that silicon prevents fractures or treats osteoporosis. No major health authority recommends silicon supplements for bone health on the basis of this evidence.

Putting it plainly: silicon looks beneficial and may even be conditionally important, but a clinically meaningful deficiency in free-living people has simply never been demonstrated. It is correct, and not a dodge, to say this is not a clinical problem you need to watch for.

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The Biology: Why a Human Shortfall Isn't Seen

Two facts about silicon's chemistry and our diet explain why no one runs low in ordinary life.

First, silicon is everywhere. Silicon (chemical symbol Si) makes up roughly a quarter of the Earth's crust by weight — it is the main ingredient of sand, quartz, and most rock. Plants pull it out of the soil as they grow, so it ends up in the parts of plants we eat. The body absorbs it not as the rock-hard mineral but as a small, water-soluble molecule called orthosilicic acid (Si(OH)₄), which dissolves readily in water and other beverages. Because plants concentrate it and water carries it, a normal mixed diet delivers silicon continuously without anyone trying. Typical Western intakes fall somewhere around 20–50 milligrams a day, with the richest contributors being whole grains and grain products (oats, barley, bran, brown rice), some fruits and vegetables (especially green beans and bananas), and — perhaps surprisingly — beer, in which barley husks leach highly absorbable silicon into the brew. A study of 76 beers measured an average of 19.2 milligrams of silicon per liter. Drinking water and some mineral waters add more.

The Framingham studies give real figures. Average silicon intake was 30 to 33 milligrams a day in men and 24 to 25 milligrams in women, and it fell with age. Beer and bananas were the main sources in men, bananas and string beans in women, and on average 41% of the silicon eaten came out in urine, a sign of how readily food silicon is absorbed.

Second, the body is forgiving about it. Orthosilicic acid is absorbed easily in the gut, circulates in the blood, and any excess is filtered out efficiently by the kidneys and passed in the urine. There is no large dedicated storage organ for silicon and no tight hormonal control system the way there is for calcium or potassium — intake in roughly equals excretion out, day to day. A balance study by Pruksa and colleagues confirmed exactly this in human volunteers: what people take in is closely matched by what they excrete. It was a pilot of 12 volunteers, 6 of whom drank a dose of 28.9 milligrams of silicon; 57% of the dose came out in urine and 39% in stool within 24 hours, 96.3% in all, and the authors say it is "not known" whether all of that came from the dose itself or partly from silicon already in the body. The practical consequence is that you cannot easily "deplete" yourself of silicon by eating a normal varied diet, because you are topping it up with every meal and drink.

Contrast this with a true essential nutrient that humans can run short of. Vitamin C is not made by the body and is destroyed by cooking, so a diet truly devoid of fresh produce causes scurvy within weeks. Iron is poorly absorbed and easily lost through bleeding, so deficiency is common worldwide. Silicon is the opposite story: abundant in food, well absorbed, freely excreted, and not depleted by everyday eating. That combination is why a deficiency state, easy to create artificially in a lab animal on a purified diet, essentially never arises in a person living a normal life.

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The Bone and Connective-Tissue Research, Honestly

This is the area where silicon earns its reputation, so it deserves a careful, non-hyped walk-through. The interest is biologically reasonable: silicon shows up in the body wherever connective tissue is being built — in growing bone, in cartilage, in the walls of arteries, and in the "scaffolding" proteins like collagen that hold tissues together. The open question has always been whether that presence is doing real work, or is just a passenger.

What the laboratory shows. In a dish, orthosilicic acid nudges human bone-forming cells (osteoblasts) to make more type-1 collagen, the main protein framework that bone mineral later hardens onto. Reffitt and colleagues demonstrated this collagen-stimulating effect directly in human bone-like cells. A useful analogy: collagen is the rebar and concrete forms of a building, and calcium and phosphate are the concrete poured in. Silicon, in these experiments, seems to help lay down a better framework — which would matter for bone quality, not just bone density. This is a plausible mechanism, but cell-dish findings do not automatically translate to whole people.

What the population studies show. Several large observational studies have linked higher dietary silicon to higher bone mineral density. In the Framingham Offspring Cohort, Jugdaohsingh and colleagues found that people in the highest silicon-intake group had meaningfully greater hip bone density than those in the lowest — an association found in men and pre-menopausal women, but not in post-menopausal women. The Aberdeen Prospective Osteoporosis Screening Study (APOSS) by Macdonald and colleagues measured 3,198 women aged 50 to 62: femoral neck (upper thigh bone) density averaged 2% lower in the lowest quarter of silicon intake (16 milligrams a day) than in the top quarter (31.5 milligrams a day). It also added an important nuance: silicon's apparent benefit seemed to depend on estrogen status, showing up mainly in women who had adequate estrogen (pre-menopausal, or post-menopausal women on hormone therapy). That estrogen interaction is a clue that silicon, if it helps, helps as part of a larger system rather than as a stand-alone fix.

