Tucker Carlson Has a Cure for Declining Virility

Are you a man worried about your testosterone levels? Hoping to give them a boost? Tucker Carlson, the Fox News host, has a solution.

A promotional video for a new installment in a video series by Mr. Carlson describes a “total collapse of testosterone levels in American men,” positing an explanation for what he and many conservatives see as a creeping loss of masculinity in today’s society.

Chock-full of oiled, shirtless men performing vaguely masculine tasks, like turning over giant tires and throwing a javelin, the video has already been widely remarked upon on social media for its bizarre erotic imagery.

But one shot in particular stands out: a naked man atop a rock pile, limbs outflung, exposing his genitals to the red light issuing from what appears to be a waist-high air purifier. Something very like the theme from “2001: A Space Odyssey” plays in the background.

This is the treatment proposed by Mr. Carlson’s “documentary”: Revive your underperforming testicles with red light, in particular a device made by a little known company called Joovv.

A leading endocrinologist says — no surprise — the whole thing is ridiculous, and not just because of the man receiving light therapy atop a pile of stone slabs in the dead of night.

First, there is precious little evidence that testosterone “levels are declining by roughly 10 percent per decade, completely changing the way people are at the most fundamental level,” as Mr. Carlson has said.

Studies examining changes in testosterone over time are challenging for several reasons, including difficulties in recruiting large populations of normal subjects, daily circadian changes in testosterone, and differences in testing methods over time, noted Dr. John Amory, an expert on male reproductive health at the University of Washington.

Mr. Carlson and Fox News did not respond to requests for comment.

Tied to the anxiety over testosterone is another hotly disputed assertion: that sperm counts have been declining among men in the Western world for decades. Huge numbers of studies have been done, and there is no scientific consensus on the scope of the problem or whether it exists at all.

So what’s all this about bathing one’s testicles in red light?

Scott Nelson, co-founder of Joovv, said in an email, “The published data around light therapy and testosterone production is pretty light, but the limited evidence is fairly compelling.”

He provided a link to a study on the Joovv website, apparently unpublished, reporting that red light worked best to boost testosterone in four men who were also on a ketogenic diet.

Dr. Amory was not impressed. “Obviously, doing two interventions — red light and diet — at once in a non-randomized, non-blinded, underpowered study with unclear methods isn’t of much use to understanding cause and effect,” he said. “Biological plausibility here is also very weak.”

The bottom line, for readers anxious about the decline of American virility: “In the absence of any evidence of benefit from clinical trials, I wouldn’t currently recommend this as a treatment for testosterone or symptoms of low testosterone,” Dr. Amory said.

“It’s notable that there is a long history of pseudoscientific treatments for low testosterone that have not proven to be useful over time,” he added.