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Walnut-inclusive diet benefits diet quality, overall cholesterol
LDL cholesterol and total cholesterol both were significantly improved in the walnut-inclusive calorie-control group, compared with the nonwalnut...
ANAHEIM, CALIF. – Eating an ounce and a half of walnuts daily led to favorable changes in gut microbiome composition and diversity in a prospective randomized controlled trial, Klaus G. Parhofer, MD, reported at the American Heart Association scientific session.
These changes in intestinal flora may account for the reductions in LDL cholesterol, triglycerides, apolipoprotein B, and non-HDL cholesterol previously documented with walnut consumption in the same trial, according to Dr. Parhofer, professor of endocrinology and metabolism at the University of Munich.
Bruce Jancin/Frontline Medical News
Dr. Klaus G. Parhofer
The gut microbiome composition during the walnut and control phases differed by about 5%. The proportion of the microbiome composed of probiotic and butyric acid–producing organisms in the phylum Bacteroidetes – especially Ruminococcacaeae and Bifidobacteria – increased during the walnut-eating phase, while the Clostridium cluster XIVa microorganisms in the genera Blautia and Anaerostipes decreased significantly, compared with the control diet.
“It is unclear whether these changes are preserved during longer walnut consumption and how these changes can be associated with the observed changes in lipid metabolism,” the endocrinologist noted.
An earlier report focused on the fasting lipid reductions seen in response to walnut consumption in the full study population. LDL cholesterol fell by an average of 7.4 mg/dL after 8 weeks of daily walnut consumption, compared with a 1.7-mg/dL reduction on the nut-free diet; triglycerides fell by 5.0 mg/dL, while increasing by 3.7 mg/dL on the control diet; non-HDL cholesterol declined by 10.3 mg/dL on the walnut diet and by a far more modest 1.4 mg/dL during the control phase; and apolipoprotein B dropped by 6.7 mg/dL compared with a 0.5 mg/dL reduction on the nut-free diet. All of these differences were statistically significant. However, levels of HDL and lipoprotein (a) weren’t affected.
The California Walnut Commission provided Dr. Parhofer with a research grant to conduct the trial.