Karela Fry

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Your teeth are not made for soft drinks

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Science magazine writes about a matter of some public health concern:

Young adults in the town of Dzilam González had three times as many cavities as those who live in a poorer, more isolated village nearby where people can’t afford soft drinks every day, according to a new study. In the poorer village, people eat a traditional diet of maize tortillas at every meal. The richer village has a pizzeria in its central square, shops with ads for soft drinks, dentists’ offices—and significantly more tooth decay in people aged 20 to 30, according to a new study by Elma Vega Lizama and Andrea Cucina of the Autonomous University of Yucatán in Mérida, Mexico.

The Maya of the two villages are before-and-after images of a population undergoing the so-called nutrition transition in which people switch from a traditional subsistence diet to an Industrial Age diet of refined sugars and processed foods.

Cavities appear in fewer than 2% of teeth from earlier than 20,000 years ago. Traditional foragers, such as Australian aboriginals in the 1940s, still had beautiful teeth, with cavities in only the very old. (Other foragers with diets rich in plant carbohydrates, which are sugars, are an exception.) Gum disease and malocclusion—problems in the way the upper and lower teeth fit together, such as overbite—are also surprisingly rare in prehistoric teeth.

Roughly 9% of Neolithic people—the first farmers—had cavities, as they began to consume cereal grains rich in carbohydrates, Ungar says. Even so, many millennia elapsed before dietary changes resulted in serious oral damage.

In Europe, less than 10% of individuals had cavities until Alexander the Great brought sugar to Greece in the 4th century B.C.E., according to earlier studies, says pediatric dentist Kevin Boyd of Children’s Memorial Hospital in Chicago, Illinois. Cavities increased first in Greece, then Rome; their incidence also rose throughout Europe in the Middle Ages. But the biggest spike was from 1800 to 1850, when Britain took control of the West Indies and imported far more sugar than previously. Sugar helped fuel the Industrial Revolution, which was a transition from an agriculture-based economy to a machine-based economy. In 1874, the British reduced the tax on sugar, and it became available to all social classes. “In London, mostly 1800 onwards, they have absolutely dreadful teeth,” Hillson says.

The damage caused by refined sugar is well known: It alters the optimum pH of 5.4 in the mouth, making saliva more acidic. That saliva, as well as acid produced by bacteria in plaque, dissolves minerals in the enamel, causing cavities. By the middle of the 20th century, between 50% and 90% of the population in Europe and the United States had cavities. This improved in the 1970s when water was fluoridated. But for the first time in 40 years, the U.S. Centers for Disease Control and Prevention recently noted an increase in cavities in children aged 2 to 5 years. Dentists blame snacking and sugars in juice and sodas.

Impaction of the third molars, or wisdom teeth, occurs 10 times more frequently in people eating an Industrial Age diet than in hunter-gatherers. “Our jaws are underdeveloped because softened, highly processed foods do not provide the chewing stresses needed to stimulate normal growth of the jaw during childhood,” Corruccini says.

As researchers at the workshop reviewed the data, it became clear that the biggest challenge for our teeth wasn’t the initial transition to agriculture, as many researchers had once thought. It was the Industrial Revolution and then, in the 1980s, another marked increase in refined sugars in processed foods, such as high fructose corn syrup in sodas. “Caries and malocclusion is not a Neolithic problem, but an industrial problem,” Boyd says.

Further research is needed on how sugar affects the balance of species of bacteria in the mouth, such as Streptococcus strains, which are linked to cavities in humans. These complex communities of bacteria mix with minerals from saliva and immune cells to form plaque on the teeth. Our immune systems react to the bacteria, causing gum disease. “Normally, young kids are more resistant to the effects of plaque than adults,” Dean says. But with more sugars in the diet, plaque-forming bacteria may flourish, which may trigger a bigger immune response and inflammatory reaction. That, in turn, can lead to a higher risk of systemic diseases such as cardiovascular disease and diabetes. But the response to plaque varies: “Everyone’s mouth is its own ecological field,” Dean says.

One solution seems to be to use more chewy, fibrous and less starchy food. In other words, eschew the 2-minute noodle and chew the jowar and bajra rotis. Also cut down on the fizzy drinks and chocolate.

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Written by Arhopala Bazaloides

May 25, 2012 at 9:25 am

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