How much walnuts per day is too much?
In the 2-year WAHA trial, older adults ate 1 to 2 oz (30 to 60 g) of walnuts a day, and no agency sets a limit for walnuts. One ounce (28 g) has 192 calories.
Where the limits are
| What sets the limit | Per ounce | Daily limit for adults | Ounces to reach it (rounded down) |
|---|---|---|---|
| Saturated fat | 1.7 g | about 20 g (10% of 2,000 calories) (Dietary Guidelines limit) | 11 |
| Zinc | 0.8 mg | 40 mg (Upper limit (NIH)) | 51 |
| Calories | 192 | 2,000 (reference day, not a limit) | 10 |
One ounce = 1 oz (28 g). USDA FoodData Central, Nuts, walnuts, English, halves, raw. Limits count everything you eat and drink that day, so other foods and supplements use up part of each one.
What 1 to 6 ounces a day add up to
| Amount | Calories | Saturated fat (% of limit) | Zinc (% of limit) |
|---|---|---|---|
| 1 ounce | 192 | 1.7 g (9%) | 0.8 mg (2%) |
| 2 ounces | 385 | 3.4 g (17%) | 1.6 mg (4%) |
| 3 ounces | 577 | 5.1 g (26%) | 2.3 mg (6%) |
| 4 ounces | 770 | 6.9 g (34%) | 3.1 mg (8%) |
| 6 ounces | 1,154 | 10 g (51%) | 4.7 mg (12%) |
What eating it daily did in studies
- Level A The 2026 meta-analysis of 49 trials found no overall change in apolipoprotein B with walnuts. A reduction appeared only when intake exceeded 50 g a day. Food Science & Nutrition, 2026
- Level B In 38 postmenopausal women with high cholesterol, 1.4 oz (40 g) of walnuts a day for 4 weeks improved microvascular function against a 5 g dose while leaving total, LDL and HDL cholesterol unchanged. J Nutr Biochem, 2015
- Level B In the WAHA trial, 628 healthy adults aged 63 to 79 who ate 1.1 to 2.1 oz (30 to 60 g) of walnuts a day for 2 years lowered LDL cholesterol by 4.3 mg/dL and total cholesterol by 8.5 mg/dL compared with a walnut-free diet. Circulation, 2021
- Level B In a controlled-feeding crossover RCT of 34 adults at cardiovascular risk, a diet with 2 to 3.5 oz (57 to 99 g) of walnuts a day lowered LDL by 6.9 mg/dL compared with a diet where oleic acid replaced walnut ALA. J Nutr, 2020
- Level B In adults with prediabetes, 2 oz (56 g) of walnuts a day for 6 months did not change fasting glucose or HbA1c, in the one walnut trial of a 5-RCT systematic review. Br J Nutr, 2019
Only studies that give the amount eaten. Levels: A is a meta-analysis of trials, B a randomized trial, C an observational study. How we grade evidence.
Reasons to keep it moderate, and who should eat less
- Level E The 2025-2030 US Dietary Guidelines keep saturated fat at no more than 10% of daily calories and state that more high-quality research is needed to know which types of dietary fat best support long-term health. U.S. Department of Health and Human Services and U.S. Department of Agriculture, Dietary Guidelines for Americans, 2025–2030 (January 2026), p. 3
- Level C A systematic review of 36 studies found challenge-confirmed tree nut allergy in under 2% of people, with walnut and cashew the most common in the US and almond and walnut among the most common in the UK. Curr Allergy Asthma Rep, 2015
If you have kidney disease, take blood thinners or other medicines, or are pregnant, the right amount for you is a question for your clinician.
What this means for a normal day
Calories are the practical ceiling for walnuts. Two ounces add 385 calories, and saturated fat stays well under its limit at that amount.
In the 2-year WAHA trial of 628 adults aged 63 to 79, 1 to 2 oz (30 to 60 g) a day lowered LDL by 4.3 mg/dL compared with a walnut-free diet (Level B). A 2026 meta-analysis found no overall change in apolipoprotein B with walnuts (Level A).
Tree nut allergy confirmed by a food challenge affects under 2% of people, and walnut is among the most common in the US (Level C). Lab studies suggest roasting does not remove the main walnut allergens, so roasted walnuts are no safer for someone who is allergic (Level D).
Evidence behind this note
- Level B In the WAHA trial, 628 healthy adults aged 63 to 79 who ate 1.1 to 2.1 oz (30 to 60 g) of walnuts a day for 2 years lowered LDL cholesterol by 4.3 mg/dL and total cholesterol by 8.5 mg/dL compared with a walnut-free diet. Circulation, 2021
- Level A The 2026 meta-analysis of 49 trials found no overall change in apolipoprotein B with walnuts. A reduction appeared only when intake exceeded 50 g a day. Food Science & Nutrition, 2026
- Level C A systematic review of 36 studies found challenge-confirmed tree nut allergy in under 2% of people, with walnut and cashew the most common in the US and almond and walnut among the most common in the UK. Curr Allergy Asthma Rep, 2015
- Level D Laboratory data suggest roasting does not remove the main walnut allergens, which stay heat stable. Allergy, 2013
Written from the data and studies on this page, reviewed by the Bioma editorial system. How we verify.
Keep exploring
Sources
- USDA FoodData Central, Foundation Foods (release 2025-12-18): Nuts, walnuts, English, halves, raw, FDC ID 2346394 (accessed 2026-10-13)
- Dietary Guidelines for Americans, 2025-2030, https://cdn.realfood.gov/DGA.pdf (accessed 2026-10-13)
- NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc, https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ (accessed 2026-10-13)
- Evidence cards: each study above links to its source. Card review dates are listed in our methodology.
Numbers checked 2026-10-13. Bioma Learn provides information, not medical advice.