Dietitian says the evidence for lactose breath testing doesn’t stack up, but many are still recommending it

Food elimination and rechallenge is the gold standard to diagnose lactose intolerance, but a recent Healthed survey suggests that a third of GPs are recommending breath testing as the first point of call, according to accredited practicing dietitian Joanna Baker of Everyday Nutrition.

Following those surprising results, Baker put the same question to 649 patients in a Facebook group targeting people with IBS, and found that 22.5% had been referred for breath testing (interestingly 10% had self-diagnosed without having had any investigations).

The problem with lactose breath testing is that about 70% of Australian adults maldigest lactose and test positive on a breath test, but CSIRO data shows that only 12% actually report GI symptoms after consuming milk or milk products.

“So there’s a very large number of people there who test positive on a breath test but don’t get symptoms when they drink milk”, Baker says.

The breath test dose is the equivalent of about 500ml to one litre of cow’s milk all in one sitting, and she questions how many people are actually drinking that much milk at a time in their daily diet and whether the findings would actually be relevant.

A 2017 review of the evidence and clinical relevance for lactose breath tests found wide variation in testing parameters, as well as in the interpretation of results. The researchers found that the tests were not reproducible in the same person.

Baker also says people with abdominal symptoms get similar results on the tests to those who don’t have abdominal symptoms.

“So my question is, do breath tests actually over diagnose lactose intolerance and does it lead to unnecessary over restriction and fear and anxiety around products that potentially may contain lactose”, she asks.

“Lactose intolerance doesn’t damage the body. It’s not dangerous”, Baker adds. Thus, the goal is purely to manage symptoms and improve quality of life.
To that end, she notes that “lactose free does not mean completely dairy free”.

Baker says people often forget that hard cheeses and butter do not contain lactose, and that the best milk alternative is lactose-free milk because it is nutritionally equivalent. Additionally, lactose is available in tablet form to allow people to continue to consume lactose if they wish. If they are completely replacing dairy, she says it’s important to choose calcium-fortified alternatives.

If removing lactose does not improve all the symptoms, Baker says it’s reasonable to trial full dairy exclusion to exclude a milk protein intolerance.

Joanna Baker will be discussing lactose intolerance in much more detail in Healthed’s free webcast on 18 April. Sign up here.