How Is Lactose-Free Milk Made?

If drinking milk makes you feel gassy and bloated or gives you diarrhea within 30 minutes to two hours, it might be time to switch to a lactose-free milk instead. Lactose-free milk is made by adding enzymes to the milk before you drink it, so your digestive system doesn't have to do the work.

Lactose free milk has the benefits of regular milk without the lactose. Credit: Tetra Images/Tetra images/GettyImages

Although anyone can drink lactose-free milk, since it has the same nutritional profile as regular milk, it's especially helpful for people who are lactose intolerant and have a hard time physically digesting lactose.

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Lactose-free milk is made by either adding a synthetic lactase enzyme to regular milk to break down the milk before you drink it or by completely straining the lactose out of the milk.

What Is Lactose Intolerance?

Lactose is the main sugar that's naturally found in milk and milk products. The sugar is classified as a disaccharide, or a complex sugar, because it's made from two different simple sugars, called glucose and galactose, that are bonded together. Normally, when you consume lactose, an enzyme called lactase, which is made in a part of your intestine called the jejunum, breaks the lactose down into the two simple sugars so your body can properly absorb them.

If you have lactose intolerance, however, your body doesn't produce enough lactase to break down lactose. As a result, the complex sugar moves through your digestive system whole. When it reaches the large intestine, the bacteria that normally live there start to break it down, or ferment it, and it can cause uncomfortable symptoms, like:

  • Bloating
  • Gas
  • Diarrhea
  • Nausea
  • Stomach pain
  • Vomiting

According to the Mayo Clinic, these symptoms usually start between 30 minutes and two hours after ingesting milk or another food or drink that contains lactose.

Cause of Lactose Intolerance

When you're a baby, your diet consists almost exclusively of milk, so your intestine makes large amounts of lactase; however, as you age, this natural production decreases because, from an evolutionary perspective, you don't need as much milk to survive.

According to a report that was published in March 2019 in the Journal of Nutrition and Intermediary Metabolism, approximately 75 percent of adults worldwide are lactose intolerant. Not everyone experiences symptoms though, and some people are more sensitive than others.

Some with lactose intolerance are able to tolerate a bit of regular milk, while others experience severe symptoms with exposure to even a small amount of the sugar. If you fall into the latter camp, you may benefit from lactose-free milk.

Lactose Intolerance or Milk Allergy?

Lactose intolerance occurs only in your digestive system and, although it can be extremely uncomfortable, especially if you're really sensitive to lactose, it's not really serious or life-threatening. On the other hand, a milk allergy, which is one of the most common allergies, involves an immune response that's triggered when you consume milk, usually due to one of the proteins: casein or whey. If you're allergic to milk, even a little bit of exposure can produce symptoms like:

  • Hives
  • Vomiting
  • Upset stomach
  • Vomiting
  • Shortness of breath
  • Itching
  • Dizziness
  • Increased heart rate
  • Swelling of the throat
  • Anxiety

Read more: 10 Facts You Need to Know About Food Allergies

Lactose-Free Milk Production

If you're allergic to milk, you'll have to avoid milk and milk products completely and indefinitely. If you're lactose intolerant, you can employ the same solution: simply avoid any foods or drinks that include lactose. Food manufacturers, on the other hand, wanted to find a different way for consumers to deal with such problems. In an effort to make milk that even people with lactose intolerance could drink, food manufacturers introduced lactose-free milk.

Most lactose-free milk is made by adding a synthetic, or man-made, version of the enzyme lactase to regular milk. The enzyme breaks down the lactose into glucose and galactose in the milk before you consume it so the lactose doesn't cause a problem once it's in your digestive system. According to the Innovation Center for U.S. Dairy, other food manufacturers just filter the lactose out.

Other Lactose-Free Milk Differences

Although lactose-free milk that has lactase added to it is nutritionally equivalent to regular milk in terms of vitamin D, B vitamins, calcium and protein content, it usually tastes sweeter since the sugars in it have already been broken down.

Lactose-free milk also tends to have a longer shelf-life than regular milk because lactose is responsible for most of milk's spoilage. According to Yale Scientific, spoiling occurs when lactose starts to break down and produces lactic acid as a result. The lactic acid imparts the sour taste of spoiled milk and is also responsible for the curdling you see when milk is way past its expiration date.

Read more: Which Type of Milk (or Nondairy Milk) Is Best? The PROs and CONs of 9 Different Kinds

Other Milk Alternatives

If you're having trouble digesting milk, but you still want to reap the nutritional benefits of dairy products, you can opt for lower lactose choices instead. One cup of conventional milk contains around 12 to 13 grams of lactose, but other dairy products, especially fermented ones, are lower in the sugar.

For example, the same size cup of half-and-half or light cream contains only 0.4 grams of lactose, while a cup of cottage cheese contains 6 grams. An ounce of cheese contains between zero and 2 grams of lactose and a cup of yogurt contains approximately 6 to 13 grams. However, it's important to note that yogurt containing probiotics, also called cultured yogurt, is usually better tolerated than milk because the probiotics help you digest the milk sugars.

If you can't digest lactose at all, even from the lower lactose choices, you'll have to avoid it completely. In addition to milk, yogurt, cheese and ice cream, lactose is also found in many processed foods. Unfortunately, the sugar isn't always listed as "lactose," so you'll have to read your labels carefully and look out for things like:

  • Buttermilk
  • Nonfat milk powder
  • Whey
  • Curds
  • Cheese flavor
  • Malted milk
  • Sweet cream
  • Sour cream
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