A new type of low-lactose milk. Tolerance by lactose malabsorbers and evaluation of protein nutritional value

Lactose intolerance in children and adults

Lactose is a disaccharide found in milk and dairy products. Children and adults with lactose intolerance are unable to tolerate significant amounts of lactose because of an inadequate amount of the enzyme lactase. The condition occurs in three main types: primary, secondary, and primary adult-type hypolactasia. The use of milk in the diet of these individuals may lead to appearance of the irritable bowel syndrome. In persons with lactose intolerance symptoms include diarrhoea, dominated by abdominal colic, loud peristaltic sounds, increased flatulence and meteorism. A diagnosis of lactose intolerance can usually be made with a careful history, elimination of lactose from the diet, lactose tolerance test, hydrogen breath test and genetic testing. In the absence of appropriate tests in patients with suspected primary adult-type hypolactasia, diagnosis can be made as in patients with food allergy. Treatment is based on the restriction of lactose intake with the use of fermented milk products. However, especially for children, if milk and dairy products are eliminated from the diet, it is important to ensure D vitamin and calcium supplementation.

Dietary approaches to alleviation of lactose maldigestion / Efectos de la dieta sobre la digestión de la lactosa

Because dairy products are a significant source of essential nutrients, elimination of all dairy foods in the diet would be nutritionally unwise and is usually not necessary in the case of lactose maldigestion. About 250 ml milk/d can generally be taken without adverse effects. If milk is taken in combination with solid foods, lactose malabsorption may be reduced by about 50%, probably due to a slower rate of colonic fermentation which may lower gastrointestinal symptoms in lactose malabsorbers. It is well established that, in lactase-deficient subjects, yoghurt is better tolerated than milk. This is only to some extent related to the fact that the lactose content of the products is reduced during fermentation, but is mainly attributed to the fact that the culture organisms- by virtue of being rich in lactase - are able to participate in the hydrolysis of ingested lactose. Up to 20 g of lactose in yoghurt is tolerated well by lactase-deficient persons. The enhanced absorp tion of lactose in yoghurt is explained as a result of the intestinal release of lactase from the yoghurt organisms. Ripened cheese is also tolerated very well by lactose-intolerant persons since virtually all of the lactose present is decomposed to lactic acid and other metabolites.

Clinical implications of lactose malabsorption versus lactose intolerance

The majority of the world's adult population and an estimated 80 million Americans are hypolactasic and hence malabsorb ingested lactose. Although lactose malabsorption is easily identified, less readily assessed is the clinically important question of how often does this malabsorption induce symptoms. This review summarizes: (1) knowledge concerning the etiology and diagnosis of hypolactasia and the pathophysiology of the symptoms of lactose malabsorption and (2) the results of well-controlled trials of the symptomatic response of lactose malabsorbers to varying dosages of lactose and the efficacy of therapeutic interventions to alleviate these symptoms. We conclude that the clinical significance of lactose malabsorption has been overestimated by both the lay public and physicians in that commonly ingested doses of lactose (ie, the quantity in a cup of milk) usually do not cause perceptible symptoms when ingested with a meal. Symptoms occur when the lactose dosage exceeds that in a cup of milk or when lactose is ingested without other nutrients. Simple dietary instruction, rather than the use of commercial products to reduce lactose intake, is recommended for the vast majority of lactose-malabsorbing subjects.

Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration

A meta-analysis was conducted to compare the lactose intolerance symptoms of lactose maldigesters after consuming lactose (as milk, lactose dissolved in water, milk products, or commercial product) with responses after a placebo under masked conditions. An English language MEDLINE search was conducted using the medical subject heading of "lactose intolerance" from 1966 to January 2002. From an initial 1,553 citations, 2 independent reviewers selected 21 studies based on study design (randomized, crossover, blind) and use of an amount of lactose likely to be found in a meal (7-25 g) and a placebo among subjects free of gastrointestinal problems and >4 years old. Mean severity of symptom responses were analyzed as standardized differences, and the presence or absence of a symptom was estimated as pooled incidence differences (ID). For severity of flatulence, the standardized difference was 0.18 (95% confidence interval [CI] -0.16 to +0.52). The CIs for abdominal bloating and pain, degree of diarrhea, frequency of bowel movements per day, and frequency of diarrhea per day also included 0. For abdominal bloating, the ID was 5.9 more people per 100 with symptoms after lactose than placebo (CI -0.07 to +0.19). This same nonsignificant relationship was found for abdominal pain. The ID for diarrhea or loose stools was 0.15 (CI 0.03 to 0.28). Although the incidence of diarrhea was significantly higher, the size of the effect was very small. The results indicate that lactose is not a major cause of symptoms for lactose maldigesters following usual intakes of dairy foods, that is, 1 cup.

