Prevalence of primary adult lactose malabsorption and awareness of milk intolerance in Italy

The Perception of Lactose-Related Symptoms of Patients with Lactose Malabsorption

Background: Dairy products are frequently considered responsible for post-prandial symptoms and are withdrawn from the diet, even against medical advice. We analysed the symptoms patients consider as lactose related; we also evaluated if psychological profile may affect the interpretation of the relationship between lactose and symptoms. Methods: In 268 patients undergoing lactose breath test, symptoms considered evoked by lactose intake were recorded and their severity measured. In the second part, symptom onset of 40 randomly selected patients was detected after both lactose and glucose breath test were blindly performed. Questionnaires evaluating anxiety, suggestibility and personality trait were administered. Key Results: Symptoms depending on functional gastrointestinal disorders or reflux disease were frequent in self-reported lactose-intolerant patients. In comparison with lactose malabsorption, these symptoms proved to be more frequent in patients with negative lactose breath test. The blinded administration of lactose and glucose demonstrated that a correct link between lactose intake and symptom onset was possible, only in 47.5% of the subjects, making this test inaccurate. None of the investigated psychological characteristics were different between patients with a nocebo response and patients not experiencing nocebo. Conclusions: Patients with self-reported lactose intolerance are frequently unaware about clinical presentation of this condition, and correct information is needed. The detection of symptom onset after lactose is an inaccurate test for lactose intolerance. Furthermore, the analysis of psychological characteristics of patients undergoing hydrogen breath test is not useful to select the subgroup at risk for a nocebo response. New strategies to diagnose lactose intolerance are mandatory.

Early hydrogen excretion peaks during breath tests. Small intestinal bacterial overgrowth or accelerated transit?

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) has been reported with varying prevalence, depending upon the criteria used for diagnosis. Lactulose and glucose breath tests are the most used in clinical settings. Early rises of hydrogen excretion during a lactose breath test suggest SIBO, but the finding could result from accelerated mouth-to-caecum transit time.

AIMS

Defining the prevalence of early hydrogen peaks during lactose breath tests and assessing the proportion of patients affected by SIBO.

METHODS

An early (≤ 60') hydrogen excretion peak was observed in 120/663 patients with positive lactose hydrogen breath test. Eighty-one of them underwent a 50 g-9sample-glucose hydrogen breath test to diagnose SIBO.

RESULTS

The glucose breath test proved positive in 11/81 (13.6%) patients. The positivity rate was 18.2% (2/11) in those with the first peak detected at 30' and 12.8% (9/70) in those with the peak occurring at 60'.

CONCLUSIONS

Early hydrogen excretion peaks are rarely associated with SIBO. The low positive predictive value indicates that the finding does not help identifying patients at high risk for this condition. Indirectly, the present data support the opinion that the prevalence of SIBO diagnosed by standard lactulose breath tests is much lower than reported, and the reliability of the test is low.

Probiotics in human health and disease: from nutribiotics to pharmabiotics

Probiotics are the most useful tools for balancing the gut microbiota and thereby influencing human health and disease. Probiotics have a range of effects, from those on nutritional status to medical conditions throughout the body from the gut to non-intestinal body sites such as the brain and skin. Research interest in probiotics with nutritive claims (categorized as nutribiotics) has evolved into interest in therapeutic and pharmacological probiotics with health claims (pharmabiotics). The concept of pharmabiotics emerged only two decades ago, and the new categorization of probiotics to nutribiotics and pharmabiotics was recently suggested, which are under the different regulation depending on that they are food or drug. Information of the gut microbiome has been continuously accumulating, which will make possible the gut microbiome-based healthcare in the future, when nutribiotics show potential for maintaining health while pharmabiotics are effective therapeutic tools for human diseases. This review describes the current understanding in the conceptualization and classification of probiotics. Here, we reviewed probiotics as nutribiotics with nutritional functions and pharmabiotics with pharmaceutic functions in different diseases.

Association of obesity and diabetes with thyroid nodules

AIM

There are conflicting data concerning the possibility that obesity and diabetes raise the risk of thyroid nodules. The incidence of thyroid nodules is increasing, as is that of obesity and diabetes; therefore, understanding whether these metabolic and nutritional disorders influence nodular thyroid disease is important for organizing prevention strategies. This study investigated the association between thyroid nodules, obesity, diabetes, and dietary habits.

