Data Accomplishments

How has the National Health and Nutrition Examination Survey (NHANES) improved the health of all Americans?

For the past 40 years, the U.S. Public Health Service has been interviewing and examining tens of thousands of Americans. Now teams of doctors, dentists, nutritionists, and health technicians are heading out to communities across the United States for the National Health and Nutrition Examination Survey (NHANES), which will be updated annually.

An interviewer may never have knocked on your door before, but you and everyone living in the United States has benefited from these surveys. Here are some examples of how we have all benefited from NHANES.

How is my baby growing? How does my child compare with other children the same age?

Those are important questions that your doctor can answer, using the growth charts developed by the National Health and Nutrition Examination Survey. The NHANES growth charts are found on the walls of pediatricians’ offices and clinics not only across the United States, but also around the world. With new information on younger babies, the current charts have been expanded and improved.

Who decides what vitamins and minerals belong in our food and diet?

Scientists and nutritionists at the U.S. Department of Agriculture and at universities make a career of studying the amount of vitamins and minerals essential for a healthy diet. They rely heavily on the information that the National Health and Nutrition Examination Survey gathers to help determine just what Americans are eating. The earlier NHANES showed that low iron levels were a serious problem for many people, including women of childbearing age, preschool children, and the elderly. As a result, the government decided to fortify grain and cereal with iron to correct this deficiency.

That’s not all. These surveys showed the need for folate to eliminate another deficiency and prevent birth defects. Today, we have a wealth of information at our fingertips and, indeed, on our food labels to make better choices about what to eat. And much of that information comes directly from the National Health and Nutrition Examination Survey.

What about cholesterol? How do I know if that is too high?

Here again NHANES helps us come up with the answers. This is probably the survey’s biggest success story. The first survey back in the 1960s led public health officials to sound the alarm about the link between high cholesterol levels and the risk of heart disease. Today, people routinely keep an eye on their cholesterol. When NHANES started testing, one-third of adults had high cholesterol. Today fewer than 1 in 5 adults has high cholesterol. Changes in diet and lifestyle all built on information from the national survey have sharply reduced our risk of dying from a heart attack. These strategies have also helped doctors find ways to better treat heart attack patients and speed their recovery.

What did this survey have to do with lead-free gasoline?

It was NHANES that gave us the first clear-cut evidence that Americans had too much lead in their blood. This led congress, the Environmental Protection Agency, and others to phase out the use of lead as an additive in gasoline, and the results have been remarkable. By the 1990s, NHANES found that only 4% of Americans had too much lead in their blood. But it remains a problem for certain groups, especially poor children living in old houses in cities where lead paint was once common. The survey helps our public health agencies pinpoint where lead remains a problem.

What else do we get from these surveys?

The National Health and Nutrition Examination Survey has helped write some of the most exciting chapters in the history of improving public health, but this story is far from finished. New chapters are still being written, thanks to the thousands of Americans who open their doors when the National Center for Health Statistics’ interviewers come calling. Here are some ways that this information will be put to use:

• Osteoporosis. This condition, in which bones get weaker as people grow old, is blamed for many of the fractures among the elderly. The National Health and Nutrition Examination Survey measures the density of participants bones.
• Environmental smoke. The last NHANES found that nearly 9 out of 10 nonsmoking Americans were exposed to smoke either at home or on the job.
• Obesity. Despite the public health gains in recent years, more Americans are overweight than ever before. Today, more than half of the adults in the U.S. are overweight, and the number of overweight children and teens has doubled in the past decade. This has led public health experts to look for ways to improve both diet and fitness.
• Changes in Food/Diet. Today consumers can find a wide range of low fat and light foods in their grocery stores, from dinner entrees to snacks. As the food we eat changes, NHANES helps monitor whether these new foods and dietary changes actually are in the best interest of our health.
• Immunizations. The National Health and Nutrition Examination Survey has turned up important information about the extent of hepatitis B infections, and led to the recommendation that all infants and children be vaccinated against it. While we think of babies and children as the primary target for immunizations, the survey also has alerted doctors to the importance of tetanus shots for older people.