Nutrients. 2015 Aug 31;7(9):7312-31.

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

Silanikove N, Leitner G, Merin U

There is no data of Japanese lactose malabsorption.

However, from China and Southeast data, it is estimated that 90-95%.

However, there was data that 19% in 1975.

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. The incidence of milk intolerance is approximately 19% in Japanese adults when 200 ml of milk is given.

Studies on the etiology of milk intolerance in Japanese adults.

Yoshida Y, Sasaki G, Goto S, Yanagiya S, Takashina K.

Gastroenterol Jpn. 1975;10(1):29-34.

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Japanese lactose intolerance is 19 percent?
 19% is the same as the Italian!
 

But, it is not correct.

In this experiment, the amount of milk was 200ml.

Lactose dose is 4.5 ~ 5g (in 100ml Japanese milk).

Namely, in this experiment, lactose was ingested only 9 ~ 10g.

Usually, experiment for lactose malabsorption is after a dose of 1 g/kg lactose.

Lactose 50g is ingested in adults.

 1979, correct research results have been reported.
 

Breath hydrogen test for detecting lactose malabsorption in infants and children. Prevalence oflactose malabsorption in Japanese children and adults.

Nose O, Iida Y, Kai H, Harada T, Ogawa M, Yabuuchi H.

Arch Dis Child. 1979 Jun;54(6):436-40.

80 healthy Japanese infants and children (aged between one month and 15 years) and 18 adults were examined for lactose malabsorption after a dose of 1 g/kg lactose.

The incidence of lactose malabsorption was 30% in 3-year, 36% in 4-year, 58% in 5-year, and 86% in 6-year-old children, 85% in schoolchildren, and 89% in adults. Thus the incidence of lactase deficiency gradually increases with age from 3 years, and about 90% of all normal Japanese adults are lactase-deficient.

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In 2007, Oku was repotet that almost all subjects were complained abdominal symptoms (abdominal pain, abdominal distention) by ingestion of 40g lactose.

Tuneyuki Oku. 2001

https://www.j-milk.jp/tool/kenkyu/gakujutsu/berohe0000000kg5-att/studyreports2001-11.pdf

Oku was described that maximum non-effective level (no-observable-efect level) of lactose was 0.61g / kg.

However, CD50 of lactose was 1.1g/ kg.

This CD50 kevel is equivalent to the volume used in the intolerance test.
 

His group was also reported CD50 of lactitol in 2007.

It was 0.7g/kg.

 
Eur J Clin Nutr. 2007 Sep;61(9):1086-93. Epub 2007 Jan 24.

Suppressive effect of partially hydrolyzed guar gum on transitory diarrhea induced by ingestion of maltitol andlactitol in healthy humans.

Nakamura S, Hongo R, Moji K, Oku T.

However, in Japanese Food Safety Commission was established that the maximum non-effective level of lactitol is 0.075g / kg in man, and 0.15g / kg in woman.

This is 11-21% of the level of CD50.

From this relationship, no-effective dose of lactose, is 0.12 ~ 0.23g / kg.

This is  6 ~ 11.5g in 50kg subject.

Safety drinking amount of milk is 130ml in Japan?