The body of evidence about nuts and heart health continues to grow, with new local and international research papers regularly published.

Large population studies

All found inverse associations between nut consumption and the risk of coronary heart disease.

• A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. (1992)
• Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. (1998).
• Frequent nut intake and risk of death from coronary heart disease and all causes in postmenopausal women: the Iowa Women’s Health Study. (2001).
• Nut consumption and decreased risk of sudden cardiac death in the Physicians’ Health Study. (2002).

Key studies: Systematic literature reviews and meta-analyses

Effect of nut consumption on blood lipids: An updated systematic review and meta-analysis of randomized controlled trials. (Nishi et al, 2024).
This research considered the findings of 113 previously-published randomised controlled trials, involving 8,060 adults, to assess the effect on blood lipids of consuming (a median of) 45.5g/day of nuts, compared to control (no nuts). Nut consumption resulted in moderate reductions in total cholesterol (TC) (mean difference, -0.14 mmol/L), and LDL-cholesterol (-0.12 mmol/L), with small reductions in triglycerides (-0.05 mmol/L), TC:HDL-cholesterol (-0.11), LDL-cholesterol:HDL-cholesterol (-0.19), and apolipoprotein B (-0.04 g/L). There was no significant impact on HDL-cholesterol or other measures.

Tree nut and peanut consumption and risk of cardiovascular disease: A systematic review and meta-analysis of randomised controlled trials. (Houston et al, 2023)
A total of 153 articles, describing 139 randomised controlled trials, were included in this systematic review, with 129 studies in the meta-analysis. It found a significant decrease in total cholesterol, LDL cholesterol, triglycerides, total cholesterol: HDL cholesterol, LDL cholesterol: HDL cholesterol, and Apolipoprotein B, following nut consumption. The researchers say this review provides evidence into a combined effect of tree nuts and peanuts on a range of cardiovascular risk biomarkers. And this, in turn, creates an overall cardiovascular disease risk reduction.

Can different types of tree nuts and peanuts induce varied effects on specific blood lipid parameters? A systematic review and network meta-analysis. (Martinez-Ortaga et al, 2023).
This study analysed the findings of 76 randomised trials to determine the effects of six types of nuts (pistachios, almond, walnuts, cashews, hazelnuts, peanuts) on specific blood lipid parameters (total cholesterol, LDL-cholesterol, triglycerides, and HDL-cholesterol). Every type of nut analyzed had a significant positive impact on some parameters, and specific nut types had enhanced advantages for certain blood lipids. The authors suggest their results endorse the use of personalized nutritional strategies to address and prevent dyslipidemia.

Effects of nut consumption on blood lipids and lipoproteins: A comprehensive literature update. (Guasch-Ferré et al, 2023)
This comprehensive narrative overview, of 19 systematic reviews and meta-analyses of randomised controlled trials, outlines current knowledge on the effects of nuts on blood lipids and lipoproteins. Among the findings was a consistent beneficial effect of most nuts (total nuts and specific nut types, including walnuts, almonds, cashews, peanuts, and pistachios), across meta-analyses in reducing total cholesterol (mean difference: −0.09 to −0.28 mmol/L), LDL-cholesterol (mean difference: −0.09 to −0.26 mmol/L), and triglycerides (mean difference: −0.05 to −0.17 mmol/L).

Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: A systematic review and meta-analysis. (Arnesen et al, 2023)
This systematic review included 42 papers from cohort studies (28 unique cohorts, 1,890,573 participants) and 18 (≥12-week) randomized controlled trials (2,266 participants). Among the findings, consumption of total nuts/seeds was associated with lower risk of CVD and CHD, in a dose dependent manner. Smaller or unclear associations were found for risk of stroke and type 2 diabetes. Nuts modestly lowered blood lipids (total and LDL-cholesterol), but had no effect on blood pressure in randomized controlled trials. The reviewers say the favourable associations with CVD and CHD are probably causal.

Nuts and cardiovascular disease outcomes: A review of the evidence and future directions. (Glenn et al, 2023)
This narrative review summarises recommendations for nuts by clinical practice guidelines and governmental organisations, epidemiological evidence for nuts and cardiovascular disease (CVD) outcomes, nut-containing dietary patterns, potential mechanisms of nuts and CVD risk reduction, and future research directions. Although there are still some uncertainties around nuts and CVD prevention which require further research, there is substantial evidence to support that consuming nuts will have a positive impact on primary and secondary prevention of CVD.

Effects of nut consumption on cardiovascular risk factors and coronary heart diseases. (Zibaeenezhad et al, 2022).
This paper summarises the role of regular nut consumption in protecting against cardiovascular risk factors and coronary artery disease. The researchers outline the possible underlying mechanisms through which nuts are protective, including by modifying lipid and glucose metabolism, reducing inflammation, improving endothelial function, weight control and reducing oxidative stress. They say further human clinical trials are needed to find the exact and most effective pathways by which nuts prevent or reduce cardiovascular risk factors.

The effect of walnut intake on lipids: A systematic review and meta-analysis of randomized controlled trials. (Alshahrani et al, 2022).
This review considered 13 randomised controlled trials which assessed the impact of walnut intake on blood lipids. Walnut intake was associated with significant reductions in total cholesterol (weighted mean difference (WMD): −0.48mmol/L), LDL-cholesterol (WMD: −0.32mmol/L), and triglycerides (WMD: −0.61mmol/L). Walnut consumption did not impact HDL-cholesterol. Subgroup analysis showed that those with comorbidities, or with overweight/obesity, had more lipid improvement.

Effect of peanut consumption on cardiovascular risk factors: A randomized clinical trial and meta-analysis. (Parilli-Moser et al, 2022).
This research had two parts: a six-month parallel randomised controlled trial (the ARISTOTLE study) involving 63 healthy participants, and also a meta-analysis of 11 clinical trials. In the ARISTOTLE study, lower total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios were found in the skin-roasted peanuts group compared to the control group. The meta-analysis found peanut consumption was associated with a decrease in triglycerides and that healthy consumers had lower total cholesterol and LDL-cholesterol/HDL-cholesterol ratios, compared to control groups.

