If Bubbe was around, her eyebrows would be approaching the ceiling.Our Friday-night favourite, chicken soup, is having a moment. The simplest of foodstuffs has been reinvented as ''must-have'' dish that only elite foodies and trend-setters know about. Except now with a new name.

"Bone broth" has taken New York and London by storm, with people queuing round the block at trendy restaurants and cafes. Takeaway hatch, Brodo (broth in Italian) in New York's East Village has been doing a storming trade serving chicken, beef and turkey broths and in LA - where it fits nicely into the Paleo diet regime - you can even have it delivered to your door.

In London, eateries like Bone Daddies are dishing up steaming bowls of various bone broths to fashionable foodies.

Food trends are always going to be limited by the number of ingredients to pick from so chefs are not averse to a bit of wheel reinvention. There is, however, something particularly emperor's-new-clothes about this.

Chicken broth is just good old Jewish penicillin in fancy takeaway boxes. We've been cooking it up for centuries. In the old country, we even termed it goldene yoich, or golden broth.

Says food writer Joan Nathan: "Sephardi scholar Moses Maimonides wrote in the 12th century that any kind of broth had so many curative properties and could help conditions from coughs to melancholia. I just had pneumonia and everyone was bringing me chicken soup."

Nathan, who is currently working on a book, King Solomon's Table (due out next year), about the roots of Jewish food, explains that even before then, the Chinese had discovered the curative powers of chicken soup. "It was something handed down from generation to generation.

"We're going back to everything that's old and this bone broth is another of those fads - we're going back to the way we used to eat."

On this side of the pond, upmarket US grocer, Wholefoods, is cashing in on the trend, offering bags of bones and vegetables for punters to take home and cook up their own. The chutzpah! In our grandparents' day, chicken soup was frugal food -the most cost-effective way of wringing every last bit of nutrition out of pricey protein.

"Chicken was expensive and reserved for celebrations," says Nathan. "You'd use an old hen to make soup, because a young hen still could lay eggs. Once it stopped laying, you'd use the chicken for broth but, before you did, the breasts would be removed to be eaten. The bones and feet were used for broth - the fibrous toes gave a lot of broth and plenty of protein to the soup."

Doyenne of Jewish food, Claudia Roden, agrees.

"When I was growing up in Egypt, I was looked after by an Italian/Slovene nanny and we always ate 'brodo' with different foods in it. It has been around for years."

Roden adds that the health-giving properties of broth - or bouillon, as the French call it - even gave its name, in the 18th century, to restaurants. "The first restaurant in France served bouillon, which was just bone stock with meat or vegetables in, as the French thought it to be 'restorative'. Hence the name restaurant, for somewhere you'd go and eat it," she explains.

Proponents of this latest food trend will claim bone broth is somehow different. Jasmine and Melissa Helmsley, healthy eating writers whose Filipino mother always had a pot of broth on the go, insist it must be cooked at least six to 12 hours - twice as long as many of us simmer our kosher boiling fowl. But we know that our protein-packed potion will cure as many colds and bring just as much comfort as this young pretender.

"In the US, they are always looking for something to make it fashionable" says Roden.

"One week they're queuing for cupcakes, the next it's meatballs. Whilst I was in New York, I was served freekeh (smoked wheat cooked in biblical times) in a restaurant and told 'it's a new grain'. I had to laugh - Jews in Israel have been eating it for hundreds of years."

Now that they've discovered one of the jewels of the Ashkenazi menu, perhaps now the fooderati will be back for more. How long before they are lining up for chopped liver or fighting over gefilte fish?