Acute effects of diets rich in almonds and walnuts on endothelial function

Impact of a Mediterranean-Inspired Diet on Cardiovascular Disease Risk Factors: A Randomized Clinical Trial

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. This study focused on evaluating the impact of a Mediterranean-type diet combined with physical exercise on CVD risk factors of high-risk individuals. A randomized clinical trial (RCT) recruited individuals (≥50 years old) with no history of acute myocardial infarction, but with high CVD risk criteria according to the SCORE2/SCORE2 OP. Anthropometric and biochemical parameters were assessed at baseline and after 12 weeks of diet and exercise intervention. Participants were randomly assigned into 3 groups: no intervention group (Group 1a), physical exercise group (Group 1b), and physical exercise (±2 h/week) plus diet group (Group 2). Briefly, the dietary intervention was based on the principles of an isocaloric Mediterranean diet (MD), with seven main meals/week centered on plant-based foods (legumes and pulses). The combined effect of exercise and the diet showed significant decrease in WC (p = 0.002), BST (p < 0.001), visceral fat (p < 0.001), and TG (p = 0.029), compared with control groups. The intervention significantly increased legume intake (p < 0.001), as well as adherence to the MD, which associates with WC decrease (p = 0.024) and visceral fat (p = 0.017). A combined intervention of exercise and diet should be endorsed as an efficient modifier of cardiometabolic parameters.

The Chemical Composition and Health-Promoting Benefits of Vegetable Oils-A Review

With population and economic development increasing worldwide, the public is increasingly concerned with the health benefits and nutritional properties of vegetable oils (VOs). In this review, the chemical composition and health-promoting benefits of 39 kinds of VOs were selected and summarized using Web of Science TM as the main bibliographic databases. The characteristic chemical compositions were analyzed from fatty acid composition, tocols, phytosterols, squalene, carotenoids, phenolics, and phospholipids. Health benefits including antioxidant activity, prevention of cardiovascular disease (CVD), anti-inflammatory, anti-obesity, anti-cancer, diabetes treatment, and kidney and liver protection were examined according to the key components in representative VOs. Every type of vegetable oil has shown its own unique chemical composition with significant variation in each key component and thereby illustrated their own specific advantages and health effects. Therefore, different types of VOs can be selected to meet individual needs accordingly. For example, to prevent CVD, more unsaturated fatty acids and phytosterols should be supplied by consuming pomegranate seed oil, flaxseed oil, or rice bran oil, while coconut oil or perilla seed oil have higher contents of total phenolics and might be better choices for diabetics. Several oils such as olive oil, corn oil, cress oil, and rice bran oil were recommended for their abundant nutritional ingredients, but the intake of only one type of vegetable oil might have drawbacks. This review increases the comprehensive understanding of the correlation between health effects and the characteristic composition of VOs, and provides future trends towards their utilization for the general public's nutrition, balanced diet, and as a reference for disease prevention. Nevertheless, some VOs are in the early stages of research and lack enough reliable data and long-term or large consumption information of the effect on the human body, therefore further investigations will be needed for their health benefits.

Perspective: Challenges and Future Directions in Clinical Research with Nuts and Berries

Consumption of nuts and berries are considered part of a healthy eating pattern. Nuts and berries contain a complex nutrient profile consisting of essential vitamins and minerals, fiber, polyunsaturated fatty acids, and phenolics in quantities that improve physiological outcomes. The spectrum of health outcomes that may be impacted by the consumptions of nuts and berries includes cardiovascular, gut microbiome, and cognitive, among others. Recently, new insights regarding the bioactive compounds found in both nuts and berries have reinforced their role for use in precision nutrition efforts. However, challenges exist that can affect the generalizability of outcomes from clinical studies, including inconsistency in study designs, homogeneity of test populations, variability in test products and control foods, and assessing realistic portion sizes. Future research centered on precision nutrition and multi-omics technologies will yield new insights. These and other topics such as funding streams and perceived risk-of-bias were explored at an international nutrition conference focused on the role of nuts and berries in clinical nutrition. Successes, challenges, and future directions with these foods are presented here.

