Lactose intolerance

Lactose intolerance is the most common problem limiting milk and dairy products consumption worldwide and is defined as experience of gastrointestinal symptoms following the intake of lactose-containing food products.¹Stone R. Acute abdominal pain. Lippincotts Prim Care Pract. 1998;2(4):341-57.   Individuals with lactose intolerance exhibit an inability to digest significant amounts of lactose due to deficiency of the intestinal lactase enzyme.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.   In this event there is an inability to break down the dietary lactose into glucose and galactose consequently resulting in intolerance to foods which contain lactose and thus a range of intestinal and systemic symptoms (figure 1).³Tomar BS. Lactose intolerance and other disaccharidase deficiency. Indian J Pediatr. 2014;81(9):876-80.  ⁴Babu J Kumar S Babu P et al. Frequency of lactose malabsorption among healthy Southern and Northern Indian populations by genetic analysis and lactose hydrogen breath and tolerance tests. Am J Clin Nutr.2010;91(1):140-6.  ⁵Data on file (Walter Bushnell).  

Figure 2 depicts approximate lactose content present in common food items consumed on daily basis. Additionally there are certain hidden sources of lactose that may require dietary consideration in individuals with lactose intolerance (table 1).⁵Data on file (Walter Bushnell).  

Types of lactose intolerance

Lactose is a disaccharide sugar found exclusively in mammalian milk that is digested by the enzyme lactase in the mucosal brush border of the intestine.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331-1332.   Physiologically lactose intolerance ensues when the maldigestion of lactose due to intestinal lactase deficiency and/or low lactase activity results in clinical symptoms;³Tomar BS. Lactose intolerance and other disaccharidase deficiency. Indian J Pediatr. 2014;81(9):876-80.  ⁷Vandenplas Y. Lactose intolerance. Asia Pac J Clin Nutr. 2015;24 Suppl1:S9-13.  ⁸Baadkar SV Mukherjee MS Lele SS. Study on influence of age gender and genetic variants on lactose intolerance and its impact on milk intake in adult Asian Indians. Ann Hum Biol. 2014;41(6):548-53.   and this can be described in three different forms i.e. congenital primary late onset and secondary. Symptoms due to the congenital lactase deficiency occur short after birth when milk is introduced; however this form is usually rare.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331-1332.  ⁹Baadkar SV Mukherjee MS Lele SS. A study on genetic test of lactase persistence in relation to milk consumption in regional groups of India.Genet Test Mol Biomarkers. 2012;16(12):1413-8.   In Asia it is proposed that vast majority of children will develop late onset congenital lactase deficiency. However this again only exceptionally causes symptoms before the age of 4-5 years.⁷Vandenplas Y. Lactose intolerance. Asia Pac J Clin Nutr. 2015;24 Suppl1:S9-13.  

In adults the prevalence of lactose malabsorption increases with increasing age.¹⁰Di Stefano M Veneto G Malservisi S et al. Lactose malabsorption and intolerance in the elderly. Scand J Gastroenterol. 2001;36(12):1274-8.   A number of hypotheses have been put forward to explain this maturational decline of lactase activity in adults but the precise underlying mechanism for adult type hypolactasia remains undefined.¹¹Kaur K Mahmood S Mahmood A. Hypolactasia as a molecular basis of lactose intolerance. Indian J Biochem Biophys. 2006;43(5):267-74.   In adults lactose intolerance can either be due to the primary lactase deficiency occurring when a glass of milk is consumed or due to secondary lactase deficiency which occurs because lactase is reduced due to diseases affecting the intestinal mucosa.¹Stone R. Acute abdominal pain. Lippincotts Prim Care Pract. 1998;2(4):341-57.   In such latter cases lactose malabsorption thus occur secondary and temporally and may be attributable to a variety of etiologies such as infectious gastroenteritis allergy to cow’s milk and celiac disease (Table 2).¹²Flasar MH Cross R Goldberg E. Acute abdominal pain. Prim Care. 2006 Sep;33(3):659-84 vi.   In secondary cases of lactose intolerance the lactase activity will gradually return to normal once the underlying cause is treated.⁷Vandenplas Y. Lactose intolerance. Asia Pac J Clin Nutr. 2015;24 Suppl1:S9-13.  

