SATURDAY, Nov. 12, 2005 (HealthDay News) -- Better lifestyle habits -- think less junk food, more fish and more exercise -- can help prevent 80 percent of coronary heart disease and 90 percent of type 2 diabetes.
That's the thrust of a report scheduled to be presented Saturday by Dr. Walter Willett, chairman of the Harvard School of Public Health's department of nutrition, at the American Society of Nephrology's annual meeting, in Philadelphia.
"There is a huge potential for reducing the major causes of death, from cardiovascular disease and diabetes," said Willett, whose report was titled "Diet and Optimal Health: A Progress Report."
He based the estimates on his own long-term study, the Nurses' Health Study II, begun in 1989, and the original that started 29 years ago, and dozens of other studies that have examined lifestyle habits and their effects on heart disease and diabetes.
When people hear the figures of 80 percent and 90 percent, they're "surprised," Willett said. "But they shouldn't be. If you look back to Greece and Japan, they had heart-disease rates that were 90 percent lower" than the United States, a finding thought to be due to healthier diets.
"We've known for a long time there is a potential for prevention," he added. But, he said, his review of dozens of studies revealed that the needed changes are not that dramatic.
So how can you reduce your risk? Not smoking cigarettes is key, Willett said.
"In the area of diet, we are only asking for fairly modest shifts," he said. The best diets, Willett said, focus on the types of carbohydrates and fats, rather than the amount of food, consumed daily.
"Change the carbohydrates from highly refined to more whole grains," he said. That means more whole grain breads and cereals, for instance.
Willett also advises eliminating trans fats, which he calls the worst kind of fat because of their effects on blood cholesterol. Trans fat is made when manufacturers add hydrogen to vegetable oil -- a process called hydrogenation that increases the shelf life and flavor stability of foods containing these fats.
Trans fat can be found in vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with or fried in partially hydrogenated oils, according to the U.S. Food and Drug Administration.
"Have fish twice a week," Willett added, to boost intake of the healthy omega-3 fatty acids. And have a variety of fish, including tuna, cod and salmon, he said.
"Keep [consumption of] red meat and butter low," Willett said. "And replace red meat with a mix of fresh fish, poultry, nuts and beans. You don't have to give up anything entirely, except maybe trans fats."
Exercise is also very important, Willett said. "Just a half hour a day of brisk walking," he said. "For weight, bring your body mass index (BMI, a ratio of weigh to height) down to under 25. It's better to be lower, but almost everyone can get to 25." (A person 5 feet, 5 inches tall who weighs 144 has a BMI of 24.)
As for alcohol intake, Willett said a drink every other day is a healthy amount, but people who don't drink shouldn't start for health reasons.
"Take a multiple vitamin to get enough folic acid," he added.
Other experts said the report makes sense. Dr. Robert Rizza, president of the American Diabetes Association, said the 80 percent to 90 percent figures "may well be underestimates."
"If you exercise, stay lean, eat your fruits and vegetables, people who do this throughout life, they might reduce their risks by 90 or 95 percent," Rizza, a professor at the Mayo Clinic added.
And it's never too late to start, he said. "Whenever you begin, you always reduce your risk," Rizza said.
Cathy Nonas, a registered dietitian who directs the obesity and diabetes program at the North General Hospital in New York City, agreed. She pointed to the Diabetes Prevention Program, a study of more than 3,000 people diagnosed with "pre-diabetes," which in 2001 found those who adopted a healthy lifestyle reduced their risk of diabetes by 58 percent.
"We know that a 5 to 10 percent weight loss has significant effects on blood glucose and on blood pressure and triglycerides. If you put them all together -- healthy weight, healthy eating, physical activity -- you will find on every level that you will see a reduction in diabetes and heart disease," Nonas said.
To learn more about diabetes, visit the American Diabetes Association.