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Acute-feeding and multiple-day studies have demonstrated that milk containing A2 β-casein only causes fewer symptoms of lactose intolerance (LI) than milk containing both A1 and A2 β-caseins. We conducted a single-meal study to evaluate the gastrointestinal (GI) tolerance of milk containing different concentrations of A1 and A2 β-casein proteins. This was a randomized, double-blind, crossover trial in 25 LI subjects with maldigestion and an additional eight lactose maldigesters who did not meet the QLCSS criteria. Subjects received each of four types of milk (milk containing A2 β-casein protein only, Jersey milk, conventional milk, and lactose-free milk) after overnight fasting. Symptoms of GI intolerance and breath hydrogen concentrations were analyzed for 6 h after ingestion of each type of milk. In an analysis of the 25 LI subjects, total symptom score for abdominal pain was lower following consumption of milk containing A2 β-casein only, compared with conventional milk ( p = 0.004). Post hoc analysis with lactose maldigesters revealed statistically significantly improved symptom scores ( p = 0.04) and lower hydrogen production ( p = 0.04) following consumption of milk containing A2 β-casein only compared with conventional milk. Consumption of milk containing A2 β-casein only is associated with fewer GI symptoms than consumption of conventional milk in lactose maldigesters.

Objectives: Consumption of milk has been declining sharply in recent decades, particularly in developed countries. One of the reasons for this decline is the diagnosis or perception of lactose intolerance. The aim of this study was to investigate average consumption of milk and dairy products in the Campania region of Italy, one of the main producers of dairy products in the country., Methods: Individuals aged 18 to 75 y and living in Campania were invited to answer an online questionnaire regarding their average consumption of milk and dairy products. The questionnaire was posted on the public access hospital site, as well as on several Facebook pages of friends and hospital personnel., Results: The study found that 22.2% (260 of 1173) of responders from Campania do not drink milk, and 18.1% (213 of 1173) drink lactose-free milk, mainly because of gastrointestinal symptoms. The vast majority of the sample population chose to avoid consuming milk without undergoing the breath test for lactose intolerance or consulting a doctor. Women and underweight people drink more lactose-free milk than milk containing lactose. The population sample does not avoid dairy products; rather, they seem to be consumed quite frequently., Conclusion: The data support the need for mandatory implementation of a nutritional campaign to increase understanding regarding, for example, unnecessary avoidance of milk and excessive consumption of cheese., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To determine attitudes, beliefs, and barriers related to adequate milk consumption in low-income women ages ≥ 60 years., Methods: Nine focus groups were conducted with a convenience sample of 59 women at congregate meal sites in a metropolitan area. Grounded in Social Cognitive Theory, focus group questions were used to explore personal, behavioral, and environmental factors associated with milk consumption., Results: Key response themes indicated a positive attitude for the taste of milk (except for low-fat), a primary belief that milk was important for bones and health, and a primary barrier of gastrointestinal side effects., Conclusions and Implications: Knowledge regarding the benefits of milk and the dislike of its taste were not the primary reason for the lack of consumption. Instead, gastrointestinal side effects seemed to be the major barrier to adequate consumption. Future nutrition campaigns should test strategies for lactose intolerance management when communicating with low-income older women., (Copyright © 2014 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.)

Discussions and debates have recently emerged on the potential positive and negative effects of cow's milk in the paediatric community, also under the pressure of public opinion. The negative effects of cow's-milk consumption seem to be limited to iron status up to 9 to 12 months; then no negative effects are observed, provided that cow's milk, up to a maximum daily intake of 500 mL, is adequately complemented with iron-enriched foods. Lactose intolerance can be easily managed and up to 250 mL/day of milk can be consumed. Allergy to cow's-milk proteins is usually transient. Atopic children may independently be at risk for poor growth, and the contribution of dairy nutrients to their diet should be considered. The connection of cow's milk to autistic spectrum disorders is lacking, and even a cause-effect relation with type 1 diabetes mellitus has not been established because many factors may concur. Although it is true that cow's milk stimulates insulin-like growth factor-1 and may affect linear growth, association with chronic degenerative, noncommunicable diseases has not been established. Finally, fat-reduced milk, if needed, should be considered after 24 to 36 months. Cow's milk represents a major source of high nutritional quality protein as well as of calcium. Moreover, it has growth-promoting effects independent of specific compounds. Its protein and fat composition, together with the micronutrient content, is suggestive of a functional food, whose positive effects are emphasised by regular consumption, particularly under conditions of diets poor in some limiting nutrients, although in industrialised countries cow's milk's optimal daily intake should be around 500 mL, adequately complemented with other relevant nutrients.

