Lactose
Learn More About Lactose
Lactose is a disaccharide—a carbohydrate that naturally occurs in milk and dairy products. It is composed of the two monosaccharides glucose and galactose. Lactose is broken down in the small intestine by the enzyme lactase, after which the monosaccharides can serve as an energy source for the body.
Common Sources of Lactose
Lactose, also known as “milk sugar,” is found primarily in milk and other dairy products. It can also appear in processed meats, chips, candy, soft drinks, breakfast cereals, certain medications and dietary supplements. Therefore, it is always important to read labels carefully. Lactose may be listed under various names such as milk powder, whey, milk sugar, and milk solids.
In the document “Overview Lactose in Food” you will find an overview of various dairy products and whether they contain high, moderate, or low amounts of lactose. You can download this document from the Educational Materials page.
Milk and Dairy Products
Lactose occurs naturally in the milk of mammals—including cow’s, goat’s, sheep’s, and other species’ milk. Dairy foods such as yogurt, cheese, cream, and ice cream also contain lactose. The exact amount varies with the product and the way it is processed.
- Whole Milk, Semi-Skimmed Milk, Skim Milk, and Buttermilk
- Goat's Milk, Sheep’s Milk, Mare’s Milk (Horse Milk)
- Soft Goat and Sheep Cheeses
- Chocolate Milk, Yogurt Drinks, and Fruit-Based Dairy Beverages
- Processed Cheese, Foreign Cheeses, Fresh Cheese and Cottage Cheese. Cheeses such as Gouda contain no lactose, because the lactose is completely broken down during the aging process.
- Yogurt, Kefir
- Custard, Porridge, Pudding, Mousse
- Whipped Cream, Sour Cream and Crème Fraîche
Fermented dairy products such as yogurt, kefir, and quark usually contain less lactose than regular milk, because the bacteria involved in fermentation partially break down the lactose content. However, even fermented dairy still contains traces of lactose.
Processed Foods- ==
Lactose can also be added as an ingredient in processed products such as baked goods, candy, and soups and sauces. It is sometimes used as a sweetener or filler in processed foods. In these cases, it is often listed on the label as “milk ingredients” or “milk powder.”
- Pastries, Cakes, Muffins, and Cake Mixes
- Many Types of Candy, Especially Milk Chocolate and Sweetened Candies
- Processed Soups (Such as Cream or Dairy-Based Soups) and Sauces
- Dressings and Mayonnaise
- Diet Shakes, Protein Powders, and Meal Replacement Drinks
- Prepackaged Meals
- Ready-to-Use Baking Mixes
- Breakfast Cereals and Muesli
- Processed Meats
- Chips and Snack Foods
Medications and Supplements
Lactose may be added to medications and supplements as a binder or filler.
How Lactose is Digested
Digestion of Lactose
The small intestine is where a large part of digestion takes place, including the digestion of lactose. Most digestive enzymes are produced in the small intestine. For lactose digestion, the body produces an enzyme called lactase. This enzyme breaks the disaccharide lactose down into the simple sugars glucose and galactose. These sugars are then absorbed into the bloodstream and serve as a source of energy for the body.
Lactose Intolerance
When the body does not produce enough lactase—such as in individuals with lactose intolerance—it cannot properly digest the lactose found in food. In this case, lactose is not broken down into simple sugars and passes undigested from the small intestine into the large intestine. There, gut bacteria begin to ferment the lactose. This fermentation process produces gases such as hydrogen, methane, and carbon dioxide, and can also draw water from surrounding tissues.
The fermentation of lactose can lead to a range of symptoms, including bloating, flatulence, and abdominal discomfort.
- Gas Production: During fermentation, gases such as carbon dioxide, hydrogen, and methane are released. When larger amounts of lactose are fermented, these gases can cause the intestines to expand and create discomfort.
- Water Retention: Fermentation may also pull water into the intestines, which can contribute to changes in bowel movements.
- Symptoms: The combination of gas buildup and water retention due to lactose malabsorption can result in symptoms like bloating, excessive gas, and stomach cramps.
It is also possible to take the enzyme Lactase in supplement form alongside a meal that is high in lactose. Lactase can be derived from plant-based sources, such as fungi. The lactase enzyme extracted from these fungi is nearly identical to the lactase naturally produced by the human body, and therefore functions the same way in aiding the digestion of lactose.
Dietary Advice for a Low-Lactose Diet
Avoiding lactose is common during the elimination phase of the low-FODMAP diet, but it can also be followed independently if a sensitivity to this disaccharide is suspected.
Lactose is primarily found in milk and dairy products, which also provide other important nutrients such as calcium, vitamin B12, vitamin D, and protein. When eliminating these products, it’s important to ensure that the individual continues to get enough of these nutrients from alternative sources to maintain a balanced and nutritious diet.
Alternatives to Milk and Dairy
Instead of lactose-rich milk and dairy products, clients can be advised to use lactose-free milk and lactose-free dairy alternatives. These products are typically identical to regular dairy but contain an added liquid form of the lactase enzyme, which breaks down the lactose. Another option is for the client to purchase liquid lactase separately to make dairy products lactose-free at home, or to enjoy regular dairy without symptoms.
There are also plant-based alternatives, such as products made from soy, almonds, or oats. It’s important to check whether these alternatives are fortified with essential nutrients commonly found in animal-based dairy, such as calcium, vitamin D, and vitamin B12. Additionally, it’s a good idea to watch for added sugars, as some plant-based products contain sweeteners to improve taste.
The Monash University FODMAP Diet App
Monash University, the Australian institution that developed the low FODMAP diet, offers a helpful app that can be used by both practitioners and clients. The app allows you to check whether a specific food contains FODMAPs, and if so, in what quantity. It also includes recipes and scientifically backed information to support dietary planning and education.