las fracturas por fragilidad asociadas a la osteoporosis suponen un gran coste econmico y personal para la sociedad . la ingesta de calcio farmacutico o diettico es necesaria para aumentar la densidad mineral y prevenir fracturas por fragilidad . aunque los productos lcteos son una buena fuente de calcio , los pacientes que no pueden digerir la lactosa tienden a evitarlos y tienen un mayor riesgo de fractura que la poblacin general . informes anecdticos indican que las personas que no digieren bien la lactosa , al consumir leche cruda , tienen una gran reduccin de sntomas en comparacin con la leche pasteurizada . el mecanismo de la reduccin notificada en los sntomas , de ser verdad , se desconoce . el propsito del estudio actual era hacer una encuesta a las personas que beben leche cruda para determinar sus motivaciones relacionadas con la salud para consumir leche cruda , sobre todo en relacin con la mala digestin de la lactosa . 153 de 1527 miembros de una comunidad que compra leche cruda complet una encuesta online en relacin a la leche cruda . el motivo principal que los encuestados citaron para beber leche cruda fue que crean que era ms sano ; el 30 % notific ciertas molestias gastrointestinales al beber leche pasteurizada , aunque casi todos ( 99 % ) notificaron consumir leche cruda sin molestias . a pesar de los informes de molestias gastrointestinales , un profesional mdico haba diagnosticado intolerancia a la lactosa en solo el 5 % de los encuestados , y solamente al 1 % se le haba diagnosticado intolerancia a la lactosa mediante el mtodo de referencia de prueba de hidrgeno en el aliento . el motivo principal para beber leche cruda es su valor saludable percibido , no su digestibilidad . aunque la leche cruda parece ser digerida ms fcilmente que la pasteurizada en la muestra de nuestra encuesta , se desconoce el mecanismo de digestibilidad . the popular media occasionally present anecdotal stories regarding the benefits of consuming raw dairy products . yet we found no reports in the literature supporting the anecdotal reports that lactose maldigesters are able to consume raw milk without discomfort . also unreported or under debate in the literature is the mechanism that allows maldigesters of pasteurized milk to consume raw milk without discomfort . if the enzyme is present in raw milk , it is very heat labile and would be denatured during the milk pasteurization process . naturally occurring lactobaccili and lactococci , which are killed during pasteurization , another proposed mechanism of lactose maldigestion is that milk from cows with the a1 -casein variant ( commonly european breeds ) contains a peptide called -casomorphin-7 that reportedly can cause an immune response , lactose intolerance symptoms , and other health - related issues . these claims are not well substantiated in the literature and are controversial . further complicating the issue , raw milk is often produced and sold from small family farms that typically use jersey or guernsey cows and pasture their cows on grass . jersey and guernsey cows typically have the a2 -casein variant , whereas holstein cows ( primarily used in large industrial dairies ) have the a1 variant . so what are perceived by some to be the benefits of raw milk may have as much to do with the type of cow ( a1 vs a2 ) and husbandry ( pastured and grass - fed vs confined and ration - fed ) as with the manner in which the milk is pasteurized ( or not ) . we intend to clinically evaluate the digestibility of raw milk vs pasteurized milk , but to guide the design of our study , we need more background information . therefore , we surveyed consumers of raw milk to determine the health - related motivations for consuming raw milk , especially as they relate to lactose maldigestion . we developed an online survey of 16 questions , which was available from december 7 , 2012 , until january 31 , 2013 . the director of a raw milk  buying consortium in maryland sent an email to its 1527 members , inviting them to complete our online survey . because trafficking in raw milk intended for human consumption is against the law in maryland , survey responses were anonymous . this study was approved by our institutional review board , and respondents were informed that completing the survey served as informed consent . most of the 153 respondents ( response rate of 10% ) were females between 30 and 50 years of age ( table ) . of the 153 respondents , 74% reported drinking at least one glass of raw milk per day . results of survey of raw milk drinkers although instructed to choose only one response , 11 respondents chose one of the letter selections , then added a comment under  other ( please specify ) . we sought to differentiate those who consumed raw milk because they considered it more healthful than pasteurized milk from those who consumed it because they found it easier to digest . the concept of  easy to digest  was based on the absence of bloating , gas , diarrhea , and cramping . we queried on the digestibility of drinking milk under three conditions : ( 1 ) the reaction to drinking pasteurized milk before switching to raw milk ; ( 2 ) the reaction experienced currently when drinking raw milk ; and ( 3 ) the reaction of drinking pasteurized milk after having switched to raw milk . we also asked if there was a transition period at the onset of drinking raw milk to identify if some colonic adaptation had occurred as a result of drinking raw milk . we sought to identify subjects who had been diagnosed by a medical professional as lactose intolerant and if the diagnosis had been confirmed by a hydrogen breath test ( hbt ) . we asked about the digestibility of other dairy products , namely yogurt , cheese , and ice cream . it has long been known that in parts of the world where prevalence of lactose maldigestion is high , those populations nevertheless consume large quantities of yogurt . fermented products such as cheese and