Aim: To estimate the prevalence of the lactase non-persistent genotype (C/C-13910) in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity., Methods: Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints., Results: We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant., Conclusion: An investigation of the lactase persistent genotype in a northern Russian population has not been performed before. The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population.

Summary: Low calcium intake hampers bone mineral acquisition in adolescent girls. This study explores dietary calcium sources and nutrients possibly associated with vertebral mass. Milk intake is not influenced by genetic variants of the lactase gene and is positively associated with serum IGF-1 and with lumbar vertebrae mineral content and density., Introduction: Low calcium intake hampers bone mineral acquisition during adolescence. We identified calcium sources and nutrients possibly associated with lumbar bone mineralization and calcium metabolism in adolescent girls and evaluated the possible influence of a genetic polymorphic trait associated with adult-type hypolactasia., Methods: Lumbar bone mineral content (BMC), bone mineral density (BMD), and area, circulating IGF-1, markers of bone metabolism, and -13910 LCT (lactase gene) polymorphism; and intakes of milk, dairy products, calcium, phosphorus, magnesium, proteins, and energy were evaluated in 192 healthy adolescent girls., Results: After menarche, BMC, BMD, serum IGF-1, and serum PTH were tightly associated with milk consumption, but not with other calcium sources. All four parameters were also associated with phosphorus, magnesium, protein, and energy from milk, but not from other sources. Girls with milk intakes below 55 mL/day have significantly lower BMD, BMC, and IGF-1 and higher PTH compared to girls consuming over 260 mL/day. Neither BMC, BMD, calcium intakes, nor milk consumption were associated with -13910 LCT polymorphism., Conclusions: Milk consumption, preferably to other calcium sources, is associated with lumbar BMC and BMD in postmenarcheal girls. Aside from being a major source of calcium, milk provides phosphates, magnesium, proteins, and as yet unidentified nutrients likely to favor bone health.

Colorectal cancer (CRC) is one of the leading causes of mortality in Western countries. Its putative pathogenesis revolves around genetic and environmental factors, particularly diet. One of the most studied dietary factors, dairy product intake, is still debated as a protective agent. The role of lactose as a candidate prebiotic (stimulating lactic acid bacteria) and its relation to genetic lactase non-persistence (LNP) status has not been evaluated. We undertook a review and analysis of national per capita dairy product consumption, national LNP prevalence, and national CRC mortality rates (CRCM) to determine whether relationships existed among these variables. Data on these three items were obtained from the available literature. A negative binomial regression model was used to compare national LNP status with national CRCM rates for three time periods. Pearson correlation was used to compare national per capita dairy food intake with national CRCM rates for the approximate midpoint time period of reviewed articles. We found that there was a significant positive correlation between per capita dairy food intake and CRCM rates. However, there was also a significant negative correlation between national LNP prevalence and CRCM rates. Population-based studies supported the suggestion that in both homogeneous high and homogeneous low prevalence LNP countries characterized by low and high dairy food intake respectively, dairy food consumption exerted a protective effect against CRC and CRCM rate. Because some population studies contradict the hypotheses that dairy food intake promotes CRC or that LNP status protects against CRC, we hypothesize that dairy food consumption may operate by two distinct mechanisms--one that operates at low doses in LNP subjects and another in high doses in non-LNP subjects.

