LACTOSE INTOLERANCE
Lactose intolerance occurs when someone does not have sufficient levels of the enzyme lactase to digest lactose. Lactose (the sugar) reaches the colon unchanged after having moved through the small intestine. Here, bacteria that occur naturally in the colon then ferment the undigested lactose.
This fermentation process may lead to the formation of acid and gas, while the body may simultaneously attempt to dilute the concentration of the lactose by reabsorbing water from the blood. This can cause vomiting or diarrhoea. Intakes of more than 12 g lactose (typically one glass of milk) at a time may lead to symptoms such as abdominal pain, discomfort, bloating, flatulence, cramping and diarrhoea.
Consuming small quantities of milk (typically half a glass of milk*) together with other foods (e.g. cereal), as well as choosing naturally fermented dairy products such as yoghurt or maas, is recommended for someone who is lactose intolerant. Hard cheese such as cheddar and Gouda contain virtually no lactose and should not have any adverse effect.
*Half a glass of milk = 6 g of lactose
Food allergies and food intolerances are very different conditions:
- A true food allergy occurs when the immune system has an abnormal reaction to a food or a component of it. In the case of cow’s milk allergy, the reaction is to the protein in milk. The reaction can lead to undesirable or even dangerous symptoms. Symptoms for cow’s milk allergy may include hives (urticaria), vomiting, diarrhoea, colic, rhinitis and gastroenteritis. Because many people are uninformed, milk allergy is often self-diagnosed. However, it is best to seek a qualified diagnosis from a health practitioner such as a medical doctor or a dietitian, who will do a series of tests as part of an elimination process. If the patient is allergic to cow’s milk, all dairy products must be avoided, including milk and flavoured milk, cheese, yoghurt, butter, ghee, ice cream, soured-milk products, milk powder, etc. Food labels have to be studied carefully to determine whether a product contains milk powder, milk solids, casein or whey, since these can all lead to an allergic reaction. Research has shown that cow’s milk allergy affects only 2–6% of infants and 0.1–0.5% of adults worldwide. Most children outgrow their allergy around 5 years of age.
- A food intolerance is merely an intolerance to a certain amount of a specific food; it is not a response elicited by the immune system. Intolerances are often due to a shortage of an appropriate enzyme or a physiological response to certain ingredients in the food, whether natural or artificial, and so an intolerance does not mean that a food should be completely excluded from the diet, but merely that smaller amounts should be ingested at a time.
Some people are lactose intolerant, meaning that they struggle to handle lactose, the type of sugar naturally found in milk of mammalian origin. The enzyme lactase helps with the digestion of lactose found in milk. If someone’s body does not produce enough lactase, they will struggle to digest the lactose in milk. The level or degree of lactose intolerance can differ from person to person. Not everyone with low levels of the enzyme lactase, are lactose intolerant or will experience symptoms after consuming milk. Bacteria that occur naturally in the colon ferment the undigested lactose when it arrives from the small intestine, which can lead to acid and gas forming in the colon, along with reabsorption of water to dilute the concentration of the lactose. As a result, someone who is lactose intolerant can experience bloating, flatulence abdominal cramping, vomiting or diarrhoea when they typically consume more than 12 g lactose (the amount of lactose in one glass of milk) at a time.
Lactose intolerant can still benefit from the nutrients in dairy by simply consuming smaller quantities of milk at a time, having dairy in combination with other foods, or choosing naturally fermented dairy products such as yoghurt or maas. Cheese contains virtually no lactose and should not have any adverse effect. Consuming hard cheese such as Cheddar and Gouda should not cause any discomfort for lactose intolerance individuals.
The global prevalence of lactose intolerance is estimated at about 65%, but it varies considerably across populations, ranging from 4% to over 80% across different parts of the world. The prevalence of lactose intolerance in South Africa is estimated at 74%. Many cases of lactose intolerance are self-diagnosed. Therefore, the need for further research to accurately determine the prevalence of lactose intolerance in the South African population is essential. People of Asian, southern European and African heritage may also produce less lactase (the enzyme needed to digest lactose) as they age.
Bacteria that occur naturally in the colon ferment undigested lactose, which may lead to the formation of acid and gas and cause bloating, flatulence, and abdominal discomfort or cramps. The body may simultaneously attempt to dilute the concentration of the lactose by reabsorbing water from the blood. This may cause vomiting or diarrhoea.
In most cases, milk-based foods do not need to be completely avoided, but they do need to be limited to the person’s individual tolerance. In fact, intake of some lactose is advised in order to promote tolerance and improve the profile of gut microbiota. Depending on the type and level of tolerance, most people can consume some lactose – typically a daily amount of 12–15 g. A 250 mL glass of milk contains approximately 12 g lactose, while the amounts in yoghurt and cheese are considerably less: 5.9 g in 125 mL plain whole yoghurt and 0.03 g in 30 g cheddar cheese. Consuming milk together with other foods also decreases the transit time of lactose through the gut and so improves tolerance. Fermented dairy products such as yoghurt, amasi and cheese are also fairly well tolerated. Supplemental lactase supplements (the enzyme that digests lactose) is available from pharmacies and health stores, which can assist with lactose digestion when taken at the correct time. In addition, there are a number of lactose-free products available commercially.
Most people with lactose intolerance do not need to exclude dairy from their diet completely. In fact, intake of some lactose is advised in order to promote tolerance and improve the profile of gut microbiota. Depending on the type and level of tolerance, most people can consume some lactose – typically a daily amount of 12–15 g. A 250 mL glass of milk contains approximately 12 g lactose, while the amounts in yoghurt and cheese are considerably less: 5.9 g in 125 mL plain whole yoghurt and 0.03 g in 30 g cheddar cheese.
Avoiding all milk and dairy products can lead to deficiencies of important nutrients such as calcium and vitamin B12. Milk and dairy are nutrient dense and an important source of good-quality protein, calcium, vitamins A, B12 and B2, magnesium, potassium, phosphorus and zinc.