Several new studies on the effects of prune consumption on bone health have been conducted— using both animal models and human subjects—and more are underway. Prunes contain small amounts of bone building calcium, magnesium, phosphorous and copper. These nutrients are likely to be well absorbed since prunes have a high organic acid content. In addition, prunes are high in boron. A 100g serving (10-12 prunes) delivers 2.1mg, which is 100% of the Daily Value for this mineral.
Eating prunes may have positive effects on bones in postmenopausal women. A randomly controlled trial of 58 postmenopausal women conducted in 2002 examined effects on indices of bone turnover by adding prunes (100g/day) or dried apples (75g/day) to their diet for three months.12 The addition of prunes positively affected insulin-like growth factor-I (IGF-I) and bone-specific alkaline phosphatase (BSAP) activity, suggesting greater rates of bone formation.
A placebo-controlled animal feeding study examined whether prune consumption could be powerful enough to reverse bone loss as is seen in osteoporosis. Osteopenic ovariectomized rats were fed a standard diet or one that included 5% of calories from prunes (low dose), 15% of calories from prunes (medium dose) or 25% of calories from prunes (high dose) for 60 days.13 Even at low doses, the equivalent of 100 calories a day in humans from prunes (e.g., four prunes), improvements were observed in bone density and quality. In a similar study on preventing bone loss in male osteoporotic rats, positive results were found once again.14
An exciting human study is currently underway at Florida State University. Researchers are comparing measurements of bone loss among postmenopausal women with osteoporosis or osteoarthritis. Subjects will either be instructed to eat 10-12 nutrient-rich prunes (100g) or a comparable amount of dried apples daily for 12 months.