But most people -- about 60 percent and primarily those of Asian and African descent -- stop producing lactase, the enzyme required to digest milk, as they mature. People of northern European descent, however, tend to retain the ability to produce the enzyme and drink milk throughout life.
80 percent of all African-Americans and Native Americans are lactose intolerant. Over 90 percent of Asian-Americans are lactose intolerant, and it is least common among Americans with a Northern European heritage.
People with lactose intolerance are unable to fully digest the sugar (lactose) in milk. As a result, they have diarrhea, gas and bloating after eating or drinking dairy products.
It is thought that Asian populations have decreased amounts of lactase in adulthood compared to Caucasian populations, especially those of northern European descent.
Experts estimate that about 68 percent of the world's population has lactose malabsorption.
Lactase nonpersistence is most prevalent in people of East Asian descent, with 70 to 100 percent of people affected in these communities. Lactase nonpersistence is also very common in people of West African, Arab, Jewish, Greek, and Italian descent.
The exceptions are certain groups of humans, such as Hindus, Europeans, and their American descendants, who consume the milk of cows or other animals throughout their lives. A sizable majority of traditional cultures in the world do not drink milk, including most Asian and African populations.
If you're of African descent, it explains the evolutionary journey behind your lactase-related mutations pretty well. In the arid environments of Africa, milk is a key source of liquid when water is scarce, so the evolutionary advantage of lactase persistence is clear.
It's believed that Japanese people have only been consuming milk for about 150 years. It all began after the country opened its ports to the world and came into contact with Western culture. This is why about 90 percent of Japanese people are lactose intolerant now.
Livestock was too busy for dairy
Which makes sense. But the biggest reason Asian cultures don't regularly incorporate cheese into their cooking is probably because so many East Asians are lactose intolerant. In fact, they're drastically more likely to be lactose intolerant than Westerners.
If you're American or European it's hard to realize this, but being able to digest milk as an adult is one weird genetic adaptation. It's not normal. Somewhat less than 40% of people in the world retain the ability to digest lactose after childhood.
All humans can digest milk in infancy. But the ability to do so as an adult developed fairly recently, likely in the past 6000 years. A handful of mutations allows adults to produce the enzyme lactase, which can break down the milk sugar lactose.
Lactase deficiency
Most people naturally produce lactase in their small intestines during infancy to help digest breast milk and make less of it as they grow up. If you don't have enough lactase, you won't be able to digest lactose. Some people produce more or less lactase than others.
Dairy milk (cow, sheep and goat) was consumed by just over two thirds (69%) of the Aboriginal and Torres Strait Islander population (see Table 4.1). This was similar to the proportion of non-Indigenous people that consumed these products (68%) (see Table 4.3).
The ability to digest lactose is most common in people of European descent, and to a lesser extent in some parts of the Middle East and Africa. Lactose intolerance is most common among people of Jewish descent, as well as in many African countries and Arab countries.
Generally, dairy consumption is much lower in Asians, especially in Koreans because dairy foods are not a part of the traditional Korean diet and 75 % of Koreans have lactose intolerance ( 5 , Reference Scrimshaw and Murray 11 ).
In China, a much-cited study estimated that 92% of adults had trouble absorbing lactose; more recently, China's preventative medicine agency suggested that by the time kids are 11 to 13 years old, around 40% have lost the ability to digest it.
It is estimated that around 4% of the Australian population is lactose intolerant, with the condition more prevalent in women than in men by a factor of three to one.
While 65% or more of the total human population are lactose intolerant, in some human populations lactase activity commonly persists into adulthood. Lactose tolerance is exceptionally widespread in Northern European countries such as Sweden and Finland, with tolerance levels of 74% and 82%, respectively.
Just 5,000 years ago, even though it was a part of their diet, virtually no adult humans could properly digest milk. But in the blink of an evolutionary eye northern Europeans began inheriting a genetic mutation that enabled them to do so.
However, a genetic trait called lactase persistence has evolved multiple times over the last 10,000 years and spread in various milk-drinking populations in Europe, central and southern Asia, the Middle East and Africa. Today, around one third of adults in the world are lactase persistent.”
According to Islamic dietary law, dairy, yogurt and cheese should be produced from halal certified animals. Gelatin in yogurt and rennet in cheese should also be halal. Jewish dietary laws state not only meat and dairy cannot be consumed together but they also need to be cooked in separate utensils.
China is not just a land of milk and honey for dairy producers since there are several factors hindering the development of China's dairy market. First, Asian people are genetically predisposed to lactase-deficiency: around 92% of adults suffer from lactose intolerance in China.