Dietary countermeasure mitigates simulated spaceflight-induced osteopenia in mice.

Spaceflight is a unique environment that includes at least two factors which can negatively impact skeletal health: microgravity and ionizing radiation. We have previously shown that a diet supplemented with dried plum powder (DP) prevented radiation-induced bone loss in mice. In this study, we investigated the capacity of the DP diet to prevent bone loss in mice following exposure to simulated spaceflight, combining microgravity (by hindlimb unloading) and radiation exposure. The DP diet was effective at preventing most decrements in bone micro-architectural and mechanical properties due to hindlimb unloading alone and simulated spaceflight. Furthermore, we show that the DP diet can protect osteoprogenitors from impairments resulting from simulated microgravity. Based on our findings, a dietary supplementation with DP could be an effective countermeasure against the skeletal deficits observed in astronauts during spaceflight.

Dietary dried plum increases bone mass, suppresses proinflammatory cytokines and promotes attainment of peak bone mass in male mice.

Nutrition is an important determinant of bone health and attainment of peak bone mass. Diets containing dried plum (DP) have been shown to increase bone volume and strength. These effects may be linked to the immune system and DP-specific polyphenols. To better understand these relationships, we studied DP in skeletally mature (6-month-old) and growing (1- and 2-month-old) C57Bl/6 male mice. In adult mice, DP rapidly (<2 weeks) increased bone volume (+32%) and trabecular thickness (+24%). These changes were associated with decreased osteoclast surface (Oc.S/BS) and decreased serum CTX, a marker of bone resorption. The reduction in Oc.S/BS was associated with a reduction in the osteoclast precursor pool. Osteoblast surface (Ob.S/BS) and bone formation rate were also decreased suggesting that the gain in bone in adult mice is a consequence of diminished bone resorption and formation, but resorption is reduced more than formation. The effects of DP on bone were accompanied by a decline in interleukins, TNF and MCP-1, suggesting that DP is acting in part through the immune system to suppress inflammatory activity and reduce the size of the osteoclast precursor pool. Feeding DP was accompanied by an increase in plasma phenolics, some of which have been shown to stimulate bone accrual. In growing and young adult mice DP at levels as low as 5% of diet (w/w) increased bone volume. At higher levels (DP 25%), bone volume was increased by as much as 94%. These data demonstrate that DP feeding dramatically increases peak bone mass during growth.

Dried plum's unique capacity to reverse bone loss and alter bone metabolism in postmenopausal osteoporosis model.

Interest in dried plum has increased over the past decade due to its promise in restoring bone and preventing bone loss in animal models of osteoporosis. This study compared the effects of dried plum on bone to other dried fruits and further explored the potential mechanisms of action through which dried plum may exert its osteoprotective effects. Adult osteopenic ovariectomized (OVX) C57BL/6 mice were fed either a control diet or a diet supplemented with 25% (w/w) dried plum, apple, apricot, grape or mango for 8 weeks. Whole body and spine bone mineral density improved in mice consuming the dried plum, apricot and grape diets compared to the OVX control mice, but dried plum was the only fruit to have an anabolic effect on trabecular bone in the vertebra and prevent bone loss in the tibia. Restoration of biomechanical properties occurred in conjunction with the changes in trabecular bone in the spine. Compared to other dried fruits in this study, dried plum was unique in its ability to down-regulate osteoclast differentiation coincident with up-regulating osteoblast and glutathione (GPx) activity. These alterations in bone metabolism and antioxidant status compared to other dried fruits provide insight into dried plum's unique effects on bone.

Dietary dried plum increases bone mass in adult and aged male mice.

Bone is progressively lost with advancing age. Therapies are limited and the only effective proanabolic regimen presently available to restore bone is intermittent treatment with teriparatide (parathyroid hormone 1-34). Recent evidence suggests that dietary supplementation with dried plum (DP) can prevent bone loss due to estrogen deficiency. To determine whether dietary DP supplementation can prevent the loss of bone with aging and whether bone that has already been lost can be restored, adult (6 mo) and old (18 mo) male mice were fed a normal diet or isoenergetic, isonitrogenous diets supplemented with DP (0, 15, and 25% DP by weight) for 6 mo. MicroCT analysis and bone histomorphometry were used to assess bone volume, structure, and metabolic activity before, during, and after dietary supplementation. Mice fed the 0% DP diet (control diet) lost bone, whereas both adult and old mice fed the 25% DP-supplemented diet gained bone. Adult but not old mice fed the 15% diet also gained bone. Cancellous bone volume in mice receiving 25% DP exceeded baseline levels by 40-50%. Trabecular structure varied with diet and age and responses in old mice were generally blunted. Trabecular, but not cortical, mineral density varied with age and measures of bone anabolic activity were lower in aged mice. Our findings suggest that DP contains proanabolic factors that can dramatically increase bone volume and restore bone that has already been lost due to aging. In turn, DP may provide effective prophylactic and therapeutic agents for the treatment of osteoporosis.