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Lactose Intolerance by Ethnic Groups
Topic Started: Dec 29 2008, 08:20 PM (11,974 Views)
Axumd
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Lactose intolerance is the inability to metabolize lactose, a sugar found in milk and other dairy products, because the required enzyme lactase is absent in the intestinal system or its availability is lowered. It is estimated that 75% of adults show some decrease in lactase activity during adulthood worldwide. The frequency of decreased lactase activity ranges from nearly 5% in northern Europe to more than 90% in some Asian and African countries.

Lactase biology
The normal mammalian condition is for the young of a species to experience reduced lactase production at the end of the weaning period (a species-specific length of time). In non dairy consuming societies, lactase production usually drops about 90% during the first four years of life, although the exact drop over time varies widely. The majority of the world's human population follows this trend, with the lactase producing genes largely inactivated in adulthood.

However, certain human populations have a mutation on chromosome 2 which eliminates the shutdown in lactase production, making it possible for members of these populations to continue consumption of fresh milk and other dairy products throughout their lives without difficulty. This appears to be an evolutionarily recent adaptation to dairy consumption, and has occurred independently in both northern Europe and east Africa in populations with a historically pastoral lifestyle. Lactase persistence, allowing lactose digestion to continue into adulthood, is a dominant allele, making lactose intolerance a recessive genetic trait.

Some cultures, such as that of Japan, where dairy consumption has been on the increase, demonstrate a lower prevalence of lactose intolerance in spite of a genetic predisposition.

Pathological lactose intolerance can be caused by Coeliac disease, which damages the villi in the small intestine that produce lactase. This lactose intolerance is temporary. Lactose intolerance associated with coeliac disease ceases after the patient has been on a gluten-free diet long enough for the villi to recover.

Certain people who report problems with consuming lactose are not actually lactose intolerant. In a study of 323 Sicilian adults, Carroccio et al. (1998) found only 4% were both lactose intolerant and lactose maldigesters, while 32.2% were lactose maldigesters but did not test as lactose intolerant. However, Burgio et al. (1984) found that 72% of 100 Sicilians were lactose intolerant in their study and 106 of 208 northern Italians (i.e., 51%) were lactose intolerant.



Lactose intolerance by group

Human groups Individuals Examined Percent Intolerant Allele frequency

Dutch N/A 1% N/A
Swedes N/A 2% 0.14
Europeans in Australia 160 4% 0.20
Northern Europeans and Scandinavians N/A 5% N/A
Danes N/A 5% N/A
Basques 85 10%><100% N/A
British N/A 05–015% 0.184-0.302
Swiss N/A 10% 0.316
European Americans 245 12% 0.346
Tuareg N/A 13% N/A
Germans N/A 15% N/A
Austrians N/A 15–020% N/A
Eastern Slavs (Russians, Belarusians, Ukrainians) N/A 15% N/A
Northern French N/A 17% N/A
Finns 134 18% 0.424
Central Italians 65 19% N/A
Indians N/A 20% N/A
African Tutsi N/A 20% 0.447
African Fulani N/A 23% 0.48
Bedouins N/A 25% N/A
Portuguese adults 102 35%><100% N/A
African American Children N/A 45% N/A
Southern Italians 51 41% N/A
Saami (in Russia and Finland) N/A 25–060% N/A
Northern Italians 89 52% N/A
North American Hispanics N/A 53% N/A
Balkans N/A 55% N/A
Mexican American Males N/A 55% N/A
Cretans N/A 56% N/A
African Maasai 21 62% N/A
Southern French N/A 65% N/A
Greek Cypriots N/A 66% N/A
North American Jews N/A 68.8% N/A
Sicilians 100 71% N/A
South Americans N/A 65–75% N/A
Rural Mexicans N/A 73.8% N/A
African Americans 20 75% 0.87
Kazakhs from northwest Xinjiang 195 76.4%
Lebanese 75 78% N/A
Central Asians N/A 80% N/A
Alaskan Eskimo N/A 80% N/A
Australian Aborigines 44 85% 0.922
Inner Mongolians 198 87.9%
African Bantu 59 89% 0.943
Asian Americans N/A 90% N/A
Northeastern Han Chinese 248 92.3%
Chinese 71 95% 0.964
Southeast Asians N/A 98% N/A
Thais 134 98% 0.99
Native Americans 24 100% 1.00

The statistical significance varies greatly depending on number of people sampled.

