Food grade mineral oil is made of hydrocarbons refined from petroleum crude oil. Specifically, it consists almost entirely of saturated hydrocarbons, chains and rings of carbon and hydrogen atoms stripped of the aromatic compounds, sulfur, and other impurities that make unrefined petroleum harmful. The refining process is where the distinction between ordinary industrial mineral oil and the food grade version is drawn, and that process turns out to be more interesting and more contested than most people assume.
From Crude Oil to Something You Can Swallow
Petroleum crude oil is a complex stew of thousands of different hydrocarbon molecules. Turning it into food grade mineral oil requires several stages of purification. The starting point is vacuum distillation, which separates crude oil into fractions based on boiling point. The distillate fractions chosen for mineral oil production are further refined to strip out undesirable compounds, particularly aromatic hydrocarbons, some of which are known or suspected carcinogens.
Three main refining techniques accomplish this cleanup. Solvent extraction uses a chemical solvent to dissolve and pull out aromatic compounds. Catalytic hydrotreating pushes hydrogen through the oil in the presence of a catalyst, which breaks apart aromatic ring structures and converts them into saturated hydrocarbons. Hydrocracking goes further, using high pressure and hydrogen to crack larger molecules into smaller, cleaner ones.1PubMed Central. Petroleum Mineral Oil Refining and Evaluation of Cancer Hazard Modern food grade oils typically undergo a combination of these methods, and the goal is always the same: get the aromatic content as close to zero as possible.
After refining, the oil may also go through a dewaxing step to remove straight-chain paraffin waxes that would make the product cloudy or waxy at room temperature. The result is a clear, colorless, odorless, and tasteless liquid that meets the standards set by pharmacopeias like the United States Pharmacopeia (USP) or the European Pharmacopoeia. Oils meeting these standards are sometimes called “white mineral oil” or “white oil” in industry language, a nod to their transparency compared to the amber or dark crude they came from.
What the Finished Oil Actually Contains
At the molecular level, food grade mineral oil is a mixture of two broad families of hydrocarbons. The dominant fraction is mineral oil saturated hydrocarbons, commonly abbreviated MOSH. MOSH includes straight-chain alkanes (imagine a backbone of carbon atoms in a line), branched alkanes (the same backbone with side branches), and cycloalkanes, which are ring-shaped carbon structures often decorated with alkyl side chains.2PubMed Central. Update of the risk assessment of mineral oil hydrocarbons in food The straight-chain portion is relatively small in finished mineral oils because the dewaxing step removes most of those molecules.
The second fraction is mineral oil aromatic hydrocarbons, or MOAH. In a properly refined food grade oil, MOAH should be present only in trace amounts or not at all. MOAH is the fraction that raises health concerns because it can include polycyclic aromatic compounds, some of which are genotoxic.3PubMed Central. Evaluation of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in pure mineral hydrocarbon-based cosmetics and cosmetic raw materials using (1)H NMR spectroscopy The entire point of the intensive refining described above is to drive MOAH levels down. A typical food grade white mineral oil has had its aromatics content reduced to levels well below what crude petroleum or even technical grade oils contain, though “below” does not always mean “zero.”
The carbon chain lengths in food grade mineral oil generally range from roughly C15 to C40 or so, meaning each molecule contains between about 15 and 40 carbon atoms. This range influences the oil’s viscosity, density, and how the body handles it. Shorter chains tend to be thinner and more easily absorbed; longer chains are thicker and pass through the gut more readily without being taken up. One USP grade white mineral oil characterized in a refining study had a density of about 0.87 grams per cubic centimeter and a viscosity of roughly 30 centipoise at 40°C, with a boiling range spanning from around 188°C at the lighter end up to about 378°C for the heaviest fraction.4Chemical Engineering Research and Design. Extraction/adsorption as applied to the dearomatization of white mineral oil These properties place it squarely in the light-to-medium lubricating oil range.
Where Food Grade Mineral Oil Shows Up in Your Diet
If you have eaten commercially baked bread, a piece of candy with a shiny shell, or an apple with a waxy sheen from the grocery store, you have almost certainly consumed food grade mineral oil. White mineral oils are used as release agents on baking pans, as anti-dust coatings on stored grain, as glazing agents on confectionery, and as protective coatings on fruits and vegetables to slow moisture loss. A U.S. dietary exposure estimate found that the average person’s intake from all mineral hydrocarbon sources combined was roughly 0.9 milligrams per kilogram of body weight per day, with about half of that coming from white mineral oil used in baking and food coatings and most of the rest from petrolatum (a semisolid relative) used as trough grease in bakeries.5Food and Chemical Toxicology. Dietary exposures to mineral hydrocarbons from food-use applications in the United States
Beyond food manufacturing, food grade mineral oil is also sold directly to consumers. It is the standard recommendation for conditioning wooden cutting boards and butcher blocks because it does not go rancid the way plant oils do. It shows up as a laxative in pharmacies, typically labeled as “liquid paraffin” or “mineral oil USP.” And it is widely used in cosmetics and pharmaceutical products, meaning your total exposure goes beyond what you eat.