Introduction: There are inflammatory bowel disease (IBD) patients avoid lacteal products without evidence of lactose malabsorption, probably because of incorrect patient perceptions and arbitrary advice from physicians and diet books., Aim: To evaluate the prevalence of lactose malabsorption in patients with IBP., Method: In 18 patients with Crohńs disease and 24 with ulcerative colitis and 25 controls the prevalence of lactose intolerance, as measured by lactose breath hydrogen tests., Results: Observed deficiencies of absorption of the lactose in 7 (16.6%) patients with IBP and 5 (20%) subjects control., Conclusions: Not all the patients with IBD are intolerant to the lactose by the suppression of the lacteal produts must not be generalized in the diet of these patients.

The disaccharide lactose is present as a natural component of foods only in milk and dairy products. In the gastrointestinal tract, lactose is hydrolysed by the enzyme beta-galactosidase (lactase) into glucose and galactose. These components are absorbed. With the exception of the caucasian race, the lactase activity decreases in most people at an age of 4 to 6 years. Lactose intake can cause symptoms of bloating, flatulence, abdominal pain, and diarrhea due to the lactose reaching the large intestine. This phenomenon is called lactose intolerance. It is generally recommended to those persons that they refrain from the consumption of milk and dairy products. However, most lactose intolerant people are able to digest small amounts of milk. They can also consume cheese that contains no (hard and semi-hard) or only small amounts of lactose (present in only 10% of soft cheeses). These products are very important sources of calcium. Compared to milk, the lactose content of yogurt is usually lower by about one third. Studies during the last 10 years have shown that in spite of its lactose content yogurt is very well tolerated by lactose intolerant persons. This advantage is ascribed to the presence of living lactic acid bacteria in fermented dairy products which survive passage through the stomach and also to the lactase present in these products.

Objective: This study investigated the role of the fat content of milk on symptoms of lactose intolerance., Design: Subjects recorded intolerance symptoms using a visual analogue scale (VAS) following ingestion of three test milks for varying fat content for a two-day period., Subjects/setting: The subjects were thirty adult volunteers, patients of two Estonian out-patient clinics with diagnosed lactose intolerance. The study milks were drunk at home or at work. All thirty subjects completed the study protocol., Intervention: Each subject drank, in random order, fat-free milk (4.9% lactose), high-fat milk (8% fat, 4.9% lactose), and a lactose-free and fat-free control milk. They drank 200 ml of the milk twice a day for two days, one milk type per session, with five days between sessions. The subjects noted their gastrointestinal symptoms during the test periods and during a 5 d milk-free period at the beginning of the study. The occurrence and severity of symptoms were compared. A global measure of the severity of symptoms was defined by computing the sum of the symptoms scores., Results: The sum of symptoms was higher during all milk periods than during the milk-free period (P < 0.01). There were no statistically significant differences in the occurrence or severity of symptoms during the fat-free milk period compared with the high-fat milk period., Conclusions: Even a marked difference in the fat content of milk did not affect the symptoms of lactose intolerance. Consequently, there seems to be no case for recommending full-fat milk products in the treatment of lactose intolerance.

We reported previously that consumption of one cup of milk (240 mL) per day produced negligible symptoms in lactase-nonpersistent (LNP) individuals self-described as being severely lactose intolerant. We hypothesized that such LNP individuals could also tolerate two cups of milk per day if taken in two widely divided doses with food, and that psychologic factors play a role in perceptions of lactose intolerance. The Minnesota Multiphasic Personality Inventory 2 (MMPI-2) was administered to 19 LNP subjects self-described as markedly lactose intolerant (S-LNP), 13 LNP subjects who denied lactose intolerance (A-LNP), and 10 lactase-persistent individuals who believed they were lactose intolerant (S-LP). Symptoms were recorded when LNP subjects ingested 240 mL regular or lactose-hydrolyzed milk twice daily for 7 d in a double-blind crossover study. The results showed that neither LNP group had a significant increase in symptoms (P < 0.05) during the regular compared with the lactose-hydrolyzed milk periods. However, S-LNP subjects reported significantly greater gaseous symptoms than did the A-LNP subjects during both treatment periods. The MMPI-2 showed a high score on the "lie" validity scale for S-LNP subjects. We conclude that LNP subjects tolerate two cups of milk per day without appreciable symptoms. S-LNP subjects have underlying flatulence that is misattributed to lactose intolerance. MMPI-2 results were of questionable validity because of the high rate of dissimulation by LNP subjects.