Lactose intolerance levels also increase with age. At ages 2 - 3 yrs., 6 yrs., and 9 - 10 yrs., the amount of lactose intolerance is, respectively:

6% to 15% in white Americans and northern Europeans
18%, 30%, and 47% in Mexican Americans
25%, 45%, and 60% in black South Africans
approximately 30%, 80%, and 85% in Chinese and Japanese
30–55%, 90%, and >90% in Mestizos of Peru
Chinese and Japanese populations typically lose between 80 and 90 percent of their ability to digest lactose within three to four years of weaning. Some studies have found that most Japanese can consume 200 ml (8 fl oz) of milk without severe symptoms (Swagerty et al, 2002).

Ashkenazi Jews can keep 20 - 30 percent of their ability to digest lactose for many years. Of the 10% of the Northern European population that develops lactose intolerance, the development of lactose intolerance is a gradual process spread out over as many as 20 years.

http://en.wikipedia.org/wiki/Lactose_intolerance

Edited by Axumd, Dec 29 2008, 11:19 PM.
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Toma
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I never got it why the Balkan and Southern groups had such high lactose intolerance. They are populations of shepherds.
Edited by Toma, Dec 29 2008, 08:31 PM.
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Maybe for cow's milk which isnt too healthy, but goat milk, ice cream and various cheeses are digested fine in Southern Italy. ;)

Here some links on this subject:

Early Europeans unable to digest milk

http://dienekes.blogspot.com/2007/02/early-europeans-unable-to-digest-milk.html

Lactose malabsorption, climate, and cattle disease

http://dienekes.blogspot.com/2005/07/lactose-malabsorption-climate-and.html

Lactase persistence in Africans and non-Africans

http://dienekes.blogspot.com/2005/06/lactase-persistence-in-africans-and.html

Lactose tolerance gene supports a Eurasian origin of Berber populations

http://dienekes.blogspot.com/2005/04/lactose-tolerance-gene-supports.html

Lactase persistence allele is clinal in Great Britain

http://dienekes.blogspot.com/2008/09/lactase-persistence-allele-is-clinal-in.html
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Robert
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Caudium
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Yep, this is strange.

I'm 100% Terron as far as I know. Nobody in my family is lactose intolerant. Even my grandmother who was born in Italy was lactose tolerant and made us all drink milk. I don't think my lips ever touched goat milk until I was 11 years old or something. And of course, ice cream is one of my vices and is a guaranteed crowd-pleaser at all of our family dinners.

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Lactose Intolerance is Normal!
Dr Julia Lee-Thorp and Dr Becky Rogers Ackermann,
Department of Archaeology, University of Cape Town



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Last month's article on cow's milk and the problems which can be associated with it was packed full (to use the advertising jargon for milk) of interesting information. But we were rather startled to see lactose intolerance - which affects a majority of the world's population - described as a "disease". In fact, it is adult lactose tolerance for cows' milk that is unusual. We thought that curious readers might be interested in why this is so.

