Tindall, A.M., K.S. Petersen, A.C. Skulas-Ray, C.K. Richter, D.N. Proctor, P.M. Kris-Etherton, 2019. Replacing saturated fat with walnuts or vegetable oils improves central blood pressure and serum lipids in adults at risk for cardiovascular disease: a randomized controlled-feeding trial. J Am Heart Assoc. 8(9):e011512. doi: 10.1161/JAHA.118.011512
Background: Walnuts have beneficial effects on cardiovascular risk factors, but it is unclear whether these effects are attributable to the fatty acid ( FA ) content, including α-linolenic acid ( ALA ), and/or bioactives. Methods and Results: A randomized, controlled, 3-period, crossover, feeding trial was conducted in individuals at risk for cardiovascular disease (n=45). Following a 2-week standard Western diet run-in (12% saturated FAs [ SFA ], 7% polyunsaturated FAs, 12% monounsaturated FAs), participants consumed 3 isocaloric weight-maintenance diets for 6 weeks each: a walnut diet ( WD ; 7% SFA , 16% polyunsaturated FAs, 3% ALA , 9% monounsaturated FAs); a walnut FA -matched diet; and an oleic acid-replaced- ALA diet (7% SFA , 14% polyunsaturated FAs, 0.5% ALA , 12% monounsaturated FAs), which substituted the amount of ALA from walnuts in the WD with oleic acid. This design enabled evaluation of the effects of whole walnuts versus constituent components. The primary end point, central systolic blood pressure, was unchanged, and there were no significant changes in arterial stiffness. There was a treatment effect ( P=0.04) for central diastolic blood pressure; there was a greater change following the WD versus the oleic acid-replaced-ALA diet (-1.78±1.0 versus 0.15±0.7 mm Hg, P=0.04). There were no differences between the WD and the walnut fatty acid-matched diet (-0.22±0.8 mm Hg, P=0.20) or the walnut FA-matched and oleic acid-replaced-ALA diets ( P=0.74). The WD significantly lowered brachial and central mean arterial pressure. All diets lowered total cholesterol, LDL (low-density lipoprotein) cholesterol, HDL (high-density lipoprotein) cholesterol, and non- HDL cholesterol. Conclusions: Cardiovascular benefits occurred with all moderate-fat, high-unsaturated-fat diets. As part of a low- SFA diet, the greater improvement in central diastolic blood pressure following the WD versus the oleic acid-replaced-ALA diet indicates benefits of walnuts as a whole-food replacement for SFA.
Tindall, A.M., C.J. McLimans, K.S. Petersen, P.M. Kris-Etherton, R. Lamendella, 2019. Walnuts and vegetable oils containing oleic acid differentially affect the gut microbiota and associations with cardiovascular risk factors: Follow-up of a randomized, controlled, feeding trial in adults at risk for cardiovascular disease. J Nutr. 150(4):806-817.