Effects of nut consumption on the blood lipid profile: A meta-analysis of randomized controlled trials. (Gunathilake et al, 2022).
This meta-analysis showed that nut consumption had no significant effect on blood total cholesterol (TC), LDL-cholesterol, HDL cholesterol (HDL-C), and triglycerides. However, it found pistachio consumption significantly reduced TC, and cashew consumption significantly increased HDL-C, compared with that in controls. The researchers note a consistent inverse relationship between nut consumption and coronary heart disease outcomes.
NOTE: An ‘expression of concern’ on this paper has since been published (November 2022).

The effect of nuts consumption on circulating oxidized low-density lipoproteins: A systematic review and meta-analysis of randomized controlled trials. (Abbasifard, 2023)
This first-of-its-kind systematic review and meta-analysis, of 15 randomised controlled trials (RCTs) involving 997 people, found nut consumption significantly reduced serum levels of oxidized low-density lipoproteins (ox-LDL). The RCTs included almonds, walnuts, Brazil nuts, pistachios, hazelnuts, pine nuts, and mixed nuts. Subgroup analyses showed pistachios had a particularly strong effect on decreasing ox-LDL. The researchers suggest the reduction in ox-LDL with nut consumption might assist in the prevention and/or progression of cardiovascular disease.

Effect of nuts on components of metabolic syndrome in healthy adults with overweight/obesity: A systematic review and meta-analysis. (Eslami et al, 2022).
This systematic review and meta-analysis, of 10 randomised controlled trials, sums up the evidence to date on the impact of nut consumption on components of metabolic syndrome, in healthy adults with overweight/obesity. It found incorporating nuts into the diet significantly reduced serum triglycerides and LDL-cholesterol. Nuts did not affect serum total cholesterol, HDL-cholesterol, glycaemic markers, and blood pressure.

Long-term consumption of ten food groups and cardiovascular mortality: A systematic review and dose response meta-analysis of prospective cohort studies. (Bhandari et al, 2022).
This review, of 22 studies with a total of 70,273 participants, assessed the relationship between long-term consumption of 10 food groups and cardiovascular mortality. Among the findings, a long-term high intake of fruits and vegetables, nuts, and whole grains were significantly linked with a 28%, 27% and 13% (respectively) lower risk of cardiovascular mortality, compared to the lowest intake of each. The researchers noted that more data on the long-term effects of legumes on cardiovascular mortality is needed.

Lifestyle changes to prevent cardio- and cerebrovascular disease at midlife: A systematic review. (Zyriax et al, 2022).
This systematic review of meta-analyses considered the evidence of lifestyle patterns, including nutrition, physical activity, smoking, and weight, in the incidence and mortality of cardio- and cerebrovascular diseases. Among the outcomes, the results affirm that high adherence to plant-based diets, including components such as fruits, vegetables, legumes, whole grains, low-fat dairy, olive oil, and nuts, results in lower risk of vascular outcomes in a dose-dependent manner.

Dietary recommendations for prevention of atherosclerosis. (Riccardi et al, 2021)
This review found consistent evidence that, for the healthy adult population, low consumption of salt and foods of animal origin, and increased intake of plant-based foods – whole grains, fruits, vegetables, legumes, and nuts – are linked with reduced atherosclerosis risk. Specific to nuts, the researchers say: ‘The evidence of an inverse relationship between habitual nut consumption and the risk of CHD incidence and mortality is very consistent’, and they support the daily consumption of a handful of nuts.

Effect of walnut consumption on markers of endothelial function in adults: A systematic review and meta-analysis of randomized controlled trials. (Hsu et al, 2024).
This research collated the findings of six trials (involving 250 participants) on the effect of walnut consumption on endothelial function. Walnut intake significantly increased flow-mediated dilation (FMD), but did not impact the other markers assessed – intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and stimulus-adjusted response measure (SARM). The authors suggest walnuts may reduce cardiovascular disease risk by improving FMD. But they say further studies are needed into the effect of walnut intake on endothelial function.

Consumption of pistachio nuts positively affects lipid profiles: A systematic review and meta-analysis of randomized controlled trials. (Hadi et al, 2021).
Twelve randomised controlled trials were included in this systematic review and meta-analysis which looked into the effect of pistachios on lipid profiles. It found consuming pistachio nuts reduced total cholesterol (WMD: −7.48 mg/dL), LDL-cholesterol (WMD: −3.82 mg/dL) and triglyceride (WMD: −11.19 mg/dL) levels, while HDL-cholesterol levels did not change. The researchers concluded that consuming pistachios may improve lipid profiles in adults and may be protective against cardiometabolic diseases.

Effect of tree nuts consumption on serum lipid profile in hyperlipidemic individuals: A systematic review (Altamimi et al, 2020).
This new systematic review, of 29 intervention studies, offers more evidence that tree nut consumption can improve serum lipid levels – this time, in adults with hyperlipidaemia. It found different nuts favourably impact different lipid parameters. But across the board, all nuts effectively raised HDL-cholesterol levels. Study intervention periods varied from three weeks to 12 months, and nut ‘doses’ ranged from 15 to 126g a day.

Does nut consumption reduce mortality and/or risk of cardiometabolic disease? An updated review based on meta-analyses. (Kim et al, 2019).
Nut consumption appears to exert a protective effect on cardiometabolic disease, possibly through improved concentrations of fasting glucose, total cholesterol, and LDL-C.

Nut consumption and incidence of cardiovascular diseases and cardiovascular disease mortality: A meta-analysis of prospective cohort studies. (Becarra-Tomas et al, 2019).
A systematic review and meta-analysis of all published studies concludes that the consumption of nuts helps reduce the risk of incidence of cardiovascular disease and mortality.

Almond consumption and risk factors for cardiovascular disease: A systematic review and meta-analysis of randomized controlled trials. (Lee-Bravatti et al, 2019).
A systematic review and meta-analysis of RCTs showed that almonds significantly reduce total cholesterol, LDL cholesterol, body weight and apolipoprotein B.