Why associations are not proof. Here is the honesty this topic requires. People who eat more silicon are not a random group. They tend to eat more whole grains, more produce, and more beer — foods and drinks that travel with many other nutrients (magnesium, potassium, fiber, polyphenols) and with whole lifestyle patterns that independently affect bone. Statisticians call the silicon signal potentially confounded: the denser bones might be caused by the overall healthier dietary pattern, with silicon merely along for the ride as a marker of eating more plants. Observational studies can adjust for some of this, but they can never fully untangle it. That is exactly why a correlation, however consistent, cannot establish that silicon itself prevents bone loss.

What the human trials show — and don't. The cleanest test is a randomized trial: give some people silicon and others a placebo, then measure what happens. Very few exist. The most cited is Spector and colleagues' 2008 trial, in which osteopenic women received choline-stabilized orthosilicic acid (a well-absorbed supplement form) plus calcium and vitamin D, versus calcium and vitamin D alone. The silicon group showed favorable movement in a marker of bone formation and a hint of benefit at the femur, but the study was small and measured biochemical signals more than hard outcomes like fractures. In numbers: 136 of the 184 women randomized completed the 12 months; the only significant marker was the one for collagen formation (PINP), at the 6 and 12 milligram doses and without a clear dose response; lumbar spine density did not change significantly; the femoral neck result came from a subgroup analysis done after the fact, at the 6 milligram dose; and no adverse events were tied to the supplement. No large trial has shown that silicon supplements prevent fractures or treat osteoporosis, and that is the outcome that would matter. Reviews in this field include the Sripanyakorn group's overview of dietary silicon and bone and Price's 2013 review, which is more confident than these trial numbers: it says "silicon plays an essential role in bone formation and maintenance" and that supplementation "in animals and humans has been shown to increase bone mineral density and improve bone strength." Silicon is a promising area for bone health that is biologically interesting and worth more research, but with the trial numbers above, the human evidence is not yet strong enough to call it a treatment, let alone to define a deficiency.

So the fair verdict is a "maybe, partly, for bone quality, as part of a good diet" — not "low silicon causes weak bones." For the established, well-proven players in bone health, see Calcium, Magnesium, and the dedicated page on Bone Loss and Osteoporosis.

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Who, If Anyone, Could Run Low

If a true silicon shortfall basically never happens in everyday life, the reasonable question is whether any situation could produce one. The honest answer is: only narrow, mostly theoretical cases — and even for these, there is no established disease and no recommendation to test or treat.

• Long-term total parenteral nutrition (TPN). The clearest candidate is someone fed entirely by vein for a long time because their gut cannot be used. Because intravenous nutrition is a manufactured formula, the silicon content can be low and is not deliberately added. In principle this is the one setting where intake could fall far below what a normal diet provides. Even here, however, there is no defined silicon-deficiency syndrome described in TPN patients, and clinical nutrition guidelines do not list silicon among the trace elements that must be supplemented — unlike zinc, copper, selenium, or chromium, which genuinely are added to long-term formulas. (Of note, the more documented silicon concern in this population is the opposite problem — trace contaminants in intravenous (IV) fluids — which belongs on the Silicon Toxicity page, not here.)
• Very restrictive or highly processed diets. Diets stripped of whole grains, produce, and unprocessed foods deliver less silicon, because refining grains removes the silicon-rich outer husk and bran. A person living mostly on heavily refined, low-fiber food would take in less silicon — but they would also be short of fiber, magnesium, potassium, and many vitamins, and it is those well-established shortfalls, not silicon, that would matter clinically. Whole, plant-based food supplies all of them.
• Aging, in theory. Some researchers have speculated that the body's ability to use silicon may decline with age, and that this could play a small part in why bones and connective tissue weaken over the years. This is a hypothesis raised to explain why silicon's bone association is not seen in post-menopausal women — it is not an established deficiency and not a reason to supplement.

Notice what is not on this list: there is no genetic silicon-deficiency disorder, no malabsorption syndrome built around silicon, and no recognized clinical picture you could point a doctor to. That absence is itself the most important piece of evidence.

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What the Evidence Means in Daily Eating

Because no deficiency has been recognized in people, there is little here to act on. For the overwhelming majority of people, a normal varied diet supplies silicon with essentially no special effort.

