Talk:Lactose intolerance

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Inaccurate Map: this map displayed in the article is 100% inaccurate and unscientific[edit]

Rates of lactose intolerance

The map displayed in the article is 100% inaccurate and unscientific. Numerous users have voiced their concerns and problems with this map yet it keeps being added onto the article with the excuse "there is nothing better". I believe showing no map is better than showing a map that actively misleads the public. There is no consensus and no reason to keep adding the map onto the article.

Why is it misleading?[edit]

1. It only uses two datapoints for South America. One of them is a study on Colombian Native populations while the other deals with Chilean Natives. Anybody that has a minimum understanding of South American demographics can realize the foolishness of extrapolating these two datapoints onto the neighbouring countries - In particular onto regions where populations of White European descent are the majority, namely Argentina, Uruguay and Southern Brazil. Thus to say the map deals with "current populations" is misleading, since that is not the case with the South American data.

2. A slew of countries in West and Central Africa are apparently mostly lactose tolerant despite the article stating that Sub-Saharan Africans are generally lactose intolerant. The only reasoning I could find in the article for this was that these countries all seem to be in the geographical distribution of the Fulani people, who, according to the article, are mostly lactose tolerant. But the Fulani are an ethnic minority in these countries, so their rate of lactose tolerance would not be indicative of the rate of lactose tolerance in the general population. One other issue is that in South Africa nearly 20% of the population has at least some European ancestry (whites and coloureds), the majority of which is northern European. And lactose tolerance being a "dominant" gene wouldn't that indicate that a person with full or partial northern European ancestry would most likely be lactose tolerant? This would put the figures of lactose intolerance lower than "91%-100%". In general I feel like if most of the African countries are just "rough guesses" than the information shouldn't really be there.

3. The map contradicts the sourced information in the article.

4. The sources listed for the map only deal with Thailand, Japan, Europe and North America. For the rest of the world it is based on extrapolation from latitude and specific native populations that may not be representative of the national situation.

5. The map contradicts known data for milk consumption per capita, which could be taken as a proxy for lactose intolerance, and a much more accurate one since it is sourced country-by-country information gathered by the FAO.

[Milk Consumption per Capita]

Finally one has to ask whether the purpose of this encyclopedia is to show articles that look good or to inform. If it is the latter, then this map should be removed, for it is better to have less information displayed than to have information that actively deceives and misleads the readers. Salem1313 (talk) 23:04, 2 July 2017 (UTC)

I agree to remove the map. The source is not reliable: [1] -> "Source. Own work Also here"
Best regards. --BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 23:36, 2 July 2017 (UTC)
Source is given as
Densupsoontorn N, Jirapinyo P, Thamonsiri N, Chantaratin S, Wongarn R (2004): Lactose intolerance in Thai adults. J Med Assoc Thai. 2004 Dec;87(12):1501-5.
Scrimshaw NS, MurrayEB (1988): Prevalence of Lactose Maldigestion. Am J Clin Nutr 48 (Suppl): 1086-1098, 1988
Sahi T (1994) Genetics and epidemiology of adult-type hypolactasia. Scand J Gastroenterol 29 (Suppl 202): 7-20, 1994
Yoshida Y, Sasaki G, Goto S, Yanagiya S, Takashina K. (1975); Gastroenterol Jpn. 1975;10(1):29-34. "Studies on the etiology of milk intolerance in Japanese adults."
Doc James (talk · contribs · email) 04:03, 3 July 2017 (UTC)
This one here at least is a review[2]. Did you read it? Anyone have access and can send me a copy?
The map of milk consumption actually is fairly close to the one of lactose intolerance. Sure not as details but close. However partly milk consumption relates to wealth. Doc James (talk · contribs · email) 04:05, 3 July 2017 (UTC)
  • Fits mostly with this map.[3][4] Except bit in the middle east and far Wast Africa needs to be adjusted.
  • User:NmiPortal you able to update and take this into account?Doc James (talk · contribs · email) 04:27, 3 July 2017 (UTC)