Background: Ingestion of a large dose of the milk sugar lactose--for example, the 50-g load in 1 liter of milk--causes symptoms such as abdominal pain, diarrhea, bloating, and flatulence in the majority of people with lactose malabsorption. It is uncertain whether the ingestion of more common doses of lactose, such as the amount in 240 ml (8 oz) of milk, causes symptoms. Some people insist that even smaller quantities of milk, such as the amount used with cereal or coffee, cause severe gastrointestinal distress., Methods: In a randomized, double-blind, crossover trial, we evaluated gastrointestinal symptoms in 30 people (mean age, 29.4 years; range, 18 to 50) who reported severe lactose intolerance and said they consistently had symptoms after ingesting less than 240 ml of milk. The ability to digest lactose was assessed by measuring the subjects' end-alveolar hydrogen concentration after they ingested 15 g of lactose in 250 ml of water. Subjects then received either 240 ml of lactose-hydrolyzed milk containing 2 percent fat or 240 ml of milk containing 2 percent fat and sweetened with aspartame to approximate the taste of lactose-hydrolyzed milk; each type of milk was administered daily with breakfast for a one-week period. Using a standardized scale, subjects rated the occurrence and severity of bloating, abdominal pain, diarrhea, and flatus and recorded each passage of flatus., Results: Twenty-one participants were classified as having lactose malabsorption and nine as being able to absorb lactose. During the study periods, gastrointestinal symptoms were minimal (mean symptom-severity scores for bloating, abdominal pain, diarrhea, and flatus between 0.1 and 1.2 [1 indicated trivial symptoms; and 2, mild symptoms]). When the periods were compared, there were no statistically significant differences in the severity of these four gastrointestinal symptoms. For the lactose-malabsorption group, the mean (+/- SEM) difference in episodes of flatus per day was 2.5 +/- 1.1 (95 percent confidence interval, 0.2 to 4.8). Daily dietary records indicated a high degree of compliance, with no additional sources of lactose reported., Conclusions: People who identify themselves as severely lactose-intolerant may mistakenly attribute a variety of abdominal symptoms to lactose intolerance. When lactose intake is limited to the equivalent of 240 ml of milk or less a day, symptoms are likely to be negligible and the use of lactose-digestive aids unnecessary.

To improve and standardize the measurement of small bowel transit time, milk was employed for the test meal instead of the conventional lactulose meal. Although 92% of the subjects were lactase deficient, only 2% were milk intolerant and 13% were lactose intolerant. Small bowel transit time with milk (milk breath hydrogen test) was 113 +/- 9 min (mean +/- SE, n = 20); the normal range calculated from the mean +/- 2 SD was 31-195 min. The coefficient of variation in the milk hydrogen breath test was 13 +/- 4% (n = 6), whereas in the lactulose hydrogen breath test, it was 39 +/- 16% (n = 10). The frequency of non-hydrogen producers, the occurrence of discomfort, and the reproducibility were better, though not significantly so, in the milk hydrogen breath test than in the lactulose. Since lactase activity in the intestine is variable in lactase-deficient subjects, small bowel transit times for milk may change from subject to subject. However, individual reproducibility of the milk hydrogen breath test is good. It could be useful for pharmacological experiments using paired comparison, for screening tests, or for the follow up of diseases in which small bowel transit time is affected.