Portfolio dietary pattern and cardiovascular disease: A systematic review and meta-analysis of controlled trials. (Chiavaroli et al, 2018).
Dietary portfolio is a plant based dietary pattern, as a ‘portfolio’ of 4 cholesterol lowering foods, incl 42g nuts (tree nuts or peanuts). Study revealed significantly lowered LDL cholesterol by 17%, which is beyond that which is seen with the NCEP Step II diet alone.

Effect of nut consumption on vascular endothelial function: A systematic review and meta-analysis of randomized controlled trials. (Xiao et al 2018).
Nut consumption significantly improved endothelial function. However, the beneficial effect was limited to walnuts. More studies examining the effect of other nuts on endothelial function are needed in the future.

Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: A systematic review and dose-response meta-analysis of prospective studies. (Aune et al, 2016).
Nut consumption may reduce the risk of coronary heart disease, stroke, cardiovascular disease, total cancer, and all-cause mortality, and possibly mortality from diabetes, respiratory disease, and infectious disease. In the dose–response analysis there was a 29% reduction in the relative risk of CHD and a 21% reduction in the relative risk of CVD for a one serving per day increase in nut intake (one serving = 28 grams).

The effect of nut consumption on markers of inflammation and endothelial function: A systematic review and meta-analysis of randomised controlled trials. (Neale et al, 2017).
This paper suggests that nut consumption, particularly walnuts, has favourable effects on flow-mediated dilation – a measure of endothelial function that may be an important predictor of cardiovascular risk – but that nuts did not affect markers of inflammation.

A systematic review and meta-analysis of nut consumption and incident risk of CVD and all-cause mortality. (Mayhew et al, 2016).
In conclusion, we found that higher nut consumption is associated with a lower risk of all-cause mortality, total CVD, CVD mortality, total CHD, CHD mortality and sudden cardiac death.

Nut consumption on all-cause, cardiovascular, and cancer mortality risk: A systematic review and meta-analysis of epidemiologic studies. (Grosso et al, 2015).
Nut consumption is associated with lower risk of all-cause, CVD, and cancer mortality, but the presence of confounding factors should be taken into account when considering such findings.

Relationship of tree nut, peanut and peanut butter intake with total and cause-specific mortality: A cohort study and meta-analysis. (van den Brandt et al, 2015).
Total nut intake was related to lower overall and cause-specific mortality (cancer, diabetes, cardiovascular, respiratory, neurodegenerative diseases, other causes) in men and women. Nut intake was related to lower overall and cause-specific mortality, with evidence for nonlinear dose-response relationships. Peanut butter was not related to mortality.

Nut consumption and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: A systematic review and meta-analysis. (Luo et al, 2014).
Our meta-analysis indicates that nut intake is inversely associated with IHD, overall CVD, and all-cause mortality but not significantly associated with diabetes and stroke. The inverse association between the consumption of nuts and diabetes was attenuated after adjustment for body mass index. These findings support recommendations to include nuts as part of a healthy dietary pattern for the prevention of chronic diseases.

Other evidence

Planetary health diet and cardiovascular disease: Results from three large prospective cohort studies in the USA. (Sawicki et al, 2024).
This study used data from three large cohorts of men and women in the US, who were free of cardiovascular disease at baseline. It found that eating more in line with the Planetary Health Diet (PHD), as measured by a higher PHD index score, was associated with a lower risk of cardiovascular disease. Similarly, a higher score was associated with a lower risk of coronary heart disease, overall stroke, and ischaemic stroke. The findings support the PHD as a promising strategy to promote both human and planetary health.

Association between planetary health diet and cardiovascular disease: A prospective study from the UK Biobank. (Sotos-Prieto et al, 2024).
This large prospective cohort study involved 118,469 middle-aged and older British adults (aged 40–69 years), who were free of cardiovascular disease (CVD) at the start of the study. They were tracked over a median of 9.4 years. It found higher adherence to the Planetary Health Diet (PHD) was linked with a lower risk of CVD. Specifically, the highest PHD index score (that is, the best adherence to the diet) was associated with a 14% lower risk of CVD, a 12% lower risk of myocardial infarction, and a 18% lower risk of stroke, compared with the lowest quintile of adherence.

Impact of dietary risk on global ischemic heart disease: Findings from 1990–2019. (Rostami et al, 2024).
This research used data from the Global Burden of Disease study to determine how dietary risks impact ischemic heart disease (IHD), which accounts for half of the CVD-related deaths worldwide. Among the findings, deaths and disability-adjusted life years (DALYs) in 2019 were lower than in 1990. The most deaths and DALYs of IHD attributable to dietary risks occurred in the low-middle socio-demographic index (SDI), in 2019. In countries with low and low-middle SDI, the greatest dietary risk factors were a diet low in fibre, fruit, nuts and seeds, PUFA, seafood omega-3 fatty acids, vegetable, and whole grain.

Plant and animal fat intake and overall and cardiovascular disease mortality (Zhao et al, 2024).
In this cohort study of 407,531 participants, with 24 years of follow-up and nearly 190 000 deaths, greater plant fat intake was associated with lower overall and cardiovascular disease (CVD) mortality, independent of other important mortality risk factors. Replacement of 5% energy from animal fat with 5% energy from plant fat, particularly fat from grains or vegetable oils, was associated with a lower risk for mortality: 4% to 24% reduction in overall mortality, and 5% to 30% reduction in CVD mortality.

Lipidome changes due to improved dietary fat quality inform cardiometabolic risk reduction and precision nutrition. (Eichelmann et al, 2024).
This 16-week dietary intervention study involved 113 participants, with one group consuming a diet high in saturated animal fats and the other a diet rich in unsaturated plant-based fats. The effects on blood lipids were summarised into a multi-lipid score (MLS), with a high score indicating a healthier blood fat profile. It showed that a high intake of unsaturated plant fats and low intake of saturated animal fats can help achieve positive MLS levels. In addition, participants with a higher MLS had a significantly reduced risk of cardiometabolic diseases.