Chinese 100% Egypt, general 73% Vietnamese 100 Germany 70 Japanese 100 Hungary, general 56 Bantu, Uganda 100 Mexico, general 53 Peru, non-Caucasian 94 Northern Italy 52 Iraqi Jews 93 Fulani 50 Australian Aborigine 84 Greece 45 Nigeria Yorba 83 UK White 22 Ashkenazi Jews (LNP) 83 Finland (LM) 17 Moroccan Jews 82 US White, general 15 US Native American 81 Central Italy 15 Brazil 80 Irish 14 Chile 80 Danes 12 African American 75 Swedes 10

Fits fairly well with this. Doc James (talk · contribs · email) 04:37, 3 July 2017 (UTC)

Thank you for starting a talk page discussion, Salem1313. However please note that we usually try to reach a consensus before making controversial changes to an article (the bold revert discuss cycle). The map has been in the article for years so please leave it until we reach a consensus here.
I don't think anybody is going to argue that the map is accurate. It's based on a small number of data points, but it is broadly correct and well-sourced (certainly not "made up"). This map (Fig 1) is based on the most up-to-date data available and you can see it differs mostly in specific regions; the global trend is the same. I don't think milk consumption is a good proxy. Milk drinking is conditioned by a variety of cultural factors and often diverges from the frequency of the LP genotype/phenotype.
It would be nice to have a better map (if I have the time I can try and make one), but until we do this should stay. The global pattern of prevalence is a key fact about lactose intolerance and needs to be illustrated. It neither deceives or misleads: it's a faithful representation of the data sources used, which are reliable and cited for anyone who cares to look, and both the caption and the broad-stroke contouring identify it as a schematic view which is not going to be accurate for specific countries. If our readers click through to lactase persistence, they can find a table of detailed statistics. – Joe (talk) 07:31, 3 July 2017 (UTC)
I had not seen the references still now.
@Doc James:I got the article you requested. I sent it to you by email.
I have not been able to read it the references nor this complete discussion, I do not have now time. I'll do it later.
Best regards. --BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 08:19, 3 July 2017 (UTC)
I appreciate taking time to address the concerns but I still do not understand your defense of this map. As you properly have listed, you've got nationwide information about lactose intolerance for only 17 nations out of 195 nations covered in the map. The other data points refer to ethnic minorities (like the Fulani) that are not representative of their respective countries. Why not color the remaining 178 nations with no data as "no data" rather than making asumptions that mislead the readers?
I do not think this map matches well with the milk per capita consumption map, in fact it greatly contradicts the information there - Greece is supposed to have 30-60% of its population as lactose intolerant, yet it is in the highest category of milk consumption. Costa Rica is listed as 60-80% lactose intolerant and Argentina as 80-100% lactose intolerant but their milk consumption per capita patterns are on par with Western Europe.
Common sense seems to suggest that extrapolating data based on geographic proximity, latitude, and ethnic minorites as has been done here will result in a misleading map.
Sadly I am afraid people will continue to bring up their issues with this map as can be seen in the history of this talkpage because the information contained there is contradictory with real life common sense and not based on real world data for the majority of the countries in question. Salem1313 (talk) 09:44, 3 July 2017 (UTC)
This map [5] seems considerably more accurate, reflecting variations in Africa which are consistent with the ethnic groups present there rather than latitude, and it shows the data points where information has been collected, with considerably more datapoints involved. Isn't there a way to add a version of this map to the article instead? It excludes the Western Hemisphere but it seems considerably more reliable based on the greater amount of datapoints used. Regards, Salem1313 (talk) 10:00, 3 July 2017 (UTC)


Percentage of adults that can digest lactose in the indigenous population of the Old World

Unfortunately we are limited to images that are available under a free license. But this discussion piqued my interest, so I spent this evening reproducing a similar map using their data that we can use. It only covers the Old World, but I think the added information is worth losing the Americas for. – Joe (talk) 21:29, 3 July 2017 (UTC)


