Lactose intolerance is relatively common in South Africa, particularly among our black population.
It's estimated that up to 70% of adults suffer from some degree of lactose intolerance (Mahan & Escott-Stump, 2000).
I'm also often asked if a variety of gastrointestinal symptoms such as bloating, diarrhoea and abdominal pain could be due to lactose intolerance, which is why I feel it's important to clear up certain misunderstandings about this condition and its dietary treatment:
What is lactose intolerance?
Lactose intolerance occurs when an individual doesn't produce the enzyme, lactase, that's required to digest milk sugar or lactose. Some people are born with a lactase deficiency and will manifest symptoms of lactose intolerance (diarrhoea, bloating, pain) from birth.
In other individuals, lactose intolerance develops as the person gets older and loses lactase activity, a condition called hypolactasia (Mahan & Escott-Stump, 2000). In some cases, lactase deficiency develops after infections of the digestive tract, or bowel surgery, or in Aids, irritable bowel syndrome (IBS) or Crohn's disease.
What is not lactose intolerance?
It's important to keep in mind that humans can also react to milk proteins (i.e. not milk sugar or lactose), with so-called milk allergy. Such persons don't develop their symptoms because of a reaction to the sugar in milk, but because of certain proteins that are found in milk.
This is an important difference because, if you have to avoid lactose, you'll use a different approach to dietary treatment than if you're allergic to milk proteins.
Testing for milk intolerance and allergy
If you think you may suffer from a reaction to milk and dairy products, please don't make a self-diagnosis, or even worse, decide that your child has a milk allergy and start cutting out all milk and dairy products from your own diet or your child's diet.
This can lead to serious nutritional deficiencies, not only of calcium (milk and dairy products are the richest and most bioavailable sources of calcium in the human diet), but also of protein, energy and B vitamins.
A typical case that was recently brought to my attention involved a mother who, because she suffered from a milk allergy, decided that her baby would also automatically be sensitive to milk and then stopped giving him any milk, formula or dairy products.
This mother, in her desire to protect her child, did exactly the wrong thing. She didn't first find out if her baby really had a milk allergy or lactose intolerance by having the baby tested, and she also didn't consider the serious deficiencies her baby could develop when deprived of these highly nutritious foods.
She also didn't consult a dietician to help her formulate a balanced diet that would make up for the lack of milk and dairy products. She just cut out all milk products from her child's diet and the infant nearly died of malnutrition.
So, if you think you have a milk allergy or lactose intolerance, or you suspect that your baby or child may be affected, please consult a paediatrician or your doctor or dietician so that you and/or your child can be tested.
If you or your child suffers from a milk allergy involving one or more milk proteins, then you'll have to avoid all food products that contain milk, but you won't need to avoid lactose (see below regarding medications).
If you or your child suffers from lactose intolerance, you'll have to avoid all food products and medications that contain lactose, but you may well be able to tolerate small quantities of milk and larger quantities of yoghurt, as most of the lactose or milk sugar in yoghurt is removed during the fermentation process.
Thus, most persons who are lactose intolerant can eat yoghurt or drink maas (fermented milk) and still enjoy the benefits of these foods (e.g. high calcium content, high protein content and B vitamins).
Other products that contain lactose
I was interested to read a recent article in the Medical Chronicle that pointed out that up to 20% of prescription medications contain lactose (Schneider et al, 2009). Lactose or starches are often added to prescription and over-the-counter medicinal products for various reasons that involve the shelf-life or drug effectiveness.
Dr Schneider and his co-authors (2009) point out that the presence of such additives may account for the paradoxical effect some patients experience when they take a medication to stop their diarrhoea and, instead of obtaining relief, develop even worse symptoms.
Many medications contain lactose as a so-called "excipient". For example, Schneider and his co-authors (2009) cite lactulose, which is used in a variety of laxatives, as a prime example. According to these authors, a 150ml dose of lactulose can contain as much as 11g of lactose, which is approximately the quantity of lactose that's used to test patients for lactose intolerance.
A variety of medications, including antidiarrhoeals, antispasmodics, anti-emetics and corticosteroids contain varying quantities of lactose. The presence of lactose in medications is particularly significant in relation to people with irritable bowel syndrome (20-30% of these people may suffer from lactose intolerance) and Crohn’s diseases, where up to 60% of patients suffer from lactose intolerance.
It's therefore vital if you suffer from confirmed lactose intolerance that you check the package inserts or ask your prescribing doctor of dispensing pharmacist if any of the medications you take contain any lactose. If they do, ask the doctor or pharmacist to change the prescription. Otherwise your treatment may cause a lactose intolerance flare-up, and make you feel worse, instead of better.
In the same way that you should avoid self-diagnosis of lactose intolerance and/or milk-protein allergies, working out a lactose- or milk-free diet should always be done with the assistance of a clinical dietician.
"But," I hear you say, "it’s so easy! I just cut out all types of milk and dairy products!"
This isn't the answer. You need a dietician to assist you, especially if your child suffers from milk allergy or lactose intolerance, to ensure that you or your child will still obtain all the essential nutrients, especially calcium, when you change your diet.
As mentioned above, individuals with lactose intolerance can usually still use fermented milk products such as yoghurt and maas, and certain types of cheese, to ensure that they obtain all the calcium they require for healthy bones and strong teeth.
People with milk-protein allergies will need to use soy milk products that have been enriched with calcium and/or calcium supplements to make up for the lack of calcium in their diets.
Visit the Association for Dietetics in SA website at www.adsa.org.za and click on "Find a Dietitian" to find a dietitian in your area who will help you sort out your lactose and milk-allergy problems.
(Dr I.V. van Heerden, DietDoc, September 2009)
Any questions? Ask DietDoc
(Mahan LK, Escott-Stump S (2000). Krause’s Food, Nutrition & Diet Therapy. 10th Edition. WB Saunders Co, Philadelphia, USA; Schneider H, Pettengell K, Wright J (2009). Anti-diarrhoeal tablets that cause diarrhoea and other paradoxes in medicinal use. Medical Chronicle, August 2009, p. 79)