The average human body contains roughly 0.2 milligrams of gold, an amount so small it would be invisible to the naked eye. For a person weighing about 70 kilograms (154 pounds), that works out to about three parts per billion by mass. You could gather the gold from tens of thousands of people and still not have enough to shape into a single wedding band. Despite this minuscule quantity, gold circulates through the bloodstream, passes through organs, and enters the body continuously through food and environmental contact. What makes the story interesting is not the tiny baseline amount but rather what happens when that amount changes, whether through medical treatment, occupational exposure, or the emerging field of gold nanoparticle medicine.
Where the Gold Actually Sits
Most of the gold in your body at any given moment is dissolved in blood plasma or loosely associated with red blood cells. Trace amounts also reside in soft tissues, particularly the liver and kidneys, which filter and process metals that enter the bloodstream. Because gold is chemically very stable, the particles that land in tissue tend to stay put rather than breaking down the way more reactive metals do. Hair and nails incorporate trace gold as they grow, which is why researchers sometimes measure gold in those tissues as a way to gauge long-term exposure. But the concentrations involved are extraordinarily low, on the order of a few parts per billion in blood and even less in most organs.
This distribution is not fixed. In people who receive gold-based medical treatments (discussed below), gold accumulates in specific cell types and organs at concentrations hundreds or thousands of times above the natural baseline. In the general population, though, the amount is so uniformly tiny that standard blood panels do not even bother measuring it.
How Gold Gets Into Your Body
Gold enters the body primarily through food. It exists at trace levels in soil and water and works its way into crops, seafood, and meat through ordinary biological processes. You also encounter gold as a food additive: edible gold leaf (designated E175 in Europe) shows up on desserts, in specialty drinks, and in certain traditional cuisines. While the amounts consumed this way are small, they are real. People who wear gold jewelry or have gold dental work are exposed through skin contact and oral mucosal contact, though absorption through intact skin is very limited.1Critical Reviews in Toxicology. GOLD: human exposure and update on toxic risks
Occupational exposure is a separate category. Gold miners, refinery workers, jewelers, and dental technicians can inhale gold dust or come into prolonged skin contact with gold compounds. These exposures push body-gold levels well above the general population’s baseline, though the health effects of chronic low-level occupational exposure remain poorly characterized in the research literature.
Does Gold Serve Any Biological Purpose?
No known biological function has been identified for gold in the human body. Unlike iron, zinc, copper, and other trace metals that serve as essential cofactors for enzymes and metabolic processes, gold appears to be biologically inert at the concentrations naturally present. Your body does not need it, does not seek it out, and would function identically with none at all.
This inertness is precisely what makes gold so paradoxical in medicine and toxicology. It is widely considered the most chemically unreactive of all metals, yet it can trigger immune sensitization in some people, causing allergic contact dermatitis from gold jewelry or oral reactions to gold dental restorations.2PubMed. Gold, the noble metal and the paradoxes of its toxicology The fact that something so chemically quiet can still provoke the immune system suggests that the story of gold’s interaction with biology is more nuanced than “inert means harmless.”
When Gold Levels Spike Far Above Normal
The most dramatic example of elevated body gold comes from chrysotherapy, the medical use of injectable gold compounds to treat rheumatoid arthritis. This practice was common from the mid-twentieth century through the 1990s before being largely replaced by newer drugs. During chrysotherapy, patients received regular intramuscular injections of gold salts, and their tissue gold concentrations rose by orders of magnitude above natural levels.
Studies of patients who underwent chrysotherapy found gold deposited not just in joint tissue but throughout the body, concentrated inside macrophages (a type of immune cell) across many organs. Gold also accumulated in kidney tubule cells, liver cells, adrenal gland cells, and even the cells lining the seminiferous tubules of the testes. Perhaps most striking, gold persisted in synovial tissue and other organs for up to 23 years after treatment was stopped.3Annals of the Rheumatic Diseases. Selective concentration and localization of gold in macrophages of synovial and other tissues during and after chrysotherapy in rheumatoid patients That extraordinary persistence reflects gold’s chemical stability: once it lodges in tissue, the body has limited mechanisms for breaking it down and excreting it.
Blood measurements during chrysotherapy showed that gold distributes between plasma and red blood cells, and the ratio matters clinically. Patients who developed toxic reactions to gold treatment tended to have significantly higher gold concentrations in their red blood cells compared to patients who tolerated the therapy without problems.4PubMed Central. Gold in erythrocytes, whole blood, and plasma during long-termed chrysotherapy This suggested that red-cell gold levels might serve as a warning marker for adverse reactions, though chrysotherapy itself has become uncommon enough that the clinical relevance has faded.
Metallic Gold Versus Gold Ions
One of the most important distinctions in gold toxicology is the difference between metallic gold and gold ions. The gold in your jewelry, the gold leaf on your dessert, and the gold naturally present in your tissues at baseline is overwhelmingly metallic (elemental) gold, and it poses minimal toxicity to human cells. Gold ions are a different story entirely. When gold is dissolved into ionic form, particularly as Au³⁺, it becomes biologically active and can interact aggressively with enzymes and DNA.
Research has documented damage to kidneys, liver, and the peripheral nervous system from exposure to gold chloride (a gold ion compound) at relatively modest concentrations.5Journal of Fluorescence. Heavy Metals Detection via Plastic-Waste-Derived Carbon Dots: Review This is why the gold compounds used in chrysotherapy, which release gold ions inside the body, carried a meaningful risk of side effects including skin rashes, kidney problems, and blood count abnormalities, while eating a gold-leaf-topped chocolate has no such consequences. The chemical form of gold dictates whether the body sees it as an inert bystander or a reactive intruder.