  1. ^ Bayless, TM; Brown, E; Paige, DM (May 2017). "Lactase Non-persistence and Lactose Intolerance". Current gastroenterology reports. 19 (5): 23. PMID 28421381. 
That is absolutely amazing!! Excellent work, thank you for putting in the effort. Yes, this map has much more datapoints and seems much more accurate and trustworthy. I wholeheartedly support the new map and its inclusion in the article. For what is worth you have completely restored my faith in this encyclopedia. Excellent job. Regards, Salem1313 (talk) 18:27, 4 July 2017 (UTC)
  • Why choose figure 1 rather than figure 2?
  • That map does not mach some of the avaliable data I mentioned above either. Doc James (talk · contribs · email) 02:51, 5 July 2017 (UTC)
    • By the way milk consumption DOES NOT equal rates of lactose intolerance in adults.
    • LP allele frequency is also not a perfect representation of the phenotype. The maps are looking at the question in different ways. The FIN map is looking at surveys of symptoms the map by User:Joe Roe is looking at allele frequency and extrapolating from there.
    • Both are reasonable IMO. And both are extrapolating from a smaller number of points. Doc James (talk · contribs · email) 03:10, 5 July 2017 (UTC)
I don't mind having both in, but for the record the data I used is not an extrapolation from allele frequency. It's actual rates from diagnostic tests of lactose digestion (see "Determination of lactase persistence status" in Ingram et al. 2009). The only real advantage the FIN map has is that it includes the Americas. – Joe (talk) 07:44, 5 July 2017 (UTC)
Thanks User:Joe Roe see it now "Most data were obtained from lactose tolerance tests using either breath hydrogen or blood glucose, though in some cases enzyme assay data were available."Doc James (talk · contribs · email) 15:23, 5 July 2017 (UTC)

Have reached out to the creators of the map in question. They state that the refs listed are only some of the data supporting the map and that they will provide the rest as they have time. Doc James (talk · contribs · email) 02:57, 10 July 2017 (UTC)

Since it is supported by references, I agree to keep the map.
Best regards.--BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 08:21, 10 July 2017 (UTC)
The original map used is accurate after all. It just needs more sources to verify the other part of the map. QuackGuru (talk) 14:41, 10 July 2017 (UTC)
Problem is both of that maps are nonsense, just level is different. The best example is Japan, both of maps are using silly stereotype that Japanese are lactose intolerant which maybe was true about 70 years ago. There was even reference about research in Japan showing that more than 80% of Japanese are lactose tolerant. "Indigenous population of the Old World" is some absolute nonsense showing whole Russia as lactose intolerant, research is just one huge nonsense, whole Russia is measured by one of indigenous small-numbered peoples sample. Rambalac (talk) 15:23, 10 July 2017 (UTC)
Sometimes accurate content is nonsense to some people.
The wording for each map:
"An estimate of the percentage of adults that can digest lactose in the indigenous population of the Old World[66]"
"Rough rates of lactose intolerance in different regions of the world"
Do you have any suggestions to improve the wording to make is more accurate (less nonsense)? QuackGuru (talk) 15:30, 10 July 2017 (UTC)
User:Rambalac are you suggesting that most people in Japan are not lactose intolerant when they become adults? If so please provide a reference to support that position. Doc James (talk · contribs · email) 15:44, 10 July 2017 (UTC)
Lactase_persistence, in the end.
When you publish reasearch about people of US dont use electronics after living in Amish village then yes, that is nonsense. Rambalac (talk) 15:55, 10 July 2017 (UTC)
Most people with lactose intolerance can "consume 200 ml of milk without severe symptoms" per "Most people with lactose intolerance can tolerate some amount of lactose in their diet and do not need to avoid milk or milk products completely."[6] Doc James (talk · contribs · email) 16:46, 10 July 2017 (UTC)
File:Lactose tolerance in the Old World.svg is not "nonsense", Rambalac. It is based on the best available data, using clear and consistent criteria from the scientific literature. The fact that it shows rates of lactose tolerance in indigenous populations is clearly stated in the caption. Recent migrant populations (e.g. ethnic Russians in Siberia) are excluded because they are not relevant to understanding the long-term evolution or phylogeography of lactose tolerance, which is what the map is intended to convey.
There is no reliable data from Japan – the study cited in lactase persistence is nearly 50 years old. Therefore its value on the map is extrapolated from the nearest available data points (Manchuria). That is a simple fact of geography and the only scientifically responsible thing to do. I do doubt that the Japanese have significantly different rates of lactose tolerance to other East Asians, though. And I have no idea why you think it would have changed in the last seventy years. – Joe (talk) 16:23, 10 July 2017 (UTC)

Management of intolerance caused by primary lactase deficiency[edit]

Since primary lactase deficiency is not a "disease", but a normal condition as in other mammals, we should not say that there is no "cure." The explanation of the NIH page is more accurate: "People with primary and congenital lactase deficiency cannot change their body’s ability to produce lactase."

