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Walnuts

Walnuts as a functional food: a 26-trial meta-analysis on LDL cholesterol and triglycerides, blood pressure findings, calories and allergy.

Content last updated . This page has not been medically reviewed.

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Overview

Walnuts are tree nuts rich in polyunsaturated fat, including alpha-linolenic acid. Nuts are energy-dense, so studies usually have people swap them for other foods.

What the research shows

  • A 2018 meta-analysis of 26 trials (1,059 participants) found walnut-enriched diets reduced total cholesterol by 6.99 mg/dL, LDL cholesterol by 5.51 mg/dL and triglycerides by 4.69 mg/dL compared with control diets. Reductions were larger when walnuts replaced typical Western diets (LDL -8.28 mg/dL). [1]
  • A 2022 meta-analysis also examined walnut intake and lipids. [2]
  • A meta-analysis examined walnuts and blood pressure. [3] We read only the title and make no claim about the size of the effect.

Not shown: these are changes in blood markers over weeks to months; the sources we read do not show fewer heart attacks from walnuts.

Safety and individual considerations

  • Tree nut allergy can be severe: avoid if allergic and call 911 for trouble breathing or swelling.
  • Nuts are calorie-dense; the trials replaced other foods.

Related

Almonds · Pistachios · Olive oil

Frequently asked questions

How many walnuts lower cholesterol?

The meta-analysis pooled trials of different amounts; we do not give an amount we did not verify. [1]

References

  1. Guasch-Ferré M et al. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials. Am J Clin Nutr 2018. PMID 29931130.
  2. Alshahrani SM et al. The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients 2022. PMID 36364723.
  3. Li J et al. Effects of walnut intake on blood pressure: A systematic review and meta-analysis of randomized controlled trials. Phytother Res 2020. PMID 32510725.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.