The effect of diet on cardiovascular disease and lipid and lipoprotein levels. (Feingold et al, 2024).
This published book excerpt sums up the evidence to date on the effect of diet on cardiovascular disease (CVD). It says observational studies have found fruits, vegetables, beans/legumes, nuts/seeds, whole grains, fish, yogurt, fiber, seafood omega-3 fatty acids, and polyunsaturated fats to be linked with a decreased risk of CVD. While unprocessed red meats, processed meats, sugar-sweetened beverages, high glycemic load carbohydrates, and trans-fats are associated with an increased risk. And randomized trials have shown that a Mediterranean diet reduces CVD.

The cardioprotective properties of selected nuts: Their functional ingredients and molecular mechanisms. (Olas, 2024).
This paper provides an overview of the research to date on the role of nuts (mixed nuts, and select nut types) in the prevention and treatment of cardiovascular disease. It outlines the current state of knowledge on the functional ingredients in nuts, including lipids, fibre, vitamin, minerals and phytosterols – and the potential mechanisms behind their cardioprotective actions. It points out that further research is needed is in this area, relating to factors such as nut dosage and the bioavailability of the various components of nuts.

Bean and nut intake were protective factors for comorbid hypertension and hyperuricemia in Chinese adults: Results from China Nutrition and Health Surveillance (2015–2017). (Piao et al, 2024).
Using nationally-representative data from the China Nutrition and Health Surveillance 2015–2017 survey, this first-of-its-kind cross-sectional study found sufficient bean (legume) and nut intake to be linked with a lower risk of both hyperuricemia and hypertension (HH) (OR = 0.734, 95% CI = 0.611–0.881). It also verified the negative effects of alcohol intake on these conditions. HH are both independent risk factors for cardiovascular disease, and public health concerns in China, especially amongst males.

Cashew nut (Anacardium occidentale L.) and cashew nut oil reduce cardiovascular risk factors in adults on weight-loss treatment: A randomized controlled three-arm trial (Brazilian Nuts Study). (Meneguelli et al, 2024).
In this randomised controlled-feeding study, involving 68 adults with overweight/obesity, all participants ate an energy-restricted diet (−500kcal/day) and were also randomly assigned to either a control (no nuts), cashew nut (30g/day), or cashew nut oil (30 mL/day) group. After 8 weeks, all groups significantly reduced body fat, body weight, and waist and hip circumferences. But those in the cashew nut and cashew nut oil groups had additional reductions in atherogenic markers, liver function biomarkers, and cardiovascular risk factors (neck circumference and apolipoprotein B levels).

The effects of almond consumption on cardiovascular health and gut microbiome: A comprehensive review. (Singar et al, 2024).
This review found that almond consumption can improve cardiovascular health markers and positively modulate the gut microbiome. Specifically, almond consumption has been linked with improvements in endothelial function, lipid profiles, and body composition (including reductions in body fat percentage and central adiposity). And it’s also been shown to increase the production of beneficial short-chain fatty acids, particularly butyrate, and change faecal microbiota composition. The dosages of almonds used in these studies varied, but were typically around 56g/day.

A walnut-enriched diet for 2 years changes the serum oxylipin profile in healthy older persons. (Cofan et al, 2023).
This trial investigated the effect of a walnut-enriched diet (at 15% energy, or 30-60g/day), over two years, on serum concentrations of 53 oxylipins in healthy older adults (63-79 years). Oxylipins, products derived from polyunsaturated fatty acids, play a role in cardiovascular disease and aging. It found that, compared with control (no walnuts), supplementation with walnuts increased the serum concentrations of most examined oxylipins derived from α-linolenic acid. The results add novel mechanistic evidence on the cardioprotective effects of walnuts.

The relationship between nut consumption and premature coronary artery disease in a representative sample of Iranians: Iran-premature coronary artery disease study (I-PAD). (Mohammadifard et al, 2023).
This multi-centre, case-control study explored the role of nut consumption on cardiovascular disease prevention at a young age, or premature coronary artery disease (PCAD). It involved 3,253 Iran-based men (<60 years of age) and women (<70 years). It found a significant inverse association between nut intake and the risk and severity of PCAD. Among the findings, the highest quartile of nut intake was associated with a substantial decreased risk of PCAD (OR = 0.32; 95% CI = 0.24, 0.43; P trend= 0.001), compared to the lowest quartile.

Portfolio diet score and risk of cardiovascular disease: Findings from 3 prospective cohort studies. (Glenn et al, 2023).
In this study, long-term adherence to the plant-based Portfolio dietary pattern was linked with a 14% lower risk of cardiovascular disease (CVD), including coronary heart disease and stroke, and a more favorable blood lipid and inflammatory profile. It involved participants from three large prospective cohort studies, without CVD at baseline, followed for up to 30 years. The Portfolio diet is low in foods rich in saturated fat and cholesterol, and encourages plant protein (legumes), nuts and seeds, viscous fibre sources, phytosterols, and plant monounsaturated fat sources.

Relationships between vegetarian or vegan diets and incidence of cardiovascular disease in the general population: An umbrella review of systematic reviews. (Raj et al, 2023).
This umbrella review, of four eligible systematic reviews, investigated the relationship between a vegetarian or vegan diet and cardiovascular disease (CVD) in healthy adults. Among the findings, a vegetarian diet was linked with a 15% reduced risk of CVD and a 21% reduced risk of ischemic heart disease (IHD), compared to non-vegetarians. The certainty of evidence was moderate due to risk of bias. It concluded that, in the general population, long-term adherence to a vegetarian diet, compared to a non-vegetarian diet, is associated with decreased CVD and IHD incidence.

Diet, cardiovascular disease, and mortality in 80 countries. (Mente et al, 2023).
This research combined findings from the Prospective Urban Rural Epidemiology (PURE) study, and five other international studies. Together, these comprised 244,597 people, both with and without prior cardiovascular disease (CVD), across 80 countries, who were tracked for an average (median) of 8.3 years. It found a diet comprised of higher amounts of fruit, vegetables, nuts, legumes, fish, and dairy to be linked with lower risk of major cardiovascular events and death from any cause in adults, in all world regions.

