(May 2007) Diabetes, cardiovascular disease, and cancer are among a group of chronic diseases that accounts for most deaths in all regions of the world except South Asia and sub-Saharan Africa. While infectious diseases, lack of nutrition, and other traditional killers are claiming fewer lives in developing countries, deaths attributable to chronic diseases are rising.
The shift away from infectious and acute illnesses is fed by better living conditions and education worldwide, as well as improved nutrition, sanitation, health practices, and medical care. The world's elderly population, more prone to chronic disease, is growing. The result is a quiet epidemic of chronic illness that has gotten less attention than deadly infectious diseases such as HIV/AIDS or tuberculosis.
Worldwide Share of Deaths, by Cause
Source: Colin D. Mathers et al., "The Global Burden of Disease in 2002: Data Sources, Methods, and Results," GPE Discussion Paper 54 (Geneva: World Health Organization, 2003), available at www.who.int/evidence.
Yet diabetes, cancer, cardiovascular disease, and other chronic conditions account for most deaths in rich, middle-income and lower middle-income countries, surpassing infectious diseases, malnutrition, and deaths of new mothers and babies combined. In low-income countries, they account for 40 percent of deaths, but are predicted to become the cause of more than half of all deaths.
Speakers at a recent PRB symposium explained that chronic diseases also are a drain on national economies and family incomes, so their spread will make it harder to win the global fight against poverty. The symposium, held on April 30 in Washington, D.C., highlighted recent research about how diet and lifestyle changes can lower the risk of chronic disease. But current trends run counter to recommendations supported by this research: People in developing countries are adopting unhealthy behaviors practiced in developed nations.
View Webcast of PRB Symposium: Confronting Chronic Diseases: Are We Prepared? Recent Nutrition Research Rewrites the Old Script
A decade ago, U.S. government nutritional guidelines emphasized sparing use of all fats and oils. All fats were deemed undesirable, based on research in seven countries that seemed to link cardiovascular disease with total saturated fat in the diet.
But subsequent research indicated that the real culprit was a particular type of fat, the trans-fats found in deep-fried fast foods such as breaded chicken nuggets, bakery products such as cookies and donuts, packaged snack foods, margarine, and crackers. It pushes up levels of LDL or "bad" cholesterol, and increases inflammation that contributes to the buildup of fatty deposits in arteries.
Trans-fat also is linked to development of adult-onset, or Type 2, diabetes. Walter Willett, professor and chairman in the Department of Nutrition at the Harvard School of Public Health, said if bad fats were replaced with good fats in people's diets, the incidence of such diabetes would fall 40 percent.
Not All Fats Are Bad, and Not All Carbohydrates Are Good
Recent research also is prompting new thinking about carbohydrates, the major source of calories in most diets worldwide. In obeying injunctions to reduce dietary fat, many people substituted rice, bread, potatoes, and other carbohydrates "without any evidence that it was good for people," Willett said.
But nutritionists now say that some carbohydrates are worse than others. Easily digestible carbohydrates, such as baked potatoes and white bread, produce a spike in glucose levels in the blood that is a risk factor for diabetes. Whole-grain pasta, apples and beans are among "low glycemic" carbohydrates that produce a lower, slower rise in blood glucose.
Researchers now know that a diet high in trans-fats and the carbohydrates that produce a spike of glucose are the two strongest predictors of cardiovascular disease, Willett said. "Ten years ago," he said, "this was on nobody's radar screen."
Obesity Becoming a Worldwide Problem
Obesity contributes to a number of chronic diseases and is the most influential risk factor for adult diabetes. The World Health Organization forecasts that by 2015, more than 700 million people worldwide will be obese, compared with 400 million in 2005.
This is a growing problem in developing countries, especially as more people move to urban areas, where they are less physically active. Many are changing their diets to reflect the same mix of foods in developed countries—high levels of fat and sugar.
Even people who are only a few pounds overweight can develop insulin resistance that progresses to diabetes, Willett said. He said that people in other parts of the world, including those in poor countries, are more susceptible to diabetes than people in well-off northern Europe who eat the same diet. "This is going to be the biggest health problem in the world," he said.
5 Ways to Lower Chronic Disease Levels
The good news, Willett said, is that "we can do a lot of if we want to." Based on research in the United States, levels of cardiovascular disease can be brought down by 82 percent and of diabetes by 92 percent, he said, by following proven lifestyle advice.
The five key factors, developed by Willett's Harvard colleague Meir Stampfer, are:
- Not smoking.
- Body Mass Index under 25.
- At least 30 minutes of moderate to vigorous exercise daily.
- Moderate alcohol consumption, if appropriate.
- Follow dietary recommendations for fats, fiber, and folate.
Chronic Disease Kills Younger People in Developing Nations
The economic impact of chronic disease is not as well-studied as its causes, but an Oxford Health Alliance research paper estimates that they consume "a significant and sizable amount" of many countries' gross domestic product, ranging from less than 1 percent to 6.8 percent. The United States is at the high end of the range. The average worldwide is 3 percent.
In developing countries, this depresses the economy in part because people spend money on medicine that they could put into education, farm equipment, or other development tools, said Rachel Nugent, senior health program associate at the Center for Global Development. In some countries, she said, spending on tobacco also diverts money that could have been put to productive use. About as many people die from smoking each year in developing countries as in industrialized nations.
Experts also believe there is an economic impact because so many people in developing countries with chronic illnesses are of working age. For example, most people who die of cardiovascular disease in developing nations are under 60; in the United States, 80 percent are over 60.
Health care systems in many developing countries are severely strained, but Nugent said some cost-effective steps can be taken outside the medical system. These include broad-based campaigns to encourage healthier diets and to persuade people not to smoke. As researchers look for interventions that work, they point to a promising new program in Sao Paolo, Brazil, that encourages physical activity.
Large Global Study May Yield New Information About Chronic Diseases
Trying to close some of the gaps in research, the Oxford Health Alliance and Yale University School of Public Health have begun a large global project to implement and evaluate programs to reduce the rates of chronic diseases.
Researchers began with seven pilot sites in six countries—India, Israel, Argentina, Mexico, Tunisia, and China—but have since expanded to 24 projects in 19 nations. Initiatives being evaluated include providing affordable fruit carts at farm markets, creating safe walking routes, and requiring regular physical activity in public schools.
The intention, Denise Stevens, president of Matrix Public Health Associates told the symposium, is to create "an evidence-based road map." It will be at least three years before results of the pilot study will be available.
D'Vera Cohn is senior editor at the Population Reference Bureau.
For More Information
Webcast of PRB Symposium: Confronting Chronic Disease: Are We Prepared?
Heidi Worley, "Chronic Diseases Beleaguer Developing Countries," Population Reference Bureau (2006).
Marc Suhrcke et al., Chronic Disease: An Economic Perspective (London: Oxford Health Alliance, 2006), accessed online at www.oxha.org.