The World Health Organization says chronic diseases, like heart disease, diabetes, and cancer, are the world's leading killer — and it says many of those lives could be saved by simple diet and lifestyle changes.

In a new report released Wednesday, the WHO said 36 million people died of chronic diseases in 2008, the most recent year for which data is available. More than a quarter of those people were less than 60 years old.

These diseases, which can progress slowly for years before becoming fatal, are creating an expensive burden for public health services, especially in small and developing nations. WHO expert Dr. James Hospedales, a WHO expert on chronic disease, says caring for people with these illnesses could “crush” health services in many countries.

But the WHO report says it estimates some 30 million lives could be saved over the next decade with simple, inexpensive measures, such as reducing salt intake by 15 to 20 percent, decreasing smoking, and increasing the number of at-risk people getting preventative care for heart attacks and strokes.

Next week the U.N. will hold a summit on the topic, at which world leaders hope to raise public awareness and to discuss the best ways to reverse the rising death rates from these diseases.