For the general population, this distinction is mostly academic. You are unlikely to encounter significant quantities of ionic gold unless you work in a gold-processing environment or receive gold-based medical treatment. The trace gold you absorb through food is elemental, and at parts-per-billion concentrations, it passes through the body without causing any detectable harm.
Gold Nanoparticles in Modern Medicine
While chrysotherapy has faded, gold is making a comeback in medicine through an entirely different avenue: engineered nanoparticles. Researchers are developing gold nanoparticles as drug delivery vehicles, imaging agents, and cancer-targeting tools. The appeal is gold’s combination of chemical stability, easy surface modification, and distinctive optical properties that make the particles useful for both diagnosis and therapy.
One promising line of research involves very small gold nanoparticles, around 2.5 nanometers in diameter, coated with glutathione (a naturally occurring molecule). These tiny particles behave somewhat like dye molecules in how the kidneys clear them, but they linger in tumors much longer than dyes do, making them potentially useful for detecting and treating cancer. The effect relies on the fact that tumor blood vessels are leakier than normal vessels, allowing nanoparticles to seep in and accumulate preferentially.6PubMed Central. Passive tumor targeting of renal-clearable luminescent gold nanoparticles: long tumor retention and fast normal tissue clearance
Safety studies of similar glutathione-coated gold nanoparticles (about 1.2 nanometers) have been encouraging so far. In animal models, the particles caused no observable illness even at relatively high concentrations, targeted expected organs like the liver and kidneys, and cleared from the body gradually over time.7Nanomedicine: Nanotechnology, Biology and Medicine. In vivo toxicity, biodistribution, and clearance of glutathione-coated gold nanoparticles This gradual clearance is important because one of the concerns with any injected nanoparticle is permanent accumulation in organs, which could eventually reach harmful concentrations. The fact that small gold nanoparticles clear through the kidneys, similar to a waste product leaving via urine, is a significant advantage over larger particles that tend to get trapped in the liver and spleen indefinitely.
None of these gold nanoparticle therapies are in routine clinical use yet. The research is largely preclinical, meaning it has been tested in cell cultures and animal models but is still working its way toward human trials for most applications. Still, the amount of gold that would be introduced for a single diagnostic imaging session would be far less than what chrysotherapy patients accumulated over months of treatment, so the safety bar is different.
Can Gold Cross the Placenta?
One question that matters for the future of gold nanoparticle medicine is whether gold particles can reach a developing fetus. Research in pregnant rats has shown that the answer depends heavily on particle size. Very small gold nanoparticles (1.4 nanometers) did cross the placenta and reach the fetuses, though in extremely tiny quantities, roughly 0.06 percent of the dose administered to the mother. Slightly larger particles (18 nanometers) crossed in even smaller amounts, and particles of 80 nanometers did not reach the fetuses at all within the 24-hour study window.8PubMed Central. Size dependent translocation and fetal accumulation of gold nanoparticles from maternal blood in the rat
This size-dependent transfer matters because the most promising gold nanoparticles for medical use tend to be on the smaller end of the size spectrum, precisely the range most likely to cross biological barriers including the placenta. These findings are from animal studies and cannot be directly extrapolated to humans, but they have prompted researchers to treat pregnancy as a key safety consideration in the design of gold nanoparticle therapies. For the general population, the natural gold in your blood is present in ionic or molecular form at such low concentrations that placental transfer of naturally occurring gold is not considered a health concern.
How the Body Clears Gold
The kidneys are the primary route for gold excretion. Gold that reaches the bloodstream in a form small enough to be filtered by the glomeruli (the kidney’s filtration units) passes into urine. Some gold also leaves through bile and ends up in feces. But gold’s excretion is slow compared to many other trace elements. The body handles gold somewhat grudgingly: it gets filtered and cleared, but not quickly and not completely. This is why chrysotherapy patients still had measurable gold in tissues decades after treatment stopped, and why researchers designing gold nanoparticles pay close attention to kidney clearance rates.3Annals of the Rheumatic Diseases. Selective concentration and localization of gold in macrophages of synovial and other tissues during and after chrysotherapy in rheumatoid patients
For people with normal gold exposure levels (no medical gold treatment, no occupational exposure), the tiny amount entering through food is largely balanced by the tiny amount leaving through urine and feces, keeping the body’s gold inventory at that stable 0.2 milligrams or so. The system is not precisely regulated the way iron or calcium homeostasis is; there are no dedicated gold transport proteins or storage molecules. Gold just drifts in and drifts out, with some fraction sticking around in tissues along the way.
Putting the Number in Perspective
At 0.2 milligrams, gold ranks among the rarest elements in the human body. You carry far more iron (roughly 3 to 4 grams), zinc (about 2 grams), and copper (about 75 milligrams). Even elements most people have never thought about, like rubidium and strontium, are present at higher levels than gold. The only elements rarer than gold in the body tend to be ones with no biological role at all, like uranium, which is present at levels similar to gold or slightly lower.
At current gold prices, the 0.2 milligrams in your body is worth a fraction of a cent. If you collected the gold from every person alive, roughly eight billion people, you would have about 1.6 metric tons. That sounds like a lot until you realize that a single large gold bar weighs about 12.4 kilograms, meaning the entire human population’s body gold would fill only about 130 bars. The world mines roughly 3,000 metric tons of gold per year, so all the gold in every living human body combined amounts to less than a single day’s global mining output. Your body’s gold is, by any measure, a truly negligible quantity of a metal that humans have obsessed over for millennia.