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  • Q&A with Australian Health Practitioners

    What causes lactose intolerance?

  • Find a professional to answer your question

  • Rebecca Charlotte Reynolds, PhD (Dr Bec) Personable and ethical registered nutritionist (RNutr) and lecturer at UNSW Australia in lifestyle and health. Regular consultant to the … View Profile

    Hi there,
    “True” lactose intolerance is caused when the small intestine doesn't make enough of an enzyme called lactase (which digests the sugar lactose).
    Great info. here:
    Dr B :)

  • Denise Burbidge

    Dietitian, Nutritionist

    Denise is an Accredited Practising Dietitian working in private practice in Melbourne, and consulting to aged care facilities throughout Victoria. Denise has a particular interest … View Profile

    Lactose intolerance occurs when the body does not produce sufficient amounts of the enzyme lactase that is required to ‘break down’ or digest the lactose sugars that are commonly found in dairy foods such as milk, yoghurt, custard and ice-cream. Without the lactase enzyme the lactose sugars avoid being absorbed into the body in the small intesting and pass through into the large bowel undigested. Once in the large bowl the lactose sugars are then fermented resutling in symptoms including bloating, flatulance and/or altered bowel habits.
    Treatment for lactose intolernace includes limiting lactose foods consumed and substituting for lactose free alternatives or ‘pre-digesting’ foods such as milk with lactase enzymes available from pharmacies.

    A dietitian can help in recommending a suitable low lactose diet to maximise symptom management.

    Denise Burbidge, DIETITIAN

  • Chris Fonda

    Dietitian, Nutritionist, Sports Dietitian

    As an Accredited Sports Dietitian, APD and athlete (springboard diver), Chris has both professional and personal experience in sport at the sub-elite and elite level.Chris … View Profile

    As my fellow colleagues have mentioned above, lactose intolerance is caused by a deficiency or lack of the enzyme “lactase” which breaks down the sugar “lactose” found in milk and dairy products such as yoghurt, ice-cream, custard and cheese.

    Another cause of lactose intolerance and is often called “secondary lactose intolerance” occurs when there is a lack of lactase due to a disease such as undiagnosed coeliac disease. Once the coeliac disease has been managed through a strict gluten-free diet, this secondary lactose intolerance generally disappears as the enzyme lactase is able to regenerate itself enabling the person to consume milk and dairy products again.

    In general those with lactose intolerance can often handle a very small amount of lactose containing foods (e.g. a small glass of milk over the day) without any uncomfortable side effects such as bloating, gas and diarrhoea. There are also enzyme solutions of lactase that can be added to milk overnight to allow the enzyme to break down the lactose before consumption. There is now lactase tablets which can taken just prior to consuming dairy which can help to digest the sugar lactose.

    If you suspect you have an intolerance to any type of food I would highly recommend a visit to an Accredited Practising Dietitian (APD) to make sure your not missing out on important nutrients such as calcium. To find an APD head to the Dietitians Association of Australia's website: and click on “find and APD”

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