Well the Doc opened up the old mailbag today and here’s what poured out.

Dear Dr. Ads,

There I was, minding my own business and working my way through the Boston Sunday Globe, when I came across this full-page ad for Mass General Brigham touting the healthcare system’s proposed expansion.

The ad’s subhed claims that “The capacity problem is preventing us from caring for the patients who need us the most.”

As you know, Doc, advertising quite often is entirely fact-free, so should we take this campaign at face value? Or what?

– Mess General

Dear Mess,

First, let’s look at the ad’s body copy.

Okay – so according to Mass General Brigham, demand has outstripped supply at the hospital for the past three years.

Except, according to this piece a few weeks ago by Boston Globe reporterJessica Bartlett, the expansion could simply be a naked power grab by the healthcare behemoth.

For weeks, Mass General Brigham has splashed its teal ads across newspaper pages, television screens, and the Internet to rally support behind its proposed $2.3 billion expansion.

The campaign, which experts estimate cost millions of dollars, has angered competitors and a legislator, who say the health system is using its deep pockets to relay misleading information to regulators and the general public. Mass General Brigham, for its part, says it’s using the ads to dispel misinformation spread by critics and to speak directly to patients.

Here is Mass General Brigham’s manifest destiny TV spot.

And here is MGB’s pitch to extend its tentacles into Westborough and Woburn.

Critics of the expansion plans include not only local competitors and community groups, but also the health insurance industry, as Bartlett’s Globe piece noted.

The Massachusetts Association of Health Plans, which counts 15 of the state’s largest insurers except Blue Cross Blue Shield, has come out against Mass General Brigham’s proposed expansion . . .

In a letter sent to the Department of Public Health on Tuesday, the association said the state’s largest and most expensive provider shouldn’t be allowed to get bigger, especially as it faces a “performance improvement plan,” — a spending audit from a state health care watchdog agency for excessive spending. MGB is the first system ever to be held to such an audit.

Beyond that, not everyone is buying the ad campaign’s claims of lower costs for consumers, Bartlett also reported: “The watchdog Health Policy Commission . . . said in its review the expansion would raise annual health care spending by $46 million to $90.1 million by drawing patients to higher-cost facilities and creating a new referral pathway to the system’s downtown hospitals.”

The problem, as always, with fact-checks is that they tend to run once, while ad campaigns just keep rolling. (To be fair, the Globe did publish a follow-up piece last week that featured much of the same material as the earlier one.)

Regardless, in the end Mass General Brigham gets to dictate which “facts” dominate the public discourse. That’s just a fact of life.