This issue was sponsored by Abbott Laboratories S.A (PTY) LTD All Abbott products are lactose and gluten free Tel: +27 (0)11 8582054

 

Contents A. Case study B. More information C. Editors' comments D. References E. CPD questions

Index

A. Case study
A 20-year-old student presented to his general practitioner (GP) with a 3-day history of vomiting and severe diarrhea. Based on a stool culture, a bacterial infection was diagnosed and the student was treated with the correct antibiotic. As the student found that eating yoghurt and drinking milk worsened his diarrhea, the doctor advised milk avoidance until the diarrhea had settled. The diarrhea started improving 3-4 days later, and he seemed to have recovered (stools had normalised, and his appetite had returned) once his 7 day course of antibiotics was complete.

On his first day back on campus, he had a cafeteria lunch, which consisted of a tuna mayonnaise sandwich, yoghurt and a cup of coffee with milk. That afternoon, he had some abdominal cramping but attributed it to hunger pangs. To alleviate the pain, he ate a slab of chocolate and drank 250 ml of flavored milk. Approximately 1-2 hours later, the cramps worsened and he developed diarrhea.

WHAT COULD THE CAUSE BE?
• He may have had a second infection, or may not have completed treatment for the first infection.
• The food at the cafeteria may not have been fresh, resulting in food poisoning.
• He had had an allergic or intolerance reaction to something which he had ingested.

He went back to the doctor, concerned that he had another “stomach bug”. Stool cultures came back negative. He had no history of previous food or environmental allergies. After discussing his intake that day, the doctor preliminarily attributed the manifestation to lactose intolerance secondary to his previous diarrhea and antibiotic therapy. He was advised to eliminate all milk and dairy products for approximately 5-7 days.

QUESTIONS AT THIS POINT:
Why did the doctor make this suggestion?

After a bout of severe diarrhea, the intestinal mucosa and the villi tend to be damaged. The degree of damage varies depending on the severity and duration of the diarrhea. Lactase is situated in the villi. The damaged villi and mucosa need to repair themselves before lactase can be replenished. Presumably, the student’s villi had not been repaired adequately, and not enough lactase had been produced since his infection for him to tolerate the milky coffee, yoghurt, drinking milk and chocolate on that day.

WHAT CAN BE DONE AT THIS STAGE?
Advise the student on milk- and dairy-containing foods to be avoided. To make the transition easier, a lactose-free milk substitute (soya, rice, oat milk) could be an alternative.

After a week, the patient should gradually reintroduce dairy-containing foods, starting with lower-lactose options, e.g., cheese and yoghurt.

The student did as he was told, and the diarrhea and cramps resolved. He managed to reintroduce dairy foods and was able to follow his usual routine again. Two weeks later, he revisited the GP again with diarrhea, severe cramping and bloating.

QUESTIONS AT THIS POINT:
• Is this a new or ongoing infection?
• Is this possibly food poisoning?
• Could the symptoms be a result of irritable bowel syndrome?
• Is this a previously undocumented intolerance?

After ruling out food poisoning and infection, the evaluated the student’s diet and lifestyle. He had started drinking a flavoured milk, which was new on the market, almost daily in between lectures. He was of black African heritage, and a primary lactase deficiency was suspected. However, the student was not convinced and enquired why he had previously been able tolerate milk in his coffee, and had been able to eat chocolate and yoghurt on various occasions.

POSSIBLE REASONS:
Being of black African descent, he had always had an underlying primary lactose intolerance, with a particular threshold. The diarrhea had resulted in damage to the villi and therefore affected lactase production, precipitating intolerance at a lower threshold level. Once the lactase had been adequately replenished, he could once again tolerate amounts of lactose lower than his normal threshold, but when he increased the intake of lactose with more frequent drinking of milk, symptoms developed again.

SUGGESTIONS:
He should determine his individual threshold for lactose tolerance, so that he can still ingest calcium-rich dairy products without inducing clinical reactions.