MATERIALS AND METHODS

A cohort of randomly selected adults (455 males, 746 females; age: 18-90 years) living in Palermo (Italy), a mild iodine deficiency area, was cross-sectionally investigated. Participants underwent high-resolution ultrasonographic evaluation of the thyroid, and answered a food frequency questionnaire. Laboratory blood measurements were obtained in 587 participants.

RESULTS AND DISCUSSION

Thyroid nodules were detected in 475 (39.5%) participants. The number of thyroid nodules was correlated with age (r = 0.19; P < 0.001), gender (r = 0.08; P = 0.005), and body mass index (r = 0.07; P = 0.02). No significant correlation was observed between the number of nodules and glycated hemoglobin, serum insulin concentrations, and homeostasis model assessment of insulin resistance. Age-adjusted and gender-adjusted prevalence of both overweight/obesity and type 2 diabetes of each group of participants divided according to the number of nodules significantly increased with the number of nodules (P < 0.05 in both cases). The group of participants with nodules exhibited a significantly lower age-adjusted and gender-adjusted habitual intake of milk (P = 0.02). Multivariate regression analysis showed that age, gender, body mass index, diabetes, and habitual consumption of milk were independently correlated with presence of thyroid nodules.

CONCLUSION

This study seems to indicate that an association exists between obesity, diabetes, and thyroid nodules.

Subadult dietary variation at Trino Vercellese, Italy, and its relationship to adult diet and mortality

OBJECTIVES

Early-life nutrition is a predisposing factor for later-life outcomes. This study tests the hypothesis that subadults from medieval Trino Vercellese, Italy, who lived to adulthood consumed isotopically different diets compared with subadults who died before reaching adulthood. We have previously used a life history approach, comparing dentine and bone of the same adult individuals ("subadults who lived"), to elucidate dietary variation across the life span. Here, we examine diets of "subadults who died" from the same population, estimated from subadult rib collagen, to explore whether dietary behaviors of subadults who lived differed from those of subadults who died.

METHODS

Forty-one subadults aged six months to 14.5 years were studied through stable carbon and nitrogen isotope analysis of collagen.

RESULTS

Individuals were weaned by age 4 years, with considerable variation in weaning ages overall. Post-weaning, diets of subadults who died comprised significantly less animal protein than diets of subadults who lived. Isotopic values of the two oldest individuals, 13.5 and 14.5 years, show the same status-based variation in diet as do adults from the population.

CONCLUSIONS

Our results suggest that incorporating animal protein in diet during growth and development supported medieval subadults' ability to survive to adulthood. Isotopic similarities between adults and older subadults suggest "adult" dietary behaviors were adopted in adolescence. Stable isotope evidence from subadults bridges a disparity between ontogenetic age categories and socioculturally meaningful age categories in the past, and sheds light on the underpinnings of health, mortality, growth, and disease in the bioarchaeological record. Am J Phys Anthropol 160:653-664, 2016. © 2016 Wiley Periodicals, Inc.

The Interrelationships between Lactose Intolerance and the Modern Dairy Industry: Global Perspectives in Evolutional and Historical Backgrounds

Humans learned to exploit ruminants as a source of milk about 10,000 years ago. Since then, the use of domesticated ruminants as a source of milk and dairy products has expanded until today when the dairy industry has become one of the largest sectors in the modern food industry, including the spread at the present time to countries such as China and Japan. This review analyzes the reasons for this expansion and flourishing. As reviewed in detail, milk has numerous nutritional advantages, most important being almost an irreplaceable source of dietary calcium, hence justifying the effort required to increase its consumption. On the other hand, widespread lactose intolerance among the adult population is a considerable drawback to dairy-based foods consumption. Over the centuries, three factors allowed humans to overcome limitations imposed by lactose intolerance: (i) mutations, which occurred in particular populations, most notably in the north European Celtic societies and African nomads, in which carriers of the lactose intolerance gene converted from being lactose intolerant to lactose tolerant; (ii) the ability to develop low-lactose products such as cheese and yogurt; and (iii) colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance. However, in a few examples in the last decade, modern dairy products, such as the popular and widespread bio-cultured yogurts, were suspected to be unsuitable for lactose intolerant peoples. In addition, the use of lactose and milk-derived products containing lactose in non-dairy products has become widespread. For these reasons, it is concluded that it might be important and helpful to label food that may contain lactose because such information will allow lactose intolerant groups to control lactose intake within the physiological limitations of ~12 g per a single meal.