Symptoms of lactose intolerance

Clinical features of lactose intolerance are attributable to most of the dietary lactose passing unaltered through the small intestine into the colon – due to hypolactasia; where it is rapidly metabolized by the colonic bacteria. Consequently the patient will typically experience excessive fluid and gas in the bowel. Common symptoms of the lactose intolerance thus include abdominal pain and bloating excessive flatus and watery stool (figure 3)¹²Flasar MH Cross R Goldberg E. Acute abdominal pain. Prim Care. 2006 Sep;33(3):659-84 vi.   and typically occur following the ingestion of lactose containing foods by individuals intolerant to lactose.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.   However the extent and severity of symptoms that patients experience will vary dependent on the quantity of the lactose ingested and individual’s ability to digest lactose. Symptoms thus depend on the amount and rate of lactose reaching the colon and also on the amount and type of colonic flora.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331-1332.   ¹³Cole E Lynch A Cugnoni H. Assessment of the patient with acute abdominal pain. Nurs Stand. 2006;20(39):67-75.   Vast majority of subjects with lactose maldigestion will tolerate only up to 12 g of lactose as a single dose with no or minor symptoms. People who suffer from severe lactose intolerance may suffer from symptoms even in very low doses of lactose (as low as 3 gms).¹⁴Bedine MS and Bayless TM. Intolerance of small amounts of lactose by individuals with low lactase levels. Gastroenterology 1973;65:735-743.  

Epidemiology of lactose intolerance

It is suggested that only about 35% of people worldwide are lactase persistent who continue to produce lactase throughout adulthood and thus are able to digest the sugar in milk without discomfort.¹⁵Leonardi M Gerbault P Thomas MG et al. The evolution of lactase persistence in Europe. A synthesis of archaeological and genetic evidence.International Dairy Journal. 2012;22:88-97.   This clearly signifies that lactase non-persistence would be highly prevalent across the world even if in different severity forms. Especially the impact could be more on Asians and American Indians due to high prevalence of lactase deficiency in these populations. Data in this context has shown that lactase deficiency can be seen in up to 15% of persons of Northern European descent up to 80% of blacks and Latinos and up to 100% of American Indians and Asians.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.   Furthermore studies conducted in India have shown certain demographic variations within the nation. In India it has been observed that the frequency and degree of lactose malabsorption is higher in the Southern Indian populations compared to the North which could be attributable to possible genetic differences among these subpopulations (table 3).⁴Babu J Kumar S Babu P et al. Frequency of lactose malabsorption among healthy Southern and Northern Indian populations by genetic analysis and lactose hydrogen breath and tolerance tests. Am J Clin Nutr.2010;91(1):140-6.   ¹⁶Tandon RK Joshi YK Singh DS et al. Lactose intolerance in North and South Indians. Am J Clin Nutr. 1981;34(5):943-6.   Milk consumption patterns thus vary in different Indian subgroups influenced not only by their dietary habits but also their genetic structure and ancestral history.⁸Baadkar SV Mukherjee MS Lele SS. Study on influence of age gender and genetic variants on lactose intolerance and its impact on milk intake in adult Asian Indians. Ann Hum Biol. 2014;41(6):548-53.   ⁹Baadkar SV Mukherjee MS Lele SS. A study on genetic test of lactase persistence in relation to milk consumption in regional groups of India.Genet Test Mol Biomarkers. 2012;16(12):1413-8.  

Furthermore as mentioned earlier a relationship has been noted between age and lactose malabsorption; as age increases the prevalence of lactose malabsorption shows an increase.¹⁰Di Stefano M Veneto G Malservisi S et al. Lactose malabsorption and intolerance in the elderly. Scand J Gastroenterol. 2001;36(12):1274-8.   Particularly the ability to absorb lactose declines in the 7th decade of life (Figure 4).⁵Data on file (Walter Bushnell).  ¹⁷Goulding A Taylor RW Keil D et al. Lactose malabsorption and rate of bone loss in older women. Age and Ageing 1999;28:175-180.  

