The U.S. Food and Drug Administration is looking to update what it means for a food item to be considered "healthy" after nutrition experts and food companies argued the existing guidelines are based on decades-old science that no longer align with dietary advice.

On Wednesday, the agency took its first step in redefining the term by soliciting comment and opinion from the public on the matter. Once the FDA determines the new standards, which could take years, food companies will have new parameters for their packaging claims.

The impetus for the change came from a petition started by Kind Snacks, maker of fruit-and-nut snack bars, that took issue with the federal limitations on fat content. The current standard reflects the thinking of the 1980s and 1990s when fats were demonized and sugars ignored. Public and scientific opinion has reversed in recent years as many health-conscious consumers and food companies argue that unsaturated fats can be good for people and even some saturated fats are acceptable.

"As our understanding about nutrition has evolved, we need to make sure the definition for the "healthy" labeling claim stays up to date. For instance, the most recent public health recommendations now focus on type of fat, rather than amount of fat," Douglas Balentine, director of the Office of Nutrition and Food Labeling at the FDA, said in a post Tuesday.

In May, the FDA unveiled a major overhaul to the Nutrition Facts labels that appear on all packaged foods. One of the key changes is the inclusion of added sugars, which offer no nutritive value and can lead to health problems, such as diabetes.

The nation's food regulatory body said this is one of the many claims it will be scrutinizing over the coming months and years.

"While we are working on the "healthy" claim, we also will begin evaluating other label claims to determine how they might be modernized," Balentine said.

The agency has said it will soon take on the term "natural" which currently lacks any sweeping definition.

Ultimately, the FDA said, its goal is to encourage companies to reformulate or create new products that are more nutritious.