To live longer? All the important news about walnuts

Editorial note: This article was previously published and has been updated according to scientific and divulgative criteria to offer a clear and transparent summary of available evidence. The information is for informational purposes only and does not replace professional medical advice.

In brief

• Observational and experimental literature shows an association between regular consumption of nuts (in the dietary sense: tree nuts and peanuts) and a reduced risk of death from all causes and from specific causes such as cardiovascular diseases and some cancers.
• A study on large cohorts highlighted up to ~20% reduction in mortality among those who ate nuts daily, a finding confirmed by subsequent meta-analyses. [1][3]
• A randomized trial on a Mediterranean diet with nut supplementation showed a reduction in cardiovascular events; other experimental evidence confirms favorable effects on lipids and metabolic biomarkers. [2][4]
• Possible biological explanations include unsaturated fats, fiber, vitamins, minerals, and bioactive compounds, but the observed associations do not prove absolute causality. [4][8]

Abstract: what does science say?

The discussion on nuts and longevity concerns the regular use of tree nuts (almonds, walnuts, hazelnuts, pistachios, cashews, etc.) and also peanuts (botanically legumes but often considered "nuts" in diet). Observational studies on large cohorts have shown that those who regularly consume nuts have, on average, a lower risk of death from all causes and from specific causes such as cardiovascular diseases, some cancers, and respiratory diseases. [1][3] Randomized clinical data in the context of the Mediterranean diet and numerous meta-analyses of feeding trials document improvements in lipid profiles and some cardiometabolic biomarkers associated with nut consumption. [2][4] The effect seems to depend on quantity (dose) and frequency: many analyses indicate benefits even for moderate daily portions (e.g., a handful ≈ 20–30 g), with a non-linear dose-response relationship. [3][8] However, the main evidence comes from observational studies, which can be influenced by related lifestyle factors (physical activity, overall diet quality, smoking). Therefore, while a direct contribution of nuts to health is plausible, it is necessary to interpret the results with caution, distinguishing association from causality and considering the overall dietary context.

In-depth look at key studies and evidence quality

The most cited data comes from the analysis of large US cohorts (Nurses' Health Study and Health Professionals Follow-up Study), which evaluated nut consumption frequency and mortality over decades of follow-up. This analysis showed that, all known conditions being equal (age, smoking, physical activity, body mass index, other dietary aspects), daily nut consumers had lower overall mortality compared to non-consumers, with estimates of around a 20% reduction in risk in habitual consumers. [1] The evidence is not limited to this investigation: prospective meta-analyses and broad reviews confirm an inverse association between nut consumption and all-cause mortality, as well as reductions in the risk of cardiovascular diseases and, in some cases, cancer incidence. [3][5][8] From an experimental perspective, the PREDIMED trial, a randomized and multicenter study, compared a Mediterranean diet enriched with nuts to a control and observed a reduction in cardiovascular events as a primary outcome; in this context, nuts are part of a complex dietary pattern in which extra virgin olive oil and other factors also contribute to the observed effect. [2] Finally, meta-analyses of controlled trials show favorable effects of nuts on LDL cholesterol levels and other cardiometabolic biomarkers, offering mechanistic plausibility that complements observational data. [4] Overall, the consistency across cohorts, meta-analyses, and contextualized trials strengthens the evidence, while maintaining the distinction between observed association and definitive proof of causality.

Plausible biological mechanisms

Nuts contain a combination of nutrients and bioactive compounds that can, at least in part, explain the observed associations with health and longevity. Among the most relevant components are mono- and polyunsaturated fatty acids (including omega-3 in some nuts like common walnuts), fiber, plant-based proteins, vitamin E, magnesium, phytosterols, and antioxidant phenols. These elements can contribute to reducing systemic inflammation, improving the lipid profile (reducing LDL cholesterol), modulating insulin sensitivity, and positively affecting endothelial function. [4][5] Metabolomic studies and research on biomarkers also suggest that metabolites derived from nut consumption can act on the gut microbiota and generate molecules that influence metabolism and distant inflammation. [8] Short and medium-term clinical interventions have documented improvements in total cholesterol, LDL, and apolipoprotein B associated with the regular intake of nut portions, supporting the plausibility of a biological pathway that reduces cardiovascular risk. [4] It is important to remember that the benefit likely does not come from a single component, but from the interaction between multiple nutrients present in the food matrix of nuts; therefore, the effects are consistent with a "food-centric" model rather than the action of a single isolated nutrient. [8]

