Lactose (milk sugar) is the sugar compound that is found in milk and milk products. It is a double sugar (disaccharide), composed of the simple sugars D-galactose and D-glucose. Besides fruit sugar (fructose), lactose is the most common trigger for malabsorption (disorder of lactose intake).
The enzyme lactase normally splits the double sugar and allows it to be absorbed through the intestinal wall. If there’s a lack of lactase and this does not succeed, stomach aches, feeling of fullness, bloating, and diarrhea can occur after eating dairy products. A low-lactose diet helps to improve symptoms.
Am I lactose intolerant?
Do you often suffer from abdominal pain and digestive problems after drinking milk, or eating yogurt, curd, cheese, cream, or ice cream? Then you may suffer from lactose intolerance. To be sure, you should do a hydrogen breath test with your doctor. This quickly determines whether your body is actually having difficulty splitting and absorbing milk sugar.
What types of lactose intolerance are there?
An intolerance to lactose arises from a lactase deficiency (beta-galactosidase deficiency). There are two types of lactase deficiency:
Primary lactase deficiency
- Hereditary lactase deficiency (rare)
- Physiological lactase deficiency: Decrease in lactase activity as we age
Secondary (acquired) lactase deficiency
- Caused by another disease (e.g. lactase deficiency in celiac disease [regenerable])
Did you know?
Lactose comes from the Latin word lac, which means milk.
How much lactose can I tolerate?
If the diagnosis of lactose intolerance is established, a low-lactose diet is recommended. Depending on how much lactase is still active in your gut, you tolerate a certain amount of lactose well. The best way to find your individual tolerance limit is an omission diet with a food and symptom diary. Since individual lactose tolerance is so different, the following can serve as a guide:
|Suitable for||Type of food||Amount of lactose|
|Free of symptoms for the majority of those affected||Lactose||8-10 grams of lactose a day|
|Very sensitive people||Strictly low in lactose||Fewer than 1 gram of lactose per day|
How do I eat lactose-free?
Most foods are naturally lactose-free. These include:
- All types of vegetables and fruits
- Cereals and rice
- Legumes (e.g. soy)
You can consume these foods to your heart's content, but be careful with industrially manufactured foods such as sausages, baked goods, and sauces as lactose is often hidden, here. A look at the list of ingredients is thus important in the supermarket. To assess the lactose content of foods, foods contain the following declarations:
- Low in lactose: less than one gram lactose per 100 grams or milliliters
- Strictly low in lactose: less than 100 milligrams lactose per 100 grams or milliliters
- Lactose free: less than ten milligrams Lactose per 100 grams or milliliters
How much lactose do foods contain?
All milk products contain lactose. The only exception is cheese: There are some varieties that contain hardly any lactose due to the ripening process. These are also digestible for people with lactose intolerance. Since lactose intolerance only reduces lactase, but it is not entirely absent, you may tolerate small amounts of lactose.
- Vegan products do not contain lactose
- Dark chocolate (> 75 percent cocoa) generally contains no milk
- Sorbet is milk-free—and low in calories
- Soy, rice, almond, or oat drinks are delicious and of course lactose-free
The table below shows average lactose values for various milk products. If you’re not very sensitive, you can try out whether you can tolerate 10 grams of lactose per day. If you develop symptoms, do without lactose-containing products for at least 2 days or until the symptoms have subsided. Then you can try out whether you can tolerate a smaller amount (half portion) better.
|Milk and dairy products||Lactose content
(in grams per 100 g of milk product)
|Suitable for a low-lactose diet?
Skimmed milk powder
|Condensed milk (7.5% fat)
Condensed milk (10 % fat)
(Cow, sheep, buffalo, camel, goat milk, whey)
(Chocolate, mocha, vanilla, strawberry etc.)
|Buttermilk||4.0||Yes (200 g)|
|Cream (coffee cream, coffee cream)||4.0||Yes (200 g)|
|Yes (200 g)|
(Chocolate, mocha, muesli, fruits etc.)
|Yes (200 g)|
|Desserts (e.g. creams, pudding, rice pudding, semolina porridge)||2.8–6.3.||Yes|
|Sour cream||3.5||Yes (200 g)|
|Whipped cream||2.7–3.5.||Yes (200 g)|
|Cream cheese preparation 10–70% fat in dry matter||2.0–3.8.||Yes (200 g)|
|Melting cheese 10–70% fat||2.8–6.3.||Yes|
|Cooking cheese 0–45%||3.2–4.0.||Yes (200 g)|
|Sliced cheese (10%)||3.8||Yes (200 g)|
|Cottage cheese||3.3||Yes (200 g)|
|Sliced cheese, layered cheese 40%||3.2||Yes (200 g)|
|Mozzarella||0.1–3.1.||Yes (200 g)|
|Ice cream||1.9||Yes (300 g)|
|Cheese fondue (finished product)||1.8||Yes (300 g)|
|Butter||0.6–0.7.||Yes (800 g)|
|Cheddar cheese, ricotta||< 0.6||Yes|
|Appenzeller, Bel Paese, Brie, Butter cheese, Camembert, Edam,
Emmentaler, Gorgonzola, Gouda, Gruyère, Limburger, Münsterkäse, Parmesan, Provolone, Romadur, Roquefort, Sour milk cheese (Harzer, Mainz, hand cheese), Tilsiter
|< 0.1||Yes, also with strictly low-lactose diet|
Why does lactose-free milk taste sweet?
Lactose is a double sugar that is broken down by the enzyme lactase. In order to produce lactose-free milk, lactase is added to the milk during the production. The enzyme breaks down the double sugar before the milk is consumed by the consumer. Lactose-free milk now contains the two simple sugars glucose (table sugar) and galactose. Since glucose has a higher sweetness than lactose, the milk tastes sweeter.
Hamscher, G. (2015). Positionspapier der Lebensmittelchemischen Gesellschaft erarbeitet von der AG Tierarzneimittelrückstände zum Thema. Lebensmittelchemie, 69(4), 97-99. Downloaded on 10.08.2018 from: https://onlinelibrary.wiley.com/doi/abs/10.1002/lemi.201590037
Hofele, K. (2012). Richtig einkaufen bei Laktose-Intoleranz: für Sie bewertet: über 900 Lebensmittel und Fertigprodukte. Georg Thieme Verlag.
Zimmer, K. P. (2007). Laktose-und Fruktosemalabsorption Malabsorption of lactose and fructose. Monatsschrift Kinderheilkunde, 155(6), 565-576. Downloaded on 10.08.2018 from: https://link.springer.com/article/10.1007%2Fs00112-007-1540-7