Effects of Curcumin C3 Complex® on Physical Function in Moderately Functioning Older Adults with Low-Grade Inflammation - A Pilot Trial.

BACKGROUND: Natural dietary compounds that can modulate the inflammation process have the potential to improve physical function through a number of biological pathways, and thus may represent an alternative approach to avert functional decline compared to more time-burdening lifestyle interventions. In this pilot trial, we tested the feasibility and explored the effect of a nutritional compound, Curcumin C3 Complex® for improving physical function and muscle strength in moderately functioning older adults with low-grade inflammation. METHODS: Moderately functioning (short physical performance battery, SPPB <10) and sedentary older adults (>65 years) with low-grade systemic inflammation (c-reactive protein >1mg/dL) were randomized to receive Curcumin C3 Complex® (n=9) (1000mg/day) or placebo (n=8) groups for 12 weeks. All participants (age range: 66-94 years, 8 females and 9 males) underwent functional testing (SPPB and walking speed by the 400-meter walk test) and lower-limb strength (knee flexion and extension peak torque by the Biodex test) at baseline and 12 weeks. Venous blood was collected at baseline, 4, 8 and 12 weeks for safety blood chemistry analyses and biomarkers of inflammation. RESULTS: A total of 17 participants were randomized and completed the study. Adherence was high (> 90%) and there were no adverse events reported or abnormal blood chemistries reported. Based on effect sizes, participants in the Curcumin C3 Complex® group demonstrated large effect sizes in the SPPB (Cohen's effect size d=0.75) and measures of knee extension (d=0.69) and flexion peak torque (d=0.82). Effect sizes for galectin-3 (d=-0.31) (larger decrease) and interleukin-6 (d=0.38) (smaller increase) were small in the Curcumin C3 Complex® group compared to placebo. CONCLUSION: This pilot trial suggests that there were no difficulties with recruitment, adherence and safety specific to the study protocol. Preliminary findings warrant a Phase IIb clinical trial to test the effect of Curcumin C3 Complex® on physical function and muscle strength in older adults at risk for mobility disability.

Experimental pain sensitivity differs as a function of clinical pain severity in symptomatic knee osteoarthritis.

OBJECTIVE: Pain in knee osteoarthritis (OA) has historically been attributed to peripheral pathophysiology; however, the poor correspondence between objective measures of disease severity and clinical symptoms suggests that non-local factors, such as altered central processing of painful stimuli, also contribute to clinical pain in knee OA. Consistent with this notion, recent evidence demonstrates that patients with knee OA exhibit increased sensitivity to painful stimuli at body sites unaffected by clinical pain. DESIGN: In order to further investigate the contribution of altered pain processing to knee OA pain, the current study tested the hypothesis that symptomatic knee OA is associated with enhanced sensitivity to experimental pain stimuli at the knee and at remote body sites unaffected by clinical pain. We further anticipated that pain sensitivity would differ as a function of the OA symptom severity. Older adults with and without symptomatic knee OA completed a series of experimental pain assessments. A median split of the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC) was used to stratify participants into low vs high OA symptom severity. RESULTS: Compared to controls and the low symptom group, individuals in the high symptom group were more sensitive to suprathreshold heat stimuli, blunt pressure, punctuate mechanical, and cold stimuli. Individuals in the low symptomatic OA group subgroup exhibited experimental pain responses similar to the pain-free group on most measures. No group differences in endogenous pain inhibition emerged. CONCLUSIONS: These findings suggest that altered central processing of pain is particularly characteristic of individuals with moderate to severe symptomatic knee OA.

Vitamin D, race, and experimental pain sensitivity in older adults with knee osteoarthritis.

OBJECTIVE: Low circulating serum levels of 25-hydroxyvitamin D (referred to hereafter as vitamin D) have been correlated with many health conditions, including chronic pain. Recent clinical practice guidelines define vitamin D levels <20 ng/ml as deficient and levels of 21-29 ng/ml as insufficient. Vitamin D insufficiency, including the most severe levels of deficiency, is more prevalent in black Americans. Ethnic and race group differences have been reported in both clinical and experimental pain, with black Americans reporting increased pain. The purpose of this study was to examine whether variations in vitamin D levels contribute to race differences in knee osteoarthritis pain. METHODS: The sample consisted of 94 participants (74% women), including 45 blacks and 49 whites with symptomatic knee osteoarthritis. Their average age was 55.8 years (range 45-71 years). Participants completed a questionnaire on knee osteoarthritis symptoms and underwent quantitative sensory testing, including measures of sensitivity to heat-induced and mechanically induced pain. RESULTS: Blacks had significantly lower levels of vitamin D compared to whites, demonstrated greater clinical pain, and showed greater sensitivity to heat-induced and mechanically induced pain. Low levels of vitamin D predicted increased experimental pain sensitivity, but did not predict self-reported clinical pain. Group differences in vitamin D levels significantly predicted group differences in heat pain and pressure pain thresholds at the index knee and ipsilateral forearm. CONCLUSION: These data demonstrate that race differences in experimental pain are mediated by differences in the vitamin D level. Vitamin D deficiency may be a risk factor for increased knee osteoarthritis pain in black Americans.