Lackey, K.A., S.A. Fleming, 2021. Brief research report: estimation of the protein digestibility-corrected amino acid score of defatted walnuts. Frontiers in Nutrition. 8, 702857. https://doi.org/10.3389/fnut.2021.702857
Introduction: Walnuts are considered a good source of essential fatty acids, which is unique among tree nuts. Walnuts are also composed of about 10–15% protein, but the quality of this protein has not been evaluated. Pistachios and almonds have been evaluated for their protein content using a protein digestibility-corrected amino acid score (PDCAAS), but it is unclear how the quality of protein in walnuts relates to that in other commonly consumed tree nuts. The objective of this study was to substantiate the protein quality of walnuts by determining their PDCAAS. Methods: A small, 10-day dietary intervention trial was conducted using male Sprague-Dawley rats (n = 8, 4 per group) with two diets: a nitrogen-free diet and a diet containing protein exclusively from defatted walnuts. Feed intake and fecal output of nitrogen were measured to estimate the true protein digestibility, and the amino acid compositions of walnuts compared to child and adult populations were used to calculate amino acid scores (AAS) and PDCAAS. Results: The true protein digestibility score of raw walnuts was calculated to be 86.22%. Raw walnuts contained 15.6 g protein/g walnut with AAS of 0.45 and 0.63 for children aged 6 months to 3 years and 3–10 years, respectively. For each population, a PDCAAS of 39 and 46% was calculated, respectively, using a protein conversion constant of 5.30. Using a protein constant of 6.25, a PDCAAS of 39% (6 months – 3 years) or 46% (3-10 years) was calculated. Conclusions: This is the first known assessment of the PDCAAS of walnuts. Like almonds, appear to have a low-to-moderate score, indicating they are not a quality source of protein.
Nishi, S. K., C.W.C. Kendall, R.P. Bazinet, A.J. Hanley, E.M. Comelli, D.J.A. Jenkins, J.L. Sievenpiper, 2021. Almond bioaccessibility in a randomized crossover trial: is a calorie a calorie? Mayo Clin. Proc. 96(9):2386–2397. https://doi.org/10.1016/j.mayocp.2021.01.026
Objective: To investigate the energy and macronutrient bioaccessibility of almonds in individuals with hyperlipidemia. Methods: In a previously reported randomized crossover trial, men and postmenopausal women with hyperlipidemia incorporated 3 isoenergetic supplements into a National Cholesterol Education Program Step 2 diet for 1 month each between September 20, 2000, and June 27, 2001. Supplements provided consisted of full-dose almonds (73±5 g/d), half-dose almonds (38±3 g/d) plus half-dose muffins, and full-dose muffins (control). Energy and macronutrients, including individual fatty acids, were measured in the dietary supplements and fecal samples using gas chromatography and Association of Official Analytical Chemists methods. Serum was measured for lipids and fatty acids. Bioaccessibility of energy and macronutrients from almond consumption was assessed from dietary intake (7-day food records) and fecal output. Results: Almond-related energy bioaccessibility was 78.5%±3.1%, with an average energy loss of 21.2%±3.1% (40.6 kcal/d in the full-dose almond phase). Bioaccessibility of energy and fat from the diet as a whole was significantly less with almond consumption (in both half- and full-dose phases) compared with the control. Bioaccessibility of fat was significantly different between treatment phases (P<.001) and on average lower by 5.1% and 6.3% in the half- and full-dose almond phases, respectively, compared with the control phase. Energy bioaccessibility was significantly different between the treatment phases (P=.02), decreasing by approximately 2% with the inclusion of the full dose of almonds compared with the control. Conclusion: Energy content of almonds may not be as bioaccessible in individuals with hyperlipidemia as predicted by Atwater factors, as suggested by the increased fat excretion with almond intake compared with the control.
Choo, J.M., C.D. Tran, N.D. Luscombe-Marsh, W. Stonehouse, J. Bowen, N. Johnson, C.H. Thompson, E.-J. Watson, G.D. Brinkworth, G.B. Rogers, 2021. Almond consumption affects fecal microbiota composition, stool pH, and stool moisture in overweight and obese adults with elevated fasting blood glucose: A randomized controlled trial. Nutr Res. 85:47-59.