TIP for Allergy Advisor users: To find a list of lactose levels in foods, click on the “Substances” tab, select “Other substances” and then “Lactose” in the top left of the window that pops up. The bottom left lists all food categories for which there are lactose levels to ease your search. The list can be used as a guide assessing the probability of whether a patient has lactose intolerance. If you click on “More info” in the top right of the window, it will open up information on lactose, including background information and all adverse reactions that have been reported to lactose. The references for all information are fully referenced.

B. More information:
Adverse reactions to cow’s milk can be divided into the following:

i. Immune reactions: • IgE-mediated • Non-IgE-mediated ii. Non-immune reactions – intolerance: • Enzyme deficiency (congenital, primary and secondary) • Maldigestion • Metabolic abnormalities • Psychological aversion

The focus of this newsletter is on the non-allergic, non-immunological condition of lactose intolerance.

Distinguishing between cow’s milk allergy and lactose intolerance
Although cow’s milk allergy and cow’s milk intolerance are different conditions, the terms are often used interchangeably, resulting in confusion in clinical practice. Cow’s milk allergy is an immunologically-mediated reaction to cow’s milk proteins that may involve the gastrointestinal tract, skin, respiratory tract or multiple systems, i.e., systemic anaphylaxis. Dietary elimination is associated with good prognosis, and the allergy in childhood is usually outgrown. Cow’s milk intolerance refers to non-immunological reactions to cow’s milk such as disorders of digestion, absorption or metabolism of certain cow’s milk components. It is generally a benign condition, with symptoms limited to the gastrointestinal tract. The most common cause of cow’s milk intolerance is lactase deficiency, and the condition may be life-long.¹

Summary of differences between cow’s milk allergy & lactose intolerance:^1,2

What is lactose and where is it found?
Lactose is the sugar found in milk and dairy products. It is a disaccharide, i.e., two sugar molecules joined together. The lactose molecule is too large to pass through the cells lining the digestive tract and requires the digestive enzyme lactase to split it into the monosaccharides glucose and galactose so that it can reach the circulation and be used as an energy source by the body.^2,3,4,5

Lactose content in dairy foods varies and may be influenced by the manufacturing process (heating, hydrolysing, fermentation):^5,6

Epidemiology and pathogenesis of lactose intolerance/lactase deficiency
Lactose intolerance means an inability to digest lactose because of a deficiency of the enzyme lactase. Lactase is located in the villus enterocytes of the small intestine. Virtually every baby has enough lactase to digest the lactose in its mother’s milk at birth. Lactase deficiency in infants is uncommon because lactose is the principle sugar in human milk and the baby needs lactase in order to digest lactose. Most adults lose some degree of lactase activity after puberty.^{2,3,4,5,6,7,8,9,10}

There are 3 main types of lactase deficiency:^2,5,9
1. Congenital: rare genetic abnormality; lactase is low or absent at birth
2. Primary: most common; due to normal physiological process leading to reduced intestinal lactase
3. Secondary: usually temporary; low lactase levels due to an underlying disease or medication affecting of the gastrointestinal tract

Primary lactose intolerance is the most common carbohydrate intolerance and tends to affect all age groups. Clinically, however, it usually only becomes evident at puberty or late adolescence. Lactose, not hydrolysed to glucose and galactose or only partially digested, remains in the gut and acts osmotically to draw water into the intestines. Colonic bacteria ferment the undigested lactose, generating short-chain fatty acids, carbon dioxide, hydrogen and methane gas.^{2,3,4,5,6,7,8,9,10}