Macadamia nut effects on cardiometabolic risk factors: A randomised trial. (Jones et al, 2023)
The randomised cross-over trial involved 35 people aged 40-75 years-old, who had abdominal obesity plus one extra cardiometabolic risk factor. Compared to control, consumption of macadamias (making up ~15% of daily kilojoules, or between 35-59g/day) over 8 weeks led to reductions in total cholesterol, LDL-cholesterol and apolipoprotein B. Macadamia intake did not impact waist circumference, body weight or percentage of body fat, or glycaemic parameters. Macadamia consumption increased total fat and mono-unsaturated fatty acid intake.

Effects of mixed nut consumption on LDL cholesterol, lipoprotein(a), and other cardiometabolic risk factors in overweight and obese adults. (Nora et al, 2023)
This 16-week randomised control trial investigated the effects of consuming 42.5g/day of mixed nuts (cashews, almonds, macadamia nuts, Brazil nuts, pecans, pistachios, walnuts, and peanuts) on LDL-cholesterol, lipoprotein (a), and inflammatory markers, compared to a control. Mixed nut consumption significantly lowered body fat percentage (without significantly changing body weight or BMI) and diastolic blood pressure, and increased adiponectin, but did not significantly affect LDL-cholesterol or lipoprotein (a).

Primary prevention of cardiovascular disease in women with a Mediterranean diet: Systematic review and meta-analysis. (Pant, 2023)
This systematic review and meta-analysis focused on the association between a Mediterranean diet and incident cardiovascular disease (CVD) and death, specific to women. Sixteen prospective cohort studies were included in the meta-analysis, with a total of 722,495 female participants. It found that a Mediterranean diet was beneficial in women, with a 24% lower risk of CVD, 25% lower risk of coronary heart disease, and a 23% lower risk of total mortality. Stroke incidence was lower in women with higher Mediterranean diet adherence, but this result was not statistically significant.

Mediterranean diet lowers all-cause and cardiovascular mortality for patients with metabolic syndrome. (Fan et al, 2023).
This prospective cohort study, using data from NHANES database, found that, in people with metabolic syndrome, adhering to a healthy Mediterranean-style diet (MED diet) was significantly associated with lower all-cause and cardiovascular mortality. It also found a MED diet may even offset the adverse effects of sedentary behavior and depression. Among the findings, greater intakes of vegetables, legumes, nuts and high MUFA/SFA ratio were all linked with lower all-cause mortality.

Pecan-enriched diet improves cholesterol profiles and enhances postprandial microvascular reactivity in older adults. (Cogan et al, 2023)
In this randomised control study, 44 older adults (59 ± 6 years) consumed 68g of pecans/day, or avoided all nuts (control group) over four weeks. Daily pecan consumption resulted in greater reductions in fasting total cholesterol, LDL-cholesterol, non–HDL cholesterol, LDL particle number, and LDL medium, compared with control. Post-prandial triglycerides were also suppressed in the pecan group. The researchers concluded that long-term pecan consumption may improve vascular health and reduce risk for cardiovascular events.

Mixed nuts as healthy snacks: Effect on tryptophan metabolism and cardiovascular risk factors. (Yang et al, 2023)  
This study examined the effect of mixed tree nuts on tryptophan metabolism, and the link to cardiovascular risk markers. Study participants (95 overweight people) were given either 42g/day of mixed tree nuts, or an isocaloric pretzel control. for 12 weeks, as part of a weight loss diet. This was followed by a weight maintenance program for another 12 weeks. Daily nut consumption led to improved tryptophan metabolism and higher serotonin levels, compared with the control – providing insights into the possible mechanisms behind the heart health benefits of nuts.

Nut consumption is associated with a shift of the NMR lipoprotein subfraction profile to a less atherogenic pattern among older individuals at high CVD risk. (Garcia-Galivan et al, 2022).
In this study, cross-sectional and longitudinal analyses were conducted after one-year of follow-up in 196 men and women, within the framework of PREDIMED trial. It looked at links between the amount and type of nuts consumed, and measures of lipoprotein atherogenity and insulin resistance in older people at high cardiovascular risk. Increasing nut consumption was associated with a shift of the lipoprotein subfraction profile to a less atherogenic pattern, as well as lower circulating concentrations of branched chain amino-acids and decreased insulin resistance.

Association of nut consumption with CVD risk factors in young to middle-aged adults: The Coronary Artery Risk Development in Young Adults (CARDIA) study. (Yi et al, 2022).
This study involved 3,092 young adults, followed over 30 years. Dietary intake, including walnuts and other nuts, was assessed over time, as were cardiovascular disease risk factors. Compared to ‘no nut’ consumers, walnut and other nut consumers had better quality diets (as assessed by higher HEI-2015 diet quality scores). Among the findings of this study, over 30 years of follow-up, walnut consumers had significantly lower BMI, waist circumference, blood pressure, and triglyceride levels than other nut consumers.

The impact of nutrition on the development and progression of peripheral artery disease: A systematic review. (Adegbola et al, 2021).
This systematic review collated the outcomes of 82 studies, published over 45 years, which looked at the impact of nutritional intake on peripheral artery disease (PAD). The nutrients were structured in fruits, vegetables and antioxidants, fats and oils, dietary fibre, meat, proteins, vitamins and trace elements, and diets and lifestyle. It found the Mediterranean diet, nuts, and polyunsaturated fat were associated with a lower incidence of PAD. On the flip side, saturated fat, cholesterol, and processed meat were linked with higher rates of cardiovascular events in people with PAD.

Effects of walnut consumption for 2 years on lipoprotein subclasses among healthy elders: Findings from the WAHA randomized controlled trial. (Rajaram et al, 2021).
The Walnuts and Healthy Aging (WAHA) randomised controlled trial looked at the effects of walnut-supplemented diets for two years, in 628 healthy older people (63-79 years of age) based in Spain and the US. Participants were allocated to either a walnut-free (control) or walnut-supplemented diet (≈15% of energy, 30-60 g/day). The ‘walnut diet’ significantly decreased total cholesterol, LDL-cholesterol and intermediate-density lipoprotein by 4.4%, 3.6%, and 16.8%, respectively. Triglycerides and HDL-cholesterol were unaffected.