dairy products with live cultures ( yogurt ) are more easily digested than other dairy because of the presence of microbial -galactosidase . in an attempt to learn more about the potential role the -casein variant ( a1 vs a2 ) has on milk digestibility , we asked from what breed of cow the raw milk came and what type of diet the cows were fed , if the participants knew . lastly , we sought to assess the importance of calcium in the motivation for consuming raw milk . lactose intolerance is related to reduced milk consumption and therefore reduced calcium intake , which is associated with an increased risk for osteoporotic fractures . we analyzed differences in reported discomfort from drinking raw vs pasteurized milk and in drinking pasteurized milk before and after drinking raw milk for significance ( p<.05 ) using mcnemar 's test . of the 16 questions on the survey , only four were answered by all respondents , but all were answered by at least 148 ( 96.7% ) ( table ) . of the 153 respondents , most ( 86 ) cited that they consumed raw milk because they believed it to be more healthful and easier to digest . : 12 said raw milk tasted better than pasteurized milk ; 8 cited social / environmental concerns such as  supporting local farmers ,   it is better for the cows ,  etc ; 6 cited that they had allergies to pasteurized milk ; two claimed it cured unspecified ills ; and six cited individual reasons such as  i grew up on it  or  [ i ] do n't eat processed food . 71 respondents reported no discomfort from drinking raw or pasteurized milk . two reported discomfort from drinking raw and pasteurized milk , and one commented that he / she does not consume cow milk but instead drinks goat milk . fifty - nine respondents claimed no discomfort after drinking raw milk but discomfort from drinking pasteurized milk . one reported no discomfort from drinking pasteurized milk but did report discomfort from drinking raw milk . eighteen consumed raw milk without discomfort but reported they  do no drink pasteurized milk . considering the number of respondents who cited discomfort drinking milk , it was surprising that only 5 ( 3% ) respondents were diagnosed as lactose intolerant and only 1 ( 0.7% ) was confirmed lactose intolerant by means of an hbt . in terms of symptoms between before and after beginning to drink raw milk , responses included , ( 70 ) ;  do not have discomfort drinking pasteurized milk  ( 41 ) ; and  still get discomfort drinking pasteurized milk  ( 28 ) . twenty - six respondents reported no discomfort from drinking pasteurized milk , but nevertheless they do not drink pasteurized milk . four reported no previous discomfort but did report discomfort since beginning to drink raw milk . five respondents reported previously having trouble drinking pasteurized milk but no symptoms since drinking raw milk . two respondents reported not drinking pasteurized milk but symptoms when they did drink pasteurized milk . there was no significant reduction in discomfort of the respondents between the before and after drinking raw milk periods . in the current study , survey results suggest that the motivation for raw milk consumption is complex . we hypothesized that one motivation for raw milk consumption was to avoid symptoms associated with lactose maldigestion . yet almost half of the respondents indicated that they had no ill effects after drinking pasteurized milk . despite the number of respondents indicating some gastrointestinal ( gi ) discomfort when having previously consumed pasteurized milk , only 5 ( 3% ) respondents were diagnosed as lactose intolerant , and only 1 ( 0.7% ) was confirmed lactose intolerant by means of an hbt . these findings suggest that the symptoms of lactose intolerance were mild enough to not warrant the respondents ' seeking a medical diagnosis or that the respondents self - diagnosed and sought alternatives to pasteurized milk . diagnosing lactose maldigestion and the severity of the maldigestion would seem straightforward using the hbt . it is intriguing that a sizable percentage of those exhibiting lactose maldigestion symptoms have not been diagnosed by a medical professional as being lactose intolerant . it would be interesting to determine the hbt diagnosis of those who report gi discomfort . some indicate that what is self - diagnosed as lactose intolerance / maldigestion may be a misinterpretation of gi dysbiosis or irritable bowel syndrome . it may also be a self - fulfilling diagnosis because those who consider themselves to be lactose maldigesters tend to avoid dairy , which causes a change in the gut microbiota , making the bacteria less adept at decomposing lactose . others have found that those diagnosed as lactose maldigesters could ingest modest amounts of milk per day without incident and that symptoms associated with lactose maldigestion were misattributed . the underlying mechanism by which lactose in raw milk may be more readily digested , if in fact that is the case , is more difficult to determine . the predominant bacteria in raw milk are lactococcus lactis ( strains of which are used commercially as starter cultures in cheese making ) , but the bacteria are virtually eliminated when milk is pasteurized . it is likely that these native bacteria account for the alleged enhanced digestibility of raw milk over pasteurized milk , but we found no report in the literature of a direct clinical comparison . in one study , yogurt with active bacterial colonies fed to maldigesters was more readily digested than pasteurized yogurt or milk with active cultures . therefore , yogurt maintains the stomach at a higher ph than milk , which protects the bacteria . in one study , heating yogurt and reintroducing live bacteria up to 10 bacteria / ml concentrations was not as effective as standard yogurt with 10 bacteria / ml in reducing h2 in lactose maldigesters . furthermore , certain strains of active bacteria appear to be more