Daily Prune Consumption Boosts Bone Health

Prunes for fiber… for regularity… and sometimes just because they taste good. But prunes for strong bones? That’s not what comes to mind for most people, but perhaps that will change. In a number of studies prunes have shown themselves to be great for your bones, helping to prevent bone loss and repair bone density as well.

The man behind much of this research is Bahram H. Arjmandi, PhD, RD, Margaret A. Sitton Professor and Chair, department of nutrition, food and exercise sciences at Florida State University in Tallahassee. He started this research back in the 1990s, when he was approached by the California Dried Plum Board. “I was skeptical,” he says, “but I figured if they wanted to fund a study, I would take a look.”  To his astonishment, he discovered that prune consumption prevented bone loss in female rats. Still, he says he knew a number of substances did that. The bigger question on his mind was if prunes could rebuild lost bone… and they actually did. In earlier research, Dr. Arjmandi had searched for “bone builders” in growth hormone, growth factors, raisins, dates, blueberries and more. Prunes out-performed all of them, he says.


Dr. Arjmandi is currently conducting a clinical study funded by the US Department of Agriculture and the California Dried Plum Board comparing the effects of dried apples versus prunes on bone mineral density in post-menopausal women. He says that thus far 30 women in the prune group have had at least a 6% increase in hip bone (a critical area for maintaining strong bones) and that one woman had a notable 11% increase over her baseline measurement. In earlier preliminary data, all prune-eaters showed at least some improvement in bone mass by six months into the trial, he says. Final results of the present study will be available in March 2009.

Research to determine what substance in prunes creates improved bone mineral density has been done in conjunction with a team from Oklahoma State University. It revealed that particular polyphenols in the dried fruit achieve two effects — they up-regulate growth factors linked to bone formation and they counter the activity of tumor necrosis factor-alpha (TNF-alpha), an inhibitor of bone formation. Prunes also contain potassium and boron (a trace mineral), both believed to contribute to bone mineral density.

Interestingly, consumption of fresh plums has not been shown to substitute for prunes in matters of bone benefits, says Dr. Arjmandi. The reason: Only certain kinds of plums become prunes. Dr. Arjmandi’s team used an offshoot of La petite d’Agen, a native of Southwest France, which at maturity has a royal purple outer skin and amber colored flesh. This is the commercially available dried plum/prune. So, while all prunes are dried plums (the preferred name these days), most fresh plums cannot become prunes.

If you want to boost prune consumption, go slow. Dr. Arjmandi advises starting with just three prunes, and increasing to nine or 10 per day as you adjust to the fiber levels. Because prunes are so low on the glycemic scale, they shouldn’t be a problem for people with diabetes, he adds.