In his article Milk Allergy and Lactose Intolerance (May 2002), Dr Steinman gives the following figures for lactose intolerance for children over 5 years old: "90-95% of black individuals and 20-25% of white individuals throughout the world". In fact, the picture is much more complicated. Many Asian populations, especially people from Far East, have rates of lactase deficiency approaching 100%. Additionally, there are a few groups in Africa, such as the Fulani, who have relatively low rates of lactose intolerance (around 20-25 percent). Conversely, some European populations like the Swedes are almost completely lactose tolerant (apx. 4% deficiency). Given that most of the world does not fall neatly into 'black' or 'white' categories, such variation is important. In fact, the world average for lactose intolerance is probably much closer to the 90-95% range given for 'blacks.' Therefore, we were very surprised to see this condition described as a "disease". Elsewhere we have seen it described as a "disorder". Why should this be when most adults in the world are lactose intolerant, clearly making this the normal adult condition? The perception of lactose intolerance as a health problem is a rather narrow Western view. We imply no offence to Dr Steinman, as this perspective is widely held, and in general misconceptions about the healthy associations of whole dairy milk are widespread and probably have a lot to do with marketing and advertising campaigns.

As the figures show, whole cow's milk is definitely not for everyone, at least not unless the milk is soured or fermented, as explained by Dr Steinman. Human infants, like other mammals, receive nourishment from mother's milk. Infants have an enzyme that allows milk sugar - lactose - to be digested. In most human populations, the manufacture of the lactase enzyme is "turned off" by around four years of age. The same is true of other mammals, which become lactose intolerant following weaning. The really interesting question, then, is why are some humans not lactose intolerant? And why are relatively few 'white' people - aka. of Western European origin - lactose intolerant?

The answer lies somewhere in the past. Human beings only began to cultivate domestic grains and keep domestic animals relatively recently. Sheep and then cattle were first domesticated just over 10 000 years ago, in the Near East where the wild progenitors of these animals lived. Grains like wheat and barley were also domesticated at around this time. All of this took place through selective breeding - and consequent genetic manipulation - with humans in control. It brought about a quantum change in the way that people lived - they settled down, cultivated most of their food and populations began to grow. Not all of the change was for the better, as amongst other new problems humans also began to inherit diseases from their animals and from close proximity to large numbers of people (like TB and other infectious diseases - but that is another story!). The new way of life spread, along with the cattle, sheep and grains, reaching Western Europe a few millennia later.

It was here in Western Europe that some populations began an evolutionary transition to lactose tolerance. This meant that in certain individuals, as a result of genetic change the enzyme allowing the digestion of milk sugar continued to be produced throughout adult life. So these individuals no longer lost their childhood lactose tolerance but carried it into adulthood. This mutation also occurred in the Fulani people in the Sahel, although somewhat later since domesticated cattle reached this area just a couple of millennia ago.

Lactase deficiency is a classic anthropological example of a genetic trait that has been influenced by cultural factors. There is a relationship between the frequency of lactase deficiency in a population and whether or not the population was involved in intensive dairy farming. Low levels of lactase deficiency are found in European populations with a long history of dairy farming, and highest levels in populations of Asian ancestry who were not dairy farmers. Low levels also occur in other populations that rely extensively on milk in their diet (like the Fulani of Western Africa, and it is believed, Khoi pastoralists of Southern Africa). These numbers suggest that the ability to digest whole milk later in life is selected for in environments where milk is a major source of nutrition and forms an important part of the diet. Genetic change resulting in lactose tolerance presumably carried strong advantages in such circumstances - i.e. in helping people to survive longer and to reproduce themselves.

This transition to lactose tolerance seems to have been most 'successful' (in evolutionary terms), in Western Europe. When Western Europeans began to colonise other areas of the world from the 16th century onwards, the lactose tolerance 'gene' travelled along with them, no doubt increasing the frequency of lactose tolerance in contact populations across the colonised world.

For further information refer to:
Cavalli-Sforza, LL, P Mendozzi, and A Piazza. (1994) The History and Geography of Human Genes. Princeton: Princeton University Press.
Harrison, GA, JM Tanner, DR Pilbeam, and PT Baker. (1988) Human Biology: An Introduction to Human Evolution, Variation, Growth, and Adaptability. 3rd edition. Oxford: Oxford University Press.
Relethford, JH (1997). Fundamentals of Biological Anthropology. 2nd edition. California: Mayfield Publishing Company.