Selective adult-type hypolactasia, the main cause of primary malabsorption of lactose, shows considerable variation in terms of its symptoms, which mainly depend on the amount of milk consumption. The article discusses congenital lactase deficiency and familial lactose intolerance. Links between hypolactasia and non-specific abdominal complaints, coronary heart disease and cataract are presented. The decrease in lactase activity in the brush border of jejunal mucosa, associated with diseases of the mucosa or any other condition which damages the enterocytes, is discussed as a cause of secondary hypolactasia. It is shown that adult-type primary hypolactasia and selective lactose malabsorption represent a major problem in the everyday work of general practitioners, particularly in populations where hypolactasia is common. Therefore, the examination and treatment of non-selected patients with vague abdominal complaints is important in primary health care. As the need for calcium in humans is largely met by the intake of milk, the consumption of milk has to be in amounts that are tolerable for the individual.

Twenty-five lactose-maldigesting and lactose-intolerant African Americans, ranging in age from 13 to 39 y, were given gradually increasing amounts of lactose in milk over a period of time until the maximum lactose dose tolerated was determined. Seventeen (77%) of the 22 subjects who completed the study tolerated > or = 12 g lactose and 5 (23%) tolerated < 12 g. Breath-hydrogen tests done on each subject with the maximum dose of lactose tolerated showed that only four (18%) had a breath-hydrogen concentration < 5 ppm above fasting concentration. This study suggests that the majority of African-American young adults who claim intolerance to moderate amounts of milk can ultimately adapt and tolerate > or = 12 g lactose in milk (the equivalent of 8 oz of full-lactose milk) with minimal or no discomfort if milk is ingested in gradually increasing amounts. The mechanism of adaptation is assumed to be an increased tolerance to colonic lactose-fermentation products.

Adult (primary) lactose malabsorption is practically universal in Africans of Bantu and San ('Bushmen') stock. Recent environmental changes, especially in rural areas, have exacerbated rates of malnutrition in hospital patients belonging to these groups. In order to assess the advisability of using milk as a nutritional supplement for such patients, the tolerance and absorption of 350 ml boluses of whole milk (containing 17 g lactose) was measured in 110 malnourished hospitalized patients in Namibia and South Africa belonging to Bantu (ie, Zulus, Hereros, and Kavangos) and San (ie, Bushmen) populations and compared with 22 healthy Westernized controls. Mild symptoms of intolerance were noted in about 10 per cent of Bantus and 20 per cent of Bushmen in comparison to 33 per cent of lactose-malabsorbing controls consuming Westernized diets and reported rates of 48 and 80 per cent in American population studies. The average increase in breath hydrogen excretion of 20 parts per million was also lower than the value of 34 parts per million in controls. Fasting breath methane concentrations were high in between 60-84 per cent of the groups of patients, but the level was not significantly affected by milk ingestion. Despite the combination of hypolactasia and malnutrition, 350 ml drinks of milk were well tolerated by African patients. Thus, milk should form an appropriate nutritional supplement for Africans hospitalized in rural areas.

Lactase deficient subjects, who form the bulk of the world population, absorb yogurt lactose because the bacteria used for fermentation produce beta-galactosidase. From a milk fermented by these bacteria and dried by a temperature-controlled process a power could be obtained which possess residual lactase activity but, unlike yogurt, does not need storage at low temperature. The lactose of this fermented powdered milk is perfectly absorbed, as proved by hydrogen respiratory tests performed in 35 lactose intolerant African subjects living in isolated villages. In 25 malnourished children under 3 years of age, this milk allowed renutrition without inducing diarrhoea--a result which could not have been obtained with ordinary milk in two-thirds of the cases. This type of food is potentially valuable to feed the large population of the third world.

Six lactose absorbers (LA) and 5 lactose malabsorbers (LM) had tests of gastric emptying with 750-ml meals of glucose in water, lactose in water, plain milk, and chocolate milk. The glucose and lactose meals emptied in a similar fashion in LA and LM subjects with a significant decrease in gastric emptying as the osmolarity of the meals was doubled. If the data are normalized by dividing lactose emptying by the emptying of glucose meals of twice the osmolality in each individual, the lactose malabsorbers empty significantly more lactose. Both LA and LM subjects emptied comparable amounts of milk meals having similar osmolarity. Chocolate milk, which had a higher osmolality than plain milk, emptied more slowly than plain milk in both groups, and this difference was significant in the LM group.