Lactose intolerance genetic testing: is it useful as routine screening? Results on 1426 south-central Italy patients

Adult-type hypolactasia is a widespread condition throughout the world, causing lactose malabsorption. Several studies suggested that the identification of C/T-13910 and G/A-22018 mutations, located upstream the gene encoding the lactase-phlorizin hydrolase (LPH), is a useful tool for the differential diagnosis of hypolactasia. We evaluated the frequencies of C/T-13910 and G/A-22018 variants in a central-south Italian population and the usefulness of lactase deficiency genetic testing in the clinic practice. The genomic DNA of 1426 patients and 1000 healthy controls from central-south Italy was isolated from peripheral whole blood and genotyped for the C/T-13910 and G/A-22018 polymorphisms by high-resolution melting analysis (HRMA) and sequencing. The frequencies of genotypes in the 1426 patients analysed were as follows: 1077 CC/GG (75.5%), 287 CT/GA (20.1%), 24 TT/AA (1.7%), 38 CC/GA (2.7%). Only 64 out of 1426 (4.5%) performed also L-BHT test, 29 of which were negative for L-BHT also in presence of different genotypes. Among the 35 individuals with L-BHT positive, 34 were CC/GG and only one CT/GA. Although lactose genetic test is a good predictor of persistence/non-persistence lactase in specific population, its use in the central-south Italy population should be limited given the high prevalence of the CCGG diplotype in normal individuals.

Perception of lactose intolerance in irritable bowel syndrome patients

INTRODUCTION

The importance of lactose malabsorption in irritable bowel syndrome (IBS) is not well defined and these patients often complain of lactose intolerance. To objectively measure lactose malabsorption, a hydrogen breath test (HBT) can be performed, but a discrepancy emerges between the results of the HBT and the symptomatic response during the HBT.

AIMS

To determine in a group of IBS patients whether self-perceived lactose intolerance and the symptomatic response to lactose HBT were conditioned by other factors besides the presence of lactose malabsorption.

MATERIALS AND METHODS

Oral challenge to lactose (50 g) was tested in 51 IBS patients to assess HBT malabsorption and the symptomatic response to lactose intolerance was scored on a validated questionnaire. Allergological screening for common inhalants and food allergens (including cow's milk) was performed. The presence of psychological factors (e.g. anxiety, depression, fatigue) was evaluated using validated questionnaires.

RESULTS

A total of 21 out of 51 patients (41.1%) were self-perceived to be lactose intolerant, 24/51 (47%) had a positive HBT, and 14/51 (27.4%) presented with symptoms of lactose intolerance during HBT. The serological screening for inhalant and food allergens was positive in 6/21 (28.6%) and 4/21 (19%) of patients who self-perceived lactose intolerance and in 5/14 (37.5%) and 3/14 (21.4%) in intolerant patients symptomatic during HBT. Only 1/51 (1.9%) presented evidence of IgE-mediated hypersensitivity to cow's milk. Patients who experienced symptoms of lactose intolerance during HBT presented more severe IBS symptoms [326 (296-398) vs. 215 (126-295) P=0.05] and a higher score of anxiety, depression, and fatigue. Factors influencing the symptoms of lactose intolerance during HBT resulted in an increase in hydrogen produced and in the severity of IBS.

CONCLUSION

In a cohort of 51 IBS patients, the symptoms of lactose intolerance during HBT were influenced by the capacity to absorb lactose and the severity of IBS. Other factors, such as the psychological status or an adverse reaction to milk, merit consideration as potential cofactors involved in lactose perception and tolerance.

Dietary calcium intake in patients with inflammatory bowel disease

BACKGROUND & AIMS

Osteopenia and increased risk for fractures in IBD result from several factors.

AIM OF THE STUDY

To investigate the dietary intake of calcium in IBD patients.

METHODS

A 22-item quantitative validated frequency food questionnaire was used for quantifying dietary calcium in relation to gender and age, in 187 IBD patients, 420 normal- and 276 diseased controls.

STATISTICAL ANALYSIS

Mann-Whitney, chi-square- and T-tests.