Lactose intolerance and self-reported milk intolerance: relationship with lactose maldigestion and nutrient intake. Lactase Deficiency Study Group

BACKGROUND

The relationship between lactose-maldigestion, self-reported milk intolerance and gastrointestinal symptoms has not been clearly defined.

OBJECTIVES

To evaluate: a) the prevalence of lactose maldigestion and lactose intolerance in a sample of the general population taken from a rural center; b) the frequency of self-reported milk-intolerance and its correlation with lactose-maldigestion; c) the influence of lactose maldigestion, lactose intolerance and self-reported milk intolerance on dietary habits and consumption of total calories, protein, and calcium.

SUBJECTS

We studied a randomized sample of the general population in a small center in Sicily. 323 subjects (150 males, 173 females), age range 5 to 85 years (median 44) were included and underwent H2-breath test after 25 g lactose load. The preliminary dietary investigation spanned 7 consecutive days using a printed dietary form and was under the daily control of a team of dietitians.

METHODS

The dietary investigation was completed in the first part of the study and the results were analyzed for nutrient composition by a computerized database. The subjects were then divided into self-reported milk-intolerants and self-reported milk-tolerants and they underwent H2 breath testing; subjects with H2 concentration >20 ppm over the baseline concentration were considered maldigesters and those with one or more symptoms were classified as intolerants.

RESULTS

104/323 subjects (32.2%) were lactose maldigesters but tolerants, while 13/323 (4%) were lactose maldigesters and intolerants. In each age-class group (pediatric, adult, and elderly subjects) only the lactose maldigester and intolerant subjects showed differences in nutrient intake with a significantly lower daily consumption of milk and a lower calcium intake. 49/323 subjects were self-reported milk-intolerants; of these, 26 (53%) were lactose maldigesters but tolerants, 18 (37%) were lactose digesters and tolerants and only 5 (10%) were lactose maldigesters and intolerants. In the whole group of self-reported milk-intolerants, dietary milk consumption was significantly reduced and calcium intake was lower than in all the other subjects studied (320 mg/day vs. 585 mg/day, p<0.05).

CONCLUSIONS

In studies of the general population, the frequency of lactose intolerance is much lower than that of lactose maldigestion. Gastrointestinal symptoms after lactose load in self-reported milk-intolerants are found in only a very low number of these subjects. Furthermore, in these subjects we observed an unnecessary reduction in milk consumption and an insufficient dietary calcium intake.

Effect of low-fat colostrum on fat accretion and lipogenic enzyme activities in adipose tissue in the 1-day-old pig

Fat accretion, body fatty acid (FA) composition and adipose tissue lipogenic enzyme activities were determined in 1-day-old piglets fed during the first day of life sow colostrum that was either normal (control) or low in fat and high in lactose, galactose or glucose as the sole source of carbohydrate. Malic enzyme activity did not change during the first postnatal day while increases (P < 0.01) were found for glucose-6-phosphate dehydrogenase and acetyl-CoA-carboxylase. However, fat accretion was closely dependent on the amount of ingested fat and FA composition of piglets indicates a shift toward that of colostrum, the extent of which was dependent on the amount of ingested fat. Plasma glucose and insulin levels were the highest (P < 0.01) in piglets fed the colostrum high in glucose and plasma free fatty acid (FFA) levels were the lowest (P < 0.01) in piglets fed the low-fat, high-carbohydrate colostra. Liver weight and glycogen concentration were higher (P < 0.01) in piglets fed the colostra low in fat and high in carbohydrate than in those on the control colostrum. It is suggested that synthesis of fatty acids from carbohydrate is negligible in the newborn pig even in the presence of high plasma insulin and low plasma FFA levels. The metabolic fate of carbohydrate is discussed.

Management of lactose intolerance

The management of lactose intolerance comprises two parts: (1) the basic principles of treatment in persons intolerant to a dietary dose of lactose, and (2) main manoeuvres to reduce the lactose content in food, and/or consumption of special products of milk or exogenous lactase enzyme. The tactics of management depend on the type of hypolactasia, the severity of intolerance, and on the age of the patient. Special attention is paid to the development of lactose intolerance in some patients via iatrogenic mechanisms such as certain drugs, gastric surgery and ionizing radiation.