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Lactose Intolerance: The Facts

How many times have you heard, “I can’t eat cheese. I’m lactose intolerant.

Chances are, if you’re in the cheese business—making it, distributing it, selling it—you’ve heard it enough to make you wonder if you’ll soon be lactose intolerant, too. How can so many Americans be cursed with a digestive system that can’t handle cheese? And what do you, as someone peddling the offending food, need to know about this condition? The facts may surprise you.

Lactose and Cheesemaking
Lactose is milk sugar, the main carbohydrate in milk. Cow, sheep and goat milk contain roughly equivalent amounts, ranging between four and five percent, with goat’s milk at the lower end of the spectrum.

The bacteria present in milk or added in the form of a culture use lactose as an energy source. They feed on lactose as we might eat a candy bar, and they ferment the sugar to lactic acid. As this bacterial feeding frenzy gets underway in the cheese vat, the acid level rises and the pH drops, creating conditions for milk proteins to coagulate and form curd.

The conversion of lactose to lactic acid enhances flavor in the finished cheese, just as a squeeze of lemon heightens flavor in a salad. Cheese with insufficient acidity tastes bland.

Once the curd forms, the whey is drained off and most of the unfermented lactose goes with it. A little lactose remains in the curds, especially in high-moisture curds like cottage cheese. Consequently, fresh unaged cheeses do have some measurable lactose—about three grams per serving for cottage cheese, compared to 12 grams in an eight-ounce glass of milk. But, as cheese ages, bacteria continue to dine on the lactose until, after three or four weeks, there is virtually no lactose left.

Lactose Intolerance Defined
Most humans produce an enzyme, lactase, that digests milk sugar. Without lactase, infants would not be able to tolerate mother’s milk. But many people lose the ability to make lactase or to make enough as they age. When they eat, say, a bowl of pasta with cream sauce, the lactose enters their intestines undigested and can cause distress, such as bloating or gas.

How many people are lactose intolerant? The National Institutes of Health estimates that 30 to 50 million Americans produce low levels of lactase, although they may have few or no symptoms. It’s a difficult number to pin down because many people who claim lactose intolerance have never been tested, although tests do exist. And self-diagnosis is often mistaken, according to the American Gastroenterological Association (AGA). “Several research studies have documented that people who believe they are lactose intolerant frequently are not, says the AGA’s website. “On the other hand, many people suffer from the disorder and are not aware of it.

Researchers do know that the condition is far more prevalent in some ethnic groups than in others. As many as 90 percent of Asians and 75 percent of African-Americans and Mexican-Americans exhibit some degree of lactose intolerance. The rate among Caucasians is closer to 15 percent.

Cheese for the Lactose Intolerant
“Generally, unless they’re extremely sensitive, cheese is not a problem for people who are lactose intolerant, says Dee Sandquist, a registered dietitian with Southwest Washington Medical Center in Vancouver, Wash. “But when you get into that food intolerance area, it’s very individualized. Most lactose-intolerant people can manage a glass of milk a day without symptoms, says Sandquist, so they should be able to enjoy a couple of ounces of any cheese, especially aged cheese such as Cheddar, Gruyère or Parmigiano Reggiano, without digestive difficulty.

Even moist cheeses such as Brie, Camembert and Limburger have only trace—meaning barely detectable—lactose levels, says Paul Kindstedt, a food-science professor at the University of Vermont in Burlington. “I can’t think of any cheese that is aged for at least 60 days that would contain significant lactose, certainly not one gram per serving, wrote Kindstedt in an email message.

As a cheese merchant, how do you respond to the customer who claims to be lactose intolerant?

Very carefully. No one likes to have his or her health complaints dismissed or disputed. But many people are unaware that most cheeses have little or no lactose, so you have a chance to educate—gently and without condescension. Explain that the milk sugar is consumed in the fermentation and aging process, so aged cheeses should present no problems. Offer to select a few favorite aged cheeses that the customer can sample slowly at home, to see if small amounts produce a reaction. If you sense any reluctance, back off, but many people who had sworn off cheese may be willing to reconsider if this information is new to them.

Janet Fletcher is a staff writer for the San Francisco Chronicle and author of The Cheese Course.