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Session: Effects of Whole Foods and Oral Nutrition Supplements on Surrogate and Clinical Outcomes (Oral 26)

(OR26-01-24) Response of Cardiometabolic Biomarkers and Gut Microbiota to Walnut Consumption

Monday, July 1, 2024

2:30 PM – 2:42 PM CT

Location: W375A

Presenting Author(s)

Tatiana Diacova, PhD, RD (she/her/hers)

Graduate student
University of California, Davis
El Macero, California, United States

Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

Co-Author(s)

Francene M. Steinberg, PhD, RD (she/her/hers)

Professor, Department Chair
University of California, Davis
Davis, California, United States

Objectives: To investigate the effect of walnut consumption on cardiometabolic biomarkers, gut microbiota and gut inflammation in overweight/obese individuals.

Methods: Men and women (n=30) 45-75 years of age, BMI >25.0kg/m² and elevated LDL- C (130-189 mg/dL) were included in this 10-week, randomized crossover trial. Intervention included daily consumption of 2 oz of walnuts vs. a no-walnut diet for 3 weeks, with 1-week run-in and 3-week washout periods. Blood, urine and fecal samples were collected at the beginning and end of each intervention. Primary outcome: blood lipid levels (LDL-C, HDL-C, TC, etc.). Secondary outcomes: circulating vascular inflammatory markers (PAI-1, ICAM-1, VCAM-1), fecal pH, moisture, consistency, microbial metabolites (urolithins, short-chain fatty acids, bile acids), fecal calprotectin & lipocalin-2, and 16S microbiota analysis.

Results: Walnut consumption did not affect anthropometric measurements. Significant changes were observed in blood lipids, fecal characteristics and indices of gut inflammation. There was a decrease in LDL and total cholesterol levels compared to control (p=0.002 and p=0.004, respectively). Levels of fecal lipocalin-2 were lower (p=0.015) after walnut (0.70 ug/mg, 95% CI: 0.39-0.94) vs. no walnut (1.31 ug/mg, 95% CI:0.79-1.79) consumption.

There was a decrease in fecal calprotectin (17.42 mg/kg, 95% CI: 8.48-27.33 vs. 29.93 mg/kg, 95% CI: 19.36-52.26; p =0.02) and pH levels (6.85±0.46 vs. 7.32±0.41; p = 0.00002) after walnuts vs. no walnut intervention. Additional outcomes (microbial metabolites, 16S microbial abundances) are being analyzed.

Conclusions: Daily walnut consumption decreased fecal levels of gut inflammatory markers and pH, as well plasma LDL-C and TC levels in generally healthy individuals with hyperlipidemia and overweight/obesity. Analysis of host and microbial metabolites along with the established CVD biomarkers is necessary for a complete understanding of how walnuts and other foods are exerting their cardioprotective effects.

Funding Sources: UC Davis internal research funds