All about lactose intolerance

Dairy-free milk alternatives are flying off the shelves in record numbers, and for good reason: About 30 million adults develop some degree of lactose intolerance by age 20. While the condition isn’t dangerous, it can cause some discomfort.

While the symptoms are similar, lactose intolerance isn’t the same as a dairy allergy. A dairy allergy is an immune response to milk protein, while lactose intolerance occurs when you have a deficiency in an enzyme called lactase. The small intestine produces lactase to break down milk sugar (lactose) into simple sugars which are then absorbed in the bloodstream. Insufficient lactase levels can cause symptoms of lactose intolerance.

Signs and symptoms of lactose intolerance usually begin within 30 minutes to two hours after eating or drinking foods containing lactose (milk, yogurt, cheese, etc.). Symptoms include:

• Nausea
• Vomiting
• Abdominal cramps
• Bloating
• Gas
• Diarrhea

Symptoms are usually mild, but can sometimes be severe. Consistently experiencing symptoms after eating or drinking dairy products may be a sign that you are lactose intolerant. But if you experience occasional bouts of discomfort following dairy consumption, it doesn’t necessarily mean that you’re lactose intolerant.

When there is a low level of lactase in the small intestine, the lactose in food moves into the colon unprocessed and interacts with intestinal bacteria, leading to symptoms of lactose intolerance.

Lactase production can decline over time due to normal aging. The body typically produces large amounts of lactase at birth and during early childhood when milk is the main source of nutrition. But as our diets become more varied over time, lactase production usually decreases. Rarely, some people are born with an insufficient level of lactase. It’s also possible, but uncommon, to develop lactose intolerance as a result of illness or injury.

An elimination diet is the preferred method for confirming lactose intolerance. An elimination diet involves removing dairy from your diet for three weeks, and then reintroducing it for up to 72 hours. If you begin having symptoms within that three-day reintroduction period, you may be lactose intolerant.

There is also a hydrogen breath test that can confirm diagnosis. If your provider orders this test, you will be asked to drink a liquid containing high levels of lactose, while he or she measures hydrogen levels in your breath. If your body doesn’t process lactose normally, it will ferment in your colon and release higher-than-normal hydrogen levels, which may indicate lactose intolerance.

While there is no cure for lactose intolerance, reducing or eliminating the amount of dairy products in your diet can cut down on symptoms. But because dairy is a major dietary source of calcium, if you choose to eliminate it altogether, consider adding other calcium-rich foods like broccoli, spinach, or canned salmon to your diet.

If you eliminate dairy, it’s also important to get adequate amounts of vitamin D from foods like eggs or liver. Sun exposure also triggers vitamin D production, but this this doesn’t occur in the presence of sunscreen. Many non-dairy alternative milks are fortified with calcium and vitamin D. Talk to your health care provider if you’d like suggestions regarding meal planning or calcium or vitamin D supplements.

Some people with lactose intolerance can actually tolerate low-fat milk products, and can gradually increase their tolerance to dairy by slowly introducing new foods. Additionally, hard cheeses like cheddar or Swiss contain smaller amounts of lactose, and may not cause symptoms in people with lactose intolerance. However, many processed foods– including cereals, instant soups, and salad dressings–contain milk and lactose, so if you’re experiencing symptoms of lactose intolerance, be sure to read nutrition labels carefully before purchasing these products.

Some people with lactose intolerance are able to relieve symptoms by taking tablets or drops containing lactase, like Dairy Ease or Lactaid, just before meals and snacks, but these products aren’t guaranteed to be effective. Some studies suggest that specific strains of probiotics (organisms that reduce the amount of harmful bacteria in the digestive system) may also help alleviate symptoms, but further research is necessary.