This is a condition caused by inability to digest one of the carbohydrate components of milk, specifically lactose, due to a lack of the intestinal enzyme lactase, which is essential for the efficient metabolism of lactose (milk sugar). It can first show itself in the neonatal period with vomiting and profuse diarrhoea after milk ingestion, which resolves when lactose-free fluids are fed to the infant. However, it can also show up later in adulthood.

Most people are born with the ability to produce the lactase enzyme because breast milk, like cow’s milk, contains lactose. The chance of developing lactose intolerance later in life is influenced by a range of factors, including genetic predisposition.

According to, lactose intolerance is relatively common in Australia, particularly among the Aboriginal population with 84 percent of Aboriginal children and adults affected by it, while between up to nine percent of Caucasian children and around 17 percent of Caucasian adults suffer from it.

The causes of lactose intolerance

Some people are born with a lactase deficiency and will manifest symptoms of lactose intolerance (diarrhoea, bloating and pain) from birth. In other individuals, lactose intolerance develops as the person gets older and loses lactase activity.

In some cases, lactase deficiency develops after infections of the digestive tract, or bowel surgery, or in HIV/AIDS, irritable bowel syndrome or Crohn's disease.

Signs and symptoms

Individuals with lactose or milk intolerance may develop some, or all of the following symptoms, while infants and children will fail to thrive and be weak and irritable:

    • Cramps

    • Nausea

    • Bloating

    • Flatulence

    • Diarrhea

If you develop such symptoms between 30 minutes and two hours after eating or drinking milk or foods that contain milk, then it may be a good idea to have your doctor test for lactose and/or milk intolerance. Don’t make this diagnosis on your own, because these symptoms can also be associated with a variety of other conditions, some of which are serious and may need other kinds of medical treatment.


It is usually diagnosed based on symptoms and relief of those symptoms when avoiding dairy products. However, certain tests for lactose intolerance may be used to help confirm the diagnosis. Many doctors will ask patients who suspect they have lactose intolerance to avoid milk and dairy products for one or two weeks to see if their symptoms subside. One of the following tests may be given:

    • Milk challenge test

    • Hydrogen breath test

    • Blood glucose test

    • Stool acidity test

    • Intestinal biopsy

Your doctor will prescribe the most appropriate test for you or your infant as some of these tests are not suitable for infants.

How is it treated?

After diagnosis you can find ways of managing your intolerance. Again, it is recommended you do this together with your dietitian or doctor, as they will help you create a diet that works for you and ensures you get all the nutrients of dairy with as little of the side-effects as possible.

The disorder is readily controlled by a lactose-free diet, or often simply by avoiding milk drinks or taking milk in smaller portions, which a trained dietitian can tell you how to do. A child who lacks the enzyme lactase can absorb fructose. If a lactose-free diet is continued, oral calcium supplements should be taken.

Recently, a number of milk substitutes have appeared on the market which can make the life of lactose or milk intolerant people much easier. Your health expert or a health food store clerk will be able to suggest some of the products specifically formulated for lactose intolerant people. These include:

    • Lactose-reduced milk: is cow’s milk which has had 95 percent of the lactose (milk sugar) removed, but still offers all the other benefits of standard cow’s milk, such as taste, nutrients (high-quality protein, B vitamins, minerals like calcium, phosphorus and magnesium) and convenience.

    • Non-dairy mlik: Almond, soy, rice and oat milk are all widely available in supermarkets and convenience stores.  The consistency and taste of each type of milk substitute is different and a personal preference will come into play.  Watch out for added sugars, oils and other unnecessary ingredients when choosing a milk substitute.

Tips for lactose intolerant people

But if you don’t want to completely shift to non-dairy products, research is increasingly showing that you could manage the amounts of dairy products you consume. Dairy Australia provides these tips to help you include your three serves of dairy every day:

    • Try taking a supplement containing digestive enzymes. Your local pharmacist or nutritionist can recommend one, or you can purchase digestive enzyme supplements from our store.

    • Drink full cream milk with other foods and not on an empty stomach.

    • Spread your milk intake into small servings throughout the day.

    • Try building up your tolerance by introducing small amounts of dairy and then slowly increase the amounts. Check with your doctor first.

    • Full cream milk may be better tolerated than low-fat or skim milk simply because fat slows the passage of lactose through your digestive system.

    • Yogurt is often better tolerated than milk.

    • Cheese is low in lactose and is well tolerated, but also check with your doctor which cheeses are suitable for you.

While these tips come from a reputable source, it is always best to consult a doctor or a dietitian before you attempt making any changes to your diet, especially when managing your lactose intolerance.

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