Background: It is unclear whether the favorable effects of walnuts on the gut microbiota are attributable to the fatty acids, including α-linolenic acid (ALA), and/or the bioactive compounds and fiber. Objective: This study examined between-diet gut bacterial differences in individuals at increased cardiovascular risk following diets that replace SFAs with walnuts or vegetable oils.Methods: Forty-two adults at cardiovascular risk were included in a randomized, crossover, controlled-feeding trial that provided a 2-wk standard Western diet (SWD) run-in and three 6-wk isocaloric study diets: a diet containing whole walnuts (WD; 57-99 g/d walnuts; 2.7% ALA), a fatty acid-matched diet devoid of walnuts (walnut fatty acid-matched diet; WFMD; 2.6% ALA), and a diet replacing ALA with oleic acid without walnuts (oleic acid replaces ALA diet; ORAD; 0.4% ALA). Fecal samples were collected following the run-in and study diets to assess gut microbiota with 16S rRNA sequencing and Qiime2 for amplicon sequence variant picking. Results: Subjects had elevated BMI (30 ± 1 kg/m2), blood pressure (121 ± 2/77 ± 1 mmHg), and LDL cholesterol (120 ± 5 mg/dL). Following the WD, Roseburia [relative abundance (RA) = 4.2%, linear discriminant analysis (LDA) = 4], Eubacterium eligensgroup (RA = 1.4%, LDA = 4), LachnospiraceaeUCG001 (RA = 1.2%, LDA = 3.2), Lachnospiraceae UCG004 (RA = 1.0%, LDA = 3), and Leuconostocaceae (RA = 0.03%, LDA = 2.8) were most abundant relative to taxa in the SWD (P ≤ 0.05 for all). The WD was also enriched in Gordonibacter relative to the WFMD. Roseburia (3.6%, LDA = 4) and Eubacterium eligensgroup (RA = 1.5%, LDA = 3.4) were abundant following the WFMD, and Clostridialesvadin BB60group (RA = 0.3%, LDA = 2) and gutmetagenome (RA = 0.2%, LDA = 2) were most abundant following the ORAD relative to the SWD (P ≤ 0.05 for all). Lachnospiraceae were inversely correlated with blood pressure and lipid/lipoprotein measurements following the WD. Conclusions: The results indicate similar enrichment of Roseburia following the WD and WFMD, which could be explained by the fatty acid composition. Gordonibacter enrichment and the inverse association between Lachnospiraceae and cardiovascular risk factors following the WD suggest that the gut microbiota may contribute to the health benefits of walnut consumption in adults at cardiovascular risk. This trial was registered at clinicaltrials.gov as NCT02210767.
Senevirathne, A., E. Neale, G. Peoples, L. Tapsell, 2019. Relationship between long‐chain omega‐3 polyunsaturated fatty acid intake and ankle brachial index, pulse wave velocity and resting heart rate in a sample of overweight adults: A secondary analysis of baseline data in the HealthTrack study. Nutr Diet. 76(1):95-103.
Aim: The present study aimed to explore the association between dietary long-chain omega-3 polyunsaturated fatty acid (LCn3PUFA) intake and cardiovascular risk indicators (ankle brachial index, resting heart rate and brachial-ankle pulse wave velocity) in a clinical sample of overweight and obese participants volunteering for a weight loss trial. Methods: This was a secondary analysis of baseline data from the HealthTrack study (n = 351). LCn3PUFA intake was calculated via a diet history and the association with ankle brachial index, resting heart rate and brachio-ankle pulse wave velocity was explored using linear regression after controlling for covariates. Results: LCn3PUFA intake was inversely associated with ankle brachial index (R(2) change = 0.021, F change (1, 339) = 8.864, P < 0.05) and resting heart rate (R(2) change = 0.014, F change (1, 342) = 5.337, P < 0.05) but not with brachio-ankle pulse wave velocity (R(2) change = 0.001, F change (1, 339) = 0.725, P > 0.05). Conclusions: In this clinical sample of overweight adults, LCn3PUFA consumption was significantly associated with a lower resting heart rate, adding to the current evidence on the potential benefits of LCn3PUFA consumption. It also supports the value of targeting a diet rich in this nutrient when planning future dietetic approaches. Relationships with ankle brachial index and pulse wave velocity require further investigation. Future research should assess the effect of changes in dietary LCn3PUFA intake on novel cardiovascular risk indicators.
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.
Gepner, Y., I. Shelef, O. Komy, N. Cohen, D. Schwarzfuchs, N. Bril, M. Rein, D. Serfaty, S. Kenigsbuch, H. Zelicha, A.Y. Meir, 2019. The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content. J Hepatol. 71(2):379-388.