RESULTS

The mean calcium intake was 991.0 ± 536.0 (105.8% Recommended Daily Allowances) and 867.6 ± 562.7 SD mg/day (93.8% RDA) in healthy and diseased controls, and 837.8 ± 482.0 SD mg/day (92.7% RDA) in IBD, P<0.001. Calcium intake was high in celiac disease (1165.7 ± 798.8 SD mg/day, 120% RDA), and non-significantly lower in ulcerative colitis than in Crohn's disease (798.7 ± 544.1 SD mg/day vs 881.9 ± 433.0). CD and UC females, but not males, had a mean calcium intake well under RDA. In all study groups the intake was lower in patients believing that consumption of lactose-containing food induced symptoms, versus those who did not (105.8% vs 114.3% RDA in normal controls; 100.4% vs 87.6% RDA in IBD).

CONCLUSIONS

Diet in IBD patients contained significantly less calcium than in healthy controls. Gender and age, more than diagnosis, are central in determining inadequate calcium intake, more so in IBD. Self-reported lactose intolerance, leading to dietary restrictions, is the single major determinant of low calcium intake. Inadequate calcium intake is present in one third of IBD patients and represents a reversible risk factor for osteoporosis, suggesting the need for tailored nutritional advice in IBD.

Dietary triggers in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a frequently occurring, benign functional gastrointestinal disorder with a complex poorly understood pathology which appears to be multifactorial in nature. There is no association with structural or biochemical abnormalities in the gastrointestinal tract. Functional variations in myoelectrical activity, visceral hypersensitivity and illness behaviours have all been observed in patients experimentally. In conjunction with environmental, psychological and alimentary factors, these mechanisms have been proposed as the major determinants of symptom genesis. Certainly, dietary factors are frequently perceived by sufferers as powerful symptom triggers, with many reporting multiple food intolerance. Physicians, however, remain divided upon the relevance of food to the disorder, with many eschewing a nutritional connection. This is unsurprising as, despite much experimental work to determine the clinical relevance of food intolerance and allergy to the aetiology of the disorder, the vast range of foodstuffs available for testing, inherent procedural problems with test foods, methodological insufficiencies and the continually evolving knowledge of the disorder, particularly the subgrouping of sufferers, have restricted the scientific validity of current findings. At the present time, it is difficult to make informed judgement upon the importance of food in IBS, and rigorously designed, large scale trials devised in the light of recent knowledge are required before conclusions can be drawn.

Diagnosis of lactose intolerance and the "nocebo" effect: the role of negative expectations

BACKGROUND

Diagnosis of lactose intolerance is based on a "positive" H(2) breath test associated with abdominal symptoms. The present study established to what extent the occurrence of symptoms during a "negative" H(2) breath test may result from a "nocebo effect" instead of lack of sensitivity of the procedure.

METHODS

Between 2005 and 2007, 636 outpatients performed a standard 4-h 25g lactose tolerance test. The test was positive in 254, negative in 325, and 57 patients were H(2) "non-producers". Twenty-seven patients reporting symptoms despite a negative H(2) breath test underwent a "sham" breath test following ingestion of 1g of glucose. Fifty-four patients presenting with documented lactose intolerance were used as controls.

RESULTS

Twelve out of 27 patients (44.4%), and unexpectedly also 14 (25.9%) controls presented abdominal symptoms during the sham test. The difference between the two groups was not significant (P<0.15) OR 2.28; C.I. 0.77-6.78.

CONCLUSION

In most instances, symptoms reported by patients during a negative lactose H(2)BT cannot be attributed to a false-negative test. Instead, a non-organic component, resulting from negative expectations ("nocebo effect") is likely implicated. Moreover, also in patients diagnosed as lactose intolerant, the need for restricting the primary source of dietary calcium should be critically reconsidered.

A worldwide correlation of lactase persistence phenotype and genotypes

BACKGROUND

The ability of adult humans to digest the milk sugar lactose - lactase persistence - is a dominant Mendelian trait that has been a subject of extensive genetic, medical and evolutionary research. Lactase persistence is common in people of European ancestry as well as some African, Middle Eastern and Southern Asian groups, but is rare or absent elsewhere in the world. The recent identification of independent nucleotide changes that are strongly associated with lactase persistence in different populations worldwide has led to the possibility of genetic tests for the trait. However, it is highly unlikely that all lactase persistence-associated variants are known. Using an extensive database of lactase persistence phenotype frequencies, together with information on how those data were collected and data on the frequencies of lactase persistence variants, we present a global summary of the extent to which current genetic knowledge can explain lactase persistence phenotype frequency.