Approximately 75% of the world’s population are affected by the primary condition. Lactase deficiency is present in up to 15% of people with Northern European descent, 80% of blacks and Latinos, and up to 100% of Asians and American Indians. Typically, lactase activity declines with the initiation of complementary feeding, and in early childhood goes down to about 10% of the neonatal level. Age of onset varies among population groups. The disease may occur in early childhood (2-5 years) in Black and Asian groups, but symptoms tend to appear after childhood, during adolescence. Adult onset lactose intolerance is the most common type of lactase deficiency. Yet up to 75-85% of white adults of Northern European descent and some ethnic groups in India, Africa and Mongolia retain high levels of lactase, although it remains half that of the other saccharidases.^{2,3,5,7,8,10,11}

Maintenance of the lactase enzyme into adulthood is attributed to inheritance of an autosomal-dominant mutation that prevents the maturational decline of lactase expression. This genetic mutation is thought to be evolutionary, having developed 10 000 years ago, when dairy farming was first introduced. The mutation possibly occurred in more than one location and then spread throughout the world with population migration. The highest incidence of lactose tolerance is in Sweden and Denmark (97%). In these extreme northern countries, there is limited skin exposure to sunlight and vitamin D, which inhibits calcium absorption. Lactose favours calcium uptake, and therefore a lactose tolerance in these areas would have provided a selective advantage for better health, reproduction and survival.^3,7,8,12

Secondary lactase deficiency is a transient condition that develops secondary to bacterial or viral infection of the small intestine or conditions causing destruction of the gut mucosal epithelial, where lactase is normally active. It is most commonly caused by gastroenteritis and severe diarrhoea, AIDS or giardiasis, which typically damage the intestinal villi, thus reducing lactase activity. The condition may require dietary manipulation or gut rest in severe cases. Strong oral drugs and medication such as antibiotics may also damage the epithelial cells. Regular lactase activity will resume once the cells have been able to repair themselves.³

Colonic flora are also very important in the condition. Colonic adaptation occurs to some sugars that remain undigested from the small intestine (non-digestible oligosaccharides, lactulose). Lactulose ingestion decreases the colonic pH, thus increasing hydrogen excretion. This higher fermentative capacity may lead to a reduction in lactose intolerance symptoms.^6,13

Clinical manifestations and symptoms
The undigested lactose molecules and products of bacterial digestion result in predominantly gastrointestinal symptoms, including diarrhoea, bloating and distension, flatulence and abdominal pain. In general, the symptoms are non-specific, highly individual and mild. Persistent, severe gastrointestinal symptoms may indicate another disorder.^2,4,5,7,11

The severity of symptoms varies with the amount of lactose, the conditions under which lactose is consumed, and the ability of the patient to tolerate the lactose load. Onset of symptoms is usually between 30 minutes and several hours after consuming lactose-containing food or drink. A person with low lactase levels does not necessarily develop intolerance or symptoms after lactose intake. Remember that tolerance of lactose is influenced by dietary and non-dietary factors (ethnicity, race). Psychological and physiological factors can also contribute to gastrointestinal symptoms that mimic the condition.^2,4,5,7,11

Diagnosis and laboratory tests
Diagnosis of lactase deficiency is made on the basis of:^{2,3,5,7,11,12}
1. a history of gastrointestinal symptoms, occurring after and aggravated by milk ingestion
2. response to an empirical trial of dietary lactose reduction or avoidance
3. a breath test demonstrating abnormal hydrogen levels
4. an abnormal lactose tolerance test
5. stool sample for reducing substances
6. small intestinal biopsy to assess direct lactase enzyme activity

Hydrogen breath test This test is considered the gold standard for diagnosing lactose intolerance. It is simple, safe and non-invasive. The standard dose varies from the physiological dose of 12.5 g lactose (1 cup milk) to the tolerance test dose of 50 g lactose (1 litre milk) and should attempt to closely approximate the usual consumption of lactose in milk products. It will lead to increased intestinal hydrogen production in intolerant individuals. The test will show a high fasting hydrogen value and, 60 minutes after lactose ingestion, a secondary rise. An increase of > 10-20 ppm above the baseline value has been selected as the cut-off point. Some studies show a poor correlation between lactose maldigestion and intolerance; low hydrogen exhalation may occur without significant improvement of clinical symptoms. The test is also not lactose-specific, as any undigested sugar in the intestine will be fermented by bacteria and produce hydrogen.2,3,10,14,15

