Lactaid’s active ingredient is lactase, a digestive enzyme that breaks down lactose, the sugar in milk. The enzyme is produced through fungal fermentation and then combined with a handful of inactive ingredients that hold the tablet together or add flavor. That’s the short answer, but the details of each component, how the enzyme works, and how it’s made are worth understanding.
The Active Ingredient: Lactase Enzyme
Lactase is a protein that splits lactose into two simpler sugars your body can absorb: glucose and galactose. Your small intestine naturally produces lactase, but people with lactose intolerance don’t make enough of it. Taking supplemental lactase before eating dairy fills that gap temporarily.
Lactaid measures its enzyme content in FCC (Food Chemical Codex) units, which reflect the enzyme’s actual digestive power rather than its weight. Lactaid Original contains 3,000 FCC units per tablet. Lactaid Fast Act, in both caplet and chewable form, contains 9,000 FCC units per tablet, three times the strength. The higher the unit count, the more lactose the tablet can break down in your digestive tract.
Inactive Ingredients by Formulation
The inactive ingredients differ depending on whether you’re taking a caplet or a chewable.
Lactaid Fast Act caplets contain five inactive ingredients:
- Microcrystalline cellulose: a plant-derived fiber that acts as the tablet’s main filler, giving it bulk and shape
- Croscarmellose sodium: helps the tablet break apart quickly once it reaches your stomach
- Crospovidone: another disintegrant that speeds up how fast the tablet dissolves
- Magnesium stearate: a lubricant that prevents the powder from sticking to manufacturing equipment
- Colloidal silicon dioxide: keeps the powder flowing smoothly during production and prevents clumping
Lactaid Fast Act chewables have a simpler ingredient list designed around taste and texture. They contain mannitol (a sugar alcohol that provides sweetness and a smooth chewable texture), natural and artificial flavor, and sucralose (an artificial sweetener). The chewable formulation skips most of the binders and disintegrants since chewing does the work of breaking the tablet apart.
How the Enzyme Is Produced
The lactase in Lactaid doesn’t come from animal intestines. It’s produced through fermentation using microorganisms, primarily fungi and yeasts. The FDA has recognized lactase preparations from specific yeast and fungal strains as generally recognized as safe (GRAS) for food use, including strains of Kluyveromyces lactis (a yeast historically used in dairy processing) and Candida pseudotropicalis.
Industrial production typically uses submerged fermentation, where the microorganism grows in a liquid nutrient broth inside controlled tanks. The organism feeds on sugars and other nutrients while secreting lactase into the surrounding liquid. Researchers have found that optimal production occurs at around 30°C with a slightly acidic pH of about 5, over roughly six days of incubation. After fermentation, the enzyme is separated from the growth medium, purified, and concentrated before being formulated into tablets.
How It Works in Your Body
Lactase belongs to a family of enzymes called glycoside hydrolases. When lactose reaches your small intestine, the enzyme latches onto the lactose molecule and uses water to snap the bond between its two component sugars. This reaction, called hydrolysis, produces one molecule of glucose and one of galactose, both of which pass easily through your intestinal wall into the bloodstream.
Without enough lactase, undigested lactose travels further down the digestive tract, where gut bacteria ferment it and produce gas, bloating, and diarrhea. Supplemental lactase intercepts the lactose before that happens, which is why timing matters. Taking a Lactaid tablet with your first bite of dairy, or just before eating, gives the enzyme the best chance to work alongside your meal.
Allergen and Dietary Considerations
Lactaid supplement tablets (both caplets and chewables) do not contain gluten. Some Lactaid dairy products like certain ice cream flavors do contain gluten due to mix-in ingredients, but the enzyme supplements themselves are gluten-free.
Because the enzyme is derived from fungal or yeast fermentation, people with severe mold allergies occasionally wonder whether it could trigger a reaction. The purification process removes most biological material from the fermentation organism, and widespread adverse reactions have not been reported. That said, the product labeling does not specifically address mold sensitivity.
One important distinction: Lactaid helps with lactose intolerance, not milk allergy. Lactose intolerance is a digestive issue caused by insufficient enzyme production. A milk allergy is an immune response to the proteins in milk, and no amount of lactase will prevent that reaction. If dairy causes hives, swelling, or breathing difficulty rather than gas and bloating, the problem is likely protein-related, not lactose-related.
Regulatory Classification
Lactaid is sold as a dietary supplement, not a prescription drug. The FDA classifies lactase enzyme preparations as GRAS for food use, meaning they’ve been evaluated and deemed safe under normal conditions. As a supplement, Lactaid doesn’t go through the same pre-market approval process as pharmaceuticals, but it must follow current good manufacturing practices and accurate labeling standards set by the FDA.