THE ROAD TO WELLVILLE (Directed by Alan Parker. Starring Anthony Hopkins, Bridget Fonda, Matthew Broderick, John Cusack, Dana Carvey)

Not many movies feature a character suffering from constipation, or derive much of their humour from rectal complaints. And for that we can probably give thanks. But once in a while it's nice to break up a constant diet of cinematic baby food with a bit of roughage.

From the earthiness of The Commitments, Alan Parker has shifted to lavatory humour, in a cranky satire of capitalism gone to the loo. Based on T Cornaghessan Boyle’s turn of the century novel about the real life Dr John Harvey Kellog, inventor of the cornflake and peanut butter, it depicts him as a more than half-crazed health pioneer, whose anal obsession makes him something of an enema of the people. Proclaiming, “We are lifeguards on the shores of the alimentary canal!” he prescribes colonic irrigation with 20 gallons of yoghurt for virtually any complaint. When he’s not boasting about the size of his stools, he’s advocating electric shocks to the groin, since the only thing worse to him than constipation seems to be congress of a sexual nature (“An erection is a flagpole on your grave!”).

The usually introspective Anthony Hopkins, almost unrecognisable beneath glasses, white moustache and beard, gives an expansive comic turn as Kellog. But this is an ensemble piece, wandering uncertainly between too many loosely-linked stories. The principal plot strand concerns the unconvincing relationship between Kellog and his slobbish adopted son, overacted by Dana Carvey as a kind of cross between Harold Steptoe and Fungus the Bogey Man. Shyster John Cusack, planning to cash in on the cornflake craze despite having no idea how the damn things are made, provides Parker’s most overtly anti-capitalist target, but is squandered by caricaturing. Better value are the episodes featuring Matthew Broderick, who in a brave move for an American leading man comes to the good doctor to sort out his bowels, while his wife, Bridget Fonda, has her sexual curiosity aroused and abused by fraudulent clitoris expert Colm Meaney.

But the real star of this sprawling and at times over-ambitious farce is the setting. Designer Brian Morris has created a stunningly archaic, almost Hogarthian vision of the Battle Creek Sanatorium, populated by grotesques and crammed with Heath Robinson-style health aids that look like they are more likely to do damage than good. Even when the plot flags, entertainment is to be had in abundance by cruising with the director through this absurd landscape of corpulent flesh and corrective machinery, descending into the very bowels of Kellog’s warped imagination. It may be no masterpiece, but you’re not going to come across any weirder shit in a movie theatre.