Secondary causes of lactose intolerance

Considering secondary causes lactose intolerance has been found to be higher in cases with active gastrointestinal etiologies such as ulcerative colitis implicated as cause of secondary lactose intolerance (figure 5).¹⁸Kochhar R Mehta SK Goenka MK et al. Lactose intolerance in idiopathic ulcerative colitis in North Indians. Indian J Med Res. 1993;98:79-82.   ¹⁹Rana SV Bhasin DK Vinayak VK. Lactose hydrogen breath test in Giardia lamblia-positive patients. Dig Dis Sci. 2005;50(2):259-61.   ²⁰Tolliver BA Herrera JL DiPalma JA. Evaluation of patients who meet clinical criteria for irritable bowel syndrome. Am J Gastroenterol. 1994;89(2):176-8.   ²¹Von Tirpitz C Kohn C Steinkamp M et al. Lactose intolerance in active Crohn’s disease: clinical value of duodenal lactase analysis. J Clin Gastroenterol. 2002;34(1):49-53.   ²²Robb TA Davidson GP. Hydrogen breath test in gastroenteritis. Arch Dis Child. 1982;57(7):561-2.   ²³Vesa TH Seppo LM Marteau PR Sahi T Korpela R. Role of irritable bowel syndrome in subjective lactose intolerance. Am J Clin Nutr. 1998; 67(4):710-5.   ²⁴Nilsson A. Lactose malabsorption and lactose intolerance in adults – a cause of irritable bowel syndrome? Scandinavian Journal of Nutrition 2001;45:175-1 76.   ²⁵Bernstein CN Ament M Artinian L Ridgeway J Shanahan F. Milk tolerance in adults with ulcerative colitis. Am J Gastroenterol. 1994;89(6):872-7.   Furthermore in irritable bowel syndrome (IBS) it has been observed that the incidence of lactose intolerance may vary in different types of IBS; with patients with diarrheal type of IBS having a higher incidence of lactose intolerance compared to other subtypes.²⁶Rana SV Mandal AK Kochhar R et al. Lactose intolerance in different types of irritable bowel syndrome in North Indians. Trop Gastroenterol.2001;22(4):202-4.  

Consequence of lactose intolerance and limiting dairy products due to it

In practice it has been observed that not all patients with lactose intolerance require absolute restriction of dairy products since many of them are not necessarily totally allergic to milk and can consume dairy foods without developing symptoms. Yet it is often seen that many individuals avoid dairy products due to the often mistaken belief that they are lactose intolerant while the truth is that many individuals who think they are lactose intolerant are not actually lactose malabsorbers.²⁷Nicklas TA. Avoidance of dairy products: implications for nutrient adequacy and health. Available at: https://www.dairynutrition.ca/scientificevidence/experts-summaries/avoidance-of-dairy-products-implicationsfornutrient- adequacy-and-health [Accessed on 16/11/2016].   A complete cessation of dairy products by these individuals can cause certain unwarranted nutritional and health consequences given that dairy products provide a nutritional package with several necessary nutrients such as calcium potassium vitamin D and riboflavin which is usually difficult to replicate (box 1).⁵Data on file (Walter Bushnell).  ¹³Cole E Lynch A Cugnoni H. Assessment of the patient with acute abdominal pain. Nurs Stand. 2006;20(39):67-75.    ²⁸Heaney RP Keith JN Duyff RL. Unintended consequences of dairy avoidance. Available at: https://www.lactaid.com/sites/www.lactaid.com/files/FINAL%20Unintended%20Consequences%20of%20Dairy%20Avoidance%20White%20Paper%207.19.11.pdf Accessed on 16/11/2016].    ²⁹Cann K. Nutrition and depression. Available at: http://robbwolf.com/2012/03/23/nutrition-depression/ [Accessed on 25/1/2017].     In fact according to the National Institute of Health (NIH) Consensus Development Conference Statement on Lactose Intolerance and Health in most cases of lactose intolerance individuals do not need to eliminate the dairy consumption completely.³⁰NIH Consensus Development Conference: Lactose Intolerance and Health.February 22-24 2010 Bethesda Maryland. Available at: https://consensus.nih.gov/2010/lactosestatement.htm [Accessed on 16/11/2016].   A systematic review by Shaukat et al³¹Shaukat A Levitt MD Taylor BC et al. Systematic review: effective management strategies for lactose intolerance. Ann Intern Med. 2010;152(12):797-803.   also showed that most individuals with presumed lactose intolerance or malabsorption can tolerate lactose. Yet many individuals with objective or perceived lactose intolerance avoid dairy and ingest inadequate amounts of calcium and vitamin D which may predispose them to decreased bone accrual osteoporosis and other adverse health outcomes. The risk may be especially higher for certain individual groups such as women throughout the life cycle and those with diseases that result in decreased calcium absorption due to intestinal inflammation. Furthermore there is a growing body of evidence that demonstrates a link between dairy intake and a decreased risk of several chronic conditions such as hypertension and type 2 diabetes. For instance calcium ingestion has been associated with decreased blood pressure and a decreased risk of development of adenomatous colon polyps. Overall dairy avoidance is not the practical solution and physicians should devise effective strategies to increase dairy food consumption even in those with documented lactose intolerance. Evidence has shown that patients suffering from lactose intolerance may also develop depression.³²Schiffner R Kostev K Gothe H. Do patients with lactose intolerance exhibit more frequent comorbidities than patients without lactose intolerance?An analysis of routine data from German medical practices. Ann Gastroenterol. 2016;29(2):174-9.  