Background & Aim: It is unclear if a reduction in hepatic fat content (HFC) is a major mediator of the cardiometabolic benefit of lifestyle intervention, and whether it has prognostic significance beyond the loss of visceral adipose tissue (VAT). In the present sub-study, we hypothesized that HFC loss in response to dietary interventions induces specific beneficial effects independently of VAT changes. Methods: In an 18-month weight-loss trial, 278 participants with abdominal obesity/dyslipidemia were randomized to low-fat (LF) or Mediterranean/low-carbohydrate (MED/LC + 28 g walnuts/day) diets with/without moderate physical activity. HFC and abdominal fat-depots were measured using magnetic resonance imaging at baseline, after 6 (sub-study, n = 158) and 18 months. Results: Of 278 participants (mean HFC 10.2% [range: 0.01%-50.4%]), the retention rate was 86.3%. The %HFC substantially decreased after 6 months (-6.6% absolute units [-41% relatively]) and 18 months (-4.0% absolute units [-29% relatively]; p <0.001 vs. baseline). Reductions of HFC were associated with decreases in VAT beyond weight loss. After controlling for VAT loss, decreased %HFC remained independently associated with reductions in serum gamma glutamyltransferase and alanine aminotransferase, circulating chemerin, and glycated hemoglobin (p <0.05). While the reduction in HFC was similar between physical activity groups, MED/LC induced a greater %HFC decrease (p = 0.036) and greater improvements in cardiometabolic risk parameters (p <0.05) than the LF diet, even after controlling for VAT changes. Yet, the greater improvements in cardiometabolic risk parameters induced by MED/LC were all markedly attenuated when controlling for HFC changes. Conclusions: %HFC is substantially reduced by diet-induced moderate weight loss and is more effectively reduced by the MED/LC diet than the LF diet, independently of VAT changes. The beneficial effects of the MED/LC diet on specific cardiometabolic parameters appear to be mediated more by decreases in %HFC than VAT loss. Lay Summary: High hepatic fat content is associated with metabolic syndrome, type 2 diabetes mellitus, and coronary heart disease. In the CENTRAL 18-month intervention trial, a Mediterranean/low-carbohydrate diet induced a greater decrease in hepatic fat content than a low-fat diet, conferring beneficial health effects that were beyond the favorable effects of visceral fat loss. ClinicalTrials.gov Identifier: NCT01530724.
Domènech, M., M. Serra-Mir, I. Roth, T. Freitas-Simoes, C. Valls-Pedret, M. Cofán, A. López, A. Sala-Vila, C. Calvo, S. Rajaram, J. Sabaté, 2019. Effect of a walnut diet on office and 24-hour ambulatory blood pressure in elderly individuals: findings From the WAHA randomized trial. Hypertension. 73(5):1049-1057.
Nut consumption lowers blood cholesterol and is associated with reduced cardiovascular disease, but effects on blood pressure (BP) are inconsistent. We assessed the 2-year effects of a walnut diet versus a control diet on office BP and 24-hours ambulatory BP in free-living elders participating in the Walnuts and Healthy Aging study, a randomized trial testing the effects of walnuts at ≈15% energy on age-related disorders. In a prespecified analysis, we enrolled 305 participants, of whom 236 (75%) completed the study (65% women; age, 69 years; 60% with mild hypertension). Walnuts were well tolerated, and compliance was >98%. Mean baseline office BP was 128/79 mm Hg. Adjusted changes from baseline in mean office systolic BP were −4.61 mm Hg (95% CI, −7.43 to −1.79 mm Hg) in the walnut group and −0.59 mm Hg (−3.38 to 2.21 mm Hg) in controls (P=0.051). Respective changes in mean systolic 24-hour ambulatory BP were −3.86 mm Hg (CI, −5.45 to −2.26 mm Hg) and −2.00 mm Hg (CI, −3.58 to −0.42 mm Hg; P=0.111). No changes in diastolic BP were observed. In participants in the upper tertile of baseline 24-hour ambulatory systolic BP (>125 mm Hg), mean 2-year systolic 24-hour BP was −8.5 mm Hg (CI, −12 to −5.0 mm Hg) in the walnut group and −2.5 mm Hg (CI,−6.3 to 1.3 mm Hg) in controls (P=0.034). During the trial, participants in the walnut group required less uptitration of antihypertensive medication and had better overall BP regulation than controls. Walnut consumption reduces systolic BP in elderly subjects, particularly in those with mild hypertension.