Pecan-enriched diet improves cholesterol profiles and enhances postprandial microvascular reactivity in older adults

Pecan-enriched diets have been linked to improved lipid metabolism; however, the impact of pecans on vascular health has yet to be examined. We hypothesized that 4 weeks of a pecan-enriched diet would improve fasting and postprandial blood lipids and vascular function compared with a nut-free diet. In this randomized control study, 44 older adults (59 ± 6 years) consumed 68 g of pecans/d (pecan; n = 21) or avoided all nuts (control; n = 23) for 4 weeks. At pre- and post-diet visits, fasting and postprandial blood lipids, macrovascular (by flow-mediated dilation), and microvascular (tissue saturation index reactive hyperemia [RH] kinetics by continuous-wave near-infrared spectroscopy) function were assessed. From the pre- to post-diet visit, there were greater reductions in fasting total cholesterol (pecan: -14 ± 4.0 vs control: -0.2 ± 5.4 mg/dL; P = .04), low-density lipoprotein (LDL) cholesterol (pecan: -15 ± 3.7 vs control: +1.9 ± 4.4 mg/dL; P = .01), non-high-density lipoprotein cholesterol (pecan: -15 ± 3.6 vs control: -0.5 ± 4.8 mg/dL; P = .02), LDL particle number (pecan: -126 ± 51 vs control: +43 ± 42 nmol/L; P = .01), and LDL medium (pecan: -34 ± 13 vs control: +16 ± 11 nmol/L; P < .01), for pecan vs control. Further, postprandial triglyceride was suppressed for pecan (P = .01) compared with control (P = .78). Postprandial RH slope (P = .04) and RH time to half (P = .004) was different by group, driven by improvements in pecan vs control. However, fasting macro- and microvascular function was unaffected. Daily pecan consumption for 4 weeks improved fasting and postprandial blood lipids and microvascular reactivity in older adults. Because changes in microvascular function typically precipitate macrovascular changes, long-term pecan consumption may improve vascular health and reduce risk for cardiovascular events. This trial was registered at clinicaltrials.gov (NCT04385537).

The effect of camelina oil on vascular function in essential hypertensive patients with metabolic syndrome: a randomized, placebo-controlled, double-blind study

BACKGROUND

The effects of a dietary supplementation with the vegetable ω-3 α-linolenic acid (ALA) on cardiovascular homeostasis are unclear. In this context, it would be interesting to assess the effects of camelina oil.

OBJECTIVE

This study aimed to assess the cardiovascular and metabolic effects of camelina oil in hypertensive patients with metabolic syndrome.

METHODS

In a double-blind, placebo-controlled randomized study, treated essential hypertensive patients with metabolic syndrome received, during 6 mo, either cyclodextrin-complexed camelina oil containing ≈ 1.5 g ALA/d (n = 40) or an isocaloric placebo (n = 41), consisting of the same quantity of cyclodextrins and wheat starch. Anthropometric data, plasma lipids, glycemia, insulinemia, creatininemia, TBARs, high-sensitivity C-reactive protein, and n-3, n-6, and n-9 fatty acids in erythrocyte membranes were measured. Peripheral and central blood pressures, arterial stiffness, carotid intima-media thickness, and brachial artery endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent dilatation were assessed.

RESULTS

Compared with placebo, camelina oil increased ALA (mean ± SD: 0 ± 0.04 compared with 0.08 ± 0.06%, P <0.001), its elongation product EPA (0 ± 0.5 compared with 0.16 ± 0.65%, P <0.05), and the n-9 gondoic acid (GA; 0 ± 0.04 compared with 0.08 ± 0.04%, P <0.001). No between-group difference was observed for cardiovascular parameters. However, changes in FMD were associated with the magnitude of changes in EPA (r = 0.26, P = 0.03). Compared with placebo, camelina oil increased fasting glycemia (-0.2 ± 0.6 compared with 0.3 ± 0.5 mmol/L, P <0.001) and HOMA-IR index (-0.8 ± 2.5 compared with 0.5 ± 0.9, P <0.01), without affecting plasma lipids, or inflammatory and oxidative stress markers. Changes in HOMA-IR index were correlated with the magnitude of changes in GA (r = 0.32, P <0.01). Nutritional intake remained similar between groups.

CONCLUSION

ALA supplementation with camelina oil did not improve vascular function but adversely affected glucose metabolism in hypertensive patients with metabolic syndrome. Whether this adverse effect on insulin sensitivity is related to GA enrichment, remains to be elucidated.

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

BACKGROUND

Walnuts contain nutrients that are associated with improved cognitive health. To our knowledge, no review has systematically examined the effects of walnuts on cognitive function and risk for cognitive decline.

OBJECTIVE

To conduct a systematic review and meta-analysis evaluating the effects of walnut intake on cognition-related outcomes and risk-factors for cognitive decline in adults.

