The power of prunes

Plum growers hope stronger bones and moister meat loaf can replace regularity as the fruit's selling points.

By Mary Roach
Published November 5, 1999 5:00PM (EST)

This is the story of a fruit, and of the power of public relations. Sometime in the 1920s, in the dark ages before Metamucil, a group of plum growers got the bright idea to promote the dried version of their product as the magic elixir for regularity. They were successful in their efforts, and the prune became linked in America's consciousness with constipation.

Now it is the 90s, and the growers would give great amounts of prune profits to undo what their forebears have done. "The stigma has carried over to the point where we don't even want to talk about it any more," says Jim Degen, a food and beverage marketing consultant retained by the California Prune Board to spruce up the geriatric image of Prunus domesticus. It isn't so much that the growers are embarrassed. It's this: "Most eaters" -- Degen divides the world into prune "eaters" and "noneaters" -- "are 60-plus, and they're dying off. We have to go after the younger market."

The Prune Board's first step was to move away from the ill-connoted word. Don't say prunes. Say dried plums. (Unless you are in a photo shoot. "Prunes" is what photographers tell models to say to make them have kissy-lips. Saying "dried plums" makes you look like a llama and is unlikely to advance your modeling career.)

The Board's next step was to dream up new and non-bathroom-related uses for their product. What dried plums do well, or more specifically what the fiber in them does well, is absorb water. As in your intestines, so in food items: It makes the product moister. What kind of products need added moisture? Processed meats, for one. "Any food," said Degen, "that's precooked, frozen and reheated."

This puts us squarely in the realm of institutionalized foods and makes prunes excellent fodder for the USDA Commodities Procurement Branch. This is the program that buys up enormous lots of surplus produce, meats and dairy goods, and distributes them free or cheap to the feeders of captive eaters: nursing homes, prisons, public schools, hospitals. (Last year the U.S. government bought 252,000 pounds of surplus pitted dry prunes.) To this end, Degen has contracted meat science professionals to come up with prototypes of prune-enhanced cafeteria entrees: prune meatloaf, prune sausages, prune turkey meatballs, prune hamburgers and frankfurters.

The recipes for the bold new prune foods were formulated by a processed meats expert in the Texas A&M meat science program named Jim Keeton. I asked Keeton if he found the addition of prune puree to frankfurter and hamburgers to be a strange or distressing idea. He did not. "It's something that would not be harmful, but yet contributes a functional attribute to the product." Coming from a processed meats man, this is probably as close as you get to a gush.

Keeton went on to say that you can't actually taste the prune puree, and that he found the prune meat products quite good. Mind you, this is a man who reads the Journal of Food Texture and who would, given the chance, try cow udder, one of the few "variety meats" forbidden from use in American sausages and processed meats. (Lungs are another no-no, though salivary glands are OK.)

But what about, to use Degen's terminology, the laxation side effects? Do we want our children constantly sprinting from classrooms with the bathroom pass? Degen countered that the hamburgers are only 3 percent prune puree, which is not enough to cause a problem. Just exactly how many prunes constitutes a problem has been the subject of formal scientific inquiry. In a 1991 study designed to test whether prunes lower cholesterol (and funded by the Prune Board), 41 men who ate 12 prunes a day for four weeks (referred to in the study as "the prune period") did not report "runny stools." They did, however, have 20 percent higher fecal weights during the prune period, confirming the regularity-promoting quality of prunes and generating deep sympathy for the author's research assistants, to whom the weighing no doubt fell.

But what if the men had eaten 12 of something else with a similar amount of fiber, say dried apricots or figs? Wouldn't the effect be the same? Is there something unique about the laxative properties of the prune?

This remains one of science's unsolved mysteries. For if fiber were to blame (or thank, depending on your gastrointestinal situation), why then would prune juice do the trick? Degen points to prunes' high levels of sorbitol, a sugar alcohol that gives some people the runs. But there are others in the industry who believe the prune's reputation as a superior cathartic to be founded in nothing other than the desire to sell more prunes circa 1920. In Northern Italy, prunes are used as both a laxative and an anti-diarrheal, which tells us something, though perhaps about Northern Italians rather than about prunes.

It's not that science hasn't tried to sort it out. In a 1934 journal paper entitled "The Laxative Principle in Prunes," researcher George Emerson applied prune extracts to rabbit, guinea pig, dog and cat intestines and noted "increases in tonus and amplitude of contraction" and concluded that perhaps caffeic acid was the culprit. As the intestines in question were outside of and down the hall from the (quite dead) animals at the time, the paper's conclusions are somewhat questionable, as is, perhaps, the psychological well-being of Dr. Emerson.

One thing is certain, and that is that if you are a rat, you can eat all the prunes you want and suffer no untoward effects. A 1999 study (funded by the California Prune Board) by Bahram H. Arjmandi, of the Department of Nutrition Sciences at Oklahoma State University, tested whether prunes reverse bone loss by feeding osteoporotic rats a 25 percent prune diet. According to Arjmandi, the rats showed "no sign of diarrhea" (and, mysteriously, regained their lost bone).

No one has ever tested a 25 percent prune diet in humans. Fearing the worst, Arjmandi chose to use a 5 percent prune diet (four or five a day) in his follow-up trial on 60 women. The results will be in soon. Meanwhile, the closest anyone has come was an unintentional experiment on monkeys in 1905. Frustrated by rising labor costs, a California prune grower imported 500 monkeys from Central America and organized them into crews of 50, each with a human foreman. The monkeys proved to be swift and tireless pickers, but could not be dissuaded from eating the prunes immediately upon picking them. Alas, history did not record whether the primates experienced "runny stools" or merely an increased fecal weight.

If Arjmandi's human subjects grow thicker bones from eating four or five prunes a day, it will be cause for celebration over at the Prune Board. They will have found their long-sought public relations panacea and will no longer need to dream up prune-enhanced cafeteria items, and it will be a fine and glorious prune period in our nation's history.

Mary Roach

Former Salon columnist Mary Roach is the author most recently of "Gulp: Adventures on the Alimentary Canal." Her previous books include "Stiff," "Spook" and "Packing for Mars."

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