The experience of adverse gastrointestinal symptoms (gas, abdominal pain, and diarrhea) after the oral ingestion of 360 mL whole milk was investigated in 25 adults who claimed to be milk intolerant. The level of customary milk consumption by all subjects was low compared with that of 13 control subjects who denied a history of milk intolerance. After drinking the milk, which was accompanied by a hydrogen breath test, most of the subjects experienced some of their accustomed intestinal discomfort and the degree of intolerance was similar for the nine (36%) who proved to be true lactose-maldigester subjects and the 16 (64%) who had flat hydrogen breath responses, ie, who were classified as lactose-digester subjects. There is a subpopulation of lactose-intolerant milk-rejector individuals that absorbs lactose efficiently and responds to other milk-related factor(s) with the same subjective symptoms and dietary conduct as do true lactose-maldigester individuals.

The effect of Lactobacillus acidophilus on lactose utilization of humans was determined by our comparing the amount of hydrogen excreted in their breath after consuming milk containing either 0, 2.5 X 10(6), 2.5 X 10(7), or 2.5 X 10(8) Lactobacillus acidophilus/ml daily for 6 days. Consumption of milk without cells of Lactobacillus acidophilus for 1 wk did not affect lactose utilization. Milk containing either 2.5 X 10(6) or 2.5 X 10(8) Lactobacillus acidophilus/ml improved lactose utilization. However, consumption of milk containing an intermediate 2.5 X 10(7)/ml did not improve utilization based on comparison of group means before and after consuming the test milk. The lack of a significant effect for the latter group of test subjects was probably due to large increases of excreted hydrogen on day 7 as compared to day 0 by two of the six test subjects. The beneficial effect of Lactobacillus acidophilus was immediate and did not require that milk be consumed daily. Improved digestion of lactose was not due to hydrolysis of the lactose prior to consumption, which indicated that the beneficial effect must have occurred in the digestive tract after consumption of milk containing L. acidophilus.

1) Most humans, like other mammals, gradually lose the intestinal enzyme lactase after infancy and with it the ability to digest lactose, the principle sugar in milk. At some point in prehistory, a genetic mutation occurred and lactase activity persisted in a majority of the adult population of Northern and Central Europe. 2) Persistence of intestinal lactase, the uncommon trait worldwide, is inherited as a highly penetrant autosomal-dominant characteristic. Both types of progeny are almost equally common when one parent is a lactose maldigester and the other a lactose digester. 3) The incidence of lactose maldigestion is usually determined in adults by the administration in the fasting state of a 50-g dose of lactose in water, the equivalent of that in 1 L of milk. Measurement is made of either the subsequent rise in blood glucose or the appearance of additional hydrogen in the breath. It is also sometimes identified by measuring lactase activity directly in a biopsy sample from the jejunum. For children the test dose is reduced according to weight. Depending on the severity of the lactase deficiency and other factors, the test dose may result in abdominal distention, pain, and diarrhea. 4) The frequency of lactose maldigestion varies widely among populations but is high in nearly all but those of European origin. In North American adults lactose maldigestion is found in approximately 79% of Native Americans, 75% of blacks, 51% of Hispanics, and 21% of Caucasians. In Africa, Asia, and Latin America prevalence rates range from 15-100% depending on the population studied. 5) Whenever the lactose ingested exceeds the capacity of the intestinal lactase to split it into the simple sugars glucose and galactose, which are absorbed directly, it passes undigested to the large intestine. There it is fermented by the colonic flora, with short-chain fatty acids and hydrogen gas as major products. The gas produced can cause abdominal distention and pain and diarrhea may also result from the fermentation products. 6) Among individuals with incomplete lactose digestion, there is considerable variation in awareness of lactose intolerance and in the quantity of lactose that can be ingested without symptoms. A positive standard lactose test is not a reliable predictor of the ability of an individual to consume moderate amounts of milk and milk products without symptoms. In usual situations the quantity of lactose ingested at any one time is much less than in the lactose-tolerance test.(ABSTRACT TRUNCATED AT 400 WORDS)