Borkowski, K., S.J. Yim, R.R. Holt, R.M. Hackman, C.L. Keen, J.W. Newman, G.C. Shearer, 2019. Walnuts change lipoprotein composition suppressing TNFa-stimulated cytokine production by diabetic adipocyte. J Nutr Biochem. 68:51-58.
Walnut consumption can provide both vascular and metabolic health benefits, and walnut-induced changes in lipoprotein particle chemical payloads may be responsible for these health benefits. To explore this possibility with a focus on metabolic health, this study investigated the impact of walnut consumption on lipoprotein lipid composition and changes in LDL anti-inflammatory properties, as reported by inflamed adipocyte. Hypercholesterolemic, postmenopausal females were treated with 40 g/day (i.e., 1.6 servings/day; n=15) of walnuts for 4 weeks. Fatty acids and their oxygenated metabolites, i.e., oxylipins, were quantified in isolated lipoproteins. Human primary adipocytes were exposed to LDL and TNFα-stimulated adipokine production was measured. Walnut treatment elevated α-linolenic acid and its epoxides in all lipoproteins and depleted mid-chain alcohols in VLDL and LDL, but not HDL. Walnuts also reduced TNFα-induced diabetic adipocyte production of IL-6 (−48%, P=.0006) and IL-8 (−30%, P=.01), changes inversely correlated with levels of α-linolenic acid-derived epoxides but not α-linolenic acid itself. In conclusion, modest walnut consumption can alter lipoprotein lipid profiles and enhance their ability to inhibit TNFα-dependent pro-inflammatory responses in human diabetic primary adipocytes. Moreover, this study suggests the oxylipins, rather than the parent fatty acids, mediate LDL action of adipocytes.
Williams, P.T., N. Bergeron, S. Chiu, R.M. Krauss, 2019. A randomized, controlled trial on the effects of almonds on lipoprotein response to a higher carbohydrate, lower fat diet in men and women with abdominal adiposity. Lipids in Health and Disease. 18: 83. doi: https://lipidworld.biomedcentral.com/track/pdf/10.1186/s12944-019-1025-4.
Background: Almonds have been shown to lower LDL cholesterol but there is limited information regarding their effects on the dyslipidemia characterized by increased levels of very low-density lipoproteins (VLDL) and small, dense low-density lipoprotein (LDL) particles that is associated with abdominal adiposity and high carbohydrate intake. The objective of the present study was to test whether substitution of almonds for other foods attenuates carbohydrate-induced increases in small, dense LDL in individuals with increased abdominal adiposity. Methods: This was a randomized cross-over study of three 3wk diets, separated by 2wk washouts: a higher carbohydrate (CHO) reference diet (CHOhigh), a higher-CHO diet with isocaloric substitution of 20% kcal (E) from almonds (CHOhigh + almonds), and a lower-CHO reference diet (CHOlow) in 9 men and 15 women who were overweight or obese. The two CHOhigh diets contained 50% carbohydrate, 15% protein, 35% fat (6% saturated, 21% monounsaturated, 8% polyunsaturated), while the CHOlow diet contained 25% carbohydrate, 28% protein, 47% fat (8% saturated, 28% monounsaturated, 8% polyunsaturated). Lipoprotein subfraction concentrations were measured by ion mobility. Results: Relative to the CHOlow diet: 1) the CHOhigh +almonds diet significantly increased small, dense LDLIIIa (mean difference ± SE: 28.6±10.4nmol/L, P=0.008), and reduced LDL-peak diameter (−1.7±0.6Å, P=0.008); 2) the CHOhigh diet significantly increased medium-sized LDLIIb (24.8±11.4nmol/L, P=0.04) and large VLDL (3.7±1.8 nmol/L, P=0.05). Relative to CHOlow, the effects of CHOhigh on LDLIIIa (17.7±10.6nmol/L) and LDL-peak diameter (−1.1±0.6Å) were consistent with those of CHOhigh + almonds, and the effects of CHOhigh +almonds on LDLIIb (21.0± 11.2nmol/L) and large VLDL (2.8±1.8nmol/L) were consistent with those of CHOhigh, but did not achieve statistical significance (P>0.05). None of the variables examined showed a significant difference between the CHOhigh + almonds and CHOhigh diets (P>0.05). Conclusion: Our analyses provided no evidence that deriving 20% E from almonds significantly modifies increases in levels of small, dense LDL or other plasma lipoprotein changes induced by a higher carbohydrate low saturated fat diet in individuals with increased abdominal adiposity.