METHODS

Medline®, Commonwealth Agricultural Bureau, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and observational studies published until April 2020 on walnut intake, cognition (e.g. cognitive function, stroke, and mood), and selected risk factors for cognitive decline (e.g. glucose homeostasis and inflammation). Risk-of-bias and strength-of-evidence assessments were conducted using standard validated tools. Random-effects meta-analyses were conducted when ≥3 studies reported quantitative data for each outcome.

RESULTS

32 RCT and 7 observational study publications were included. Meta-analysis of cognition-related outcomes could not be conducted due to heterogeneity of tests. None of the 5 cognition RCTs found significant effects of walnuts on overall cognition, although 3 studies found improvements on subdomains and/or subgroups. All 7 observational studies found significant associations and a dose-response relationship between walnut intake and cognition-related outcomes. Meta-analyses of 27 RCTs reporting glucose homeostasis and inflammation outcomes, selected risk factors for cognitive decline, did not show significant effects of walnut intake.

CONCLUSIONS

Due to the non-uniformity of tests for cognition-related outcomes, definitive conclusions regarding the effect of walnut consumption on cognition could not be reached. Additionally, evidence does not show associations between walnut intake and glucose homeostasis or inflammation, cognitive decline risk-factors. High-quality studies with standardized measures are needed to clarify the role of walnuts in cognitive health.KEY MESSAGESThis is a systematic review and meta-analysis of 5 randomized clinical trials and 7 observational study articles of the impact of walnut intake on cognition decline and 27 randomized clinical trials of the effect of walnut intake on risk factors for cognitive decline including glucose homeostasis and inflammation.The non-uniformity of tests performed to measure cognitive function in the various studies did not allow for a meta-analysis of these studies. A definitive conclusion could therefore not be reached regarding the effect of walnut intake on cognitive decline.The evidence available does not show an association between walnut intake and glucose homeostasis or inflammation.

Effect of Almond Consumption on Metabolic Risk Factors-Glucose Metabolism, Hyperinsulinemia, Selected Markers of Inflammation: A Randomized Controlled Trial in Adolescents and Young Adults

A large percentage of the Indian population has diabetes or is at risk of pre-diabetes. Almond consumption has shown benefits on cardiometabolic risk factors in adults. This study explored the effect of almond consumption on determinants of metabolic dysfunction—blood glucose, lipids, insulin and selected inflammatory markers in adolescents and young adults aged 16–25 years from Mumbai city. This randomized controlled trial was conducted for a period of 90 days on individuals with impaired levels of fasting glucose levels between 100–125 mg/dL (5.6–6.9 mmol/L) and 2-h post-glucose value 140–199 mg/dL (7.8–11.0 mmol/L) and/or fasting insulin (≥15 mIU/ml)/stimulated insulin (≥80 mIU/ml). Of 1,313 individuals screened, 421 met the inclusion criteria, of which 275 consented to participate and 219 completed the trial. The trial was registered with Clinical Trials Registry India (CTRI) CTRI/2018/02/011927. The almonds group (n = 107) consumed 56 g almonds daily, the control group (n = 112) was provided an iso-caloric cereal-pulse based snack. At baseline and endline, blood glucose, insulin, HbA₁c, LDL-c, HDL-c, total and ox-cholesterol, triglycerides, hs-CRP, IL-6, TNF-α, adiponectin, leptin were measured and HOMA-IR and FG:FI ratios were calculated. Dietary intakes were assessed. The anthropometric measurements, biochemical markers as well as macronutrient intakes did not differ significantly between the two groups at baseline. Almond consumption significantly decreased HbA₁c, total cholesterol and LDL-c. Stimulated insulin decreased post-intervention in both groups, but the decrease was greater in the almonds group. Fasting glucose was reduced post intervention in the controls with no change in the almonds group. FG:FI ratio decreased in the almonds group. TNF-α and IL-6 decreased in the almonds group, while it increased in the control group. Our results showed that almonds reduced HbA1c, LDL-c and total cholesterol levels in just 12 weeks of consumption in these adolescents and young adults who were at risk for developing diabetes. Almonds can be considered as part of food-based strategies for preventing pre-diabetes.

Clinical Trial Registration:ClinicalTrials.gov, identifier: CTRI/2018/02/011927.

