WASHINGTON — Lawmakers on Wednesday asked federal officials whether Americans should trust the government’s dietary guidelines, which inform everything from school lunches to advice from a doctor.

Health and Human Services Secretary Sylvia Burwell and Agriculture Secretary Tom Vilsack defended the guidelines before the House Agriculture Committee, pointing out that the latest guidelines haven’t even been written yet. They are released every five years and the 2015 version is due by the end of this year.

Lawmakers from both parties expressed frustration about how the government recommendations have shifted. A government advisory committee’s recommendations in February, for example, said dietary cholesterol now is “not considered a nutrient of concern for overconsumption” after years of doctors saying that Americans consume too much cholesterol and shouldn’t eat too many eggs.

The advisory committee, which is charged with making preliminary recommendations for the guidelines, also backed off stricter limits on salt, though it said Americans still get too much.

“People may be losing confidence in the guidelines,” said Minnesota Rep. Collin Peterson, the top Democrat on the agriculture panel. “Given the public’s skepticism we should maybe reconsider why we are doing this.”

The chairman of the committee, Texas Republican Michael Conaway, said it’s important for the government to get the recommendations right because changing guidelines cause consumer confusion.

“It is essential that the guidance that comes out of this process can be trusted by the American people,” Conaway said.

Skeptical lawmakers did get some good news: Vilsack and Burwell both said that the final guidelines would not follow the government advisory committee’s suggestions that Americans should consider the environment when deciding what foods to eat and that the government should consider taxes on sugary drinks and foods. Both said those recommendations are outside the scope of the guidelines after lawmakers, the meat industry and beverage companies pushed back.

The Cabinet secretaries said the guidelines have stayed generally consistent over the years, recommending consumption of fruits and vegetables, grains, dairy, lean meats and seafood while encouraging Americans to limit saturated fats, sugars and sodium.

Still, they said recommendations will change as scientific consensus evolves on some issues, like cholesterol, and that’s why the guidelines are rewritten every five years.