Why the Aromatic Fraction Matters So Much
The entire regulatory and refining apparatus around food grade mineral oil exists because of what the oil might still contain, not because of what it is mostly made of. The saturated hydrocarbon fraction, MOSH, is considered far less concerning than MOAH. MOSH can accumulate in body tissues over time, particularly in the liver, spleen, and lymph nodes, but the evidence linking MOSH itself to disease in humans is weak. MOAH is a different story. Aromatic hydrocarbons with multiple fused rings have well-established genotoxic and carcinogenic potential, and even trace amounts in food are treated seriously by European food safety authorities.
This is why testing for MOAH contamination in food products has become a significant analytical challenge. A standardized method for detecting both MOSH and MOAH in vegetable oils and other foods has been developed and adopted by the German Society of Fat Sciences, designed to reliably detect these contaminants at levels below 10 milligrams per kilogram.6PubMed. Determining MOSH and MOAH with High Sensitivity in Vegetable Oil─A New, Reliable, and Comparable Approach Using Online LC-GC-FID─Evaluation of Method Precision Data Contamination can come not just from deliberate mineral oil use but also from recycled cardboard packaging, printing inks, lubricants used in food processing equipment, and environmental sources. So even foods that do not intentionally contain mineral oil can end up with detectable MOSH and MOAH levels.
Does “Food Grade” Guarantee Safety?
Regulatory bodies classify mineral oils into tiers. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) uses a system of Class I, II, and III, based on viscosity and the degree of refining. Class I oils are the most refined, with the highest viscosity and the lowest aromatic content. These are the ones typically labeled food grade. The assumption behind this classification is that higher refining and higher viscosity translate to lower absorption, lower tissue accumulation, and therefore lower risk.
That assumption has been challenged. A study measuring mineral oil saturated hydrocarbons in human tissues, including liver, spleen, fat, and lymph nodes, found that the composition of accumulated MOSH did not support the idea that Class I oils accumulate less than Class II or III oils.7Food and Chemical Toxicology. Mineral oil in human tissues, Part I: concentrations and molecular mass distributions In other words, the neat regulatory categories may not reflect what actually happens inside the body. This finding does not mean food grade mineral oil is dangerous, but it does mean the label “food grade” carries less biological meaning than most consumers assume. The classification tells you about refining quality and intended use; it does not guarantee that the oil passes through you without leaving a trace.
A comprehensive review of highly refined mineral oils used in food, cosmetics, and medicine noted that the long history of widespread consumer use without clinical or epidemiological evidence of harm provides a degree of indirect safety documentation.8Critical Reviews in Toxicology. Mineral oil in food, cosmetic products, and in products regulated by other legislations That is a real argument, but it is also a weaker kind of evidence than, say, a long-term randomized trial showing no adverse effects. It essentially says: millions of people have been eating and applying this stuff for decades, and we have not seen an epidemic of disease clearly linked to it. Whether that is reassuring or merely reflects a gap in monitoring depends on your risk tolerance.
Synthetic Alternatives to Petroleum-Derived Mineral Oil
Partly because of the MOAH concern and partly because of broader interest in moving away from petroleum, researchers have explored synthetic alternatives. One approach is gas-to-liquid (GTL) technology, which converts natural gas into liquid hydrocarbons. The resulting oils are composed almost entirely of branched alkanes, without the cycloalkane (naphthenic) structures that dominate conventional mineral oil. In a 90-day feeding study in rats comparing a GTL oil made up of about 99% branched alkanes to a naphthenic mineral oil made up of about 84% cycloalkanes, the GTL oil resulted in lower tissue accumulation and faster excretion at the same dose.9PubMed. GTL synthetic paraffin oil shows low liver and tissue retention compared to mineral oil The retained fractions in the liver were also qualitatively different, suggesting the body handles GTL hydrocarbons differently than conventional MOSH.
These synthetic oils are not yet widely used in food applications, but they highlight something important about what food grade mineral oil is “made of” at a deeper level. The health profile of the oil is not just about being “hydrocarbon” or “petroleum-derived.” It depends heavily on the specific molecular shapes in the mixture. Branched chains behave differently from rings. Short chains behave differently from long ones. The blanket category of “mineral oil” lumps together substances that the body treats quite differently.
