When Mark Thomas, professor of evolutionary genetics at UCL and co-author of the Nature study, examined data from the UK Biobank, he found little relationship between the ability to produce lactase and milk consumption habits. “People who don’t produce lactase usually don’t really have any symptoms, without drinking large amounts of milk, more than a liter of milk or anything like that,” he says.
On closer examination, many lactose intolerances are self-diagnosed, often through dubious methods. The bioresonance-based testing method used by Curtis is not scientifically proven.
Then there is the case of Anne Larchy, a 50-year-old woman in Finchley, who maintained that she had never “liked” milk since childhood, finding that consuming dairy products such as cottage cheese, yoghurt or cheesecake often left her with rashes or a tummy ache. She was diagnosed with lactose intolerance through a form of alternative medicine called muscle kinesiology testing, in which a doctor applies force to a group of muscles and asks the body about its nutritional status. While Curtis and Larchy have reported improved health since excluding all forms of dairy from their diet, both bioresonance testing and muscle kinesiology have been described as forms of pseudoscience.
Scientists suspect that many of these cases of lactose intolerance are often confused with cow’s milk allergy, which is a serious and, in some cases, dangerous condition in which the body overreacts to casein protein found in many dairy products. “A good way to tell if someone has a milk allergy rather than lactose intolerance is if he says he has symptoms when he eats cheese,” says Thomas. “Hard cheese has practically no lactose, butter has practically none. Yogurt has about a third of the lactose of milk, and soft cheese has some, but not a lot.”
Instead of testing yourself, Tom Sanders, emeritus professor of nutrition and dietetics at King’s College London, recommends a hydrogen breath test. “It’s not something GPs do, as they consider it a minor thing, but it’s a pretty easy test,” he says. “You give someone a standard dose of lactose, you wait half an hour, and then you make them breathe, a bit like an alcohol breath test. If hydrogen is present, it shows that the lactose has not been fully digested.”
But at the same time, pediatricians are alarmed by the rise of alternative dairy products for infants and toddlers. Cow’s milk allergy is thought to only affect about 1 percent of children under the age of two.
“There is unnecessary concern about lactose intolerance in babies and milk allergy,” says Robert Boyle, an expert in pediatric allergies at Imperial College London. “Babies have a lot of symptoms when they drink milk, whether it’s breast milk or formula milk, because they’re drinking large volumes. Babies will drink up to a fifth of their body weight in milk each day, so it’s no wonder they’ll have a tummy ache, stool and vomit. But this is labeled as lactose intolerance or allergies much more than necessary.