What the evidence says. Several controlled trials; effects real but modest or context-dependent.
Nutrition per serving 1 oz (28 g, ~14 halves)
Sugars0.7 g3%
Fibre1.9 g7%
Other carbs1.2 g4%
Protein4.3 g15%
Fat18.3 g65%
Other1.6 g6%
What's in one serving, by weight — average composition (USDA).One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
Walnut (Juglans regia) is a nut or seed used for lowers ldl cholesterol, total cholesterol and triglycerides in pooled rcts (no consistent hdl change). NutriDex grades the human evidence as Moderate. Walnuts have some of the strongest human data among individual tree nuts, though the overall evidence base is best graded moderate. Meta-analyses of randomized controlled trials consistently show that adding roughly an ounce of walnuts a day modestly lowers LDL ('bad') cholesterol, total cholesterol and triglycerides, with little effect on HDL; a 2018 RCT meta-analysis (Guasch-Ferre) and a 2022 dose-response meta-analysis both confirm this, and the benefit appears independent of weight change. For hard outcomes, the landmark PREDIMED randomized trial found a Mediterranean diet supplemented with mixed nuts (half walnuts) cut major cardiovascular events versus a low-fat diet. Evidence for lower type-2 diabetes risk comes mainly from large observational cohorts (Nurses' Health Studies) rather than trials, so it is weaker. Walnuts are distinctive for being rich in the plant omega-3 ALA. Bottom line: good RCT support for cholesterol, supportive trial/cohort data for cardiovascular and metabolic benefit.
Purported Benefits
✓Lowers LDL cholesterol, total cholesterol and triglycerides in pooled RCTs (no consistent HDL change)
✓Lipid improvements occur largely independent of body weight change
✓Richest common nut source of the plant omega-3 ALA (alpha-linolenic acid)
✓Associated with lower cardiovascular event risk as part of a Mediterranean diet (PREDIMED RCT)
✓Higher intake linked to lower type-2 diabetes risk in large cohorts (observational)
✓Does not promote weight gain at typical ~1 oz/day servings despite calorie density
Dosing & Compounds
Typical Dose
1 oz (~28 g) per day, a small handful (about 14 halves)
Active Compounds
Polyunsaturated fat (PUFA), notably alpha-linolenic acid (ALA, plant omega-3)Monounsaturated fat (MUFA)Dietary fibreL-arginineVitamin E (gamma-tocopherol)MagnesiumPhytosterolsPolyphenols (ellagitannins/urolithin precursors)Copper and manganese
Safety & Cautions
⚠
Tree-nut allergy is common and can cause life-threatening anaphylaxis; walnuts are a major allergen and should be strictly avoided by allergic individuals, who may also react to other tree nuts or peanuts. Walnuts are calorie-dense (~185 kcal per 1 oz), so portion control matters for weight management. Whole or large nut pieces are a choking hazard for children under about 4 years. Those with cross-reactive pollen-food (oral allergy) syndrome may experience mild mouth itching. Educational only — always check with your doctor or pharmacist before combining Walnut with any medicine.
Walnut is most often taken for Lowers LDL cholesterol, total cholesterol and triglycerides in pooled RCTs (no consistent HDL change), Lipid improvements occur largely independent of body weight change, Richest common nut source of the plant omega-3 ALA (alpha-linolenic acid), Associated with lower cardiovascular event risk as part of a Mediterranean diet (PREDIMED RCT). ALA-rich tree nut with solid RCT evidence for lowering LDL cholesterol
Does Walnut work — what does the evidence say?
Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Walnuts have some of the strongest human data among individual tree nuts, though the overall evidence base is best graded moderate. Meta-analyses of randomized controlled trials consistently show that adding roughly an ounce of walnuts a day modestly lowers LDL ('bad') cholesterol, total cholesterol and triglycerides, with little effect on HDL; a 2018 RCT meta-analysis (Guasch-Ferre) and a 2022 dose-response meta-analysis both confirm this, and the benefit appears independent of weight change. For hard outcomes, the landmark PREDIMED randomized trial found a Mediterranean diet supplemented with mixed nuts (half walnuts) cut major cardiovascular events versus a low-fat diet. Evidence for lower type-2 diabetes risk comes mainly from large observational cohorts (Nurses' Health Studies) rather than trials, so it is weaker. Walnuts are distinctive for being rich in the plant omega-3 ALA. Bottom line: good RCT support for cholesterol, supportive trial/cohort data for cardiovascular and metabolic benefit.
What is the typical dose of Walnut?
1 oz (~28 g) per day, a small handful (about 14 halves)
Is Walnut safe? Any cautions or side effects?
Tree-nut allergy is common and can cause life-threatening anaphylaxis; walnuts are a major allergen and should be strictly avoided by allergic individuals, who may also react to other tree nuts or peanuts. Walnuts are calorie-dense (~185 kcal per 1 oz), so portion control matters for weight management. Whole or large nut pieces are a choking hazard for children under about 4 years. Those with cross-reactive pollen-food (oral allergy) syndrome may experience mild mouth itching.
How many studies support Walnut?
NutriDex cites 13 sources for Walnut, graded "Moderate".
Cite this page
APA
Peh, D. (2026). Walnut (Juglans regia): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/walnut
BibTeX
@misc{nutridex_walnut,
author = {Peh, Daryl},
title = {Walnut (Juglans regia): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/walnut},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.