The science writer and libel reform campaigner Simon Singh has been threatened with legal action after criticising an alternative health magazine on Twitter.

Earlier this week, Singh took to the social media network to denounce a magazine called What Doctors Don't Tell You (WDDTY). Described by its editor, Lynne McTaggart, as being aimed at "intelligent women between 35-55" the magazine claims to provide information about what works and what does not work in both conventional and alternative medicines. Coverlines on the current issue include "sunbathe your diabetes away" and "how I avoided my hysterectomy through diet".

Writing on Facebook on Tuesday, McTaggart called on the magazine's supporters to fight the actions of "bully boys" who wanted to push it off newsagents' shelves. "Simon Singh, who was leading the charge, was just told by our distributor essentially to shove off and reminded that tweeting untrue statements about us or them is, well, libel," she wrote.

Singh confirmed that he had contacted Comag, the distributors of WDDTY, to say that in his opinion the magazine was largely unscientific and was promoting advice that could potentially harm readers.

"Also, many of the adverts appear to make pseudoscientific and unsubstantiated claims," he said. "I even offered to meet with Comag and introduce them to medical experts, but they have not accepted this invitation. When I suggested that I would blog about our email exchange, their reaction was to tell me in no uncertain terms: 'I should inform you that we have sought legal advice in respect of this matter. We would take any attempts to damage our reputation on social media or elsewhere very seriously.'"