Many people needlessly avoid dairy products because they mistake their symptoms for lactose intolerance, new research reveals. As a result, individuals with self-diagnosed lactose intolerance often avoid dairy products, which are primary sources of essential nutrients like calcium, vitamin D, and riboflavin. This avoidance can lead to deficiencies in these nutrients, which are crucial for bone health, other physiological functions and overall well-being (2).
They miss out on some key nutritional benefits, say the researchers who are calling on health professionals to educate patients on how to manage symptoms without compromising their healthy diet.
The researchers suggest that lactose intolerance is less common than generally perceived, because many people wrongly diagnose themselves with the condition when they have irritable bowel syndrome (IBS).
Around 10% of people worldwide suffer from IBS, which can cause distressing symptoms that can easily be confused for lactose intolerance.
The latest systematic review compared the reliability of self-reported lactose intolerance with confirmed cases in people with IBS (1). Their findings highlight the need for accurate diagnosis and management of lactose intolerance to avoid unnecessary dietary restrictions.
Measuring self-reported versus confirmed lactose intolerance
In most people, lactose is broken down by lactase enzymes in the small intestine. However, in people with lactase deficiency, lactose is broken down by bacteria in the large intestine, producing gases including hydrogen. This hydrogen is then absorbed into the bloodstream, exhaled through the lungs, and can be measured using a hydrogen breath test (3).
With this in mind, researchers set out to review the diagnostic accuracy of self-reported lactose intolerance in adults with IBS. They analysed the results of six observational studies with 845 participants, comparing self-reported symptoms with objective hydrogen breath testing for lactose malabsorption.
The accuracy of self-reported lactose intolerance varies widely
Results showed significant variability in the accuracy of self-reporting for diagnosing lactose intolerance among people with IBS. There was a large gap between self-reported and confirmed cases according to hydrogen breath testing:
- Less than half (38%) of participants had lactose intolerance identified through both self-reporting and hydrogen breath testing
- Conversely, 16% of participants self-reported as lactose intolerant but were tolerant according to hydrogen breath testing
- Another 16% of participants were lactose tolerant according to both self-reporting and hydrogen breath testing
- Just over a quarter of participants (27%) self-reported as lactose tolerant but were intolerant according to hydrogen breath testing
Self-reporting of lactose intolerance identifies a high number of false positives
Study findings demonstrated a high prevalence of lactose intolerance across different populations, emphasizing the need for effective dietary and clinical management strategies. However, there were also high numbers of false positives:
- Self-reporting correctly identified 68% of participants who were truly lactose intolerant
- However, self-reporting only correctly identified 36% of participants who were not lactose intolerant
These results suggest that many people may incorrectly perceive themselves as lactose intolerant. Symptoms of IBS and lactose intolerance were very similar across studies. This highlights the complexity of diagnosing lactose intolerance in IBS patients based on symptoms alone.
People with lactose intolerance may still be able to consume dairy products
Based on their findings, the researchers propose that lactose-free diets should not be recommended without clear indications of lactose intolerance. Research indicates that people who perceive themselves as lactose intolerant can often consume dairy foods without symptoms (3). In fact, the unnecessary exclusion of dairy products can result in an imbalanced diet, affecting not only bone health but also other physiological functions that depend on these nutrients (2,5,6). The EFSA recommends that individuals with lactose intolerance should not completely avoid dairy products but rather manage their intake to avoid symptoms while ensuring adequate nutrient intake… to prevent nutrient deficiencies and maintain diet quality (4).
Even people with clinically confirmed lactose intolerance can still consume dairy foods with proper guidance to meet nutrient recommendations. Unabsorbed lactose offers significant health benefits including promoting the growth of beneficial bifidobacteria in the gut and improving calcium absorption, which is essential for maintaining strong bones and teeth(7). Supplementation with Bifidobacteria and galacto-oligosaccharides (GOS) can improve lactose digestion and tolerance. This is due to the ability of these probiotics and prebiotics to modify the gut microbiota and enhance the fermentation of undigested lactose. This pre and probiotics approach allow to avoid dairy exclusion (7).
Avoiding dairy foods without proper medical advice can lead to unnecessary dietary restrictions and potential nutrient deficiencies. It is therefore important for healthcare providers to diagnose lactose intolerance accurately and educate patients on managing symptoms without compromising their nutritional status, say the researchers.
What is the difference between lactose intolerance and lactose malabsorption?
Lactose intolerance happens when the body doesn’t produce enough lactase, the enzyme needed for lactose digestion. Without enough lactase, consuming dairy foods can lead to uncomfortable symptoms such as bloating, gas, and diarrhoea.
There are two different types of lactose intolerance (8,9):
- Congenital lactose intolerance – lactose intolerance from birth, due to a genetic inability to produce lactase.
- Lactose malabsorption – can occur temporarily due to secondary causes like infectious gastroenteritis, cow’s milk allergy, and coeliac disease. Once these underlying conditions are addressed, lactase activity typically returns to normal levels, allowing for the proper digestion of lactose.
While congenital lactose intolerance is extremely rare, lactose malabsorption is relatively common, affecting up to half of European adults (4).
“A lactose-free diet should not be routinely recommended for IBS patients… Future investigations should focus on gaining a better understanding of the factors involved in lactose perception and tolerance.”
