Lactose is a carbohydrate sugar found in dairy products, which is digested, in the small bowel by the enzyme lactase. Acquired lactose intolerance occurs in most non-milk drinking populations and develops in late childhood. The prevalence of lactose intolerance is ethnically based:
Secondary lactose intolerance can occur after small bowel mucosal damage following gastroenteritis and Coeliac disease.
Tolerance of milk products is very variable in lactase deficient people; many can still consume 10-14g lactose (200 ml of milk) spread through the day.
How is lactase deficiency diagnosed?
In practice, a trial of withdrawal of milk and milk products can be instituted for 2 weeks, if problems resolve then a presumptive diagnosis can be made.
Lactase deficiency is diagnosed by a biopsy from the small bowel during endoscopy, which can measure the lactase level; this can also test for Coeliac disease.
What changes should you make in your diet?
Lactose free milk or Soy milk can be substituted during a trial of lactose withdrawal for 2 weeks, if symptoms improve, lactose can be added back to the diet to see how much can be tolerated. As noted above, most lactase deficient people can have (8-10gm lactose) 200 ml milk spread through a day.
Why shouldn’t you give up dairy foods?
Dairy foods are an important source of vitamins and minerals you need for good health. You can continue to enjoy them by making some simple changes in your diet. As you can see from the table, many dairy foods have little or no lactose, so they will not cause your symptoms. Here are some general principles to keep in mind when selecting food.
Choose full cream milk instead of low fat or skim milk. Fat slows the passage of lactose through your digestive system, giving your body more time to digest it.
Most cheeses have virtually no lactose, so you can continue to enjoy them.
In small servings of 1 tablespoon or so, butter and cream have very little lactose and can probably be enjoyed without causing symptoms.
Ask your pharmacist about lactase products that may help you enjoy dairy foods without causing symptoms
In some Australian states, long-life low lactose milks are available in supermarkets.
After your symptoms have stopped for a while, you may be able to increase your lactose without further problems. Many people find that they become more tolerant of lactose with time.
Remember to include the milk in your coffee if you have flat white or latte.
Yoghurt actually loses lactose while it sits in your fridge. Keeping it for a while before you eat it may reduce the chance that it could cause symptoms.