The prevalence of food allergies and intolerances are on the rise. In Westernized countries, up to 20% of the population may suffer from adverse reactions to food of which the largest majority belongs to food intolerances (Valenta et al., 2015). Lactase insufficiency is defined when the concentration of the lactose-cleaving enzyme lactase, also called β-galactosidase, located in the border membrane of the mucosa of the small intestine is too small. This could lead to incomplete digestion of the disaccharide lactose, a phenomenon called lactose maldigestion. Lactose maldigestion is defined by an increase in blood glucose concentration of <1.12 mmol/L (Gigante et al., 2011). In addition to intestinal lactase activity there are other factors known to influence lactose digestion such as the rate of gastric emptying, gastrointestinal transit time, dietary components ingested together with lactose (meal effect), and interactions among these factors.
There are several types of lactose maldigestion. In primary or adult-type lactase activity is high at birth, decreases in childhood and adolescence, and remains low in adulthood. Secondary form of lactose maldigestion is mainly due to inflammation or functional loss of the small intestinal mucosa which can result as a consequence of various gastrointestinal disorders (Crohn, bacterial or parasitic infections, or small bowel syndrome), and by protein-energy malnutrition. Congenital lactose maldigestion on the other hand is a rare autosomal-recessive heritable genetic disorder which is evident immediately after birth.
Lactose maldigestion accompanied by clinical symptoms such as bloating, flatulence, nausea, diarrhoea, and abdominal pain is termed lactose intolerance. Symptoms are caused by undigested lactose in the large intestine, where the lactose serves as a fermentable substrate for the bacterial flora and osmotically increases water flow into the lumen. Whether and to what extent undigested lactose causes the above-mentioned symptoms depends first on the amount of lactose ingested but also on individual sensitivity, the rate of gastric emptying, gastrointestinal transit time, and the pattern of the flora in the large intestine. Lactose-intolerant people can ingest a certain amount of lactose without having adverse symptoms. Most of these people tolerate ≥9–12 g which is equivalent to 200 mL or 1 glass of milk (De Vrese et al., 2001).
Figure 1. Colonic metabolism of lactose (Vonk et al., 2012).
Figure 1 explains the metabolism of lactose. Lactose enters the colon (1) and is fermented by the microbiota into glucose and galactose. Gasses such as hydrogen, methane and carbon dioxide are formed (2). Lactate is also formed and converted into short chain fatty acids (SCFA)(3,4). These SCFAs can be taken up by epithelial cells (5) or can be used by the microbiota (6) or excreted in the faeces (7).
Undigested lactose will become fermented by the bacterial flora and lead to osmotically enhanced water secretion into the small intestine, accelerated transit through the small intestine, disordered peristalsis and water absorption in the colon, which could lead to diarrhoea and loose stool. Additional symptoms such as abdominal bloating, flatulence, and borborygmus are also caused by gaseous products of lactose fermentation, such as hydrogen, CH4, and carbon dioxide (De Vrese et al., 2001).
Probiotics for lactose intolerance
Increasing healthy bacteria in the gut may help to spur greater lactase production, or at the very least, aid in digestion. The use of probiotics in alleviating clinical symptoms of lactose intolerance is gaining worldwide recognition from a growing number of studies. Strains of both, Lactobacillus and Bifidobacterium, have shown promising indications in expressing bacterial β-galactosidase activity, both in preclinical and clinical settings (Almeida et al., 2012; Li et al., 2012; Masood et al., 2011). This can occur by increased hydrolysis of lactose in the small intestine; it can also be achieved by manipulation of the colonic metabolism. Almeida et al. (2012) demonstrated that combination of Lactobacillus and Bifidobacterium species can survive gastrointestinal transit and improve symptoms of lactose intolerance by increasing the activity of β-galactosidase.
In another study done by Turnbull (2000), probiotics demonstrated a reduction in bloating symptoms in subjects with lactose intolerance as a consequence of present microbial lactase and influence on colonic metabolism. In particular, strains of Lactobacillus have been identified as highly beneficial in improving lactose intolerance symptoms by producing β -galactosidase, important to cleave lactose into glucose and galactose. Li et al. (2012) demonstrated the effectiveness of probiotics in vitro in which the recombinant Lactobacillus lactis strain was shown to effectively alleviate diarrhoea symptoms induced by lactose uptake in lactose intolerance model mice with the probable mechanism of promoting lactic acid bacteria which then differentiate and predominantly colonize the gut microbial community.
Other natural remedies for lactose intolerance
Fermented dairy are natural source of probiotic bacteria which improve the digestibility of the lactose, fats and protein in dairy, but also help to spur healthy digestive processes of other foods. Magnesium deficiency is common in people with digestive tract disorders including lactose intolerance. Therefore, supplements containing the most absorbable form of magnesium such as magnesium citrate are highly recommended.
Supplementing cow’s milk with goat’s milk could also benefit lactose intolerant people. This is because goat’s milk is high in fatty acids, and it is more easily absorbed and assimilated in the body. Also, the actual fat particles in goat milk are smaller, and contain lower concentrations of lactose.
Taking digestive enzymes that contain lactase could be highly beneficial, especially if taken at the beginning of each meal, to ensure that foods are fully digested. This would also help to decrease the probability that partially digested foods including proteins, fats and carbohydrates will sit in the gut.
Many people who are lactose intolerant also are vitamin K deficient, so it is important to add foods rich in vitamin K to lactose intolerant diet such as green leafy vegetables, scallions, Brussels sprouts, cabbage, broccoli, cucumbers, and dried basil. In addition, the fermented organic dairy is also rich with this essential vitamin.
It is also important to substitute butter for ghee. Ghee contains no lactose. The long simmering process and skimming of the butter removes lactose and casein, so individuals with sensitivity or allergies to dairy products should try ghee. In addition, when created from milk from grass-fed cows, levels of conjugated linoleic acid or CLA, are double or triple that of traditional grain fed cows.
BSc Alternative Medicine; MSc Pharmacology
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Almeida, C.C., Lorena, S.L.S., Pavan. et al. (2012). Beneficial effects of long-term consumption of a probiotic combination of Lactobacillus casei and Bifidobacterium breve. Nutrition in Clinical Practice. 27 (2), 247-251.
De Vrese, M., Stegelmann, A. et al. (2001). Probiotics—compensation for lactase insufficiency. The American Journal of Clinical Nutrition. 73(2), 421–429.
Gigante, G. et al. (2011). Role of gut microbiota and food tolerance and allergies. Dig Dis. 11 (29), 540-549.
Li, J., Zhang, W., Wang, C. et al. (2012). Lactococcus lactis expressing food-grade β-galactosidase alleviates lactose intolerance symptoms in post-weaning mice. Applied Microbiology and Biotechnology. 96 (12), 1499-1506.
Masood, M.I., Qadir, M.I. et al. (2011). Beneficial effects of lactic acid bacteria on human beings. Critical Reviews in Microbiology. 37 (11), 91-98.
Turnbull, G.K. (2000). Lactose intolerance and irritable bowel syndrome. Nutrition. 16 (2), 665–666.
Valenta, R. et al. (2015). Food allergies: the basics. Gastroenterology. 14 (8), 1120-1131.
Vonk, R.J. et al. (2012). Probiotics and lactose intolerance. Intech. 10 (5), 414-423.