Background: Postprandial metabolic impairments in diabetes have been shown to play an important role in vascular complications. Dietary polyphenols and other bioactive compounds in berries have been shown to improve postprandial hyperglycemia and related metabolic impairments, but few clinical studies have been reported in diabetes. Objective: To examine the effects of daily dietary raspberries on postprandial and 4-week fasting glucose, lipids and biomarkers of inflammation in obese adults with type 2 diabetes. Design: This was a randomized crossover study with 2 different phases: a “postprandial phase” of acute raspberry supplementation (2 separate days at least 1 week apart), followed by a 1-week washout phase and then a 10-week “diet supplement phase”, with and without raspberry supplementation periods of 4 weeks each, separated by 2-week washout phase. Results: The postprandial phase revealed significantly lower levels of serum glucose at 2 and 4 h postprandial after raspberry versus control phase. In addition, among the serum biomarkers of inflammation, interleukin (IL)-6 and high-sensitivity tumor necrosis factor alpha (hsTNF-α) were also lower at 4 h postprandial following raspberry versus control meal (all p < 0.05). Finally, postprandial serum triglycerides showed a decreasing trend at 4 h in the raspberry versus control phase. Four-week daily raspberry supplementation continued to show a significant lowering effects on IL-6 and hsTNF-α versus control phase (all p < 0.05); systolic blood pressure revealed a decreasing trend after 4-week of raspberry supplementation. No effects were noted on fasting glucose and lipids, C-reactive protein and arterial elasticity. Conclusions: Thus, dietary raspberries, which are low in calories and high in polyphenols and other nutrients may lower postprandial hyperglycemia and inflammation, and in general exert selected anti-inflammatory effects in adults with diabetes. These findings deserve further investigation.

Osteoarthritis (OA), the most common form of arthritis, is a significant public health burden in U.S. adults. Among its many risk factors, obesity is a key player, causing inflammation, pain, impaired joint function, and reduced quality of life. Dietary polyphenols and other bioactive compounds in berries, curcumin, and tea have shown effects in ameliorating pain and inflammation in OA, but few clinical studies have been reported. The purpose of the present study was to examine the effects of dietary strawberries on pain, markers of inflammation, and quality of life indicators in obese adults with OA of the knee. In a randomized, double-blind cross-over trial, adults with radiographic evidence of knee OA (n = 17; body mass index (BMI): (mean ± SD) 39.1 ± 1.5; age (years): 57 ± 7) were randomized to a reconstituted freeze-dried strawberry beverage (50 g/day) or control beverage daily, each for 12 weeks, separated by a 2-week washout phase (total duration, 26 weeks). Blood draws and assessments of pain and quality of life indicators were conducted using the Visual Analog Scale for Pain (VAS Pain), Measures of Intermittent and Constant Osteoarthritis Pain (ICOAP), and Health Assessment Questionnaire-Disability Index (HAQ-DI) questionnaires, which were completed at baseline and at weeks 12, 14, and 26 of the study. Among the serum biomarkers of inflammation and cartilage degradation, interleukin (IL)-6, IL-1β, and matrix metalloproteinase (MMP)-3 were significantly decreased after strawberry vs. control treatment (all p < 0.05). Strawberry supplementation also significantly reduced constant, intermittent, and total pain as evaluated by the ICOAP questionnaire as well as the HAQ-DI scores (all p < 0.05). No effects of treatment were noted on serum C-reactive protein (CRP), nitrite, glucose, and lipid profiles. Dietary strawberries may have significant analgesic and anti-inflammatory effects in obese adults with established knee OA.

Arthritis is a global health concern affecting a significant proportion of the population and associated with reduced quality of life. Among the different forms of arthritis, osteoarthritis (OA) and rheumatoid arthritis (RA) are the most common and lacking a definite cure in the affected individuals. Fruits, such as berries and pomegranates are rich sources of a variety of dietary bioactive compounds, especially the polyphenolic flavonoids that have been associated with antioxidant, anti-inflammatory and analgesic effects. Emerging research demonstrates a protective role of fruits and their polyphenols in pre-clinical, clinical and epidemiological studies of OA and RA. In this context, commonly available fruits, such as blueberries, raspberries and strawberries, and pomegranates have shown promising results in reducing pain and inflammation in experimental models and in human clinical studies of arthritis. There is also some evidence on the role of specific fruit polyphenols, such as quercetin and citrus flavonoids in alleviating RA symptoms. These emerging data deserve further investigation in rigorous scientific studies to determine the mechanisms, dosing and selection of fruits and fruit extracts in arthritis management.