Lactose tolerance test
In lactose intolerance, an oral dose of less than 50 g lactose will cause an increase in blood glucose less than 25 µg/100 ml above the fasting level, and gastrointestinal manifestations. Little or no increase in blood glucose indicates that lactose has not been broken down.^3,10

Fecal reducing sugars
This test is considered very reliable. After ingestion of a lactose-containing drink, a stool sample is collected and Fehling’s solution is added. The presence of lactose will cause a change in colour from blue to red. A simple kit is available to perform this test.¹⁰

Fecal pH test
Stools collected after ingestion of a lactose-containing drink will be acidic (< pH 6) in cases of intolerance. This indicates fermentation of undigested sugars by the colonic bacteria.¹⁰

For absolute confirmation, a double blind placebo controlled food challenge should be done. This helps identify individuals who may be convinced of intolerance despite normal lactase levels and no symptoms after reasonable lactose intakes.²

Treatment & management
Symptoms are alleviated by complete elimination or reduced consumption of lactose-containing foods. Most lactose-intolerant adults can consume some lactose without major symptoms, thereby reducing the need for strict elimination of dairy. Regular milk consumption in some lactose-intolerant individuals has been found to increase the threshold tolerance level at which diarrhea occurs due to colonic adaptation.^2,3,9,16

Tolerance seems to be improved with yoghurt (which may have bacterial culture containing beta-galactosidase to facilitate lactose digestion) or other cultured dairy products, and when lactose foods are eaten as part of a meal. Fermentation of dairy products breaks down much of the lactose into its monosaccharides. Frozen yoghurt is not well accepted, as the microbial enzyme is destroyed by freezing. In general, dairy products that tend to be better tolerated include more-solid and semi-solid forms such as cheeses (which cause delayed and slower gastric emptying).^{2,3,6,12,15,17}

Commercial forms of lactase enzyme exist in both liquid and tablet forms (Liquid Lactase, Lactaid), and various milk products have been treated with lactase (Parmalat Zymil) to facilitate better digestion of dairy products and ultimately a less restrictive diet. There appears to be no need for these preparations when the dosage of milk is limited to 1 cup.^2,3,10,16,18

Soy-based infant formulas are the milk substitute of choice in lactose-intolerant infants, due to the formulas’ palatability and affordability. Modern soy formulas also meet all the nutritional requirements and safety standards of the Infant Formula Act of 1980. Regarding concerns about the isoflavones present in these formulas, the evidence from both adult and infant human populations indicates that the dietary isoflavones in soy infant formulae do not adversely affect human growth, development and reproduction.¹⁹

If dairy products are eliminated, it should be kept in mind that they are excellent sources of calcium (provide 3/4 dietary calcium consumed), phosphorous, magnesium, vitamin A, riboflavin and protein. Adequate nutrition must be provided both in growing children and in adults to ensure appropriate bone growth, development and mineralization, and to avoid rickets and osteoporosis. Traditionally, relationships have been observed between lactose maldigestion and low levels of dietary calcium on the one hand, and osteoporosis in Caucasian populations on the other. Although research in ethnically diverse populations is limited, there appears to be an increased risk for osteoporosis in Hispanic-American and Asian-American populations who have low calcium intakes or extensive lactose intolerance.^2,3,20,21,22

Dietary management items to increase calcium consumption in lactose-intolerant groups should include:
1. dairy foods consumed with meals
2. yoghurt and other fermented dairy products
3. calcium-fortified foods
4. digestive aids
5. dairy foods daily in the diet to enhance colonic metabolism of lactose