How Food Grade Mineral Oil Differs from Cooking Oils
People sometimes wonder why food grade mineral oil is used at all when plant-based oils like olive, coconut, or canola are readily available. The answer comes down to chemistry and shelf life. Plant oils are triglycerides, meaning they consist of glycerol molecules bonded to fatty acid chains. Those fatty acid chains contain double bonds (in unsaturated fats) that are vulnerable to oxidation. Oxidation is what makes cooking oil go rancid, producing off flavors and potentially harmful breakdown products.
Mineral oil, by contrast, is fully saturated. It has no double bonds to attack, so it resists oxidation far better than most plant oils. In a direct comparison of oxidative stability, a mineral oil sample showed an induction period of about 44 minutes under accelerated oxidation conditions, compared to roughly 22 minutes for castor oil.10Industrial Crops and Products. Assessment of biodegradability and oxidation stability of mineral, vegetable and synthetic oil samples That roughly double resistance to oxidation explains why mineral oil is preferred for applications where the oil will sit on a surface for a long time, like a cutting board or a food conveyor belt. A plant oil in the same situation would oxidize, grow sticky, and eventually smell terrible.
The flip side of this stability is that mineral oil provides zero nutritional value. Plant oils deliver calories and essential fatty acids. Mineral oil passes through the digestive tract largely undigested, which is exactly why it works as a laxative but also why it should not be confused with a cooking fat. You would never fry food in mineral oil or dress a salad with it. Its role in the food system is functional, not nutritional.
What Happens When It Reaches the Environment
The same chemical stability that makes food grade mineral oil useful in the kitchen makes it persistent in the environment. Biodegradability testing of mineral base oils has shown that none of the tested samples met the threshold for being classified as readily biodegradable under OECD standards. Ultimate biodegradation values stayed below 45%, well short of the 60% pass criterion that would indicate rapid and extensive breakdown in the environment within 28 days.11International Biodeterioration & Biodegradation. Primary and ultimate biodegradabilities of mineral base oils and their relationships with oil viscosity
For food grade mineral oil used in tiny amounts on cutting boards or baked goods, this persistence is unlikely to matter at a meaningful environmental scale. But in industrial food processing, where mineral oil lubricants are used on machinery and can enter wastewater streams in larger quantities, the slow breakdown rate is worth noting. It is another reason researchers are interested in alternatives, whether plant-derived, synthetic, or otherwise.
Common Misconceptions About the Ingredients
One widespread misunderstanding is that food grade mineral oil is somehow chemically different from the mineral oil in industrial lubricants. It is not. The base molecules are the same hydrocarbons. The difference is entirely about purity. Food grade oil has been refined more aggressively to remove aromatics, sulfur compounds, and other contaminants. Calling it “food grade” does not change what it is made of; it describes how thoroughly the problematic components have been removed.
Another misconception runs in the opposite direction: that because food grade mineral oil comes from petroleum, it must be toxic or unnatural in a way that makes it inherently dangerous to consume. Petroleum itself is a natural substance, a product of ancient organic matter transformed by heat and pressure over millions of years. The hydrocarbons in mineral oil are not synthetic chemicals invented in a lab. They are naturally occurring molecules isolated and purified from a complex natural mixture. That does not automatically make them safe, but the “petroleum equals poison” framing misses the point. The safety question is always about specific molecules at specific doses, not about the origin of the raw material.
A third misconception is that “mineral oil” and “baby oil” are completely different products. Baby oil is typically mineral oil with added fragrance. The base is the same highly refined petroleum hydrocarbon mixture. The food grade, pharmaceutical grade, and cosmetic grade designations overlap heavily, and in many cases the same refined oil meets the specifications for all three. The labeling differences reflect intended use and regulatory jurisdiction more than meaningful chemical distinctions.
Choosing and Using Food Grade Mineral Oil at Home
If you are buying food grade mineral oil for kitchen use, look for products labeled “USP grade” or “food grade.” These designations mean the oil meets the purity specifications of the United States Pharmacopeia, which sets limits on aromatic hydrocarbon content, heavy metals, and other contaminants. Products marketed specifically for cutting board care almost always meet this standard, though checking the label is still worthwhile.
For cutting board maintenance, a thin application rubbed into the wood and allowed to soak in for several hours or overnight is the standard approach. The oil fills the pores of the wood, reducing moisture absorption and helping prevent cracking and warping. Unlike plant oils, it will not polymerize into a sticky film or go rancid. Reapply when the wood starts looking dry, which for a regularly used board might be monthly.
For anyone using mineral oil as a laxative, the relevant safety consideration is that long-term daily use can interfere with the absorption of fat-soluble vitamins (A, D, E, and K) because the oil can dissolve these vitamins and carry them out of the gut before they are absorbed. Occasional use is generally considered benign, but chronic use as a laxative is not recommended without medical guidance. This is one context where the fact that the oil is “food grade” and inert can create a false sense that unlimited use is harmless.