This study presents the anti-inflammatory and antioxidative properties of dried plum (Prunus domestica L.) polyphenols in macrophage RAW 264.7 cells. We hypothesized that dried plum polyphenols have strong anti-inflammatory and antioxidant properties against lipopolysaccharide (LPS)-induced production of the pro-inflammatory markers, nitric oxide (NO) and cyclooxygenase-2 (COX-2), and the lipid peroxidation product, malondialdehyde, in activated macrophage RAW 264.7 cells. To test this hypothesis, macrophage RAW 264.7 cells were stimulated with either 1 μg ml⁻¹ (for measurement of NO production) or 1 ng ml⁻¹ (for measurement of COX-2 expression) of LPS to induce inflammation and were treated with different doses of dried plum polyphenols (0.0, 0.1, 1, 10, 100 and 1000 μg ml⁻¹). Dried plum polyphenols at a dose of 1000 μg ml⁻¹ was able to significantly (P < 0.05) reduce NO production by 43%. Additionally, LPS-induced expression of COX-2 was significantly (P < 0.05) reduced by 100 and 1000 μg ml⁻¹ dried plum polyphenols. To investigate the antioxidant activity of dried plum polyphenols, macrophage RAW 264.7 cells were stimulated with 100 μg ml⁻¹ of FeSO₄ + 1 mM ml⁻¹ of H₂O₂ to induce lipid peroxidation. Dried plum polyphenols at a dose of 1000 μg ml⁻¹ showed a 32% reduction in malondialdehyde production. These findings indicate that dried plum polyphenols are potent anti-inflammatory and antioxidative agents in vitro.

Although several studies have confirmed the bone-protective properties of dried plum, its exact mechanisms of action remain unclear. Recent research has shown that osteocytes may control bone formation via the production of sclerostin and bone resorption via the receptor activator of NF-κB ligand (RANKL) and its inhibitor osteoprotegerin (OPG). To investigate the mechanism of action of dried plum in reversing bone loss, we measured serum levels of RANKL, OPG and sclerostin in osteopenic postmenopausal women (n 160). Participants were randomly assigned to the treatment group of either 100 g dried plum/d or 75 g dried apple/d (comparative control) for 1 year. All participants received 500 mg Ca plus 400 IU (10 μg) vitamin D daily. Bone mineral densities (BMD) of the lumbar spine, forearm, hip and whole body were assessed at baseline and at the end of the study using dual-energy X-ray absorptiometry. Blood samples were collected at baseline and after 12 months to assess bone biomarkers. Dried plum significantly increased the BMD of the ulna and spine in comparison with the control group. In comparison with corresponding baseline values, dried plum increased the RANKL levels by only +1·99 v. +18·33 % and increased the OPG levels by +4·87 v. − 2·15 % in the control group. Serum sclerostin levels were reduced by − 1·12 % in the dried plum group v. +3·78 % in the control group. Although percentage changes did not reach statistical significance (P≤ 0·05), these preliminary data may indicate that the positive effects of dried plum on bone are in part due to the suppression of RANKL production, the promotion of OPG and the inhibition of sclerostin.

Although some studies have demonstrated the beneficial effects of watermelon supplementation on metabolic diseases, no study has explored the potential mechanism by which watermelon consumption improves body weight management. The objective of this study was to evaluate the effects of fresh watermelon consumption on satiety, postprandial glucose and insulin response, and adiposity and body weight change after 4 weeks of intervention in overweight and obese adults. In a crossover design, 33 overweight or obese subjects consumed watermelon (2 cups) or isocaloric low-fat cookies daily for 4 weeks. Relative to cookies, watermelon elicited more (p < 0.05) robust satiety responses (lower hunger, prospective food consumption and desire to eat and greater fullness). Watermelon consumption significantly decreased body weight, body mass index (BMI), systolic blood pressure and waist-to-hip ratio (p ≤ 0.05). Cookie consumption significantly increased blood pressure and body fat (p < 0.05). Oxidative stress was lower at four week of watermelon intervention compared to cookie intervention (p = 0.034). Total antioxidant capacity increased with watermelon consumption (p = 0.003) in blood. This study shows that reductions in body weight, body mass index (BMI), and blood pressure can be achieved through daily consumption of watermelon, which also improves some factors associated with overweight and obesity (clinicaltrials.gov, NCT03380221).

Emerging research indicates that nuts are a source of health-promoting compounds demonstrating cardioprotective benefits. However, most studies have assessed the effect of single nuts rather than a nut mixture. The objective of this study was, therefore, to examine the effect of mixed-nut consumption on cardiovascular disease (CVD) risk factors in overweight and obese adults. In a randomized, parallel-arm, controlled trial, 48 participants consumed isocaloric (250 kcal) amounts of pretzels or mixed-nuts. Body weight (BW) (p = 0.024), BMI (p = 0.043), and insulin levels (p = 0.032) were significantly lower in the nut group compared to the pretzel group. Mixed-nut consumption also significantly reduced glucose (p = 0.04) and insulin (p = 0.032) levels after 4 and 8 weeks compared to baseline, respectively. Lactate dehydrogenase of the nut group was significantly lower than the pretzel group (p = 0.002). No significant differences were detected between groups for triglycerides, LDL-C, and HDL-C. However, pretzel consumption increased triglycerides (p = 0.048) from 4 weeks to 8 weeks. Moreover, LDL-C increased (p = 0.038) while HDL-C transiently decreased (p = 0.044) from baseline to 4 weeks. No significant lipid changes were detected within the nut group. Our results suggest that supplementing the diet with mixed-nuts could improve CVD risk factors by improving BW and glucose regulation in comparison to a common carbohydrate-rich snack without promoting the negative effects on lipids detected with pretzels.

Several male animal studies have demonstrated bone-protective effects of dried plum; however, no human male study has evaluated the effect of dried plum on bone health. We conducted a randomized controlled clinical study to test if daily inclusion of 100 g of dried plum in the diet positively influenced bone mineral density (BMD), bone strength, and bone biomarkers in men. Sixty-six men were randomly assigned to one of two daily treatment groups: (1) control (0 g dried plum) or (2) 100 g dried plum. Blood samples were collected at baseline and after 3, 6, and 12 months to assess bone biomarkers. Bone was measured at baseline and after 6 and 12 months via dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Tartrate-resistant acid phosphatase-5b (TRAP5b) and C-terminal collagen cross-link (CTX) levels decreased significantly in the dried plum group at 3-, 6-, and 12-month intervals compared with baseline. No changes were observed in the control group for TRAP5b and CTX levels. Bone-specific alkaline phosphatase levels decreased significantly after 6 and 12 months in the control and dried plum groups. BMD for total body, spine (L1–L4), hip, and ulna did not change in the control and dried plum groups from baseline to 6 or 12 months. In the proximal tibia, endosteal circumferences increased significantly within the dried plum group during the course of treatment. The results suggest that daily consumption of 100 g dried plum for 12 months has modest bone-protective effects in men. ClinicalTrials.gov identifier: NCT04720833.