RESULTS

We used surface interpolation of Old World lactase persistence genotype and phenotype frequency estimates obtained from all available literature and perform a comparison between predicted and observed trait frequencies in continuous space. By accommodating additional data on sample numbers and known false negative and false positive rates for the various lactase persistence phenotype tests (blood glucose and breath hydrogen), we also apply a Monte Carlo method to estimate the probability that known lactase persistence-associated allele frequencies can explain observed trait frequencies in different regions.

CONCLUSION

Lactase persistence genotype data is currently insufficient to explain lactase persistence phenotype frequency in much of western and southern Africa, southeastern Europe, the Middle East and parts of central and southern Asia. We suggest that further studies of genetic variation in these regions should reveal additional nucleotide variants that are associated with lactase persistence.

Beneficial effects of oral tilactase on patients with hypolactasia

BACKGROUND

A lactose-free diet is commonly prescribed to subjects with hypolactasia. We tested the effectiveness of a single ingestion of tilactase (a beta-D-galactosidase from Aspergillus oryzae) in adults with hypolactasia, previously assessed by lactose H(2)-breath test.

MATERIALS AND METHODS

After measurement of orocecal transit time (OCTT, by lactulose H(2)-breath test) and lactose H(2)-breath testing plus placebo, a total of 134 subjects were positive to hypolactasia and underwent lactose H(2)-breath testing plus either low (6750 U) or standard (11,250 U) doses of tilactase. The appearance of gastrointestinal symptoms during the tests was monitored.

RESULTS

OCTT was longer in malabsorbers (subjects without bloating, abdominal pain and/or diarrhoea, n = 25) than in intolerants (bloating, abdominal pain and/or diarrhoea, n = 109, P < 0.02). Malabsorbers had longer time to H(2) peak (P < 0.03), lower H(2) peak levels (P < 0.002) and smaller integrated H(2) excretion levels (P < 0.005) than intolerants. After tilactase ingestion, integrated H(2) levels were decreased by 75% (low dose) and 87% (standard dose) in malabsorbers, and by 74% (low dose) and 88% (standard dose) in intolerants. In the latter group, total symptom score were decreased by 76% (low dose) and by 88% (standard dose) (P < 0.0001).

CONCLUSION

A single oral administration of tilactase is highly effective in decreasing symptoms and hydrogen excretion of hypolactasia assessed by lactose H(2)-breath test. If confirmed by long-term observations, ingestion of tilactase might be a better option than exclusion diets in intolerant subjects with hypolactasia.

Hydrogen breath test for the diagnosis of lactose intolerance, is the routine sugar load the best one?

AIM: To evaluate the prevalence of lactose intolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25.

METHODS: Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g. Peak hydrogen production, area under the curve of hydrogen excretion and occurrence of symptoms were recorded.

RESULTS: Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5. Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) ± 29.54 SD vs 99.43 ppm ± 40.01 SD; P < 0.001). Symptoms were present in only 13 patients. The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test. The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31).

CONCLUSION: Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a “standard” HBT is, in most instances, unnecessary. Thus, the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI, and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance.

Hydrogen breath test in the diagnosis of lactose malabsorption: accuracy of new versus conventional criteria

Increased hydrogen excretion in the breath after carbohydrate ingestion, an expression of carbohydrate malabsorption, represents the pathophysiologic basis of the hydrogen breath test, a simple, noninvasive, reproducible test for the diagnosis of this condition. Few data are available concerning the breath hydrogen response that most accurately identifies carbohydrate malabsorption. In this article we report our application for the first time in clinical practice of 2 recently described, more accurate criteria for the diagnosis of lactose malabsorption (ie, breath hydrogen excretion value > 6 parts per million (ppm) 6 hours after carbohydrate load and a sum greater than 15 ppm for the breath hydrogen values obtained 5, 6, and 7 hours after carbohydrate load). On 3 separate days, we subjected 84 consecutive patients with functional or organic gastrointestinal disease to measurement of hydrogen excretion in the breath after the administration of lactose to test for lactose malabsorption; after the administration of lactulose as a means of ruling out false-negative results resulting from hydrogen-nonproducer status; and after the administration of a nonabsorbable electrolyte solution as a means of ruling out false-positive results caused by the mixing of intestinal content and release of preformed hydrogen trapped in the feces. According to the conventional criterion, 51% of the subjects proved to be lactose malabsorbers. Positive results were obtained with the use of the 6th-hour criterion in 76% of patients, and positive results were found in 80% when the sum of the excretion at hours 5, 6, and 7 was used as the criterion (P < .05 for both comparisons). Ten of 21 and 11 of 25, respectively, showed intolerance symptoms. It was therefore possible for us to diagnose lactose malabsorption in 24% and 27% of patients, respectively, who tested negative according to the conventional criterion. The conventional criterion must be abandoned and these new criteria adopted.