A Comprehensive Review of Almond Clinical Trials on Weight Measures, Metabolic Health Biomarkers and Outcomes, and the Gut Microbiota

This comprehensive narrative review of 64 randomized controlled trials (RCTs) and 14 systematic reviews and/or meta-analyses provides an in-depth analysis of the effect of almonds on weight measures, metabolic health biomarkers and outcomes, and the colonic microbiota, with extensive use of figures and tables. Almonds are a higher energy-dense (ED) food that acts like a lower ED food when consumed. Recent systematic reviews and meta-analyses of nut RCTs showed that almonds were the only nut that had a small but significant decrease in both mean body mass and fat mass, compared to control diets. The biological mechanisms for almond weight control include enhanced displacement of other foods, decreased macronutrient bioavailability for a lower net metabolizable energy (ME), upregulation of acute signals for reduced hunger, and elevated satiety and increased resting energy expenditure. The intake of 42.5 g/day of almonds significantly lowered low-density lipoprotein cholesterol (LDL-C), 10-year Framingham estimated coronary heart disease (CHD) risk and associated cardiovascular disease (CVD) medical expenditures. Diastolic blood pressure (BP) was modestly but significantly lowered when almonds were consumed at >42.5 g/day or for >6 weeks. Recent RCTs suggest possible emerging health benefits for almonds such as enhanced cognitive performance, improved heart rate variability under mental stress, and reduced rate of facial skin aging from exposure to ultraviolet (UV) B radiation. Eight RCTs show that almonds can support colonic microbiota health by promoting microflora richness and diversity, increasing the ratio of symbiotic to pathogenic microflora, and concentrations of health-promoting colonic bioactives. Almonds are a premier healthy snack for precision nutrition diet plans.

Beneficial effect of walnuts on vascular tone is associated with Akt signalling, voltage-dependent calcium channel LTCC and ATP-sensitive potassium channel Kv1.2

Consumption of walnuts is beneficial for cardiovascular health. To study walnut effects on proteins involved in vascular tone regulation, control and fructose-fed rats were subjected to walnut diet for 6 weeks. In contrast with increased energy intake and body mass gain, aortic protein level of L-type calcium channel alpha subunit was decreased and the level of SUR2B subunit of ATP-sensitive K + channel was increased in healthy rats subjected to walnuts, together with improved Akt phosphorylation. Upon the walnut diet in rats subjected to fructose overload, the rise in energy intake and body mass gain, was followed by an increase in blood insulin. Although SUR2B level was elevated, the level of sodium-calcium exchanger NCX1 and inducible nitric oxide synthase were reduced and increased, respectively. In summary, walnut consumption was accompanied with moderate beneficial vascular effect in healthy rats, while an effect of walnut in rats with metabolic disturbances was rather controversial.

Effect of Prunus dulcis and Salvia hispenica in the management of polycystic ovary syndrome in Wistar rats

OBJECTIVE

Research has shown that polycystic ovary syndrome (PCOS) is a common cause of infertility in women. The drugs used to treat PCOS tend to manage the symptoms rather than cure the disease. Furthermore, these drugs have severe side-effects and influence the quality of life for the patients. There is therefore a need for natural medicine that can effectively treat PCOS without side-effects.

METHOD

PCOS was induced in adult female Wistar rats by daily oral administration of letrozole (1 mg/kg) for 21 days. From day 22 until the end of the experiment (day 36), these rats were given a daily oral dose of either Prunus dulcis (walnut) or Salvia hispenica (chia seed) alone, or in combination. Animals were subsequently examined for morphological, biochemical, and histopathological changes.

RESULT

When compared with the control and standard groups, rats who had consumed P. dulcis and S. hispenica, either as individual agents or in combination, had significantly lower body and ovarian weights, and hormone concentrations were maintained at healthy levels. The presence of polyphenolic compounds in these substances induced ovulation in the PCOS model animals.

CONCLUSION

This study demonstrated that animals fed with P. dulcis and S. hispenica either individually or in combination were able to overcome infertility. Hormone levels and metabolism were restored in these animals. Therefore, P. dulcis and S. hispenica can be used as therapeutic agents to treat patients who are infertile due to suboptimal oocyte competence and anovulation.

