We’re lactose intolerant, so why all the cheese?

It’s ironic that traditional Chanukah desserts include rugelach (sweet pastries made from cream-cheese dough) and sufganiyot (doughnuts) even though Jews and dairy tend not to get along – intestinally speaking.

Nearly 62% of the 110 Jewish Israeli children who were part of a 1985 study were lactose intolerant or more specifically suffered from lactose malabsorption, the inefficient absorption of lactose due to imperfect or impaired digestion.

In the June 2003 issues of Hadassah and Reform Judaism magazines, an advert for lactose-free milk claimed that 60% of Jewish Americans suffered from the painful cramps and other uncomfortable symptoms associated with lactose intolerance.

A meta-analysis study published in 2017 reported an 89% prevalence of lactose intolerance in Israel.

According to the Jewish Telegraphic Agency, several studies in 2019 suggested that 60% to 80% of Ashkenazi Jews were lactase-deficient, meaning they lacked the enzyme that allows for easy digestion of the lactose sugar in milk products. Sephardic and Mediterranean Jews, though less studied, were also considered prone to the condition.

“Studies have shown that the frequency of the variant of the lactose intolerance gene is about 75% in certain Jewish populations, which would then result in lactose intolerance,” says Helen Gautschi of DNALYSIS Biotechnology.

Gayle Landau, a registered dietician working at the Wits Donald Gordon Medical Centre in Parktown, Johannesburg, says, “I see patients for a wide range of medical conditions including inflammatory bowel disease, celiac disease, and irritable bowel syndrome. These conditions, irrespective of ethnicity, are commonly associated with lactose intolerance.”

There is a range of possible causes for lactose intolerance, with Landau citing underlying autoimmune disease and genetic predisposition as reasons for Jews presenting with this condition. Symptoms may include abdominal pain, bloating, diarrhoea, gas, and nausea, which typically start 30 minutes to two hours after eating or drinking milk-based food.

Landau says lactose tolerance may improve once the underlying disease is treated. “I always take a careful family history, consider the person’s medical history, and review their current presenting symptoms rather than make any assumptions that simply because this person is Jewish, they will have lactose intolerance.”

After all, Jews aren’t the only group affected. According to the Crohn’s and Colitis Foundation, “Chinese, Koreans, Japanese, Jews in Israel and elsewhere, and most Africans and their descendants demonstrate very high levels of lactose intolerance.”

Lactose tolerance is actually unusual, said gastroenterologist Mark Walsh in 2003. “A lot of adults will lose a lot of the activity of lactase as they get older,” he said.

According to a study by Storhaug et al., the prevalence of lactose intolerance in South Africa was at 81% as of 2018. Another source, Rediscoverdairy.co.za, reported that 11% of people in this country had the condition, although this figure doesn’t include those who have self-diagnosed lactose intolerance.

Across the globe, about 65% of people experience some form of lactose intolerance as they age past infancy, but there are significant differences between regions and populations. Rates are as high as more than 90% of adults in some communities of Asia, and as low as 5% among northern Europeans.

From an evolutionary perspective, some populations have a better genetic makeup for tolerating lactose than others. Regions of the south, such as Africa, adopted dairy farming much later than the northern European countries, and therefore have lower frequencies of people with a tolerance of lactose.

Gluten intolerance is another frequently occurring condition. Certain lineages of the Jewish population may be more prone to gluten intolerance, says Gautschi. “This is possibly due to the higher frequency of certain gene variants linked to the condition,” she says.

Lactose and gluten intolerance aside, other gastrointestinal troubles are common amongst Jews, according to Landau, Gautschi, gastroenterologist Joseph Murray of the Mayo Clinic, and Ernest Abel, the author of Jewish Genetic Diseases: A Layman’s Guide.

“There’s a genetic predisposition for celiac disease as well as Crohn’s and Ulcerative Colitis [the two main types of inflammatory bowel disease],” says Landau. “Irritable Bowel Syndrome [IBS] often co-exists with these autoimmune conditions.”

She says many of her patients, not only the Jewish ones, who are finally diagnosed with inflammatory bowel disease or celiac disease, were often misdiagnosed as having IBS.

“IBS is, in fact, very common. I cannot comment if it’s more common amongst Jews.”

Says Gautschi, “Certain Jewish lineages have been shown to have a higher prevalence of these autoimmune disorders because of factors such as environmental exposure, habitual dietary intake, and the likelihood of common risk variants being inherited in smaller communities.”

Some geneticists theorise that there might have been historic benefits to Jews having a sensitive stomach. It might be a defensive response to substances that come in contact with the lining of the digestive system, serving as a selective advantage in unhygienic conditions. This might explain why gastrointestinal troubles are prevalent among Jews, suggested Abel. It may have been a genetic advantage for Jews forced to live in tightly packed, often unsanitary ghettoes.