Lactose intolerance and quality-of-life

All chronic conditions are well-known to impair the perception of well-being and being the most frequent form of malabsorption lactose intolerance seems no different. Therefore in affected individuals lactose intolerance and its symptoms can be disabling enough to interfere with the daily life.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331–1332.   A 3-year prospective crosssectional study performed in patients who were referred for lactose intolerance evaluation found that both self-perception of lactose intolerance and objective lactose malabsorption were associated with poorer perceived quality-of-life.³³Casellas F Aparici A Pérez MJ et al. Perception of lactose intolerance impairs health-related quality of life. Eur J Clin Nutr. 2016;70(9):1068-72.   Health-related quality of life HRQOL scores were significantly lower in lactose malabsorbers than in absorbers (figure 6) signifying the effect of lactose malabsorption/intolerance on daily life.

Diagnosis of lactose intolerance

In practice diagnosis of lactose intolerance is mainly done by taking history of symptoms that patient gives. Patients can go for lactose challenge test which they themselves can do. They are advised to take 500 ml of milk (25 grams of lactose) followed by fasting for 1-3 hours. If they experience symptoms of abdominal pain bloating flatulence borborygmi diarrhea nausea and vomiting it is suggestive of lactose intolerance. Nevertheless if required the diagnosis may be further supported by additional testing such as breath hydrogen test and/or lactose tolerance test. These diagnostic tests are based on the changes in breath hydrogen levels or serum glucose levels after ingesting standard doses of lactose.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.   In most of the suspected cases of lactose intolerance a positive breath test accompanied by clinical symptoms that are induced by ingestion of a lactose load and relieved by removal of lactose from the diet will likely be definitive of the lactose intolerance.³⁴Blumenthal I Kelleher J Littlewood JM. Recurrent abdominal pain and lactose intolerance in childhood. Br Med J (Clin Res Ed). 1981; 282(6281):2013–2014.   However the specificity and sensitivity of breath hydrogen test and lactose tolerance test vary leading to both false negative and positive results making the diagnosis of lactose intolerance more difficult.¹²Flasar MH Cross R Goldberg E. Acute abdominal pain. Prim Care. 2006 Sep;33(3):659-84 vi.  

Furthermore a consideration of differential diagnoses seems especially important in individuals suspected to have primary hypolactasia. Table 4 enlists some leading differential diagnoses such as IBS which can possibly be present in patients being evaluated for lactose intolerance.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.  ⁵Data on file (Walter Bushnell).  ³⁵Litschauer-Poursadrollah M El-Sayad S Wantke F et al. Abdominal spasms meteorism diarrhea: fructose intolerance lactose intolerance or IBS? Wien Med Wochenschr. 2012;162(23-24):506-12.   These individuals will require further investigation to identify and manage the underlying primary problem.

