Food grade diatomaceous earth (DE) is generally considered safe to ingest in small amounts. The FDA classifies it as “Generally Recognized as Safe” (GRAS) for use as a food additive, and it contains less than 1% crystalline silica, the form of silica that poses serious health risks. That said, “food grade” and “safe to consume freely” are not the same thing, and the distinction matters.
What Makes DE “Food Grade”
Diatomaceous earth is a fine powder made from the fossilized shells of tiny aquatic organisms called diatoms. These shells are mostly silicon dioxide, a mineral compound found throughout nature. The critical safety question is which form that silicon dioxide takes.
Food grade DE is uncalcined, meaning it hasn’t been heat-treated. The silica stays in its natural amorphous form, which your body can handle in small quantities. It must contain less than 1% crystalline silica, no more than 10 mg/kg of arsenic, and no more than 10 mg/kg of lead. Pool grade (also called filter grade) DE, by contrast, is heated to extremely high temperatures during a process called calcination. That heat converts much of the silica into crystalline form, making it effective as a filter medium but genuinely dangerous to ingest or inhale. These are completely different products despite sharing a name, and pool grade DE should never be consumed.
What Happens When You Eat It
Your digestive system absorbs some of the silicon from DE and distributes it to tissues including the liver. Animal research shows this absorption is dose-dependent: higher intake leads to more silicon uptake, though the body appears to have a built-in ceiling that limits how much accumulates in any one organ. Silicon that isn’t absorbed passes through the digestive tract and is excreted.
DE also physically interacts with your gut lining. In rat studies, supplementation caused moderate shortening of intestinal villi (the tiny finger-like projections that absorb nutrients) and increased the number of mucus-producing cells. Together, these changes created a stronger barrier to fat absorption, which may partly explain the lipid-lowering effects some people report. Whether this intestinal remodeling is beneficial or problematic over long periods isn’t well established.
The Cholesterol Study
The most cited human study on DE involved 19 adults with moderately high cholesterol who took 250 mg of diatomaceous earth three times daily for eight weeks. Their total cholesterol dropped 13.2% from baseline by week six, falling from about 286 mg/dL to 248 mg/dL. LDL (“bad”) cholesterol and triglycerides also decreased significantly, while HDL (“good”) cholesterol rose, with that increase becoming statistically significant four weeks after participants stopped taking DE.
These results are interesting but limited. Nineteen people is a very small sample, there was no placebo control group, and the study hasn’t been replicated in a larger trial. It’s not enough evidence to recommend DE as a cholesterol treatment.
The Real Risk: Breathing It In
The biggest safety concern with diatomaceous earth isn’t eating it. It’s inhaling it. Even food grade DE is a fine, easily airborne powder, and breathing it in can irritate your lungs. For people with asthma, COPD, or other respiratory conditions, inhaled DE dust can worsen symptoms.
The danger escalates dramatically with crystalline silica exposure. CDC research on workers in the diatomaceous earth industry found that long-term occupational exposure to crystalline silica dust at levels currently permitted by OSHA still carried a risk of 75 per 1,000 workers developing silicosis, a serious and irreversible scarring of the lungs. The risk of dying from non-cancer lung disease was 54 per 1,000 at that same exposure level. These numbers come from decades of industrial exposure, not occasional home use, but they illustrate why keeping DE out of your lungs matters. When handling the powder, work in a ventilated area, avoid creating dust clouds, and consider wearing a mask.
Skin and Eye Contact
DE is mildly abrasive by nature, which is actually why many people use it as a pest control powder (it damages the waxy coating on insects). On skin, it can cause dryness or mild irritation, particularly with repeated exposure. If it gets in your eyes, it acts as a foreign body irritant. Rinsing thoroughly with water is typically enough to resolve discomfort, but prolonged contact or rubbing can scratch the surface of the eye.
Who Should Avoid It
There is no reliable safety data on diatomaceous earth use during pregnancy or breastfeeding, so it’s best avoided during those times. No appropriate dosing range has been established for children. People with existing lung conditions should be especially careful to avoid inhaling the dust.
Because DE physically interacts with the intestinal lining and can alter how fats are absorbed, there’s a reasonable concern that it could affect the absorption of fat-soluble vitamins or medications taken at the same time. No human studies have directly tested this, but the mechanism is plausible. If you take prescription medications, separating your doses from any DE intake by a couple of hours is a sensible precaution.
The Bottom Line on Safety
Food grade diatomaceous earth, specifically the product that meets Food Chemicals Codex standards with under 1% crystalline silica, is not toxic when consumed in small amounts. The FDA’s GRAS designation supports that. But GRAS status applies to its use as a processing aid in food production, not as a daily supplement in unlimited quantities. The human research is thin, with only one small cholesterol study and no long-term safety trials. The powder is far more dangerous when inhaled than when swallowed, and pool grade DE is never safe to consume under any circumstances.