Good non-dairy sources of calcium, phosphorous, magnesium and protein include soya milk, soya yoghurt, tofu, canned fish (including the bones), seeds and nuts, beans and other legumes, dark green leafy vegetables and oranges. Some breakfast cereals and fruit juices are fortified with calcium. Additional calcium supplementation is suggested in lactose-intolerant individuals to achieve the recommended daily calcium intake of 1000-1300 mg/day for adults. Individuals also need to obtain adequate vitamin D from moderate sunlight or vitamin D-enriched foods, e.g., margarine.^{2,3,5,9,10,20,21,22}

Lactose-containing medication and vitamin supplements as well as certain sweeteners and other additives may pose a problem for severely intolerant individuals.²⁰

Public misunderstanding of lactose intolerance is at an all-time high. Scientific findings indicate that the prevalence of actual intolerance is grossly overestimated, and that many people erroneously believe they develop intolerance symptoms after the intake of dairy products, which they then eliminate unnecessarily from the diet. Unrelated psychologic and physiologic factors can contribute to gastrointestinal symptoms that mimic the condition.²

One recent study suggests there is a concerning increase in individually self-described “lactose intolerance”, with subsequent restriction of dairy and calcium intake. These individuals have demonstrated reduced peak bone mass, increased incidence of osteopenia and greater risk of osteoporosis and bone fractures. Food challenges may be helpful in these cases, as seen in a study where individuals with self-reported lactose intolerance did not differ in response to milk chocolate samples containing different amounts of lactose. It is necessary that health professionals alleviate clients’ fears about lactose intolerance, discuss the importance of calcium-rich foods and recommend dietary strategies to improve lactose tolerance only when intolerance is clinically proven.^2,12,23,24

In 2 other reports of lactase-deficient individuals, 1/3 and 1/2 of the lactose-intolerant subjects in the respective studies experienced symptoms to both a lactose-containing and a lactose-hydrolysed milk under double-blind conditions, further highlighting the influence of social and cultural beliefs and attitudes concerning milk tolerance.^25,26

Dairy products with added probiotics (Lactobacillus and Bifidobacterium species) may modulate gut microbial composition, leading to improved gut health. Probiotics may improve symptoms of lactose intolerance; however, more research is needed regarding their possible therapeutic application in this condition.^3,12,27

a. Fermentation, fermented foods and lactose intolerance
Yoghurt and other fermented milk products improve lactose digestion and eliminate symptoms of lactose intolerance. Yoghurt with lactic acid-producing bacteria (including Lactobacillus & Streptocuccus species) has showed health benefits for lactose intolerance in some studies. These beneficial effects are due to microbial beta-galactosidases present in the fermented milk products, delayed gastrointestinal transit, positive effects on intestinal functions and colonic microflora, reduced sensitivity to symptoms and enhancement of gastrointestinal innate and adaptive immune responses.^{2,6,15,16,17,28,29}

Inconsistency in reported results may be due to differences in bacteria strains used, routes of administration, or varying investigative procedures. Further well-designed, controlled human studies of adequate duration are needed to confirm the ultimate beneficial effect of yoghurt consumption on gastrointestinal health in general and lactose intolerance in particular.¹⁷

b. How much lactose can be tolerated? What does the literature say?
Lactose intolerance is dose-related; however, the degree of lactose malabsorption differs greatly among individuals, and a positive diagnosis does not mean that all lactose-containing dairy foods need to be eliminated. Often a diagnosis or even a suspicion of lactase deficiency leads people to unnecessarily avoid milk and milk products or to consume these foods only with lactose digestive aids. Most lactose-intolerant adults can consume some lactose without major symptoms, but the literature expresses differing views on how much is needed to cause actual clinical symptoms.^2,3,10

Age and the size of the individual will also affect the actual amount of lactose that can be tolerated before symptoms develop; e.g., a 6-year-old child of 12 kg is unlikely to tolerate the same amount of milk that can be safely consumed by a 60 kg adult with the same degree of intolerance severity.