Association of nut consumption with risk of stroke and cardiovascular disease: The Million Veteran Program. (Ivey et al, 2021).
In this prospective cohort study, researchers tracked 179,827 US-based veterans (male and female adults of any race and age) over a median of 3.5 years. They found frequent nut consumers (having around 30g nuts, ≥ 5 times per week) were 19% less likely to have a stroke, 22% less likely to suffer from coronary artery disease, and 24% less likely to die from cardiovascular disease, compared with those who rarely or never ate nuts. Consumption of peanut butter was not linked with risk of stroke.

Pecan-enriched diets decrease postprandial lipid peroxidation and increase total antioxidant capacity in adults at-risk for cardiovascular disease. (Guarneiri et al, 2021).
This randomised controlled trial looked into the impact of daily pecan consumption for eight weeks on lipid peroxidation, total antioxidant capacity (TAC), and tocopherols in adults at higher risk for cardiovascular disease (CVD). There were three treatment groups: the ADD group (n = 15) ate pecans as part of a free-living diet, the SUB group (n = 16) substituted the pecans for isocaloric foods from their habitual diet, and a control group (n=16). In the ADD and SUB groups, postprandial lipid peroxidation was suppressed and TAC was elevated, compared to baseline. And there was an increase in γ-tocopherol within the ADD group. These findings suggest that daily pecan consumption protects against oxidative stress that occurs following a high-fat meal in adults at risk for CVD.

Pecan-enriched diets alter cholesterol profiles and triglycerides in adults at risk for cardiovascular disease in a randomized, controlled trial. (Guarneiri et al, 2021)
In this randomised controlled trial, 56 adults at-risk for cardiovascular disease (CVD) were allocated to either a control group, or one of two pecan groups: an ADD group, which added 68g of pecans to their regular diet, and a SUB group, that substituted the pecans (68g) for isocaloric foods from their diet. After 8 weeks, total cholesterol (TC), LDL cholesterol, triglycerides, TC/HDL cholesterol ratio, non–HDL cholesterol and apolipoprotein B were reduced in both pecan groups, with no changes in the control group.

The 3-year effect of the Mediterranean diet intervention on inflammatory biomarkers related to cardiovascular disease. (Urpi-Sardi et al, 2021)
This study investigated the 3-year effect of the Mediterranean diet (MD), compared to a low-fat diet (LFD) on changes on inflammatory biomarkers related to atherosclerosis in people with a high-risk of cardiovascular disease. Participants (n = 285) in the PREDIMED trial were randomly assigned into three intervention groups: MD with extra-virgin olive oil (EVOO) or MD-Nuts, and LFD. After 3 years, both MDs showed a significant reduction in plasma levels of inflammatory biomarkers, and levels of IL-1β, IL-6, IL-8, and TNF-α after MD significantly differed from those in the LFD.  This study supports the MD as a healthy long-term dietary pattern in populations at high cardiovascular risk.

A calorie-restricted diet with nuts favourably raises plasma high-density lipoprotein-cholesterol in overweight and obese patients with stable coronary heart disease: A randomised controlled trial. (Ghanavati et al, 2021).
This study found that including nuts as part of a calorie-restricted diet improves the concentrations of HDL (good) cholesterol and apolipoprotein A1 (apoA-1) in overweight or obese adults withcoronary heart disease, receiving statins. The 67 study participants were assigned to an energy-restricted diet, either with or without nuts. Plasma lipids and lipoproteins were assessed at baseline and after 8 weeks. In both groups, total cholesterol, LDL (bad) cholesterol and triglycerides reduced significantly, compared to baseline. And in the nut group only, HDL cholesterol and apoA1 increased.

Total nut, tree nut, and peanut consumption and metabolic status in southern Italian adults. (Micek et al, 2021).
This study looked at associations between nut consumption and hypertension, type 2 diabetes and dyslipidaemia in 2,044 Southern Italian adults. The average (mean) intake of nuts in the ‘high nut intake’ group was about 40g/day, while for those in the ‘low nut intake’ group, it was around 4g/day. It found higher nut intake was inversely linked with hypertension (in particular) and also type 2 diabetes. After adjusting for numerous factors, including energy intake and a Mediterranean dietary pattern, higher nut intake was linked with a 56% decrease in the odds of having hypertension. And high nut consumers had nearly double the polyphenol intake of people with a low intake.

Whole almond consumption is associated with better diet quality and cardiovascular disease risk factors in the UK adult population: National Diet and Nutrition Survey (NDNS) 2008–2017. (Vita et al, 2021).
This research, a secondary analysis of the UK’s National Diet and Nutrition Survey 2008–2017, estimated whole almond consumption among the UK population, and looked at how this impacted diet quality. Around 7.6% of the population were eating almonds, with a median intake of 5g/day. Almond consumption was linked with better dietary quality scores and lower cardiovascular disease risk factors. BMI and waist circumference were lower in whole almond consumers, compared to non-consumers. UK almond consumers also had overall healthier dietary patterns.

Effects of 2-year walnut-supplemented diet on inflammatory biomarkers. (Cofan et al, 2020).
In this randomised controlled trial, 634 healthy adults, aged 63 to 79 years, were assigned to either a control diet, without walnuts, or a diet incorporating daily ‘doses’ of walnuts at ≈15% of energy (or 30 to 60g walnuts) for two years. Those who ate walnuts daily had reduced concentrations of several inflammatory biomarkers, compared to the control group. This anti-inflammatory effect of long-term walnut intake could help explain how these nuts reduce cardiovascular disease risk – beyond that of lipid lowering.

A pilot study on the effects of nut consumption on cardiovascular biomarkers. (Adashek et al, 2020).
The US-based research found that eating a handful of nuts daily, over just four weeks, drastically improved the blood markers that are linked with heart disease. The researchers asked 11 study participants, with an average age of 52 years and who all had undesirable blood lipid levels, to eat a combination of three almonds, three hazelnuts and three walnuts each morning for four weeks. This led to a positive shift in all five markers they measured. That is, higher HDL (good) cholesterol; lower total cholesterol; lower total cholesterol: HDL cholesterol ratio; lower LDL (bad) cholesterol; lower triglycerides.

