What is going on
This one surprises people because the sugar itself contains no animal matter. Some cane-sugar refineries pass the syrup through bone char, a filter made from charred cattle bones, to strip colour and produce a bright white product. The char never enters the sugar, but an animal product is used to make it, which is why strict vegans treat bone-char-refined sugar as non-vegan.
Why it depends
The practice is far from universal, so the answer really is it depends. Beet sugar is not processed this way, organic cane sugar generally avoids bone char, and a growing number of brands are certified vegan or state their process. Raw and unrefined cane sugars skip the whitening step too. If a recipe just calls for sugar and this matters to you, beet or a labelled vegan sugar is the simple safe choice.
How it works
Bone char, also called bone black, is made by heating cattle bones to around 700C in low-oxygen kilns until they carbonise into a hard, porous granular material much like activated carbon. Refineries pack it into tall columns and run raw cane sugar liquor through the bed. The char adsorbs plant pigments, trace minerals and coloured impurities, turning the brownish liquor pale before it crystallises. It is reactivated by reburning and reused for months, then discarded.
No bone particles reach the packet. The char is a filter medium, separated out entirely before crystallisation, and char-filtered sugar is chemically identical to any other sucrose. The objection is about process rather than content: refining this way creates industrial demand for slaughterhouse bone, so the purchase helps fund that supply chain even though nothing survives into the bag. That is enough to fail most vegan standards, including the Vegan Society’s, which excludes a product whose manufacture involved an animal byproduct whether or not traces remain.
Which sugar, exactly
Only cane sugar ever meets bone char. Beet sugar refining has no equivalent decolorising filtration step, so beet sugar is reliably free of it whatever the brand. Within cane, practice varies plant by plant rather than company by company: the Vegetarian Resource Group’s refinery reporting found the same corporate group running some refineries without bone char and others with it. Treat any brand claim as a snapshot; refineries change equipment, and no regulator requires anyone to announce it when they do.
How to tell
The reliable shortcut in the US is certification. Bone char is not on the National List of substances organic processors may use, so USDA Certified Organic cane sugar cannot legally have been filtered through it. Beet sugar, turbinado, demerara and muscovado skip heavy decolorising anyway. In the UK and EU most table sugar is beet by default, and cane sugar carrying a Vegan Trademark has been checked for animal-derived processing aids. Brown sugar is usually refined white sugar with molasses added back, so it inherits whatever the white sugar did.
What the rules say
The FDA treats bone char as a processing aid rather than an additive: it is fully removed before packaging and has no function in the finished product, so it never has to appear on an ingredient list. That is precisely why the practice is invisible on a US label and why a shopper cannot read their way to an answer. No comparable mandatory disclosure exists for conventional sugar in the US or, generally, the EU.