Effect of predominant methanogenic flora on the outcome of lactose breath test in irritable bowel syndrome patients

BACKGROUND

The relationship between hydrogen and methane production is a possible confounding factor in the interpretation of H(2) breath tests (HBT), but is usually disregarded for the interpretation of HBT and, in most instances, only H(2) excretion is measured. The present study was designed to evaluate the effect of predominant fasting methane CH(4) or H(2) production on the outcome of lactose HBT, in a large, homogeneous series of adult patients with irritable bowel syndrome (IBS).

PATIENTS AND METHODS

A lactose HBT was performed in 237 IBS patients with predominant fasting methane production (CH(4)>H(2)), recording the outcome of the test, amount of gas excreted and occurrence of clinical symptoms. Data were compared to those of 237 age- and sex-matched IBS patients with low fasting CH(4) excretion.

RESULTS

The test was positive in 124 predominant CH(4) producers (52.3%) (PMP), as compared to 201 (84.8%) low methane producers (LMP) (P<0.0001). Peak hydrogen concentration and area under the curve of H(2) were significantly (P<0.001) lower, and the occurrence of symptoms during the test less frequent, in PMP vs LMP patients. During the test, CH(4) excretion doubled in 57/113 (50.4%) patients with negative HBT, and in 49/124 (39.5%) with positive HBT.

CONCLUSIONS

Patients with predominant fasting methane production excrete less H(2) than LMP, after an oral load of lactose. The lower prevalence of severe lactose intolerance in PMP, as well as lower incidence of symptoms during the test, is, indeed, related to lower and slower H(2) excretion. The assumption that H(2) excretion is an effective means of quantifying the amount of malabsorbed carbohydrates is questionable in PMP. Methane-producing patients likely have a higher 'false negative' rate as compared to LMP after an oral load of lactose. Nonetheless, as symptoms are related to the amount of gas produced in the colon, HBT identifies patients with 'lactose intolerance', irrespective of the presence of lactose malabsorption, and helps in predicting the effect of lactose-restricted diet.

Prevalence of osteoporosis and fractures in a migrant population from southern to northern Italy: a cross-sectional, comparative study

The purpose of this study was to assess whether a migrant population from southern regions of Italy showed differences in osteoporosis (OP) and fracture prevalence in comparison to a population born and living in Milan, a city in northern Italy. The study group consisted of 1764 postmenopausal women born in southern Italy who migrated after age 20 to Milan, where they had lived for at least 15 years. This group was compared with a sample of 4018 postmenopausal women born, raised and living in Milan. Bone mineral density (BMD) was measured at lumbar spine by dual-energy X-ray absorptiometry. Univariate analysis showed a significantly higher BMI, a greater parity, a lower postmenopausal estrogen (HRT) usage and a lower calcium intake in the Southern group (SG). Densitometric values showed a mean lumbar BMD significantly lower in SG ( P<0.001), resulting in a greater prevalence of OP (30.5% versus 24.9%; P<0.001). Consistent with this result, the number of women reporting low energy fractures after menopause was higher in SG (4.8% versus 3.6%; P=0.01). Multiple logistic regression analyses showed that OP was predicted by well-recognized variables, such as age, age at menopause, BMI, HRT, calcium intake together to belonging to SG, which independently increased the risk for OP by 42%. Age, age at menopause, BMI and belonging to SG significantly influenced the fracture risk, but the last variable was no longer associated with an increased fracture risk when BMD was entered in the model. Despite the results of previous epidemiological studies and protective anthropometric measures, a higher OP and fracture prevalence was found in the migrant group from southern Italy to Milan in comparison with the native sample. These differences are not solely explained by lifestyle variables. Our data suggest that changing environmental exposures can influence bone mass and fracture risk.

[Lactose intolerance and consumption of milk and milk products]

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.

Does lactose maldigestion really play a role in the irritable bowel?