In addition, it is possible to reduce lactose intolerance through regular consumption of foods containing lactose: "colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance." "However, regular dairy food consumption by lactase non persistent people could lead to colonic adaptation by the microbiome. This process may mimic a prebiotic effect and allows lactase non persistent people to consume more dairy foods enhancing a favorable microbiome."

I adjusted the page [7].

Best regards. --BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 01:56, 13 August 2017 (UTC)

Agreed about "cure", it doesn't make sense in this context.
The info you added about adapting to lactose is appreciated but it duplicates the "Rehabituation to dairy products" section just below, so I have moved it accordingly. This seems to be a re-occurring problem with this article: people insert the same bits of information where it seems relevant to them, without checking if it's already in there, making the structure very confusing and repetitious. Please do skim the whole article (or at least the whole section) before editing it. – Joe (talk) 12:11, 13 August 2017 (UTC)
Thank you very much for your comments. However, it was not just a duplicate but a summary, since the sections normally contain a summary of the subsections. Anyway, it is better after your edit.
It is clear that this was not with bad intention, but please do skim copyright policies before saying that wording is a "copyvio" (and it was not even just a copy paste...). See NIH copyright policies [8] and, if you download the text in pdf format, you will be able to read "This publication is not copyrighted. The Clearinghouse encourages users of this publication to duplicate and distribute as many copies as desired." IMO, This explanation is more clear than this one.
Best regards. --BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 14:24, 13 August 2017 (UTC)

Not seeing support[edit]

Were does the source say "progressive exposure to induce tolerance" as a treatment?[9] Doc James (talk · contribs · email) 20:39, 15 August 2017 (UTC)

My intention with this edit was to paraphrase, unify, and summarize the information not only of the source you are mentioning PMID 26893059 [10] but also from the NIH source already present (ref number one):
NIH. Lactose Intolerance. Eating, Diet, and Nutrition. People may find it helpful to talk with a health care provider or a registered dietitian about a dietary plan. A dietary plan can help people manage the symptoms of lactose intolerance and make sure they get enough nutrients. Parents, caretakers, childcare providers, and others who serve food to children with lactose intolerance should follow the dietary plan recommended by the child’s health care provider or registered dietitian. Milk and milk products. Gradually introducing small amounts of milk or milk products may help some people adapt to them with fewer symptoms.
PMID 26893059 Due to the beneficial prebiotic effects of lactose, it has been speculated that lactose nondigesting adults9,24 and premature infants with low and immature production of lactase16 should not avoid lactose but rather consume smaller amounts frequently to obtain the beneficial effects and avoid lactose intolerance symptoms. In adults, it has been shown that long-term ingestion of lactose can lead to diminished lactose intolerance as measured by the breath hydrogen test. This adaptation may be due to changes in the colonic microbiota or an upregulation of lactase.24
Maybe I should have put also this other two references:
PMID 26404364 4. How Do Humans Cope with Lactose Intolerance? ... Since most people with lactose intolerance can tolerate some amount of lactose in their diet they do not need to avoid milk or milk products completely. There are considerable variations in the amount of lactose that can be tolerated among lactose intolerant individuals. NIH experts suggest that adults and adolescents with lactose mal-absorption could eat or drink at least 12 g of lactose (the amount of lactose in 1 cup of milk) without symptoms or with only minor symptoms. Increasing lactose consumption may be possible if taken with meals or in small amounts throughout the day 51,52. Although no way to reinstate lactase production has been found as of 2015, some individuals have reported that their intolerance varies over time, depending on health status, pregnancy and adaptation to lactose intake 53, particularly through adaptation of the colon microbial system to lactose 54. ... A gradual introduction of small amounts of milk or milk products may help some people adapt to lactose with minor symptoms 55.
PMID 26287234 However, regular dairy food consumption by lactase non persistent people could lead to colonic adaptation by the microbiome. This process may mimic a prebiotic effect and allows lactase non persistent people to consume more dairy foods enhancing a favorable microbiome. This process then could lead to alterations in outcome of diseases in response to dairy foods in lactose maldigesters.
Another problem is to call it "treatment", but since it is a parameter of the infobox, we can not change it.
Best regards. --BallenaBlanca BallenaBlanca.jpg Blue Mars symbol.svg (Talk) 23:33, 15 August 2017 (UTC)
Maybe "Gradually introducing small amounts of milk or milk products may help some people adapt to them with fewer symptoms." would fit best in the body of the text.
It is already there. Doc James (talk · contribs · email) 04:35, 16 August 2017 (UTC)