efficient than others at digesting lactose . exposing the intestinal microflora to lactose allows the lactose - fermenting non  hydrogen - producing organisms to thrive . the resulting colonic adaptation results in lactose being metabolized to short - chain fatty acids and lactate instead of hydrogen , which is the main component in flatus . this colonic adaptation may confound the study results , which is why we included the question regarding discomfort from drinking pasteurized milk after the respondent had been consuming raw milk . our results did not indicate any evidence of colonic adaptation , but our results may be skewed because most respondents , after drinking raw milk , reported never drinking pasteurized milk , so it is impossible to know how they would react to pasteurized milk consumption . other investigators have suggested a placebo effect instead of colonic adaptation because clinical symptoms of maldigestion ( eg , bloating , diarrhea ) decreased in lactose - treated and control groups . yet objective analysis of h2 excretion decreased significantly in the lactose - exposed group compared with controls , suggesting some adaptation . in our survey , 95% of the respondents reported eating yogurt with active cultures at least once a month . our survey did not ask if the yogurt with active cultures consumption was similar before and after raw milk consumption , so it is unknown what role yogurt might have in colonic adaptation in our survey group . however , after the survey , we learned that some of the respondents made their own cheese and ice cream from raw milk . therefore , it is unknown what percentage of responses was associated with pasteurized commercial cheese and ice cream compared with raw - milk cheese and ice cream . when asked about drinking raw milk , almost 99% of respondents indicated no ill effects . this result suggests that , in the 20% to 30% who initially reported gi discomfort drinking pasteurized milk , the symptoms abated when consuming raw milk . although these findings might argue the case that raw milk is more easily digested , it is unlikely that the result would apply to all who experience gi discomfort when consuming pasteurized milk because of a selection bias in our data set . it is unlikely that those who would experience gi discomfort from drinking raw milk would be part of a raw dairy  buying club . thus , there is likely an overestimate of those lactose maldigesters who would benefit from raw milk . that 99% of the respondents could drink raw milk without incident is high but consistent with the published finding that 82% of patients diagnosed as lactose intolerant after ingesting pasteurized milk were capable of ingesting raw milk without incident . the patients in that survey were self - reporting their diagnosis by a healthcare professional , but the definition of  healthcare professional  was unclear . nevertheless , the information contained in that report is the best currently available for comparison . the current finding suggests that , at least among the group of survey respondents , milk is an important source of calcium . one might surmise that for those who are not able to digest milk easily , milk as a source of calcium may be eliminated from their consideration . in terms of osteoporosis prevention , it should be noted that calcium absorption from milk was not affected by lactose maldigestion status . the reduction in calcium intake in patients with lactose maldigestion more than 75% of the respondents reported consuming at least one glass of milk per day . the size of the glass was not specified , so it is unknown what magnitude of nutrients would be available for ingestion on a daily basis . finally , the role of a1/a2 -casein variant in cow genetics and the role of husbandry on digestibility remain elusive . almost 90% of the respondents reported that their milk came from grass - fed cows . although these results are consistent with expectations of the cows and husbandry that are associated with raw milk for human consumption , it is unknown how reliable the reporting of this information is . more than half of the respondents readily admitted not knowing from which breed of cow their milk came .
background : fragility fractures associated with osteoporosis extract a large financial and personal toll on society . pharmaceutical or dietary calcium intake is needed to increase bone mineral density to prevent fragility fractures . 
 although dairy products are a good source of calcium , patients who are unable to digest lactose tend to avoid them and are put at a greater risk for fracture than the general population . 
 anecdotal reports suggest that lactose maldigesters , when consuming raw milk , have a dramatic reduction in symptoms relative to pasteurized milk . 
 the mechanism of the reported reduction in symptoms , if true , is unknown . 
 the purpose of the current study was to survey raw milk drinkers to ascertain their health - related motivations for consuming raw milk , especially as they relate to lactose maldigestion.methods:an online survey regarding raw milk was completed by 153 of 1527 members of a raw milk  buying community.results:the primary reason the respondents cited for drinking raw milk was that they believed it was more healthful ; 30% reported some gastrointestinal discomfort when drinking pasteurized milk , yet almost all ( 99% ) reported consuming raw milk without discomfort . 
 despite the reports of gastrointestinal discomfort , only 5% of respondents had been diagnosed as lactose intolerant by a medical professional , and only 1% had been diagnosed as lactose intolerant via the gold - standard hydrogen breath test.conclusions:the primary motivation for drinking raw milk is its perceived health value , not its digestibility . 
 although raw milk appears to be more easily digested than pasteurized milk in our survey sample , the mechanism of digestibility remains unknown .