ACCORDING to a recent survey, GPs are finding perceived lactose intolerance is the number one concern patients have when it comes to dairy consumption. Digestive problems such as bloating, abdominal pain, diarrhoea or flatulence can be caused by a range of factors, including stress, medication, inadequate exercise and food intolerance. In many cases, people self-diagnose lactose intolerance in a quest for symptom relief.
When it comes to understanding lactose intolerance there is some confusion in the community. Many people eliminate dairy from their diet completely when they believe they are lactose intolerant. There is a misconception that “low lactose” or “lactose-free” should mean “dairy-free”. Yet, as evidenced by the Australian Dietary Guidelines, patients with lactose intolerance can still enjoy some dairy.
To begin the conversation about cutting the confusion on lactose intolerance, Dairy Australia partnered with CSIRO scientists Dr Malcom Riley and Dr Jane Bowen to review the latest science on lactose intolerance. Here are some excerpts from their white paper Dairy food for people with lactose intolerance.
What is lactose intolerance?
Primary lactase deficiency in adult life, or genetically determined lactase non-persistence (LNP), is the normal human condition. It is much more common than lactase persistence (where adults have the continuous ability to produce high levels of lactase throughout adult life), which results from a number of distinct genetic mutations. The common condition of LNP is, therefore, the natural decline in intestinal lactase to a low level, which leaves adults with minimal ability to digest lactose.
LNP is common, with an overall prevalence of two-thirds of the world’s adult population, but with a wide variation between regions. In western, southern and northern Europe (and people with this heritage), the adult prevalence ranges from 19% to 37%.
Lactose maldigestion is defined as the inability to digest lactose regardless of cause, resulting in undigested lactose reaching the colon. Importantly, lactose maldigestion may, or may not, cause symptoms.
Lactose intolerance is characterised by symptoms resulting from the ingestion of lactose, including flatus, gas, bloating, cramps, diarrhoea and (rarely) vomiting. For lactose intolerance to be positively diagnosed, these symptoms must not be present when an inert placebo is exchanged for lactose.
For people who have LNP, there is substantial variation in the symptoms of lactose intolerance.
Why is lactose intolerance a problem?
The symptoms of lactose intolerance are very unpleasant, to the extent that most people would want to avoid them. Lactose is found mainly in milk and dairy products, but also in many manufactured foods and medications.,
Many people self-diagnose lactose intolerance when this is not the reason for their symptoms. If they are restricting their dietary behaviour on this basis, they may therefore have the wrong nutrient focus.
The impact of lactose intolerance, or perceived lactose intolerance, is generally that people avoid dairy foods. In fact, this has been identified by the US National Institutes of Health as the main health impact of lactose intolerance.8 This type of restricted diet may have an impact on eating pleasure and social interaction as well as raise health risks through suboptimal nutrition.
In general, people who suspect they have lactose intolerance should ensure an accurate diagnosis of their condition. They should also be aware of the dietary choices they have to control their symptoms while allowing consumption of a wide range of foods.
Dietary management of lactose intolerance
There is considerable individual variation in response to lactose-containing foods because of individual differences in gastrointestinal transit, differences in the bacterial content of the gut, different gut mucosal function, and different sensitivity to the symptoms of lactose maldigestion. For every person, there is some lactose dose that will overwhelm the ability of the lactase system to digest the sugars, resulting in lactose intolerance symptoms. The lactose dose ingested depends on the concentration of lactose in the food and the amount of the food consumed.
For people with lactose intolerance, it has been concluded that 12 g of lactose in single dose can be tolerated by the majority of people — this is approximately the amount of lactose in one cup (250 mL) of regular milk. Over a full day (in divided doses), it has been stated that approximately 18 g of lactose can be tolerated.,, Cow’s milk is also produced and available that is lactose free, or very low in lactose.
In dairy foods other than milk, the lactose content varies according to the method of production. Hard and matured cheeses usually have a lower lactose content than softer cheese because lactose is lost when whey is removed and the maturation process uses up lactose.
The lactose in yoghurt is digested more efﬁciently than other dairy sources of lactose because the bacteria inherent in yoghurt assist with its digestion. The lactase within the yoghurt fermenting bacteria survives the acidic conditions of the stomach, apparently because it is physically protected within the bacterial cells and is facilitated by the buffering capacity of yoghurt. The change in pH as the yoghurt enters the small intestine and a slower gastrointestinal transit time allow the bacterial lactase to be active, digesting the lactose in the yoghurt sufﬁciently to prevent symptoms in people with lactose intolerance.
For patient resources and the complete white paper, Dairy food for people with lactose intolerance, visit www.dairyhealth.com.au.
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