Patients who met International Congress of Gastroenterology criteria for irritable bowel syndrome (IBS) and had breath hydrogen lactose testing were interviewed to determine whether detection of lactose maldigestion (LM) had an impact on their symptoms. Of 199 patients initially evaluated, 161 (81%) were contacted and asked to rate their symptoms. At baseline, 47 (29%) of the IBS group had LM. Before testing, 23 (49%) were aware that ingestion of lactose-containing food was associated with their gastrointestinal symptoms. Lactose-maldigesting IBS subjects (IBSLM, n = 47) and those who had IBS and no LM (n = 114) were similar in terms of age, sex, and ethnic background. Interviews performed 41 +/- 1.1 (SEM) months after baseline evaluation revealed no significant differences in abdominal pain, altered bowel habits, bloating/distension, mucus, and relief with defecation among those with IBS or LMIBS. Overall symptoms resolved, improved, did not change, or worsened in a manner not statistically different between IBS and IBSLM groups. IBSLM subjects (a) felt that identifying LM helped them gain awareness of food-symptom relationships (78.7%), (b) experienced some improvement in symptoms (83%), (c) were avoiding lactose foods (87.2%), or (d) used lactase enzyme supplements (38.3%). Identifying LM did not significantly affect rated variables.

Does lactose intolerance predispose to low bone density? A population-based study of perimenopausal Finnish women

The relationship of lactase malabsorption to osteoporosis is unclear. We examined the relationship of self-reported lactose intolerance (LI) to bone mineral density (BMD) in perimenopausal Finnish women. A random population sample of 2025 women aged 48-59, who underwent spinal and femoral BMD measurement with dual X-ray absorptiometry in Kuopio, Finland during 1989-1991 formed the study population. Out of these women, 162 women reported LI. The mean dairy calcium intake was 558 mg/day in women with LI and 828 mg/day in other women (p < 0.0001). The mean spinal BMDs were 1.097 and 1.129 g/cm2 (-2.8%) (p = 0.016) and the mean femoral BMDs were 0.906 and 0.932 g/cm2 (-2.8%) (p = 0.012) for the LI and other women, respectively. After adjusting for weight, age, years since menopause, and the history of hormone replacement therapy, these differences changed to -2.7% (p = 0.016) for the spinal and -2.4% (p = 0.012) for the femoral BMD, respectively. Dairy calcium intake was an independent determinant of femoral BMD. The addition of calcium intake variables into the multivariate model did not affect the spinal BMD difference, but weakened the femoral BMD difference to -1.9% (p = 0.075). Our results suggest that LI slightly reduces perimenopausal BMD, possibly through reduced calcium intake.

Lactose intolerance and bone mass in postmenopausal Italian women

Previous studies on the role of lactose malabsorption in the pathogenesis of postmenopausal osteoporosis have yielded conflicting results and further information is needed. To date, all studies have been carried out on populations with a low prevalence of lactose malabsorption and the lactose intestinal absorptive capacity was tested using a non-physiological dose of lactose. In fifty-eight Italian postmenopausal women (mean age 57 (SD 7) years), bone mineral density (BMD) at lumbar spine, H2 breath response after ingestion of 20 g lactose, intensity of symptoms of intolerance after a lactose load and daily Ca intake were evaluated. No differences were found between women with or without a positive H2 breath test with regard to BMD (-1.2 (SD 0.9) v. -0.9 (SD 0.8)) and Ca intake (509 (SD 266) v. 511 (SD 313) mg/d). On the contrary, both BMD and Ca intake were significantly lower in women with lactose malabsorption and symptoms of intolerance (-1.5 (SD 0.7) and 378 (SD 220) mg/d) than in those with malabsorption without symptoms (-0.9 (SD 0.9) and 624 (SD 254) mg/d). Moreover, in lactose malabsorbers Ca intake was correlated inversely with symptom score (rs -0.31, P < 0.05) and positively with BMD (rs 0.42, P < 0.005). Our results show that in Italian postmenopausal women Ca intake and BMD are not influenced directly by lactose malabsorption; the appearance of symptoms of intolerance seems to influence BMD unfavourably through a reduced Ca intake.

