JEFFREY BROWN: This week, we have reported extensively on the health impacts of soda and junk food and some moves in this country to counter them.
Tonight, from our occasional reports from journalism students around country, a story about the situation in El Salvador.
Producer Roberto Daza and correspondent Carl Nasman are graduates of the Journalism School at the University of California, Berkeley.
A note: There are some images that viewers may find disturbing.
CARL NASMAN, reporter: This is Santa Ana, El Salvador, where the American shopping mall and diet have arrived. It's El Salvador's second largest city, but the food and the waistlines are straight out of the United States.
Companies like Pepsi, Coca-Cola, and McDonald's have become part of the local diet. Junk food here is cheap, and it's everywhere, from the mall to the most remote villages.
In cities like Santa Ana, junk food is leading to a very American problem: obesity. But in the countryside, it's causing something different.
We're headed into the mountains about two hours north of San Salvador. Out here, there's still plenty of junk food for sale, but there's little or no access to proper dental care. This mobile clinic is one of the few places to see a dentist. It's run by a local non-profit called ASAPROSAR, which provides free health services in rural areas.
Dentists like Jorge Granillo treat children with mouths full of painful, rotting teeth.
MAN (through translator): There's many cavities. There are many signs of tooth decay. There are some that are rotten down to the roots.
CARL NASMAN: Dentists here say they're seeing an epidemic of tooth decay across the countryside. More than half of the smiles at today's clinic look just like this. They blame the sugar and starch from junk food and a lack of education about dental care.
MAN (through translator): It's sad to see that the child could have been better if the parent had known that the only way to prevent a cavity is with a toothbrush. And that is a sad part of the story.
CARL NASMAN: Silvia Canales is one of the nearly 100 mothers at today's clinic. She says her daughter's mouth pain made it difficult to eat.
SILVIA CANALES, Mother (through translator): She told me that it hurt. It hurt and the tooth was inflamed and swelled up here.
CARL NASMAN: Most parents here can't afford to take their children to a dentist. But even with a high level of poverty, health experts say kids' teeth used to be better.
DR. KAREN SOKAL-GUTIERREZ, University of California, Berkeley: I was shocked.
CARL NASMAN: One of the first to notice a decline in dental health was Karen Sokal-Gutierrez, a pediatrician and professor at U.C. Berkeley. She showed us pictures from 30 years ago, when kids had healthy teeth. But just one generation later, the photos look different.
DR. KAREN SOKAL-GUTIERREZ: This is a child who has all of the teeth on the bottom rotten and all of the teeth on the top.
Years later, when I go into a village and the kid would come flock around us and hug us and smile, that's when I saw, oh, my God, their teeth are all black and rotten. I have never seen this before. What happened?
CARL NASMAN: Professor Gutierrez and her team of volunteers work on the ground in El Salvador, training health workers and donating supplies.
She estimates that 85 percent of kids in rural areas of El Salvador have tooth decay, and nearly half experience mouth pain, leading to serious problems, like jaw infections, tooth loss, and malnutrition. She puts much of the blame on snack food imported from the United States.
With sales peaking at home, American companies are searching for new markets. In 2009, 25 percent of Coca-Cola's operating profits came from Latin America. And, last year, nearly half of Pepsi's sales were from outside the U.S.
DR. KAREN SOKAL-GUTIERREZ: The marketing of junk food, candy, chips, soda at very low price really takes advantage of the poorest people. So, they're trying to show this image that if you drink soda or eat the junk food, you will be healthy, happy, modern.
CARL NASMAN: But Coke and Pepsi insist their products shouldn't be singled out for the rise in tooth decay.
In a statement for the NewsHour, PepsiCo officials said: "With basic dental hygiene practices, people have enjoyed our products for decades without risk to their dental health."
Coca-Cola officials said: "We believe that parents should decide what their children eat and drink. Any food or beverage containing sugars and starches, including some of our beverages, can contribute to the development of cavities."
CARL NASMAN: But in El Salvador, it's not just imported soda and chips. Local companies also churn out cheap, unhealthy food. The local brand of cola costs less than a quarter. And soda here is supersized. These three-liter bottles are bigger than most you would find in the United States.
MAN (through translator): I have three liters of orange soda and Pepsi.
CARL NASMAN: Just down the road from the dental clinic, we find kids buying soda and chips from a store next to the local school.
Pedro Lemus is the owner.
PEDRO LEMUS, store owner (through translator): What the kids ask for most are these chips.
CARL NASMAN: He sells more than 100 bags of chips each day.
PEDRO LEMUS (through translator): At about 10:00 in the morning, I know that they need something in their stomach, juice, soda, pastries, a treat. I know junk food isn't healthy, but they want it, and I have to take advantage of what they want.
CARL NASMAN: Here in the countryside, tortillas are still made the old-fashioned way. But local health officials say the change in diet is a matter of economics.
MARLENE GUERRERO, Ministry of Health supervisor (through translator): We ate real food. Food and fruit carts would go by selling chilled fruit and real food. But now junk food is cheaper. This shouldn't be. How is it possible that a tortilla chip is cheaper than a tortilla?
CARL NASMAN: The Salvadoran Association for Rural Health, or ASAPROSAR, is doing what it can to stem the damage with free dental clinics and health classes. The lessons include what not to put in the baby bottle.
MARTA-IRIS MIRANDA, ASAPROSAR health worker (through translator): When mothers don't know better, when they don't have milk to put their kid to sleep, the put soda, coffee, lemonade, or sugar water in the baby bottle.
CARL NASMAN: Both Pepsi and Coca-Cola have pledged to stop marketing directly to kids. But their products and other snack foods are as popular as ever.
SILVIA CANALES (through translator): Whenever I go shopping, she says, mommy, bring me sweets, bring me candy. And she starts to cry if I don't bring it. I tell her they're not good for you. But I always give her candy, always.
CARL NASMAN: For parents here, prevention is a big part of dealing with the American diet. But, like moms everywhere know, it can be hard to say no to your kids.
JEFFREY BROWN: Online, you can find our earlier reports on the spike in childhood obesity and the proposed tax on sodas in Richmond, Calif.