The federal government has recommended flossing since 1979, first in a surgeon general’s report and later in the Dietary Guidelines for Americans issued every five years. The guidelines must be based on scientific evidence, under the law.

Last year, the Associated Press asked the departments of Health and Human Services and Agriculture for their evidence, and followed up with written requests under the Freedom of Information Act.

When the federal government issued its latest dietary guidelines this year, the flossing recommendation had been removed, without notice. In a letter to the AP, the government acknowledged the effectiveness of flossing had never been researched, as required.

“The majority of available studies fail to demonstrate that flossing is generally effective in plaque removal,” said one review conducted last year. Another 2015 review cites “inconsistent/weak evidence” for flossing and a “lack of efficacy.”

One study review in 2011 did credit floss with a slight reduction in gum inflammation — which can sometimes develop over time into full-fledged gum disease. However, the reviewers ranked the evidence as “very unreliable.” A commentary in a dental magazine stated that any benefit would be so minute it might not be noticed by users.

If you have doubts about flossing, I would advise you talk to your dentist before stopping. Flossing takes very little time and is very low in cost to keep this as part of your daily habit is still worth even sight benefits if you tend to believe more in the recent study.