More than half the people in the world – including 50 million Americans – are lactose-intolerant, which means they do not make enough of an enzyme called lactase, which helps digest lactose, the sugar in dairy products.
Most people are born with the gene that makes lactase. But humans are designed by evolution to be weaned from their mother’s milk. So, over time, as kids grow, the lactase gene begins to shut down, to a modest degree in some people and dramatically in others. said Dr. Ciaran Kelly, a gastroenterologist at Beth Israel Deaconess Medical Center.
Many people of northern European ancestry keep making plenty of lactase, for instance, while many African-Americans, Asians, Native Americans, Mexican-Americans and some Jews lose lactase production.
Depending on the degree of lactase insufficiency, people can have mild to severe diarrhea, gas, bloating and abdominal pain if they consume products containing lactose, said Kathy McManus, director of nutrition at Brigham and Women’s Hospital.
The solution to the problem is to avoid foods that cause these symptoms, including, if your lactose intolerance is severe, hidden sources of lactose in foods like breads and some other baked goods, processed breakfast cereals and lunch meats. There are also supplements and specially-formulated milk like Lactaid that can minimize severe reactions.
To get enough calcium and vitamin D, adults should increase their consumption of foods like salmon and sardines, tofu, and dark green vegetables. Adults need a total of 1,200 milligrams a day of calcium, from food and/or supplements. For vitamin D, the recommendation is at least 400 International Units a day, preferably 800 to 1,000 said McManus.