Genetics and epidemiology of adult-type hypolactasia

The prevalence of adult-type hypolactasia varies from less than 5% to almost 100% between different populations of the world. The lowest prevalence has been found in northwestern Europe, around the North Sea, and the highest prevalence in the Far East. The reason for the variation is that selective (primary) hypolactasia is genetically determined by an autosomal recessive single gene. It is assumed that thousands of years ago all people had hypolactasia in the same way as most mammals do today. At that time in cultures where milk consumption was started after childhood, lactase persistence had a selective advantage. Those people with lactase persistence were healthier and had more children than people with hypolactasia, and the frequency of the lactase persistence gene started to increase. The present prevalence of hypolactasia can be explained fairly well by this culture historical hypothesis. This article reviews the evidence for the inheritance of adult-type hypolactasia and the occurrence of hypolactasia in different countries and populations of the world.

Clinical picture of hypolactasia and lactose intolerance

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.

Prediction of lactose malabsorption in referral patients

Two hundred forty-two patients referred for various gastrointestinal complaints were evaluated for clinical parameters that would predict findings of lactose malabsorption. Breath hydrogen and blood glucose lactose tests were performed after ingestion of 50 g lactose. Presenting complaints, duration of symptoms, and patient demographics such as age, sex, and ethnic heritage were not different between lactose malabsorbers and absorbers as defined by the breath hydrogen lactose test. Food-related symptoms in general and after specific foods such as milk, ice cream, cheese, and yogurt were also similar between groups. Prior to testing, 30% of malabsorbers (N = 161) and 36% of absorbers (N = 81) reported lactose-related symptoms (P = NS). The blood glucose response to lactose was abnormal in 60% of malabsorbers and 15% of absorbers. This study confirmed our impression that it is difficult to predict lactose absorption status by clinical parameters. The majority of our lactose malabsorber patients were unaware of lactose-associated symptoms. Furthermore, symptom assessment, demographics, food history, and blood glucose testing did not predict abnormal hydrogen responses to lactose.

Primary adult lactose intolerance protects against development of inflammatory bowel disease

We have compared the incidence of inflammatory bowel disease (IBD) to the prevalence of lactose malabsorption (LM) in several countries. Our observations indicate that IBD is rare where LM is highly prevalent. The correlation between incidence of Crohn's disease and LM is -0.93, p less than 0.01, the correlation between incidence of ulcerative colitis and LM is -0.89, p less than 0.01. We, therefore, propose that LM results in the formation of volatile fatty acids which may inhibit multiplication of potentially pathogenic organisms.

Hydrogen breath test quantification and clinical correlation of lactose malabsorption in adult irritable bowel syndrome and ulcerative colitis

Lactose malabsorption was studied, by hydrogen breath test, in 72 adults suffering from irritable bowel syndrome, in 20 ulcerative colitis patients, and in 69 healthy subjects. The minimum dose of lactose required to cause a positive breath test was determined, and the symptoms caused and the resulting hydrogen eliminated quantified. A high incidence of lactose malabsorption was shown at standard doses (up to 50 g) in both the healthy subjects (70%) and the patients (86% and 85%, respectively). In the irritable bowel syndrome and the ulcerative colitis groups, symptoms occurred with a smaller quantity of breath hydrogen, presumably in association with a greater individual sensitivity of the colon to distension. The threshold lactose dose was notably lower in the diseased subjects who registered as evidence a prevalence of malabsorption at a 20-g lactose load. The pathogenetic role of lactose malabsorption in the irritable bowel syndrome is emphasized, as is the importance of the personal lactose tolerance.

Prevalence of primary adult lactose malabsorption in three populations of northern China

Lactose absorption capacity was examined in 641 apparently healthy adolescents and adults (447 males and 194 females with an average age of 22.9 years and an age range of 16-46 years) using a field version of the lactose tolerance test with breath hydrogen determination. In the total sample, 89 lactose absorbers and 552 lactose malabsorbers were identified. Lactose malabsorption was most frequent in a subgroup of Han (Chinese) from northeastern China (229 of 248 subjects, 92.3%). Among 198 Mongols from Inner Mongolia, there were 174 lactose malabsorbers (87.9%). The frequency of lactose malabsorption was lowest in a group of Kazakhs, traditional herders from the northwestern region of Xinjiang (149 of 195 subjects, 76.4%). Reported symptoms of lactose intolerance were significantly more frequent in lactose malabsorbers. The findings in northern Han are similar to the reported lactose malabsorption frequency in southern (mainly overseas) Chinese, and correspond with the absence of animal milk from traditional Chinese diets. The relatively low prevalence of lactose malabsorption among the Kazakhs suggests that lactose persistence may be frequent in herding pastoralist populations of southwest Asia.