What this means in practice

For the reader: the evidence suggests that including nuts in the habitual diet can be part of a dietary strategy aimed at reducing the risk of chronic diseases and, in general, mortality. This is not equivalent to a universal clinical prescription, but indicates that, within the framework of a balanced diet and a healthy lifestyle, a moderate daily portion of nuts (often defined as ~20–30 grams, a "handful") is associated with favorable effects in many studies. [3][8] Practically, nuts can replace snacks richer in sugars or saturated fats; they are useful as a source of quality fats, fiber, and minerals. However, those with nut allergies must avoid them; those following specific therapeutic plans (for example, anticoagulant therapies or very stringent energy restrictions) should consult their doctor before changing their diet. Finally, if the goal is long-term prevention, the most solid benefit is observed when nut consumption is part of a healthy dietary pattern (e.g., Mediterranean diet) and not when nuts are added without modifying overall less healthy eating habits. [2][8]

Key takeaways

• Regular nut consumption is associated with reduced mortality and lower cardiovascular risk in many large cohorts. [1][3]
• Experimental evidence and meta-analyses of trials suggest favorable effects on LDL cholesterol and other cardiometabolic biomarkers. [2][4]
• The observed useful dose is moderate: often a handful (≈20–30 g) per day has been associated with benefits. [3][8]
• Associations are consistent but, being largely observational, require cautious interpretation: possible confounding by other lifestyle factors. [3]

Limitations of the evidence

It is essential to distinguish between different levels of evidence: observational studies (cohorts) show associations and are excellent for identifying real-life patterns, but they cannot alone prove definitive causality due to possible residual confounding factors (e.g., overall diet quality, education, income, physical activity, smoking). [1][3] Randomized trials provide greater control, but often test the effect of a complex dietary model (e.g., PREDIMED: Mediterranean diet with nuts) rather than the isolated effect of a single food; thus, separating the specific effect of nuts is difficult. [2] Methodological limitations include self-reported dietary intake (questionnaires), variable control of confounding factors, and variability in the definition and quantity of "nut portion" across studies. Furthermore, geographical, cultural, and genetic differences can modulate the association, so results observed in one population are not automatically generalizable to all populations. [3][8]

Editorial conclusion

The overall evidence indicates that regular nut consumption is associated with health benefits and can contribute to reducing the risk of mortality and cardiovascular diseases. These results are consistent across large observational cohorts, meta-analyses, and contextual trials, and are supported by plausible biological mechanisms. However, cautious interpretation remains central: associations do not automatically imply unequivocal causality, and the observed benefits are situated within the context of a set of healthy behaviors. For the general population, considering nuts as part of a balanced diet is reasonable; for individual clinical decisions, always consult a doctor or nutrition professional.

Editorial note: This article was originally published in the past and has been updated based on available evidence to improve clarity, accuracy, and transparency. The information is for informational purposes and does not replace medical advice.

Scientific research

1. Association of Nut Consumption with Total and Cause-Specific Mortality. N Engl J Med. 2013;369:2001–2011. https://doi.org/10.1056/NEJMoa1307352. [1]
2. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. N Engl J Med. 2013;368:1279–1290. https://doi.org/10.1056/NEJMoa1200303. [2]
3. 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. BMC Med. 2016;14:207. https://doi.org/10.1186/s12916-016-0730-3. [3]
4. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose–response of 61 controlled intervention trials. Am J Clin Nutr. 2015;102(6):1347–1356. https://doi.org/10.3945/ajcn.115.110965. [4]
5. Nut consumption in relation to all-cause and cause-specific mortality: a meta-analysis of 18 prospective studies. Food Funct. 2017;8:3893–3905. https://doi.org/10.1039/C7FO00915A. [5]
6. Nut consumption and risk of metabolic syndrome and overweight/obesity: a meta-analysis of prospective cohort studies and randomized trials. Nutr Metab (Lond). 2018;15:46. https://doi.org/10.1186/s12986-018-0282-y. [6]
7. Meta-analysis of the association between nut consumption and the risks of cancer incidence and cancer-specific mortality. Aging (Albany NY). 2019;11:69–98. https://doi.org/10.18632/aging.103292. [7]
8. Consumption of Nuts and Seeds and Health Outcomes Including Cardiovascular Disease, Diabetes and Metabolic Disease, Cancer, and Mortality: An Umbrella Review. Adv Nutr. 2022;nmac077. https://doi.org/10.1093/advances/nmac077. [8]