(P20-37-26) Impact of California Grape Polyphenols on Cardiometabolic Markers and Vascular Function in Adults With Overweight or Obesity

Objectives: Evaluating the capacity of California table grape polyphenols to counteract vascular function changes associated with excess adiposity in healthy adults.

Methods: This randomized, double-blind, placebo-controlled, cross-over study involves 40 healthy adults (men, postmenopausal women), age 45-70 y, BMI 25-35kg/m². Intervention: 48g/d freeze-dried grape powder (~200 mg polyphenols) vs. sensory-matched, isocaloric, polyphenol-free placebo, in a randomized sequence, blinded as A or B, consumed daily in water on low-polyphenol diet. Two 3-week periods are preceded by a 3-day low-polyphenol run-in and separated by a 3-week washout. Adherence: 24h recalls and sachet counts. Anthropometrics, blood pressure (BP), carotid-femoral pulse wave velocity (cfPWV, primary outcome), and blood markers are assessed at beginning and end of each period. Linear mixed-effects models account for treatment, period, and sequence effects.

Results: Of 10 study completers, 6 were analyzed (Age 62.3 ± 8.7 y, BMI 28.4 ± 1.1 kg/m²); 4 were excluded due to low adherence (n = 2) or cfPWV variance > 0.5 m/s (n = 2). Weight remained stable (B: Δ -0.08 ± 0.9 kg; A: Δ -0.3 ± 1.2 kg; p = 0.41). Sachet counts (100%) and recalls confirmed high protocol adherence. Mean baseline cfPWV (6.39 ± 1.25 m/s) was within the healthy range, yet a large effect size was observed: cfPWV showed mean reduction in B (Δ -1.48 ± 1.90 m/s; -17.3%; 95% CI: -3.48, 0.51) vs. mean increase in A (Δ +0.26 ± 1.06 m/s; +8.3%; 95% CI: -0.86, 1.37; Cohen’s d = 0.72). Secondary outcomes showed moderate effects (d > 0.20): increased HDL in B (2.67 ± 1.97 mg/dL; 5.2%; 95% CI: 0.6, 4.73) vs. A (-0.50 ± 3.51 mg/dL; -0.22%; 95% CI: -4.18, 3.18; d = 0.63), diastolic BP (d = 0.24), fasting glucose (d = 0.21), cholesterol (d = 0.46), LDL (d = 0.38), and non-HDL (d = 0.31). The recruitment is ongoing.

Conclusions: Preliminary findings show the intervention may improve arterial stiffness (cfPWV) and lipid metabolism, suggesting a role of grape polyphenols in vascular function, pending treatment unblinding.

Funding Sources: California Table Grape Commission, UC Davis (Jastro-Shields, Campbell Award, Rucker Fellowship, Schneeman Award); USDA NIFA CA-D-NTR-6316-H