I could perfectly digest dairy till the age of 35. One fine day when I went to doctor to ask about stomach problems I had in past some days that year, I was told that I am lactose intolerant. How did that happen after so many years? Now I am stuck to the lactose-free milk. Is it possible to regain/rebuild lactose tolerance? That would be a life saver as I do not eat meat and milk is a major source of protein for me.
First, here is a small background on lactose intolerance:
Lactose is a disaccharide present in high quantity in mammalian milk. Once in the intestine, it is hydrolysed into glucose and galactose, which are then absorbed. Lactase hydrolisation is dependent on an intestinal brush border enzyme called lactase.
Intestinal lactase activity is highest during the perinatal period (where milk is essential for the nourishment of newborn). After this period (in general after the weaning period) lactase activity decreases at variable rates following a normal maturational down-regulation. As such, two groups of individuals emerge:
- the lactase non-persistence group with low lactase activity (hypolactasia)
- the lactase persistence group where the level of lactase activity in the adulthood in similar or slightly less (moderate to high lactase activity) to the one found in the neonatal period.
Some studies have suggested a geographic pattern for the distribution of genes associated with the two conditions (the review by Misselwitz et al provides a good overview).
Interestingly, reduction in lactase activity does not always lead to symptoms. However, when symptoms occur, lactose intolerance is diagnosed.
The most frequent cause of lactose malabsorption is the so-called “lactase non-persistence” (primary lactase deficiency), which is characterised by a decrease in lactase expression during infancy. Note, in some rare cases, lactase can be complete lacking causing severe symptoms in the newborns (congenital lactase deficiency).
There are other secondary causes of lactase malabsorption (secondary or acquired lactase deficiency): small bowel bacterial overgrowth, giardiasis (a type of infectious enteritis), coeliac disease, inflammatory bowel disease. In these cases, gastrointestinal disorders damage the brush border of the small intestine and leads to a decrease in lactase activity.
I was told that I am lactose intolerant. How did that happen after so many years?
There are several possible explanations. First, some studies have shown an increased incidence of lactose intolerance in the elderly, suggesting that lactase activity might decline further with age. In particular, individuals with already intermediate to low lactase activity might be at higher risk of developing lactase intolerance decades after the infancy period. Second a secondary cause for lactase deficiency cannot be excluded. Finally, a study conducted in 1998 showed that there is sometimes a confusion between lactose maldigestion and lactose intolerance. My two later points are of course only hypothesis, as you don't provide enough information in your question (in particular how the diagnosis of lactose intolerance was made)
Is it possible to regain/rebuild lactose tolerance?
I have found no studies conducted in humans showing that lactase activity could be regained.
Current treatment of lactose intolerance aims at improving symptoms while maintaining sufficient calcium intake, which can be affected by mil restricted diet. According to a concensus of experts, initial management of lactose intolerance is to aim for remission of symptoms by avoiding milk and dairy products. Here an interesting extract of the recommendations:
most individuals with lactose malabsorption can tolerate up to 12 g of lactose without significant symptoms. After the initially restricted diet, lactose should be gradually reintroduced until the patient’s threshold for symptoms is reached. At this point, several behavioral measures can be adopted to overcome possible symptoms, including having fermented and matured milk products in the diet, consuming lactose together with other foods, and distributing lactose intake over the day.
If the above mentioned measures don’t provide any relief, pharmacological strategies can be considered such as lactase supplements, lactose-hydrolyzed or lactose-reduced milk, probiotics, colonic adaptation, and rifaximin. However, some of these intervetions lack evidence based data and show large inter-individual variability.
- Misselwitz B, Pohl D, Frühauf H, Fried M, Vavricka SR, Fox M. Lactose malabsorption and intolerance: pathogenesis, diagnosis and treatment. United European Gastroenterology Journal. 2013;1(3):151-159.
- Mattar R, de Campos Mazo DF, Carrilho FJ. Lactose intolerance: diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology. 2012;5:113-121.
- Lomer M et al. Review article: lactose intolerance in clinical practice – myths and realities. Alimentary Pharmacology & Therapeutics. 2008:27: 93–103.
- Carroccio et al. Lactose intolerance and self-reported milk intolerance: relationship with lactose maldigestion and nutrient intake. Lactase Deficiency Study Group.J Am Coll Nutr. 1998 Dec;17(6):631-6.