— -- Since 1980 the U.S. government has released dietary guidelines every five years aimed at helping Americans stay healthy. While the core tenants of a healthy diet (lots of vegetables, fruits and lean meats) have not changed, guidelines for how much added sugar, cholesterol, sodium and saturated fats have evolved through the years.
The guidelines released today recommends limiting or completely avoiding saturated fats, sodium and added sugars in favor of nutrient-dense foods. Added sugars should comprise of less than 10 percent of daily calories and Americans should "eat as little dietary cholesterol as possible," the guidelines said.
Sheila Tucker, executive dietitian and nutritionist at Boston College, told ABC News the changes are a natural result of more research and study into nutrition over the last 35 years.
"I think that nutrition is a moving target and that certainly things have been changing and some criticisms that have come out from dietary guidelines are [due to] the expectation that we’re supposed to know everything and we don’t," said Tucker. "Things change over time and that’s okay."
Tucker said that five years may seem like a long time between updates, but releasing nutritional guidelines yearly would create even more confusion.
"I think if it came out more frequently...there would not be the body of evidence behind it," she said. "Plus the American consumer would be completely confused if we did that."
Here's a look back at some past government recommendations.
From 1980 to 1990, the U.S. Department of Agriculture and the U.S. Department of Health and Human Services said to avoid cholesterol altogether.
However, in 1995, that advice changed. The government agencies recommended that individuals consume no more than 300 milligrams of cholesterol a day. In 2005, the agencies expounded on that advice, suggesting that people withhigh cholesterol consume no more than 200 milligrams of dietary cholesterol a day. High cholesterol foods include meat, dairy and eggs.
Now, there is no longer a limit for cholesterol. The new recommendation is that people "eat as little dietary cholesterol as possible" while sticking to a healthy diet.
Lisa Cimperman, a registered dietician at University Hospitals Case Medical Center, said one of the biggest overall changes in the guidelines released today is helping Americans focus on what to add to their diets rather than what to exclude.
"We’re getting away from focusing on single nutrients and single food groups," Cimperman told ABC News. "We're "really focusing on the way Americans eat and giving specific recommendations toward shifting toward a healthier eating pattern."
The term "added sugar" didn't even show up in the government's dietary guidelines until 2000. Previously, guidelines warned people with a sweet tooth to "avoid excessive sugars" or "use [sugar] only in moderation."
The new dietary guidelines now stipulate that added sugars should not make up more than 10 percent of the average American's daily diet.
Cimperman said people need to realize that added sugar includes natural sweeteners like honey and agave. She said a person on a 2,000 calorie diet should have no more than 12 teaspoons of added sugar a day. The Institute of Medicine recommends an adult woman eat between 1,600 to 2,000 calories per day depending on age and height. Men are advised to eat between 2,000 to 3,000 depending on age and height.
"Sugar is sugar and whether it’s white sugar, brown sugar, honey or agave nectar, all of these things represent a source of added sugar," Cimperman said. "It’s not that you can never have these things but all of them should be limited."
In 1980 the first dietary guidelines told Americans to "avoid" saturated fat. That was amended in 1990 to keep saturated fats at under 10 percent of one's daily calories. The top sources of saturated fat are beef, cheese, pizza, butter, lard and ice cream.
In 2005 people with high cholesterol were told that saturated fats should only make up 7 percent of their daily caloric intake. Today's guidelines keep the percentage of saturated fat in one's diet at 10 percent and do not mention that people with high cholesterol should cut their daily intake further.
The government continues to recommend no more than 2,300 milligrams of sodium a day for those over 14 years of age.
In 1980 the advice was a simple: "avoid too much" sodium. In 2000 the government dietary guidelines gave the first recommended limit to sodium, advising that no more than 2,400 milligrams of sodium a day are consumed.
In 2005 the recommendation was amended for African-Americans, older adults and those with high blood pressure: eat just 1,500 milligrams per day. In 2010 that recommendation was also expanded to include people with high blood pressure, kidney disease or cardiac disease. This year that group was narrowed to just people who were either at risk of or were already suffering from high blood pressure.
Dr. Sapna Iyer is a senior medical resident in Internal Medicine at Kaiser Permanente Medical Center in Oakland, CA.