The foods richest in silicon are the same foods that dietary guidance already lists for general and bone health:

• Whole grains — oats, barley, brown rice, bran, and whole-grain bread are the single biggest dietary source, because silicon concentrates in the bran and husk that refining removes.
• Certain fruits and vegetables — green beans, bananas, and other plant foods contribute steadily. Leafy greens and root vegetables add smaller amounts across the day.
• Beverages — beer is unusually high in well-absorbed silicon (from the barley), and some mineral waters and drinking waters contribute a meaningful share. This is a point of interest, not a health endorsement: any benefit of beer's silicon is far outweighed by the well-established harms of alcohol, so beer is not counted here as a "silicon source."

On supplements: silicon supplements exist — choline-stabilized orthosilicic acid (the form used in the research), plus older preparations like silica gel and horsetail-plant extracts. The research has shown no proven reason for the general public to take them. The human evidence for benefit is preliminary, no deficiency is being corrected, and the foods that supply silicon are cheap, pleasant, and good for you for many other reasons. People sometimes try silicon supplements hoping for stronger hair, skin, and nails; the evidence there is similarly thin and is discussed on the Silicon for Hair and Nails page. For bone health, the proven essentials — adequate calcium, vitamin D, protein, weight-bearing exercise, and not smoking — have far more evidence behind them than silicon.

One caution worth flagging: horsetail, an herb marketed as a "natural silicon" source, contains an enzyme (thiaminase) that can break down vitamin B1 (thiamine), and products vary widely in quality and purity. Food supplies silicon without either of those two concerns.

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Related Nutrients and Minerals

Silicon does not act alone, and several of the minerals it is grouped with are far better established — which helps put silicon in perspective.

• Calcium and Phosphorus are the actual building blocks of bone mineral — the "concrete." If silicon helps at all, it is by improving the collagen framework that calcium and phosphate harden onto, not by replacing them. Real, common deficiencies of these (and of vitamin D, which governs calcium absorption) are what genuinely threaten bone.
• Magnesium is essential, frequently low in real diets, and important for bone and hundreds of other processes — a far higher-priority mineral to get right than silicon.
• Boron is, like silicon, a "possibly beneficial" ultra-trace element studied for bone, with similarly modest and preliminary human evidence — a useful comparison, since both occupy the same honest gray zone between "essential" and "irrelevant."
• Manganese and Zinc are genuine essential trace minerals involved in connective-tissue and bone enzymes; unlike silicon, true deficiencies of these are recognized clinical entities with defined consequences.
• Vitamin C and collagen connect to silicon through the collagen story: vitamin C is required to build collagen, collagen is the protein silicon appears to influence, and all three are part of how the body maintains connective tissue. Vitamin C deficiency (scurvy) is a real, dramatic illustration of what a true connective-tissue nutrient shortfall looks like — a striking contrast to silicon, where no such picture exists.

For the full picture of silicon's possible roles, see the Silicon overview and its benefits pages on bone density and connective tissue.

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The Real Causes Behind Silicon Worries

Because silicon deficiency is not a real clinical condition, there are no silicon-deficiency symptoms to watch for, and a silicon blood test has no established use — such testing is not part of standard care and would not guide any treatment. The underlying concerns people bring to silicon — usually bones, joints, hair, skin, or nails — do have recognized causes and facts of their own:

• Bone thinning or osteoporosis — a concern especially after age 50, after menopause, after a fracture from a minor fall, with long-term steroid use, or with a family history. Bone density is measured with a dual-energy X-ray absorptiometry (DEXA) scan, and the proven essentials above carry far more evidence than silicon. See Bone Loss and Osteoporosis and Osteoporosis.
• Sudden, marked changes in hair, skin, or nails — significant hair loss, very brittle or spooned nails, or notable skin changes can signal real, treatable issues such as thyroid disease, iron deficiency, or other nutritional gaps, none of which a silicon supplement corrects.
• Silicon-containing supplements — particularly horsetail-based products, which can interfere with thiamine (vitamin B1) and vary in purity. These concerns weigh most for people who are pregnant, breastfeeding, taking other medications, or living with kidney disease, since the kidneys are the route by which silicon leaves the body.
• Long-term feeding by vein (TPN) — trace-element needs in this setting are real and are managed by a clinical nutrition team, which supplements the trace minerals that genuinely require it; silicon is not currently among them.

The unifying message: when something is wrong with bones, joints, or connective tissue, the answer almost certainly lies with well-established nutrients and conditions, not with a silicon shortage.