Figure caption:
Seventeenth century ink and wash drawing of a Khoikhoi cow being milked, from The Khoikhoi at the Cape of Good Hope, (1993) published by the South African Library, with text by Andrew Smith and Roy Heiffer.


http://www.scienceinafrica.co.za/2002/june/lactose.htm
Edited by Caudium, Dec 29 2008, 09:40 PM.
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Rhino
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Don't mongolian people eat/drink only milk? lol? :confused:
Edited by Rhino, Dec 29 2008, 09:39 PM.
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Axumd
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African Adaptation to Digesting Milk Is "Strongest Signal of Selection Ever"

For many adults in the world, the phrase "got milk?" is quickly followed by "got a nearby toilet?" Lactose, the primary sugar in milk, is a universal favorite in infancy but into adulthood the level of lactase-phlorizin hydrolase, the enzyme that metabolizes lactose in the small intestine, decreases and digestion of dairy products becomes difficult. In some populations, however, such as those located in northern Europe, the ability to digest milk remains most likely as a result of lifestyles based around cattle domestication. In 2002 Finnish scientists localized the genetic mutation that conferred this trait in northern Europeans to two regions on chromosome 2.

Now, the results of a four-year, international research project find that communities in East Africa leading traditionally similar pastoral lives evolved their ability to drink milk rapidly and independently of the northern Europeans. According to University of Maryland biologist Sarah Tishkoff, the lead author of a study appearing in today's Nature Genetics, the mutation allowing them to "get milk" arose so quickly and was so advantageous that "it is basically the strongest signal of selection ever observed in any genome, in any study, in any population in the world."

Tishkoff and her students tested 470 people representing over 43 ethnic factions in the Sudan, Kenya and northern Tanzania for lactose intolerance using glucose-monitoring kits, familiar to most diabetics. The team then selected the 40 most lactose intolerant participants and the 69 most tolerant and sequenced parts of their genomes around the two markers identified in the Finnish lactase persistence study. The researchers determined there were 123 single nucleotide polymorphisms--SNPs, or changes to one base in the genetic code--associated with digestibility. Of these, three SNPs were more promising than the others and one of them was very common among Tanzanians and Kenyans, showing up in 40 to 50 percent of the sequences.

Working with this highly correlated locus, Tishkoff's team sequenced a broad region of the chromosome around this nucleotide to determine whether it arose in concert with the European mutation. "It turns out they're on completely different chromosome backgrounds," she explains. "So it had a completely different origin." Next, the team tested to see if the mutation was positively selected, conferring a reproductive advantage and spreading quickly through the population. People who had this particular SNP on both copies of chromosome 2 had identical genetic scripts for the next two million base pairs--a phenomenon that occurs when there is a strong benefit to having a particular trait, known as "hitchhiking" or a "selective sweep." Because this section has been preserved intact without being mutated or broken up by recombination, it indicates that it is very recent and very strong. In addition, Tishkoff's team determined the date range when the mutation likely occurred: 3,000 to 7,000 years ago, which matches up well with the archaeological record that places pastoralization coming to East Africa about 5,000 years ago. The European trait dates back about 9,000 years.

Tishkoff believes that because she found so many markers associated with lactose tolerance in the sequencing of her 109 subjects, evolution clearly develops multiple solutions when there is a strong selective force. "There are some populations that can digest milk, and they don't have any of these mutations," she says. "There are more out there." Dallas Swallow, a human geneticist at University College London, agrees with that assessment. She released a study on a small Sudanese tribe in Human Genetics this past November, finding three markers, two of which Tishkoff had isolated in her study. Oddly enough, Swallow found no data on the Maryland study's primary variant. Tishkoff argues this disparity is due to geographic specificity of these mutations. Swallow, for her part, notes that Tishkoff's dramatic results may be a result of "the relative relatedness" of her sample. "If you have an ethnic group which is rather a small population in size but happens to migrate over geographic distances then they might be more related to each other than the surrounding people," she points out.Nevertheless, both researchers are pleased that their studies found at least two genetic markers in common. Swallow concedes: "It looks jolly well as though drinking milk as an adult was good for some of us at some time in our history, that's for sure."


