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Clinical Trial
. 2014 Nov;17(11):1204-13.
doi: 10.1089/jmf.2014.0037. Epub 2014 Oct 1.

Consumption of Dried Apple Peel Powder Increases Joint Function and Range of Motion

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Free PMC article
Clinical Trial

Consumption of Dried Apple Peel Powder Increases Joint Function and Range of Motion

Gitte S Jensen et al. J Med Food. .
Free PMC article

Abstract

The goal for this study was to evaluate the effects of consumption of dried apple peel powder (DAPP) on joint function and range of motion (ROM). Additional in vitro and clinical testing was performed to suggest specific mechanisms of action. An open-label clinical pilot study involved 12 healthy people with moderate loss of joint ROM and associated chronic pain. The subjects consumed 4.25 g DAPP daily for 12 weeks, with evaluations at baseline, 2, 4, 8, and 12 weeks. ROM was evaluated at each visit using dual digital inclinometry. Pain scores were collected using Visual Analogue Scales. Blood draws enabled testing of serum antioxidant protective capacity using the cellular antioxidant protection (CAP-e) bioassay. Additional in vitro testing involved testing of cyclooxygenase-2 (COX-2) and lipoxygenase inhibition, cellular antioxidant protection by the CAP-e bioassay, and formation of reactive oxygen species (ROS) by polymorphonuclear (PMN) cells by flow cytometry. Twelve weeks of consumption of DAPP was associated with improved ROM. DAPP provided antioxidants that were available to enter into and protect cells from oxidative damage in vitro, and consumption of DAPP for 12 weeks was associated with a statistically significant improvement in serum antioxidant protective status. DAPP inhibited both COX-2 and lipoxygenase enzymes, and pretreatment of inflammatory PMN cells with DAPP before inflammatory stimulus resulted in reduced ROS formation. This suggests multifaceted anti-inflammatory properties of DAPP. Consumption of DAPP was associated with improved joint function and improved serum antioxidant protection status. The observed pain reduction may be associated with the improved antioxidant status and linked to the apple polyphenols' anti-inflammatory effects.

Keywords: anti-inflammatory; antinociceptive; antioxidant; chronic pain; digital inclinometry.

Figures

<b>FIG. 1.</b>
FIG. 1.
Diagram showing the study design for the 12-week open-label study. Range of motion (ROM) along the vertical weight-bearing column (neck to knees) and shoulders was performed using dual digital inclinometry. Additional data involved questionnaire-based data collection pertaining to pain levels in areas of primary and secondary pain areas identified at study start. Blood draws for serum testing was performed at baseline, 2, 4, 8, and 12 weeks.
<b>FIG. 2.</b>
FIG. 2.
Changes in joint ROM during 12 weeks of consumption of dried apple peel powder (DAPP). The ROM was evaluated along the vertical weight-bearing column (neck to knees) as well as shoulders, using dual digital inclinometry. Rapid improvements were seen in lumbar and shoulder ROM, where some types of ROM improvements were statistically significant already at 2 weeks, when compared with baseline ROM (P<.05). The cervical lateral ROM and thoracic ROM showed improvements at 4 weeks, where the cervical lateral ROM was significantly improved compared with baseline ROM (P<.05). Cervical lateral ROM, thoracic and lumbar rotation, hip ROM, as well as all ROM associated with the left and right shoulders were significantly improved after 12 weeks of DAPP consumption when compared with baseline ROM (P<.05). The level of significance, as calculated by the paired t-test (“within-subject” analysis), is indicated by * if P<.05 and by ** if P<.01.
<b>FIG. 3.</b>
FIG. 3.
Changes in serum antioxidant protection during 12 weeks of consumption of DAPP. Serum samples collected during the study were tested in a modified cellular antioxidant protection (CAP-e) bioassay, where the antioxidant protection data reflect whether serum contained antioxidants of a chemical composition that are available to enter into and protect cells from oxidative stress. An improvement in serum antioxidant protection status was statistically significant already after 2 weeks of consumption, and continued to increase until 8 weeks, after which a plateau was seen. The improvement from baseline remained statistically significant at all time points (*P<.05).
<b>FIG. 4.</b>
FIG. 4.
Pain scores during 12 weeks of consumption of DAPP. Joint pain was evaluated at baseline and at all the next visits using Visual Analogue Scales. Pain reduction was observed already after 2 weeks of DAPP consumption, and it was statistically significant after 4 weeks of consumption (*P<.05). The improvement continued throughout the 12 week study, at which time the improvement from baseline was highly significant (**P<.01).
<b>FIG. 5.</b>
FIG. 5.
Cellular antioxidant protection provided by DAPP was measured using the CAP-e bioassay. Human erythrocytes were treated with serial doses of DAPP before being exposed to oxidative stress. The fluorescence intensity of a reporter dye reflected the level of intracellular oxidative damage. The inhibition of intracellular damage is shown as the average+standard deviation of duplicate data points, in reference to negative and positive controls, each of which are performed in hexaplicate. The protective effects provided by antioxidants in DAPP, able to enter into and protect the living cells, were dose dependent, with an IC50 around 20 mg/mL.
<b>FIG. 6.</b>
FIG. 6.
Changes in intracellular production of reactive oxygen species (ROS) were evaluated using an in vitro bioassay with inflammatory polymorphonuclear (PMN) cells from three healthy donors. Pretreatment of PMN cels with DAPP before an inflammatory insult was introduced resulted in reduction of the levels of ROS in cells from all three donors, across the dose range of 0.0001–0.1 mg/mL DAPP (P<.05). The level of significance, as calculated by the independent two-tailed t-test, is indicated by * if P<.05 and by ** if P<.01.
<b>FIG. 7.</b>
FIG. 7.
Cellular migration in response to the inflammatory chemo-attractant leukotriene B4 (LTB4) was evaluated using PMN cells in vitro. Pretreatment of PMN cells with DAPP before cells were placed within range of the chemotactic compound LTB4 in transwell migration chambers resulted in a reduction in migratory behavior of the cells. The<3 kDa low-molecular-weight fraction of DAPP (DAPP LMW) showed high potency at very low doses where cellular migration in response to LTB4 was reduced to baseline levels (UT: untreated cells). Asterisks indicate doses where the results were statistically signficant when compared with the positive control (LTB4) where cells were exposed to LTB4 in the absence of DAPP or DAPP LMW (P<.05). The level of significance was calculated by the independent two-tailed t-test and is indicated by * if P<.05 and by ** if P<.01.
<b>FIG. 8.</b>
FIG. 8.
DAPP was tested for its ability to inhibit two enzymes involved in inflammatory processes: Cyclooxygenase-2 (COX-2) and lipoxygenase. The tests compared a crude water extract of DAPP to a<3 kDa DAPP LMW. The crude extract showed inhibition of both enzymes at a dose of 10 mg/mL. The<3 kDa LMW fraction provided a proportionally better inhibition of COX-2 than lipoxygenase when compared with the crude water extract, suggesting that compounds below 3 kDa are involved in the inhibition of COX-2.

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