Lactose Intolerance in Adults: Biological Mechanism and Dietary Management (Deng, Misselwitz, Dai and Fox, 2015 Sep)[edit]

By Yanyong Deng, Benjamin Misselwitz, Ning Dai and Mark Fox.

Published online 2015 Sep 18. doi: 10.3390/nu7095380


Lactose intolerance related to primary or secondary lactase deficiency is characterized by abdominal pain and distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products. The biological mechanism and lactose malabsorption is established and several investigations are available, including genetic, endoscopic and physiological tests. Lactose intolerance depends not only on the expression of lactase but also on the dose of lactose, intestinal flora, gastrointestinal motility, small intestinal bacterial overgrowth and sensitivity of the gastrointestinal tract to the generation of gas and other fermentation products of lactose digestion. Treatment of lactose intolerance can include lactose-reduced diet and enzyme replacement. This is effective if symptoms are only related to dairy products; however, lactose intolerance can be part of a wider intolerance to variably absorbed, fermentable oligo-, di-, monosaccharides and polyols (FODMAPs). This is present in at least half of patients with irritable bowel syndrome (IBS) and this group requires not only restriction of lactose intake but also a low FODMAP diet to improve gastrointestinal complaints. The long-term effects of a dairy-free, low FODMAPs diet on nutritional health and the fecal microbiome are not well defined. This review summarizes recent advances in our understanding of the genetic basis, biological mechanism, diagnosis and dietary management of lactose intolerance.

Keywords: lactose intolerance, lactase deficiency, lactose malabsorption, FODMAP, genetic test, hydrogen breath test, irritable bowel syndrome

Lactose and Lactase[edit]

Lactose is a disaccharide consisting of galactose bound to glucose and is of key importance in animal life as the main source of calories from milk of all mammals, all except the sea lion. Intestinal absorption of lactose requires hydrolysis to its component monosaccharides by the brush-border enzyme lactase. From week 8 of gestation, lactase activity can be detected at the mucosal surface in the human intestine. Activity increases until week 34 and lactase expression is at its peak by birth. The ability to digest lactose during the period of breast-feeding is essential to the health of the infant as demonstrated by congenital lactase deficiency that is fatal if not recognized very early after birth. However, following the first few months of life, lactase activity starts to decrease (lactase non-persistence). In most humans, this activity declines following weaning to undetectable levels as a consequence of the normal maturational down-regulation of lactase expression (Vesa, Marteau, Korpela, 2000). The exceptions to this rule are the descendants of populations that traditionally practice cattle domestication maintain the ability to digest milk and other dairy products into adulthood. The frequency of this “lactase persistence trait” is high in northern European populations (>90% in Scandinavia and Holland), decreases in frequency across southern Europe and the Middle East (~50% in Spain, Italy and pastoralist Arab populations) and is low in Asia and most of Africa (~1% in Chinese, ~5%–20% in West African agriculturalists); although it is common in pastoralist populations from Africa (~90% in Tutsi, ~50% in Fulani) (Swallow, 2003). (talk) 15:50, 23 October 2017 (UTC)

What is the suggestion? Doc James (talk · contribs · email) 18:27, 23 October 2017 (UTC)