Making a show for Radio 4 on the history of diet fads, I began to wonder what our modern gurus will end up with, when the cheques are all cashed, and the companies fold. Dudley J Le Blanc was a Louisiana senator in the 1940s, and the greatest quack ever. After a doctor cured his gout with a secret potion, Dudley copied the ingredients to make his own: Hadacol. "I hadda call it something", he would later explain, once he had nothing to lose.

Hadacol was made from B vitamins and alcohol. It cured everything, cost $100 a year for the recommended dose, and the bottles sold in millions.

Le Blanc made no medicinal claims, but pushed customer testimonials to an eager media. He appointed a medical director who had been convicted in California of practising medicine with no licence or medical degree. A diabetic patient almost died when she gave up insulin to treat herself with Hadacol. Nobody cared.

By 1950 sales were more than $20m, with an advertising spend of a million dollars a month. Senator le Blanc used Hadacol's success to drive his political career, and his competitors, the Longs - descended from the democrat reformer Huey Long - panicked. In a moment of genius they launched their own patent medicine, Vita-Long. Suddenly, it was a two quack race.

By 1951 the game was up.

Le Blanc was spending more in advertising that he was making in sales. He sold the company to Yankee investors and, on February 28, shortly before disappearing for a decade facing charges of fraud, he made a television appearance on You Bet Your Life with his friend Groucho Marx.

"Hadacol?" said Marx, "What's that good for?" "Well," said Le Blanc. "It was good for about $5.5m for me last year."

· The Rise of the Lifestyle Nutritionists is on Radio 4 tonight at 8pm.