What does the (D) on some food lables stand for?
May contain Dairy products?
There are a number of hechshers or kosher certification organizations. The primary one in the U.S. is the The Union of Orthodox Jewish Congregations, usually abbreviated OU, but there are many others worldwide.
Each not only puts its symbol on foods it has certified kosher, but may also add other identifying letters or words for additional clarity or informational value. Marketing pressures have made these correspond to one another, but some variations still exist.
Kosher diners must separate meat and dairy at meals. Foods that contain meat are normally readily apparent, but foods that contain dairy are sometimes harder to discern. A symbol is therefore used to alert potential customers to the presence of dairy.
The (D) symbol may mean one of two things, depending on the hechsher. It could indicate the actual presence of dairy products in the ingredients or it could merely mean that the food was processed on equipment that at other times had been used for foods that did contain dairy, even though this particular food does not. This occurs because even though there is a process of high temperature washing and scrubbing that returns the line to acceptance, its expense and the time required for the changeover makes it uneconomical. Only a very few companies take these measures regularly.
Either way, the food is prohibited from being used with meat. While identifying whether an actual milk product is used is easy enough from the mandatory ingredients list, the processing line aspect creates a potential for great confusion for other groups who rely on the symbol, such as those who are lactose intolerant, milk allergic, or vegans. Those who are LI are safe with foods processed on dairy equipment lines. because any tiny amount of lactose is too small to notice. Those with milk allergies may or may not display symptoms depending on the severity of the allergy. Vegans have to make an individual moral determination each time.
At one point there was a push on to use a separate (DE) or dairy equipment symbol to at least assure that the product did not contain a milk-based ingredient, but I guess it didn’t really answer the needed questions and I haven’t seen it very often lately.
The way to be assured that no dairy at all is involved is the word parve (sometimes spelled pareve) which means neutral, neither milk nor meat. Many foods use this word even if they don’t have kosher certification. There are technical reasons why tiny amounts of milk can still be present at times even in a food marked parve, but unless you are at risk from death from anaphylactic shock from the tiniest amount of milk protein, parve is the best assurance of milk-freeness.