Walnut Consumption Induces Tissue-Specific Omega-6/Omega-3 Decrease in High-Fructose-Fed Wistar Rats

Abstract

Increased dietary, blood, and tissue n-6/n-3 fatty acid ratios are associated with obesity and metabolic syndrome. Due to Westernized dietary patterns, the increasing n-6/n-3 ratio is of growing concern worldwide, and dietary strategies aimed at its lowering are of public health importance. Walnuts are rich in dietary fats, and their consumption promotes cardiometabolic health. This study aimed to examine the effect of 6-week walnut consumption on tissue-specific n-6/n-3 ratio and fatty acid metabolic conversion in fructose-fed rats with a cluster of metabolic disorders. Male Wistar rats were fed a standard diet with or without 10% fructose in drinking water for 9 weeks. Diets of half of the animals were then supplemented with walnuts (2.4 g/day) for 6 weeks, upon which fatty acid profiles were determined in plasma, liver, adipose tissue, and kidney total lipids. Results showed that walnuts induced significant decreases in the n-6/n-3 content of total lipid pool in plasma and examined tissues, irrespective of metabolic burden. Walnut intervention decreased plasma and liver palmitoleic/palmitic, arachidonic/linoleic, and docosahexaenoic/α-linolenic acid ratios. It also modulated individual fatty acid levels by reducing arachidonic and palmitic acid and increasing α-linolenic, eicosapentaenoic, and docosapentaenoic acid in plasma and most tissues. Our study demonstrated that 6-week consumption of walnuts favorably modulated n-6/n-3 plasma and tissue ratio in male Wistar rats regardless of high-fructose feeding, underscoring the promising potential of walnuts in both prevention and treatment of the metabolic syndrome.

Walnut Supplementation Restores the SIRT1‐FoxO3a‐MnSOD/Catalase Axis in the Heart, Promotes an Anti‐Inflammatory Fatty Acid Profile in Plasma, and Lowers Blood Pressure on Fructose‐Rich Diet

“…In addition, we demonstrated an increased omega-6/omega-3 ratio in FRD rats, which has been suggested to be highly prothrombotic and proinflammatory and to contribute to the prevalence of atherosclerosis and MetS-related diseases [ 16 , 42 ]. The tissue-specific omega-6/omega-3 decrease after walnut consumption in high-fructose-fed Wistar rats was recently demonstrated [ 37 ]. An increase in the AA/EPA ratio as a result of fructose feeding in our study could be deleterious for the heart; previously, it has been suggested that higher levels of the AA/EPA ratio are associated with a greater risk for CVD and has been proposed as a biochemical marker of CVD events [ 16 , 42 ].…”

Fructose‐rich diet and walnut supplementation differently regulate rat hypothalamic and hippocampal glucose transporters expression

“…Briefly, these animals displayed normoglycemia, elevated serum insulin and triglyceride levels, and increased adiposity and body weight. 17,18 Walnut kernels were administered at a dose of 2.4 g per day for 6 weeks. Special care was taken to ensure that each animal regularly consumed a provided daily dose of walnut kernels.…”

“…The fatty acid composition in the brain tissue was determined according to the methodology described previously. 18 Briefly, total lipids were extracted following the Folch method, using chloroform-methanol (2:1, v/v) with 0.05% (w/v) butylated hydroxytoluene. 24 Furthermore, fatty acids were esterified to methyl esters with 3 mol L −1 hydrochloric acid in methanol with 2% (w/v) butylated hydroxytoluene, then incubated, mixed with hexane, centrifuged and dried under N 2 stream.…”

“…17 Additionally, irrespective of metabolic burden, dietary walnuts improved fatty acid composition profiles across plasma, liver, kidney and adipose tissue. 18 Considering that walnuts represent dietary source of polyunsaturated fatty acids (PUFA) that are involved in modulation of brain function, it is not surprising that walnut consumption has been associated with improved cognitive and motor performance and decreased neuroinflammation. 19 However, no previous study has investigated the effects of walnut consumption on the brain glucose uptake of healthy or metabolically challenged animals.…”

Can Walnut Serve as a Magic Bullet for the Management of Non-Alcoholic Fatty Liver Disease?

“…NAFLD development is also associated with genetic makeup such as the Patatin-like phospholipase domain-containing 3 (PNPLA3) polymorphism [93]; therefore, investigating the interactions between walnut and genes would be helpful to understand the individually different effects of walnut on NAFLD. Male C57BL/6J mice Walnut oil capsule (6, 12, 18 mL/kg) through intragastric administration with D-galactose injection Improved hepatic necrosis, hydropic degeneration, vacuolar degeneration, and lymphocytic infiltration along with increased total anti-oxidant capacity [97] Male Wistar rats Walnut-enriched diet (2.4 g/day) with high fructose in drinking water (10% w/v) Lowered the n-6/n-3 ratio in plasma, liver and epididymal adipose tissue, and increased LA and αLNA contents in the liver [98] Participants with obesity (n = 10) Randomized placebo-controlled crossover clinical trial with five-day consumption of either walnuts (48 g/day) or placebo Improved the lipid profile and reduced insulin resistance and blood levels of ceramides, sphingomyelins, and N-glycans [74] Participants with abdominal obesity and dyslipidemia (n = 278)…”