Symptoms of lactose intolerance seem rarely to cause distress until more than 4-12 g lactose (in 100-240 ml milk) is ingested. Consumption of quantities greater than 12 g (equivalent of 240 ml of milk) usually leads to bloating, flatulence, abdominal cramps and diarrhea. Adults with more moderate intolerance may be able to adapt, developing tolerance to more than 12 g lactose if amounts are increased gradually over 6-12 weeks.3,12,16 Most lactose-intolerant people can ingest 200-400 ml of milk daily without symptoms. Symptoms tend to occur after large quantities of lactose (>50 g) are taken in a single dose. These individuals can consume cheese without lactose (hard & semi-hard cheese) or low in lactose (lactose is only 10% of soft cheese).4,11,30,31 Yoghurt contains less lactose than milk and is often well tolerated, as previously mentioned.31

Scientific findings indicate that people with laboratory-confirmed low levels of lactase enzyme can consume 1 serving of milk (1 cup = 12 g lactose) with a meal or 2 servings of milk (2 cups) per day in divided doses with breakfast and dinner without experiencing symptoms. Researchers concluded that people who describe themselves as severely “lactose intolerant” may mistakenly attribute a variety of abdominal symptoms to lactose intolerance. A lactose intake limited to approximately 1cup of milk (240 ml) leads to negligible symptoms, and use of lactose digestive aids are unnecessary.^2,32

In an attempt to determine whether lactose maldigesters could consume a usual lactose intake, i.e., 2 cups of milk per day with meals, a double-blind, randomised crossover study was conducted in 2 groups with confirmed positive hydrogen breath tests: those who believed they were symptomatic and those who believed lactose intake did not induce symptoms. Both groups reported only minimal symptoms after intake of regular or lactose-free milk, leading the researchers to conclude that most self-described lactose-intolerant subjects can easily tolerate 2 cups of milk daily when consumed in divided doses with breakfast and dinner.^2,33

Controlled trials in unselected lactose malabsorbers or subjects claiming severe lactose intolerance indicate that symptoms from a cup of milk are no greater than from a cup of a lactose-hydrolysed control. An increasing fraction of subjects experience symptoms as the lactose load is increased, with the majority having symptoms when the equivalent of 1L of milk is ingested in a single dose.¹⁸

Another study demonstrated the large psychological element in manifestation of symptoms. From lactose at doses ranging from 0-7 g, there were no differences in symptoms between subjects who consumed 7 g of lactose and subjects who consumed no lactose. All subjects demonstrated symptoms of malabsorption, which can be attributed to a placebo effect, whereby people reported symptoms without ingesting the substance thought to cause the symptoms.⁶

The essence of lactose intolerance is the relationship between the amount of lactose ingested and the symptoms shown: the more lactose ingested, the more lactose will be malabsorbed, and the greater the symptoms will be. But ingestion of low levels of lactose (below 7 g) produced no difference in non-specific intolerance.⁶

The high incidence figures for primary lactose maldigestion among various groups grossly misrepresent the number who will experience intolerance symptoms after drinking a glass of milk with a meal. Randomised, double blind, controlled clinical trials have demonstrated that by using a few simple dietary strategies, those who maldigest lactose can easily tolerate a dairy-rich diet that meets calcium intake recommendations. Health professionals can help these patients and the general public understand how to improve calcium nutrition by overcoming the mythology around lactose intolerance and in so doing reduce the incidence of calcium-related chronic diseases in high-risk populations.^12,34

Lactose intolerance may offer protection against large bowel diseases
Research has found a lower incidence of “developed society” large bowel diseases such as diverticulitis, colorectal adenomas and carcinomas, ulcerative colitis and Crohn’s disease in African black people. This disparity exists despite an adopted urbanised lifestyle and changes in dietary patterns by many black Africans. Dietary fibre intake has also decreased from 30-35 g to 12-14 g daily.³⁵