http://www.sciam.com/article.cfm?id=african-adaptation-to-dig&ref=sciam
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Axumd
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Rhino
Dec 29 2008, 09:37 PM
Don't mongolian people eat/drink only milk? lol? :confused:
I think it's funny because they drink it, but could be possible that they are ethier tolerant or intolerant to it.
Axumd
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Axumd
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I reckon people here are right that Africans and most Asians along with Amerindians would be more on the side to be intolerant to milk and other dairy products which seems to be more common amongst them than any other people.


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Who is at risk for lactose intolerance?
Between 30 and 50 million Americans are lactose intolerant and certain ethnic and racial populations are more affected than others. Up to 80 percent of African Americans, 80 to 100 percent of American Indians, and 90 to 100 percent of Asian Americans are lactose intolerant. The condition is least common among people of northern European descent.

Babies that are born prematurely are also more likely to be lactose intolerant, because lactase levels do not increase until the third trimester of a woman’s pregnancy.


http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/
Edited by Axumd, Dec 29 2008, 11:26 PM.
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Forrester
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Dec 29 2008, 08:31 PM
I never got it why the Balkan and Southern groups had such high lactose intolerance. They are populations of shepherds.
Maybe it depends on what you herd. You can actually give goat and sheep milk to lactose intolerant people. Camel milk is actually lactose free.

Cheese also has very low lactose in it for the less mobile groups.
Edited by Forrester, Dec 30 2008, 02:27 AM.
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oneonezero
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sucks for east Asians an Amerindians.
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Axumd
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^^ Yeah does so much man.
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YigalSchmendrik
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im lactose sensitive and my mom is full on intolerant,cheese and dairy products do not do much to me, but if i drink a galss of real milk fuggedabouit
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rockstar135
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I think that the fact that such a large proportion of the world's adult population being lactose intolerant signifies we were probably never supposed to be drinking cow's milk in the first place.

Give me soy 'milk' any day.
"Let's just call things what they are. When a man's love of finery clouds his moral judgment, that is vanity. When he lets a demanding palate make his moral choices, that is gluttony. When he ascribes the divine will to his own whims, that is pride. And when he gets angry at being reminded of animal suffering that his own daily choices might help avoid, that is moral cowardice."
-Matthew Scully

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Europa
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Give me soy 'milk' any day


EEEEEW. :puke: Soy milk is vile. It just tastes like bean juice.

Love milk, but MS means I can't drink it. Lactose seems to lower uric acid levels. Good for gout, not for MS.
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Simurgh
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I just love milk and diary products since I remember myself. I drink milk almost everyday without any problems (at least visible ones) and the same is with the rest of my family. My grandmother, for instance drank a liter of cow milk almost every day.
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rockstar135
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Jan 5 2009, 08:57 PM
EEEEEW. :puke: Soy milk is vile. It just tastes like bean juice.

Don't drink any dairy then you'll find it just as vile. :)
"Let's just call things what they are. When a man's love of finery clouds his moral judgment, that is vanity. When he lets a demanding palate make his moral choices, that is gluttony. When he ascribes the divine will to his own whims, that is pride. And when he gets angry at being reminded of animal suffering that his own daily choices might help avoid, that is moral cowardice."
-Matthew Scully

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Toma
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Yeah, and then wait for your bones to crack.
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Simurgh
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Jan 5 2009, 09:24 PM
Yeah, and then wait for your bones to crack.
Sounds stupid and unlogical, but milk can prevent the good assimilation of calcium in the body.

P.S. Soy milk makes me sick - I have a quickened pulse after drinking it.
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The best milk for human consumption is human female breast milk I think. There is other sources for calcium than (cow)milk, like orange juice or broccoli for instance.

*I'm not 100% sure at the moment, but I seem to remember some articles mentioning the relationship between cows milk and diabetes.
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