Women who ate about 50 grams of prunes, roughly five to six, every day for a year held onto bone mineral density at the hip. A control group who ate no prunes lost bone at both six and twelve months. The findings come from a randomized controlled trial led by Mary Jane De Souza at Pennsylvania State University and published in July 2022 in the American Journal of Clinical Nutrition.
The trial, known as the Prune Study, followed 235 postmenopausal women who were assigned to eat 50 grams of prunes daily, 100 grams daily, or no prunes for 12 months. Hip fracture risk rose in the control group over the year, while the two prune groups saw no such increase.
What the researchers actually measured
Bone mineral density, or BMD, is the amount of mineral packed into a given area of bone. It is the standard measure used to diagnose osteoporosis, the silent thinning of the skeleton that raises fracture risk after menopause. The Penn State team scanned the hip at the start of the study, at six months, and at twelve months.
The lower 50-gram dose proved easier to stick with. In the higher-dose group, more women dropped out before the year was up, which the researchers attributed to the volume of fruit. The takeaway from the trial is that a modest daily amount of prunes appears to be enough.
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Why polyphenols may protect the skeleton
Prunes are rich in phenolic compounds, plant chemicals that act on the cells that build and break down bone. A comprehensive review in Nutrients summarized that dried plums and their extracts enhance bone formation and inhibit bone resorption through their actions on the signaling pathways that guide osteoblasts and osteoclasts, the cells that respectively add and remove bone tissue.
The review flagged that daily doses of 50 to 100 grams have been tested in postmenopausal women, with measurable effects on bone turnover markers within about three to six months, and with density changes visible at twelve months.
The gut is a separate reason to eat them
Prunes are the only whole fruit with an authorized European health claim for bowel function. The European Food Safety Authority concluded in 2012 that 100 grams of prunes a day, about ten fruits, contribute to normal bowel function. The effect is driven by fiber and sorbitol, a natural sugar alcohol that draws water into the intestine.
That same sorbitol content is why prunes can trigger bloating or loose stools in people with sensitive digestion. Anyone with irritable bowel syndrome may want to start with one or two prunes a day and see how the gut responds before working up to the bone-friendly serving.
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How to fit five prunes into a normal day
Five to six prunes is a small handful, roughly 100 calories. Chopped, they blend into oatmeal, yogurt, or cottage cheese without changing the meal much. A trail mix of prunes with almonds or walnuts adds calcium-friendly protein and healthy fat. They can also be simmered into a compote for the freezer and spooned over toast during the week.
Penn State's next trial is tracking how a daily prune habit affects bone, inflammation, and gut health over 18 months in postmenopausal women.
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This article is made and published by Emil Martesen, who may have used AI in the preparation.