It is hypothesised that the increased concentration of substrate available for fermentation in the colon due to carbohydrate malabsorption in this group, compensates for the low dietary fibre intake. This would be protective of the large bowel, and helpful in the prevention of large bowel disease in the African population.³⁵

Controversial areas
Symptoms of irritable bowel syndrome (IBS) resemble the non-specific reactions of lactose intolerance. Subjects with IBS tend to self-diagnose lactose intolerance and eliminate dairy without evidence that the foods in question are solely responsible for symptoms. Research suggests that a lactose-restricted diet should be reserved for patients who demonstrate symptoms of diarrhoea, abdominal pain and flatulence during hydrogen breath testing, irrespective of what was previously reported. Certain individuals may benefit occasionally from a reduced lactose load; however, this should not be general practice in IBS patients. These patients should be reassured that small amounts of lactose are unlikely to cause abdominal symptoms even in lactose-intolerant individuals with demonstrated symptoms.^16,36

Infantile colic has been linked to lactose intolerance, but research remains inconclusive. Although there is no consensus as yet about the disease’s aetiology, it is likely to be multifactoral. Two randomised controlled trials found no benefit from lactase treatment of breast milk or cow’s milk formula. One double-blind placebo-controlled study found a modest but variable benefit from pre-incubation of foods with lactase. As yet, low lactose or lactose-free formulas or pre-treatment of feeds with lactase are not recommended as treatment for colic.⁴

Inflammatory bowel disease (Crohn’s and ulcerative colitis) are commonly treated with exclusion of dairy products; however, most affected people are able to consume a glass of milk daily without discomfort. The prevalence of lactose intolerance tends to be greater in Crohn’s patients with small bowel involvement than in those with colon involvement or ulcerative colitis. In the latter colonic conditions, lactose malabsorption results from ethnic/genetic factors. Also, lactose malabsorption in Crohn’s disease of the small bowel may be caused by factors other than lactase enzyme activity, such as bacterial overgrowth and/or small bowel transit time. Despite these facts, dairy avoidance in these patients is extensive and can be attributed to patient misconceptions as well as poor medical advice and minimal nutritional consultation. It is suggested that all IBD patients receive hydrogen breath tests to ensure better nutritional management and avoid unnecessary dairy elimination and prescription of commercial lactase preparations.³⁷

Conflicting evidence exists as to whether any link exists between lactose intolerance and an increased risk of cataract formation, development of diabetes and ovarian cancer.¹²

Compiled by Gina Stear RD(SA) Private Practising Food & Allergy Consulting & Testing Services (FACTS) PO Box 565 Milnerton 7435 South Africa

C. Comments by our editors

Prof Janice M. Joneja Ph. D., RDN Lactose intolerance is a condition that is often puzzling, because there are so many variables that influence the development and severity of symptoms, even within a specific individual. The quantity of lactase being produced by the intestinal villi; the amount of lactose entering the digestive tract; whether the lactose intolerance is due to maldigestion or malabsorption of the sugar; the types of microorganisms in the large bowel; and the composition of food material consumed with the lactose, are some of the factors that influence the onset and intensity of symptoms. Persons with reduced lactase activity can treat their lactose-containing foods and beverages with lactase in the form of a liquid, or consume tablets or capsules of lactase to augment their own lactase sufficiently to be able to tolerate the lactose they consume. However, contrary to popular belief, the quantity of lactase produced by brush-border villi cannot be increased. The observation that gradually increasing the quantity of lactose-containing products in the diet of lactose-intolerant individuals serves to boost their lactose tolerance is explained by the observation that the diet is providing a nutritional substrate for micro-organisms in the large bowel that are capable of fermenting lactose and other constituents of milk. This will result in an increase in the numbers of such bacteria, and therefore will reduce the amount of lactose in the large bowel and normalize the osmotic pressure therein. Increased osmotic pressure within the bowel is a major factor in the development of the symptoms of lactose intolerance. It is important to understand that it is not necessary for anyone suffering from lactose intolerance to avoid milk and milk products, unless they are also allergic to milk proteins. It is only the lactose that needs to be eliminated. This is especially important in infant feeding. Soy-based infant formulas should not be used in the management of lactose intolerance. Some clinicians recommend the use of soy-based formulas when cow’s milk protein allergy precludes the use of milk-based formulas, but even in these cases, many paediatricians greatly prefer the extensively hydrolysed casein formulas such as Enfamil Nutramigen (Mead Johnson), or Alimentum (Ross); both of these formulas are lactose-free and are therefore also suitable for infants with lactose intolerance. When cow’s milk protein allergy is not a concern, lactose-free cow’s milk based formulas such as Enfalac LactoFree (Mead Johnson) should be used to manage lactose intolerance.