Mediterranean diet and atherothrombosis biomarkers: A randomised controlled trial. (Hernaez et al, 2020).
This study assessed whether following a Mediterranean diet (MedDiet) improved atherothrombosis biomarkers in high cardiovascular risk individuals. In 358 random volunteers from the PREvención con DIeta MEDiterránea trial, the authors assessed the one-year effects on atherothrombosis markers of an intervention with MedDiet, enriched with virgin olive oil (MedDiet-VOO; n = 120) or nuts (MedDiet-Nuts; n = 119), compared with a low-fat control diet (n = 119). Increases in nut, fruit, vegetable, and fatty fish consumption, and decreases in processed meat intake, were linked to beneficial changes in atherothrombosis biomarkers. The researchers concluded that following a MedDiet improved atherothrombosis biomarkers in high cardiovascular risk individuals.

Association of nut intake with risk factors, cardiovascular disease, and mortality in 16 countries from 5 continents: Analysis from the Prospective Urban and Rural Epidemiology (PURE) study. (de Souza et al, 2020).
Higher nut intake was associated with lower mortality risk from both cardiovascular and non-cardiovascular causes in low-, middle-, and high-income countries.

Association between healthy eating patterns and risk of cardiovascular disease. (Shan et al, 2020).
In 3 large prospective cohorts with up to 32 years of follow-up, greater adherence to various healthy eating patterns was consistently associated with lower risk of CVD. These findings support the recommendations of the 2015-2020 Dietary Guidelines for Americans, emphasising diets rich in wholegrains, fruits and vegetables, nuts and legumes.

Daily almond consumption in cardiovascular disease prevention via LDL-C change in the U.S. population: a cost-effectiveness analysis. (Wang et al, 2020)
This study assessed the cost-effectiveness of almond consumption in the short term and up to 10 years for CVD prevention. The authors found that consuming almonds may be a cost-effective solution for the primary prevention of CVD in both the short and long term.

Effects of a healthy diet enriched or not with pecan nuts or extra-virgin olive oil on the lipid profile of patients with stable coronary artery disease: A randomised clinical trial. (Campos et al, 2020)
This trial investigated changes in the lipid profiles of patients with coronary artery disease, randomised to a control group (healthy diet); pecan group (healthy diet plus 30g pecans/day) or olive oil group (health diet plus 30ml olive oil/day). Whilst no differences were observed for LDL or HDL cholesterol, LDL: HDL cholesterol ratio, or the HDL: triglyceride ratio between groups, the pecan group exhibited significant reductions in other lipid parameters.

Effect of a 12-week almond-enriched diet on biomarkers of cognitive performance, mood, and cardiometabolic health in older overweight adults. (Coates et al, 2020)
This study examined supplementing habitual diets with almonds or carbohydrate-rich snack foods (providing 15% energy) on biomarkers of cardiovascular and metabolic health, mood and cognitive performance. The inclusion of almonds in the diet improves aspects of cardiometabolic health without affecting cognitive performance or mood in overweight/obese adults.

Snacking on whole almonds for 6 weeks improves endothelial function and lowers LDL cholesterol but does not affect liver fat and other cardiometabolic risk factors in healthy adults: The ATTIS study, a randomised controlled trial. (Dikariyanto et al, 2020)
Whole almonds consumed as snacks markedly improve endothelial function, in addition to lowering LDL cholesterol, in adults with above-average risk of CVD.

Oxidative stress biomarkers, nut-related antioxidants, and cardiovascular disease. (Lorenzon Dos Santos et al, 2020)
This article briefly highlights the interaction between oxidative stress, atherosclerosis, and cardiovascular disease, in addition to the effect of the consumption of different nuts and related dietary antioxidants—like polyphenols and vitamin E—on biomarkers of oxidative stress in primary and secondary cardiovascular prevention.

Changes in nut consumption and subsequent cardiovascular disease risk among US men and women: 3 large prospective cohort studies. (Liu et al, 2020)
This study of 3 large prospective cohorts, evaluated the association of within-individual changes in consumption of total and specific types of nuts and the subsequent risk of incident cardiovascular disease (CVD) in over 34,000 US men from the Health Professionals Follow-Up Study, and over 158,000 women from the Nurses’ Health Study I and II. Compared with participants who made no changes to their nut intake, participants who increased their total nut consumption had a lower risk of CVD, CHD, and stroke. The findings support the recommendation of including a variety of nuts as part of healthy dietary patterns, and provide theoretical evidence that replacing animal‐based protein with plant‐based protein can be helpful in the prevention of CVD.

Replacing Saturated Fats with Unsaturated Fats from Walnuts or Vegetable Oils Lowers Atherogenic Lipoprotein Classes Without Increasing Lipoprotein(a). (2020).
A randomized, crossover, controlled-feeding study was conducted in 34 individuals at risk of cardiovascular disease (CVD). Participants were assigned each of the following diets for six weeks: 1) walnuts diet (57-99g/day); 2) walnut fatty-acid matched diet devoid of walnuts, and; 3) a diet replacing ALA with oleic acid without walnuts. The study concluded that the replacement of saturated fatty acids with unsaturated fats from walnuts improved lipid/lipoprotein classes, including LDL-cholesterol, non-HDL cholesterol, and total cholesterol.

Almond consumption and risk factors for cardiovascular disease: A systematic review and meta-analysis of randomized controlled trials. (Lee-Bravatti et al, 2019).
A systematic review and meta-analysis of RCTs showed that almonds significantly reduce total cholesterol, LDL cholesterol, body weight and apolipoprotein B.

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. (2019)
Researchers found that eating walnuts daily as part of a healthy diet was associated with increases in certain bacteria that can help promote health. Additionally, those changes in gut bacteria were associated with improvements in some risk factors for heart disease.

Does Nut Consumption Reduce Mortality and/or Risk of Cardiometabolic Disease? An Updated Review Based on Meta-Analyses. (2019)
This review updates a previous review published in December 2018 by the same authors. The results of this update found that nut consumption has beneficial effects on cardiometabolic disease with reduced CVD mortality, CHD mortality, stroke mortality, CVD incidence, CHD incidence and stroke incidence comparing high with low categories of nut consumption.

