 Welcome to Spotlight. I'm Adam Navas. And I'm Katie Blake. Spotlight uses a special English method of broadcasting. It is easier for people to understand no matter where in the world they live. What do you think is the most common disease in the world? It is not cancer or heart disease or malaria. It is tooth decay or dental caries or cavities. Half of the world's population has problems with their teeth. The doctors and experts who treat these issues are dentists. Dr. Wagner Marcenes is a professor of dentistry at the University of London. He is part of an international research team. They study tooth or dental health around the world. In a study from 2010, he explained how big this issue is. There are close to 4 billion people in the world who suffer from untreated problems with their teeth. These problems cause tooth pain. They prevent people from eating and possibly sleeping properly. We are facing serious problems in the population's mouth health. Dental caries are a very painful and unpleasant problem. But one main reason for them is sweet. It is eating sugar and sugary food. Eating sugary food is bad for teeth. But sugary food is becoming more popular around the world. So how can people prevent these tooth problems? Today's spotlight is on your teeth and sugar. Most adult humans have 32 teeth. Teeth help our faces keep their correct shape. They help us communicate through talking or smiling. And, of course, they help us eat food. Everything we eat and drink passes through our mouths. The Mayo Clinic calls teeth the window to your overall health. They explain on their website. Did you know that the health of your mouth offers clues about your overall health? Did you know that problems in your mouth can affect the rest of your body? Like other areas of the body, your mouth is filled with bacteria. Most of it is harmless. But your mouth is the entry point to your body systems. Some of these bacteria can cause disease. Your oral or mouth health may add to other diseases and conditions, including problems with your heart, lungs, or difficulties during pregnancy. So how do we keep our mouths healthy? What we eat and drink has a great effect on our whole body. And it has particular results on the health of our teeth. One way to see these results is to look at what humans have eaten over many years. As our diet has changed, our dental health has changed too. Middle income countries have the highest level of tooth decay in the world. But levels of tooth decay in lower income countries are increasing quickly. Habib Benzian is the Director of Global Health and Policy at New York University's College of Dentistry. He explained to NPR how diet changes affect people's teeth. Low income countries usually have traditional diets. They eat more plant and meat based foods. They eat less sugar and processed foods. But each country's social and economic conditions change. As that happens, there is a change in what people eat. It is a part of convenience. If you work all day and come home, you want quick food. Fast foods are fried, high in fat, sweet, and very cheap. Eating a lot of sugar is one of the most unhealthy things you can do. The World Dental Federation says eating and drinking sugar is the main cause of tooth decay. And globally, people are eating and drinking more and more sugar. The World Health Organization suggests each person should eat and drink less than 25 grams of sugar a day. But in many countries, the average person eats and drinks much more than that. In some countries, the average person eats two, three, or even four times more than that. As a result, there are a lot of ideas about how to reduce the amount of sugar people eat and drink. One idea is to put higher tax on sugary foods and drinks. Another idea is a legal limit on the amount of sugar in foods for babies and children. Another idea is to stop selling sugary products to young people and children. Sugar is a big part of one of the largest health crises in the world. But sugar is also one of the most important agricultural industries in the world. Many people make money from this industry. They do not want to sell less sugar. This makes dental health a complex global issue. Sugar is only one thing that affects people's dental health. A person's dental health depends on many things. An individual can usually make their own decisions about diet and hygiene, such as tooth brushing. But people cannot always control their economic situation. They cannot always control how much money they have or where they live. They cannot control their access to dental care. The effect of dental decay is much worse in very poor populations. This is true even in wealthy countries. There are many large systems that affect people's teeth. These problems can seem too big to solve. But the World Dental Federation says we can improve people's teeth around the world. In their document, The Challenge of Oral Disease, they give ideas of what groups can do to help on different levels. They think that everyone around the world should be able to pay for good ways to prevent tooth problems, such as treatment with fluoride, a mineral that protects teeth. They also think everyone should have health care that will help them pay to see a doctor for their teeth when they need to. The World Dental Federation thinks that caring for our teeth and mouths should be connected to caring for the rest of our bodies. Strong, healthy teeth are important for the health of our whole body and sense of well-being. Most people cannot change the global dental system. But they do have some control over how well they take care of their teeth. And one easy thing everyone can do to take better care of their teeth is reduce how much sugar they eat. Do you eat or drink a lot of sugar? Do you have any teeth problems? You can leave a comment on our website or email us at radio at radioenglish.net. You can also comment on Facebook at facebook.com slash spotlight radio. The writer of this program was Reena Dam. The producer was Michio Ozaki. The voices you heard were from the United Kingdom and the United States. All quotes were adapted for this program and voiced by Spotlight. You can listen to this program again and read it on the internet at www.radioenglish.net. This program is called Sugar and Your Teeth. Visit our website to download our free official app for Android and Apple devices. We hope you can join us again for the next Spotlight program. Goodbye.