Biochemistry of blood platelet activation and the beneficial role of plant oils in cardiovascular diseases

The main function of blood platelets is to form hemostatic plugs and enable thrombosis. These properties, however, can be greatly influenced by dietary components which may inhibit certain steps of platelet activation, including platelet aggregation. Such inhibition can play a role in the prophylaxis and treatment of cardiovascular diseases associated with blood platelet hyperactivation. In fact, plant and fish oils have been identified and specifically used for this purpose. Numerous in vivo and in vitro experiments have explored the potential use of these oils to inhibit platelet activation as well as their role in reducing oxidative stress and blood pressure, and lowering triglyceride and cholesterol. This chapter presents and compares the anti-platelet effects of fish and plant oils and their constituents, especially fatty acids. Studies on healthy subjects and patients with various cardiovascular diseases are also examined. Findings indicate that both fish and plant oils contain protective components with anti-platelet activity having clearly defined mechanisms of action. Although both are excellent sources of omega fatty acids and vitamins, plant oils contain components with cardioprotective benefit in hypercholesterolemics, i.e., phytosterols. Plant oils may hence play a key role in strategies for preventing and treating cardiovascular diseases associated with platelet hyperactivation. Further studies are clearly needed to determine the precise dose of these components needed for effective prophylaxis and treatment.

The Physiological Effect of n-3 Polyunsaturated Fatty Acids (n-3 PUFAs) Intake and Exercise on Hemorheology, Microvascular Function, and Physical Performance in Health and Cardiovascular Diseases; Is There an Interaction of Exercise and Dietary n-3 PUFA Intake?

Physical activity has a beneficial effect on systemic hemodynamics, physical strength, and cardiac function in cardiovascular (CV) patients. Potential beneficial effects of dietary intake of n-3 polyunsaturated fatty acids (n-3 PUFAs), such as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid on hemorheology, vascular function, inflammation and potential to improve physical performance as well as other CV parameters are currently investigated. Recent meta-analysis suggests no effect of n-3 PUFA supplementation on CV function and outcomes of CV diseases. On the other hand, some studies support beneficial effects of n-3 PUFAs dietary intake on CV and muscular system, as well as on immune responses in healthy and in CV patients. Furthermore, the interaction of exercise and dietary n-3 PUFA intake is understudied. Supplementation of n-3 PUFAs has been shown to have antithrombotic effects (by decreasing blood viscosity, decreasing coagulation factor and PAI-1 levels and platelet aggregation/reactivity, enhancing fibrinolysis, but without effects on erythrocyte deformability). They decrease inflammation by decreasing IL-6, MCP-1, TNFα and hsCRP levels, expression of endothelial cell adhesion molecules and significantly affect blood composition of fatty acids. Treatment with n-3 PUFAs enhances brachial artery blood flow and conductance during exercise and enhances microvascular post-occlusive hyperemic response in healthy humans, however, the effects are unknown in cardiovascular patients. Supplementation of n-3 PUFAs may improve anaerobic endurance and may modulate oxygen consumption during intense exercise, may increase metabolic capacity, enhance endurance capacity delaying the onset of fatigue, and improving muscle hypertrophy and neuromuscular function in humans and animal models. In addition, n-3 PUFAs have anti-inflammatory and anti-nociceptive effects and may attenuate delayed-onset muscle soreness and muscle stiffness, and preserve joint mobility. On the other hand, effects of n-3 PUFAs were variably observed in men and women and they vary depending on dietary protocol, type of supplementation and type of sports activity undertaken, both in healthy and cardiovascular patients. In this review we will discuss the physiological effects of n-3 PUFA intake and exercise on hemorheology, microvascular function, immunomodulation and inflammation and physical performance in healthy persons and in cardiovascular diseases; elucidating if there is an interaction of exercise and diet.

Health Benefits of Nut Consumption in Middle-Aged and Elderly Population

Aging is considered the major risk factor for most chronic disorders. Oxidative stress and chronic inflammation are two major contributors for cellular senescence, downregulation of stress response pathways with a decrease of protective cellular activity and accumulation of cellular damage, leading in time to age-related diseases. This review investigated the most recent clinical trials and cohort studies published in the last ten years, which presented the influence of tree nut and peanut antioxidant diets in preventing or delaying age-related diseases in middle-aged and elderly subjects (≥55 years old). Tree nut and peanut ingestion has the possibility to influence blood lipid count, biochemical and anthropometric parameters, endothelial function and inflammatory biomarkers, thereby positively affecting cardiometabolic morbidity and mortality, cancers, and cognitive disorders, mainly through the nuts' healthy lipid profile and antioxidant and anti-inflammatory mechanisms of actions. Clinical evidence and scientific findings demonstrate the importance of diets characterized by a high intake of nuts and emphasize their potential in preventing age-related diseases, validating the addition of tree nuts and peanuts in the diet of older adults. Therefore, increased consumption of bioactive antioxidant compounds from nuts clearly impacts many risk factors related to aging and can extend health span and lifespan.