Regular almond consumption has been shown to improve body weight management, lipid profile and blood glucose control. We hypothesized that almond consumption would alter fecal microbiota composition, including increased abundance and activity of potentially beneficial bacterial taxa in adults who are overweight and obese with elevated fasting blood glucose. A total of 69 adults who were overweight or obese with an elevated plasma glucose (age: 60.8 ± 7.4, BMI ≥27 kg/m2, fasting plasma glucose ≥5.6 to <7.0 mmol/L) were randomized to daily consumption of either 2 servings of almonds (AS:56 g/day) or an isocaloric, high carbohydrate biscuit snack for 8 weeks. AS but not biscuit snack experienced significant changes in microbiota composition (P= .011) and increases in bacterial richness, evenness, and diversity (P< .01). Increases in both the relative and absolute abundance of operational taxonomic units in the Ruminococcaceae family, including Ruminiclostridium (false discovery rate P = .002), Ruminococcaceae NK4A214 (P = .002) and Ruminococcaceae UCG-003 (P = .002) were the principal drivers of microbiota-level changes. No changes in fecal short chain fatty acid levels, or in the carriage of the gene encoding butyryl-CoA:acetate CoA-transferase (an enzyme involved in butyrate synthesis) occurred. Almond consumption was not associated with reduced gut permeability, but fecal pH (P= .0006) and moisture content (P = .027) decreased significantly in AS when compared to BS. Regular almond consumption increased the abundance of potentially beneficial ruminococci in the fecal microbiota in individuals with elevated blood glucose. However, fecal short-chain fatty acid levels remained unaltered and the capacity for such microbiological effects to precipitate host benefit is not known.
Yaskolka M.A., E. Rinott, G. Tsaban, H. Zelicha, A. Kaplan, P. Rosen, I. Shelef, I. Youngster, A. Shalev, M. Blüher, U. Ceglarek, M. Stumvoll, K. Tuohy, C. Diotallevi, U. Vrhovsek, F. Hu, M. Stampfer, I. Shai, 2021. Effect of green-Mediterranean diet on intrahepatic fat: the DIRECT PLUS randomised controlled trial. Gut. 0:1–11. doi:10.1136/gutjnl-2020-323106.
Objective: To examine the effectiveness of green-Mediterranean (MED) diet, further restricted in red/ processed meat, and enriched with green plants and polyphenols on non-alcoholic fatty liver disease (NAFLD), reflected by intrahepatic fat (IHF) loss. Design: For the DIRECT-PLUS 18-month randomized clinical trial, we assigned 294 participants with abdominal obesity/dyslipidaemia into healthy dietary guidelines (HDG), MED and green-MED weight-loss diet groups, all accompanied by physical activity. Both isocaloric MED groups consumed 28 g/day walnuts (+440 mg/day polyphenols provided). The green-MED group further consumed green tea (3–4 cups/day) and Mankai (a Wolffia globosa aquatic plant strain; 100 g/ day frozen cubes) green shake (+1240 mg/day total polyphenols provided). IHF% 18-month changes were quantified continuously by proton magnetic resonance spectroscopy (MRS). Results: Participants (age=51 years; 88% men; body mass index=31.3 kg/m2; median IHF%=6.6%; mean=10.2%; 62% with NAFLD) had 89.8% 18 month retention-rate, and 78% had eligible follow-up MRS. Overall, NAFLD prevalence declined to: 54.8% (HDG), 47.9% (MED) and 31.5% (green-MED), p=0.012 between groups. Despite similar moderate weight-loss in both MED groups, green-MED group achieved almost double IHF% loss (−38.9% proportionally), as compared with MED (−19.6% proportionally; p=0.035 weight loss adjusted) and HDG (−12.2% proportionally; p<0.001). After 18 months, both MED groups had significantly higher total plasma polyphenol levels versus HDG, with higher detection of Naringenin and 2-5-dihydroxybenzoic- acid in green-MED. Greater IHF% loss was independently associated with increased Mankai and walnuts intake, decreased red/processed meat consumption, improved serum folate and adipokines/lipids biomarkers, changes in microbiome composition (beta-diversity) and specific bacteria (p<0.05 for all). Conclusion: The new suggested strategy of green-Mediterranean diet, amplified with green plant-based proteins/polyphenols as Mankai, green tea, and walnuts, and restricted in red/processed meat can double IHF loss than other healthy nutritional strategies and reduce NAFLD in half.
