Njike, V.Y., V.C. Costales, P. Petraro, A. Annam, N. Yarandi, D.L. Katz, 2019. The resulting variation in nutrient intake with the inclusion of walnuts in the diets of adults at risk for type 2 diabetes: A randomized, controlled, crossover trial. Am J Health Promot. 33(3):430-438.
Purpose: We previously demonstrated that including walnuts in the diets of adults at risk for type 2 diabetes mellitus (T2DM) led to improved overall diet quality. This report examines the specific changes in their nutrient intake. Design: This was a randomized, controlled, modified Latin square parallel design trial with 2 treatment arms. Participants were randomized to walnut intake with, or without, dietary advice to regulate caloric intake. Within each treatment arm, they were further randomized to one of 2 sequence permutations (walnut-included/walnut-excluded or walnut-excluded/walnut-included diet), with a 3-month washout between treatment phases. Setting: Community hospital in Lower Naugatuck Valley in Connecticut. Participants: Cohort of 112 participants (31 men and 81 women) at risk for T2DM. Intervention: Participants included 56 g (366 kcal) of walnuts in their daily diets for 6 months. Measures: Nutrient intake was assessed using web-based Automated Self-Administered 24-Hour Dietary Assessment. Analysis: Data were analyzed using generalized linear models. Results: Walnut inclusion led to increased intake of total fat, calcium, magnesium, thiamin, total saturated fatty acids, and monounsaturated and polyunsaturated fatty acids (379.0 ± 90.3 g vs -136.5 ± 92.7 g, P < .01; 230.7 ± 114.2 mg vs -95.2 ± 117.4 mg, P = .05; 111.0 ± 33.9 mg vs -32.3 ± 34.9 mg, P < .01; 0.28 ± 0.2 mg vs -0.47 ± 0.2 mg, P = .02; 8.6 ± 3.4 g vs -1.1 ± 3.5 g, P =.05; 6.3 ± 3.9 g vs -6.3 ± 4.0 g, P = .03; and 25.4 ± 4.0 vs -6.6 ± 4.2 g, P < .01, respectively). Vitamin C intake decreased (-65.3 ± 55.3 mg vs 98.9 ± 56.8 mg, P = .04). Protein intake increased from baseline with the inclusion of walnuts (20.0 ± 8.8 g, P < .05). Walnut inclusion led to an increase in total calories consumed when caloric intake is not regulated. Conclusion: Including walnuts in the diets of these adults led to increased dietary intake of some nutrients associated with lower risk of developing T2DM and other cardiometabolic risk factors.
Nakanishi, M., A. Matz, C. Klemashevich, D.W. Rosenberg, 2019. Dietary walnut supplementation alters mucosal metabolite profiles during DSS-induced colonic ulceration. Nutrients. 11(5). pii: 1118. doi: 10.3390/nu11051118
Walnuts contain a complex array of natural compounds and phytochemicals that exhibit a wide range of health benefits, including protection against inflammation and colon cancer. In this study, we assess the effects of dietary supplementation with walnuts on colonic mucosal injury induced in mice by the ulcerogenic agent, dextran sodium sulfate (DSS). C57Bl/6J mice were started on the Total Western Diet supplemented with freshly-ground whole walnuts (0, 3.5, 7 and 14% g/kg) 2 weeks prior to a 5-day DSS treatment and walnut diets were continued throughout the entire experimental period. Mice were examined at 2 days or 10 days after withdrawal of DSS. In a separate study, a discovery-based metabolite profiling analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed on fecal samples and colonic mucosa following two weeks of walnut supplementation. Dietary walnut supplementation showed significant effects in the 10-day post-DSS recovery-phase study, in which the extent of ulceration was significantly reduced (7.5% vs. 0.3%, p < 0.05) with 14% walnuts. In the metabolite-profiling analysis, walnuts caused a significant increase in several polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and 9-oxo-10(E),12(E)-octadecadienoic acid (9-oxoODA), as well as kynurenic acid. In colon tissue samples, walnuts caused a significant increase in the levels of S-adenosylhomocysteine (SAH) and betaine, important components of fatty acid β-oxidation. These metabolite changes may contribute in part to the observed protection against DSS-induced inflammatory tissue injury.
McArthur, B., R. Mattes, 2019. Energy extraction from nuts: walnuts, almonds, pistachios. Br J Nutr. 17:1-21.
The bioaccessibility of fat has implications for satiety and postprandial lipidemia. The prevailing view holds that the integrity of plant cell wall structure is the primary determinant of energy and nutrient extraction from plant cells as they pass through the gastrointestinal tract. However, comparisons across nuts (walnuts, almonds, pistachios) with varying physical properties do not support this view. In this study, masticated samples of three nuts from healthy adults were exposed to a static model of gastric digestion followed by simulated intestinal digestion. Primary outcomes were particle size and lipid release at each phase of digestion. Walnuts produced a significantly larger particle size post-mastication compared to almonds. Under gastric and intestinal conditions, the particle size was larger for walnuts compared to pistachios and almonds (P<0.05). However, the masticated and digesta particle sizes were not related to the integrity of cell walls nor lipid release. The total lipid release was comparable between nuts after the in vitro intestinal phase (P>0.05). Microstructural examination showed ruptured and fissured cell walls that would allow digestion of cellular contents and this may be governed by internal cellular properties such as oil body state. Furthermore, the cell walls of walnuts tend to rupture rather than separate and as walnut tissue passes through the gastrointestinal track, lipids tend to coalesce reducing digestion efficiency.
Koh, S.J., Y.I. Choi, Y. Kim, Y.S. Kim, S.W. Choi, J.W. Kim, B.G. Kim, K.L. Lee, 2019. Walnut phenolic extract inhibits nuclear factor kappaB signaling in intestinal epithelial cells, and ameliorates experimental colitis and colitis-associated colon cancer in mice.
Eur J Nutr. 58(4):1603-1613.
Purpose: Walnuts (Juglans regia) are known to have anti-cancer and immunomodulatory effects. However, little information is available on the effects of walnut phenolic extract (WPE) on intestinal inflammation and colitis-associated colon cancer. Methods: COLO205 cells were pretreated with WPE and then stimulated with tumor necrosis factor (TNF)-α. In the acute colitis model, wild type mice (C57BL/6) were administered 4% dextran sulfate sodium (DSS) for 5 days. In the chronic colitis model, interleukin (IL)-10-/- mice were administered with either the vehicle or WPE (20 mg/kg) by oral gavage daily for 2 weeks. In an inflammation-associated tumor model, wild type mice were administered a single intraperitoneal injection of azoxymethane followed by three cycles of 2% DSS for 5 days and 2 weeks of free water consumption. Results: WPE significantly inhibited IL-8 and IL-1α expression in COLO205 cells. WPE attenuated both the TNF-α-induced IκB phosphorylation/degradation and NF-κB DNA binding activity. The administration of oral WPE significantly reduced the severity of colitis in both acute and chronic colitis models, including the IL-10-/- mice. In immunohistochemical staining, WPE attenuated NF-κB signaling in the colons of both colitis models. Finally, WPE also significantly reduced tumor development in a murine model of colitis-associated colon cancer (CAC). Conclusions: WPE ameliorates acute and chronic colitis and CAC in mice, suggesting that WPE may have potentials for the treatment of inflammatory bowel disease.
