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  • Q&A with Australian Health Practitioners

    What is the difference between galactosemia and lactose intolerance?

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    Joy Anderson

    Dietitian, Nutritionist

    Joy is an Accredited Practising Dietitian and Accredited Nutritionist, as well as an International Board Certified Lactation Consultant (IBCLC). She has a special interest in … View Profile

    Galactosaemia is an ‘inborn error of metabolism’, that is, a genetic mistake that means that the person cannot convert the sugar, galactose into anything else and it accumulates in the body, causing problems. Galactose is produced in the intestine and absorbed when lactose is digested - lactose consists of glucose and galactose joined together and when digested by lactase (the enzyme), is split apart into these two smaller sugars. Galactosaemia is a serious lifelong condition.

    Lactose intolerance is lack of the digestive enzyme, lactase, and the inability to split the lactose molecule into glucose and galactose, so it cannot be absorbed. Lactose continues through to the large intestine and is either broken down by bacterial flora or excreted unchanged. Lactose intolerance in adults is a normal human condition for 70% of the world's people. See other questions about lactose intolerance for more details.

  • 43


    Specializing in weight reduction, diabetes and cholesterol management, high blood pressure, GIT disorders - including IBS, coeliac disease, food intolerance and food chemical sensitivity, childhood … View Profile

    Galactosemia (British Galactosaemia) is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly. Although the sugar, lactose, metabolizes to galactose, galactosemia is not related to and should not be confused with lactose intolerance. Galactosemia follows an autosomal recessive. mode of inheritance that confers a deficiency in an enzyme responsible for adequate galactose degradation.

    Lactose in food (such as dairy products) is broken down by the enzyme lactase into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues as in the case of classic galactosemia, resulting in hepatomegaly (an enlarged liver), cirrhosis, renal failure, cataracts, brain damage, and ovarian failure. Without treatment, mortality in infants with galactosemia is about 75%.Galactosemia is inherited in an autosomal recessive manner, meaning a child must inherit one defective gene from each parent to show the disease. Heterozygotes are carriers, because they inherit one normal gene and one defective gene. Carriers show no symptoms of galactosemia.

    Galactosemia is a very serious condition. If lacotse or galactose is consumed it may cause permanent damage.It is usually diagnosed in infancy.

    Lactose intolerant individuals have an acquired or inherited shortage of the enzyme lactase (to break down milk sugars from dairy products), and experience abdominal pains, bloating, gas or diarrhoea after ingesting dairy products, but no long-term effects.

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