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Key Research Papers

1. Carlisle EM (1972). Silicon: An Essential Element for the Chick. Science;178(4061):619-621. — DOI: 10.1126/science.178.4061.619. — doi:10.1126/science.178.4061.619
2. Schwarz K, Milne DB (1972). Growth-promoting Effects of Silicon in Rats. Nature;239(5371):333-334. — DOI: 10.1038/239333a0. — doi:10.1038/239333a0
3. Jugdaohsingh R, Tucker KL, Qiao N, Cupples LA, Kiel DP, Powell JJ (2004). Dietary Silicon Intake Is Positively Associated With Bone Mineral Density in Men and Premenopausal Women of the Framingham Offspring Cohort. Journal of Bone and Mineral Research;19(2):297-307. — DOI: 10.1359/jbmr.0301225. — doi:10.1359/jbmr.0301225
4. Macdonald HM, Hardcastle AC, Jugdaohsingh R, Fraser WD, Reid DM, Powell JJ (2012). Dietary silicon interacts with oestrogen to influence bone health: Evidence from the Aberdeen Prospective Osteoporosis Screening Study. Bone;50(3):681-687. — DOI: 10.1016/j.bone.2011.11.020. — doi:10.1016/j.bone.2011.11.020
5. Spector TD, Calomme MR, Anderson SH, Clement G, Bevan L, et al. (2008). Choline-stabilized orthosilicic acid supplementation as an adjunct to Calcium/Vitamin D3 stimulates markers of bone formation in osteopenic females: a randomized, placebo-controlled trial. BMC Musculoskeletal Disorders;9:85. — DOI: 10.1186/1471-2474-9-85. — doi:10.1186/1471-2474-9-85
6. Reffitt DM, Ogston N, Jugdaohsingh R, Cheung HFJ, Evans BAJ, et al. (2003). Orthosilicic acid stimulates collagen type 1 synthesis and osteoblastic differentiation in human osteoblast-like cells in vitro. Bone;32(2):127-135. — DOI: 10.1016/s8756-3282(02)00950-x. — doi:10.1016/s8756-3282(02)00950-x
7. Jugdaohsingh R, Anderson SHC, Tucker KL, Elliott H, Kiel DP, et al. (2002). Dietary silicon intake and absorption. The American Journal of Clinical Nutrition;75(5):887-893. — DOI: 10.1093/ajcn/75.5.887. — doi:10.1093/ajcn/75.5.887
8. Sripanyakorn S, Jugdaohsingh R, Elliott H, Walker C, Mehta P, et al. (2004). The silicon content of beer and its bioavailability in healthy volunteers. British Journal of Nutrition;91(3):403-409. — DOI: 10.1079/bjn20031082. — doi:10.1079/bjn20031082
9. Sripanyakorn S, Jugdaohsingh R, Thompson RPH, Powell JJ (2005). Dietary silicon and bone health. Nutrition Bulletin;30(3):222-230. — DOI: 10.1111/j.1467-3010.2005.00507.x. — doi:10.1111/j.1467-3010.2005.00507.x
10. Pruksa S, Siripinyanond A, Powell JJ, Jugdaohsingh R (2014). Silicon balance in human volunteers; a pilot study to establish the variance in silicon excretion versus intake. Nutrition & Metabolism;11:4. — DOI: 10.1186/1743-7075-11-4. — doi:10.1186/1743-7075-11-4
11. Price CT, Koval KJ, Langford JR (2013). Silicon: A Review of Its Potential Role in the Prevention and Treatment of Postmenopausal Osteoporosis. International Journal of Endocrinology;2013:316783. — DOI: 10.1155/2013/316783. — doi:10.1155/2013/316783
12. Jugdaohsingh R, Calomme MR, Robinson K, Nielsen F, Anderson SH, et al. (2008). Increased longitudinal growth in rats on a silicon-depleted diet. Bone;43(3):596-606. — DOI: 10.1016/j.bone.2008.04.014. — doi:10.1016/j.bone.2008.04.014

PubMed Topic Searches

1. PubMed: Silicon as an essential trace element in human nutrition
2. PubMed: Dietary silicon intake and bone mineral density
3. PubMed: Orthosilicic acid, collagen, and bone formation
4. PubMed: Silicon bioavailability and dietary absorption
5. PubMed: Choline-stabilized orthosilicic acid supplementation

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Connections

• All Minerals
• Silicon Overview
• Silicon Toxicity
• Silicon Benefits Hub
• Silicon and Bone Density
• Silicon and Connective Tissue
• Silicon for Hair and Nails
• Calcium
• Bone Loss and Osteoporosis
• Magnesium
• Phosphorus
• Boron
• Manganese
• Zinc
• Vitamin C
• Collagen
• Osteoporosis
• Comprehensive Metabolic Panel

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