Management of lactose intolerance

Dietary management

Milk/dairy avoidance is not recommended by guidelines like European Food Safety Authority and National Institute of Health (US) as it can lead to conditions like nutritional deficiency poor bone health and depression.¹²Flasar MH Cross R Goldberg E. Acute abdominal pain. Prim Care. 2006 Sep;33(3):659-84 vi.    ³⁰NIH Consensus Development Conference: Lactose Intolerance and Health.February 22-24 2010 Bethesda Maryland. Available at: https://consensus.nih.gov/2010/lactosestatement.htm [Accessed on 16/11/2016].   Patients should be informed that having lactose malabsorption does not necessarily mean that they are totally allergic to milk dairy products or dairy foods.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.  This is because evidence from the clinical practice has shown that some people with lactose intolerance can consume milk and dairy foods without developing symptoms whereas others will require more strict lactose restriction.³⁶Lomer MC Parkes GC Sanderson JD. Review article: lactose intolerance in clinical practice–myths and realities. Aliment Pharmacol Ther. 2008;27(2):93-103.   In the former subgroup therefore intake of milk could carefully be limited to < 250 mL per day. This seems supported by the observation that lactose is not a major cause of symptoms for lactose maldigesters following usual intakes of dairy foods that is about 1 cup.³⁷Savaiano DA Boushey CJ McCabe GP. Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration.J Nutr. 2006;136(4):1107-13.   It may further be of help to divide this daily milk intake into several small portions and to take it with other foods.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331-1332.   Furthermore the amount of lactose may depend upon quantity of milk or milk product used in the food preparation.³⁸Lami F Callegari C Tatali M et al. Efficacy of addition of exogenous lactase to milk in adult lactase deficiency. Am J Gastroenterol. 1988;83(10):1145-9.   Yoghurt cheeses and curds may be better tolerated because lactose is partially hydrolyzed by bacteria during their preparation and gastric emptying is slower because these products have a thicker consistency.⁶Bhatnagar S Aggarwal R. Lactose intolerance. BMJ. 2007; 334(7608):1331-1332.   Nevertheless for patients with a lower threshold to lactose intolerance the key to management is dietary removal of the lactose. Such patients must also be advised of the “risk” foods inadequately labeled such as processed meats bread cake mixes and soft drinks (table 1).³Tomar BS. Lactose intolerance and other disaccharidase deficiency. Indian J Pediatr. 2014;81(9):876-80.   Furthermore since dairy products are expected to provide most of the dietary calcium (table 5)⁵Data on file (Walter Bushnell).   adult patients with lactose intolerance should also be advised to maintain a calcium intake of 1200 to 1500 mg per day notwithstanding actual dairy products up to their individual symptoms’ threshold. Patients may thus consider drinking lactosereduced milk or taking calcium supplements to maintain the body calcium levels. In addition it is also rational to advise the lactose intolerant patients to avoid medications containing lactose as filler and certain food products which may contain unrecognized lactose.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.  

Lactase enzyme supplementation therapy

Enzyme supplementation therapy with lactase from nonhuman sources is an important adjunct to diet therapy in patients with lactose intolerance.²Swagerty DL Jr Walling AD Klein RM. Lactose intolerance. Am Fam Physician. 2002;65(9):1845-50.  ¹³Cole E Lynch A Cugnoni H. Assessment of the patient with acute abdominal pain. Nurs Stand. 2006;20(39):67-75.   ³⁹Ibba I Gilli A Boi MF Usai P. Effects of exogenous lactase administration on hydrogen breath excretion and intestinal symptoms in patients presenting lactose malabsorption and intolerance. BioMed Research International 2014 (2014);Article ID 680196:7 pages.   This exogenous lactase is obtained from several microbial sources (yeasts or fungi) with aim to hydrolyze the dietary lactose and has been found to be highly effective in decreasing the symptoms of lactose intolerance.

