LOS ANGELES — Think something is healthy just because it’s chock full of fruit or labeled as a “salad”? Not necessarily so, according to the Food & Drug Administration.

The agency said Tuesday that it is re-evaluating regulations about what foods can be labeled “healthy,” along with other nutrient content claims.

“Just because a food contains certain ingredients that are considered good for you, such as nuts or fruit, it does not mean that the food can bear a ‘healthy’ nutrient claim,” FDA spokeswoman Lauren Kotwicki wrote in an e-mail.

The FDA will ask for public comment on these issues in “the near future,” the agency said in a statement.

As ideas of healthy eating has evolved, the FDA has faced pressure to update its guidelines for which foods are healthy, especially from food companies who spend large resources lobbying for particular labeling requirements, nutrition experts say. The current regulations reflect more simplistic beliefs during the 1980s and 1990s that shunned fat and pushed carbohydrates as good for you.

“The FDA has got a really tough job,” said Marion Nestle, a professor of nutrition, food studies and public health at New York University. “It is fighting to hold some sort of semblance of a standard against an enormous food industry that wants to sell product.”

For decades, Nestle said, the FDA banned any health claims on food packaging. That changed when Congress passed the Nutrition Labeling and Education Act of 1990.

“All the pressure ever since has been to enlarge the definition of healthy to include whatever product food manufacturers happen to be selling,” she said.

As a result, there has been consumer confusion over the healthfulness of products such as granola bars, frozen yogurt, fruit juices and smoothies, and other items that seem to be healthy at the outset.

Health experts hope the FDA takes this opportunity to modernize and expand the definition of healthy foods.

The U.S. dietary guidelines released last year, for example, focused more on increasing intake of certain foods such as fruits and vegetables, rather than on specific nutrients like fat or carbs.