Dr. Harris Steinman M.B.Ch.B. Many patients attribute symptoms following milk ingestion to milk allergy when in fact these individuals are lactose intolerant. An elimination diet for milk allergy is more constricting on an individual than one for lactose intolerance. Pathophysiological effects of constant intake of milk proteins are generally more harmful in the medium or long term than that of lactose. It is therefore important to differentiate between these two conditions before any dietary intervention.

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27. Monalto M et al. Probiotics: history, definition, requirements and possible therapeutic applications. Ann Ital Med Int. 2002 Jul-Sep; 17 (3): 157-65
28. Stanton C et al. Market potential for probiotics. Am J Clin Nutr. 2001 Feb; 73 (Suppl 2): 476S-483S
29. Solomons NW. Fermentation, fermented foods and lactose intolerance. Eur J Clin Nutr. 2002 Dec; 56 (Suppl 4): S50-55
30. de Vrese M et al. Lactose in human nutrition. Schweiz Med Wochenschr. 1998 Sep 19; 128(38): 1393-400
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32. Suarez FL et al. A comparison of symptoms after consumption of milk or lactose-hydrolyzed milk by people with self-reported severe lactose intolerance. N Engl J Med. 1995; 333: 1-4
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36. Vernia P et al. Self-reported milk tolerance in irritable bowel syndrome: what should we believe? Clinical Nutrition 2004; 23: 996-1000
37. Dairy sensitivity, lactose malabsorption and elimination diets in inflammatory bowel disease. Am J Clin Nutr 1997; 65: 564-7

E. CPD Questions (For South African dietitians only. Australian dietitians: where you have relevant learning goals, CPD hours related to this resource can be included in your APD log.)

4. Dietary treatment of lactose intolerance involves complete avoidance of milk and milk-containing products in all cases.
(a.) True
(b.) False

5. Yoghurt may contain what component that facilitates lactose digestion?
(a.) Alpha-galactosidase
(b.) Lactase
(c.) Sucrase
(d.) Beta-galactosidase
(e.) None of the above

6. Carbohydrate malabsorption in black African populations may be protective against:
(a.) Diverticulitis disease
(b.) Colorectal adenomas and carcinomas
(c.) Ulcerative colitis and Crohn’s disease
(d.) All of the above
(e.) None of the above

7. Studies have suggested that people with confirmed lactose intolerance can safely consume 1 cup of milk with a meal or 2 cups of milk per day in divided doses with breakfast and dinner.
(a.) True
(b.) False

8. Which of the following can be helpful in rare cases in which a patient is unable to tolerate even small amounts of lactose?
(a.) Commercially available lactose-reduced milk and other dairy products
(b.) The addition of a lactase preparation (liquid) to regular milk and leave overnight
(c.) Taking an oral enzyme replacement tablet, which can withstand the stomach’s acidity, at the beginning of a meal
(d.) All of the above

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This issue was sponsored by Abbott Laboratories S.A (PTY) LTD All Abbott products are lactose and gluten free Tel: 011-8582054