Mechanisms underlying the cardiometabolic protective effect of walnut consumption in obese people: A cross-over, randomized, double-blind, controlled inpatient physiology study. (2019)
Results from a small RCT showed walnut consumption improved several cardiometabolic variables in obese adults.

Comparative effect of different types of tree nut consumption on blood lipids: a network meta-analysis of clinical trials. (2020).
Researchers compared the effects of diets enriched with almonds, cashews, hazelnuts, pistachios or walnuts, and ranked the pistachio-enriched diet as the best for lowering total cholesterol, LDL and TGs; walnut-enriched diets were ranked second for reducing total cholesterol and TGs, while almond-enriched diets were second for lowering LDL.

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. (2019).
Replacing saturated fatty acids with walnuts into a healthy dietary pattern significantly lowered diastolic BP as well as reducing total and LDL cholesterol – which the authors suggest could be due to their unique fatty acid profile and phenolic compounds.

Effects of daily consumption of cashews on oxidative stress and atherogenic indices in patients with type 2 diabetes: A randomized, controlled-feeding trial. (2019).
A recent RCT concluded daily consumption of cashews significantly reduced insulin and LDL: HDL cholesterol ratio in patients with diabetes.

Nut consumption in relation to cardiovascular disease incidence and mortality among patients with diabetes mellitus. (2019).
In men and women with diabetes, higher tree nut consumption, is associated with a lower risk of CVD and CHD incidence by 20% and 23% respectively.

Mixed nut consumption may improve cardiovascular disease risk factors in overweight and obese adults. (2019).
Supplementation of 42.5g/day of mixed nuts into a usual diet significantly decreased insulin levels, glucose, BMI and body weight, compared to an isocaloric pretzel snack in an 8-week RCT.

Almond oil for patients with hyperlipidaemia: A randomized open-label controlled clinical trial. (2019).
10ml of almond oil twice daily for 30 days significantly reduces total and LDL cholesterol in hyperlipidemic patients.

Cardiovascular mortality attributable to dietary risk factors in 51 countries in the WHO European Region from 1990 to 2016: a systematic analysis of the Global Burden of Disease Study. (2019).
An altered diet is the most effective means of preventing premature deaths, with a diet low in nuts and seeds one of the top three dietary risk factors across the 51 countries analysed.

Cashew nut consumption increases HDL cholesterol and reduces systolic blood pressure in Asian Indians with type 2 diabetes: A 12-week randomized controlled trial. (2018).
This randomised controlled trial is the first to look at the effect of cashew consumption on blood pressure, serum lipids, body weight, and glycemia in Asian Indian adults with type 2 diabetes. Three hundred adults were randomly assigned to either a standard diabetic diet (control), or a similar diet plus 30g cashew nuts/day (intervention), for 12 weeks. It found that cashew consumption reduced systolic blood pressure and increased HDL cholesterol, without increasing body weight, waist circumference, glycemia, or other lipid markers. 

Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: the Adventist Health Study-2 cohort. (2018).
Associations between the ‘Meat’ and ‘Nuts & Seeds’ protein factors and cardiovascular outcomes were strong and could not be ascribed to other associated nutrients considered to be important for cardiovascular health. Healthy diets can be advocated based on protein sources, preferring low contributions of protein from meat and higher intakes of plant protein from nuts and seeds.

Effect of hazelnut on serum lipid profile and fatty acid composition of erythrocyte phospholipids in children and adolescents with primary hyperlipidaemia: A randomized controlled trial. (2018).
Hazelnuts, both with and without skins significantly reduced LDL cholesterol and increased HDL: LDL cholesterol ratio.

The effect of almonds on vitamin E status and cardiovascular risk factors in Korean adults: a randomized clinical trial. (2018).
The addition of 56g of almonds/day as snack to the typical Korean diet resulted in increases in healthy fats, vitamin E, fibre and a decrease in the amount of energy from carbohydrates. Almonds also improved lipid status, thereby reducing the risk for CVD.

The impact of nuts consumption on glucose/insulin homeostasis and inflammation markers mediated by adiposity factors among American adults. (2018).
Participants with a higher nut intake had a more cardioprotective profile of glucose/insulin homeostasis and inflammatory markers. The authors suggest the low GI and anti-inflammatory effects of nuts provides reasons for their inclusion in diets aimed at reducing the risk of type 2 diabetes, impaired glucose metabolism and CVD.

Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts. (2018).
The new results published in June, (after the mistake was rectified) still concluded that those who ate a Mediterranean diet supplemented with nuts or olive oil resulted in a 30% reduction in cardiovascular events, compared to the low-fat group.

Nuts and cardiovascular disease. (2018).
A review of literature spanning the last 25 years – increasing evidence to suggest mechanisms for this benefit related to lowering of oxidative stress, inflammation; and improvement in endothelial function; in addition to the primary mechanism of improvement of lipid and apolipoprotein profile.

Walnut consumption in a weight reduction intervention: effects on body weight, biological measures, blood pressure and satiety. (2017).
Walnut-enriched reduced energy diet promotes weight loss and improves heart health via reducing cholesterol and blood pressure more-so than reduced energy diet without walnuts.

Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. (2014).
This systematic review supports inverse associations between eating nuts and incident IHD and diabetes, and eating legumes and incident IHD.

Nuts, inflammation and insulin resistance. (2010).
As chronic inflammation is a key early stage in the atherosclerotic process that predicts future CVD events and is closely related to the pathogenesis of insulin resistance, many recent studies have focused on the potential effect of nut consumption on inflammation and insulin resistance. Through different mechanisms, some components of nuts such as magnesium, fibre, alpha-linolenic acid, L-arginine, antioxidants and MUFA may protect against inflammation and insulin resistance.

The effect of nuts on inflammation. (2008).
The relationship observed between frequent nut consumption and the reduced risk of cardiovascular mortality and type 2 diabetes in some prospective studies could be explained by the fact that nuts are rich in all of these modulator nutrients. In fact, frequent nut consumption has been associated with lower concentrations of some peripheral inflammation markers in cross-sectional studies. Nut consumption has also been shown to decrease the plasma concentration of CRP, IL-6 and some endothelial markers in recent clinical trials.