Bowen, J., N.D. Luscombe-Marsh, W. Stonehouse, C. Tran, G.B. Rogers, N. Johnson, C.H. Thompson, G.D. Brinkworth, 2019. Effects of almond consumption on metabolic and liver function in overweight and obese adults with elevated fasting blood glucose: A randomized controlled trial. Clin. Nutr. ESPEN 30:10-18.
Background: Almonds are a rich source of bioactive components. This study examined the effects of daily almond consumption on glycaemic regulation, liver fat concentration and function, adiposity, systemic inflammation and cardiometabolic health. Methods: 76 adults with elevated risk of type 2 diabetes (T2D) or T2D (age: 60.7 ± 7.7 years, body mass index: 33.8 ± 5.6 kg/m2) were randomly assigned to daily consumption of either 2 servings of almonds (AS:56 g/day) or an isocaloric, higher carbohydrate biscuit snack (BS) for 8 weeks. Glycosylated haemoglobin (HbA1c), glycaemic variability (GV), liver fat, serum aminotransferases, body weight and composition, markers of cardio-metabolic risk and systemic inflammation were assessed at baseline and week 8. Results: No group differential effects were observed on HbA1c, GV, body weight and composition, liver fat and aminotransferases, cardio-metabolic health and inflammatory markers (all P > 0.05). For serum TC/HDL-C ratio a significant gender × treatment × time interaction occurred (P < 0.01), such that in women TC/HDL-C ratio was significantly reduced after AS compared to BS (-0.36 [0.26] mmol/L [n = 14] vs. -0.14 [0.32] mmol/L [n = 17]; P = 0.05), but not in men (P = 0.52). Conclusions: Compared to BS, AS consumed between meals did not substantially alter glycaemic regulation, liver fat or function, adiposity, and metabolic health and inflammatory markers. Serum TC/HDL-C ratio improved in women, but not in men with AS; but as this sub-analysis was not defined a priori the results should be interpreted with caution. Further research should examine the longer-term health effects of regular almond consumption and differential gender responses.
Tahir, F.N., M. Danyal, S.I.A. Shah, J.A. Qureshi, 2019. Lipid lowering effect of almonds (Prunus Dulcis) in healthy adults. Pakistan Journal of Medical and Health Sciences. 12(4):1356-1358.
Background: Almonds (Prunus dulcis) are low in saturated fats and cholesterol and high in unsaturated fatty acids. Almonds also contain high concentrations of other nutrients like vitamin E, plant sterols, phytochemicals and dietary fibers. Almonds are associated with a reduced risk of cardiovascular disorders (CVD) by having a potentially beneficial impact of on serum lipids due to their nutrient composition. Aim: To investigate the effect of regular almond consumption on the serum lipid profile of normolipidemic adults. Methods: In this non-randomized prospective study, 19 normolipidemic adults (10 males, 9 females) with an age range from 21 to 60 years consumed 50 grams of raw almonds for 30 days. Fasting blood samples were collected from each participant at baseline and on the 31st day for lipid profile analysis. Results: Marked decreases in serum total cholesterol level (p-value= 0.000) and serum low-density lipoprotein (LDL) level (p-value= 0.047) were observed from baseline values following almond treatment for a month. An increase in high density lipoprotein (HDL) level was also seen but it was not statistically significant (p-value=0.081). Conclusion: Regular intake of almonds can help maintain a normal lipid profile in healthy adults and reduce the risk of CVD. Almond consumption should be encouraged in the local healthy population for improved metabolic and cardiovascular health outcomes.