Source of lactase impacts the pH stability of final preparation which decides the dosage efficacy safety and cost. The good source is Aspergillus oryzae. European Food Safety Association (EFSA) and the United States Food and Drug Administration (USFDA) both approve and recommend Aspergillus oryzae. Lactase from Aspergillus oryzae source is considered GRAS (Generally Regarded as Safe).¹²Flasar MH Cross R Goldberg E. Acute abdominal pain. Prim Care. 2006 Sep;33(3):659-84 vi.   ⁴⁰Enzyme Preparations Used in Food (Partial List). Available at: http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/EnzymePreparations/default.htm [Accessed on 14/2/2017].   ⁴¹GRAS Notice (GRN) No. 510. Available at: http://www.fda.gov/downloads/Food/IngredientsPackagingLabeling/GRAS/NoticeInventory/ucm400718.pdf [Accessed on 14/2/2017].   Lactase preparations from Aspergillus oryzae are stable in an acidic environment and are practically pH independent. High activity throughout the GI tract even in lower stomach where pH is less than 3.5 is unlike other formulations which are unstable at pH of less than 3.5.⁴²Park YK De Santi MSS Pastore GM. Production and characterization of β-galactosidase from Aspergillus Oryzae. Journal of Food Science 1979;44(1):100-103.  

Several studies conducted in the past in different populations have shown that lactose supplementation is an effective available way to increase the dairy consumption and promote health of lactose intolerant people.⁴³He M Yang Y Bian L et al. Effect of exogenous lactase on the absorption of lactose and its intolerance symptoms. Wei Sheng Yan Jiu. 1999;28(5):309-11.   Furthermore it is also likely to prevent complications of reduced calcium intake vitamin deficiency and to ensure a better quality-of-life. In an Asian study investigators evaluated the effects of exogenous lactase on lactose malabsorption and its intolerance symptoms and to identify the available way to improve lactose absorption.⁴³He M Yang Y Bian L et al. Effect of exogenous lactase on the absorption of lactose and its intolerance symptoms. Wei Sheng Yan Jiu. 1999;28(5):309-11.   Healthy adults with a history of lactose intolerance were screened by 25 g lactose tolerance test and those with higher hydrogen expired and/or lactose intolerance symptoms were selected for evaluation. These selected individuals were challenged twice with “400 ml low fat milk” and “400 ml low fat milk + 9000Fcc lactase” separately in three days interval. Concurrently breath hydrogen concentration and intolerance symptoms were tested in four hours following the challenge. The results of the study showed that exogenous lactase administration could significantly decrease the incidence of lactose malabsorption (the abnormal expiration of hydrogen decreased from 100% to 48.9%; figure 7) and milk intolerance symptoms (from 51.1% to 13.3%; figure 8). Overall the study thus potentiated that lactose malabsorption and symptoms of intolerance result from the reduced enzyme activities of individuals and that exogenous lactase supplementation can improve this lactose absorption and intolerance symptoms.

Sanders et al⁴⁴Sanders SW Tolman KG Reitberg DP. Effect of a single dose of lactase on symptoms and expired hydrogen after lactose challenge in lactoseintolerant subjects. Clin Pharm. 1992;11(6):533-8.   investigated the effect of a single dose of oral lactase on symptoms breath hydrogen concentration and glucose absorption in lactoseintolerant subjects challenged with lactose. The findings showed that single doses of a chewable lactase tablet were able to reduce the concentration of expired hydrogen and symptoms of lactose intolerance after a lactose challenge. Subjects of the study included volunteers whose breath hydrogen concentrations increased > 20 ppm on a lactose challenge test and who met other admission criteria as well. After fasting subjects were given three chewable lactase tablets or placebo tablets in a randomized double-blind crossover manner. In addition subjects also consumed ~236 ml of whole milk in which 37.5 g of lactose powder was dissolved (total lactose content 50 g). There was at least one week washout period between the lactose challenges. For evaluation breath hydrogen and plasma glucose concentrations were measured before and at intervals after the challenges. Moreover subjects were asked to complete symptomevaluation questionnaires every 8 hours for 4 days. Overall a total of 24 subjects completed the study. The results showed that the maximum mean breath hydrogen concentration was significantly lower after lactase treatment than after placebo treatment. In 21 subjects the area under the hydrogen concentration-time curve was found to be lower after lactase than after placebo. There were no significant differences in the plasma glucose levels. Furthermore subjective ratings of the symptoms’ severity (abdominal cramping belching flatulence and diarrhea) were noted to be lower during the first eight hours after challenge in lactase-treated subjects; ratings for bloating were lower during the next eight hours as well.

