Lacto

Lacto is a prefix derived from the Latin lact- meaning milk. It is widely used in science, nutrition, and food science to indicate a relationship to milk or milk-derived substances. In many terms, lacto- forms part of a larger word rather than standing alone.

In biochemistry and food chemistry, the lacto- prefix appears in words such as lactose, the milk sugar; lactase, the enzyme that digests lactose; and lactalbumin, a milk protein component. Other related terms include lactoglobulin and lactoprotein. The prefix helps distinguish dairy-related compounds from non-dairy counterparts.

In nutrition, lacto- is also used to describe lacto-vegetarian diets, where dairy products are consumed but eggs and meat are excluded. The term is typically hyphenated (lacto-vegetarian) in dietary literature.

In microbiology and fermentation, lacto- is associated with lactic acid bacteria, notably species within Lactobacillus and Lactococcus. These bacteria ferment sugars to lactic acid and are central to yogurt, cheese, and other fermented foods. The descriptor 'lacto-' appears in phrases such as lacto-fermentation to indicate this process.

Because 'lacto' is a prefix rather than a standalone term, its precise meaning depends on context. When encountered without context, it generally signals a link to milk, dairy products, or lactic acid bacteria.