In another study Portincasa et al⁴⁵Portincasa P Di Ciaula A Vacca M et al. Beneficial effects of oral tilactase on patients with hypolactasia. Eur J Clin Invest. 2008;38(11):835-44.   tested the effectiveness of single ingestion of a lactase preparation in adults with hypolactasia previously assessed by lactose H2-breath test. A total of 134 subjects – positive to hypolactasia – underwent lactose H2-breath testing [performed by administering 500 mL of cow’s whole milk (25 g of lactose)] plus either placebo or low (6750 U) or standard (11250 U) doses of the lactase. Of the 134 subjects 25 subjects were lactose malabsorbers and 109 were lactose intolerant. A small subgroup of intolerant subjects underwent lactose breath test with both the doses. Appearance of gastrointestinal symptoms was monitored during the tests. The results showed that after lactase ingestion there was a time-dependent change of H2 in breath (figure 9) and integrated H2 levels were decreased by 74% (low dose) and 88% (standard dose) in intolerants (n=109). Lactase ingestion (both doses) resulted in a significant decrement in symptom score with total the total symptom score decreasing by 76% (low dose) and by 88% (standard dose). The authors thus concluded that a single oral administration of lactase is highly effective in decreasing the symptoms and hydrogen excretion of hypolactasia assessed by lactose H2-breath test. Ingestion of lactase might therefore be a better option than exclusion diets in intolerant subjects with hypolactasia.

The above mentioned studies seem to clearly suggest that lactase supplementation with milk and dairy products could be an effective strategy in correcting the lactose maldigestion and may represent a convenient approach in milk/ lactose intolerance.⁴⁶Rosado JL Solomons NW Lisker R et al. Enzyme replacement therapy for primary adult lactase deficiency. Effective reduction of lactose malabsorption and milk intolerance by direct addition of betagalactosidase to milk at mealtime. Gastroenterology. 1984;87(5):1072-82.  

Lactase supplementation in secondary lactose intolerance

Lactase deficiency also occurs in various gastrointestinal diseases. In acute situations like acute gastroenteritis and in chronic conditions like irritable bowel disease inflammatory bowel disease Coeliac disease and many other conditions there is decrease of lactase enzyme as there is destruction of intestinal lining (epithelial cells). Patients are unable to digest milk and are often advised to restrict milk and dairy products. Avoidance of milk and dairy products impairs the quality-of-life in these patients. External lactase enzyme is an exceptionally good option in these situations. It helps patients to take milk and dairy products.

Conclusion

Lactose intolerance is a common problem worldwide that occurs due to deficiency of the gastrointestinal lactase enzyme. The burden of the disease may be typically higher in Asia where most individuals may have some sort of lactase deficiency and are unable to digest lactose present in milk and milk products. While diagnosis of lactose intolerance can be made by clinical history and supported by findings of breath hydrogen or lactose tolerance test the management typically initiates with dietary modulation. Patients are often advised or they try to reduce or stop their intake of milk and other dairy products. Nevertheless such a practice of restriction of milk ingestion is not rational since many patients may tolerate adequate amount dependent on their symptoms’ threshold. Moreover avoiding dairy products may lead to nutritional deficiency and poor quality of life of these patients. Oral supplementation of exogenous lactase enzyme is an important adjunct to dietary restriction approach that seems to ensure efficacy at any level of lactose intolerance. Source of lactase impacts the pH stability of final preparation which decides the dosage efficacy safety and cost. The good source is Aspergillus oryzae. European Food Safety Association (EFSA) and United States Food and Drug Administration (USFDA) both approve and recommend Aspergillus oryzae. Lactase from Aspergillus Oryzae source is considered GRAS (Generally Regarded as Safe). Lactase preparations from Aspergillus oryzae are stable in an acidic environment and are practically pH independent. High activity throughout the GI tract even in lower stomach where pH is less than 3.5 is unlike other formulations which are unstable at pH of less than 3.5. While lactase enzyme supplementation decreases the symptoms of bloating abdominal pain and disturbed bowel movement in majority of patients with lactose intolerance this may also possibly alleviate certain long-term consequences of diary restriction that people begin to follow while suffering from self-perceived or real lactose intolerance. Several evidences have shown the benefits of enzyme supplementation in patients with lactose intolerance. Lactase enzyme prevents the symptoms of lactose intolerance (abdominal pain and bloating) and disturbed bowel movement) by up to 88%.

References

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