Walnuts: Nutrition Facts, Health Benefits, and the Nut With the Most Omega-3

Walnuts stand apart from every other tree nut in a single nutritional dimension that defines them: 9.7g of alpha-linolenic acid (ALA) omega-3 fatty acids per 100g — the highest omega-3 content of any commonly eaten tree nut, more than 100 times the ALA found in cashews or almonds, and more than a tablespoon of flaxseed oil provides. Combined with 134% of daily copper, 130% of manganese, 39% of vitamin B6, 34% of magnesium, 29% of phosphorus, 25% each of zinc and folate, and 5.2g of fiber, walnuts deliver a nutrient profile that is both broadly excellent and distinctively specific in its omega-3 density.

Understanding what that 9.7g of ALA means nutritionally — what it does, what it doesn’t do, and how it relates to the EPA and DHA in fish oil — is the central intellectual question this page answers.

Walnuts Nutrition Facts (per 100g)

* From USDA’s SR Legacy data for raw walnuts, used where the newer Foundation Foods data has no value, with the fat breakdown scaled to the Foundation Foods total fat. † Polyunsaturated fat minus omega-3: in walnuts, virtually all polyunsaturated fat is one or the other. Everything else is from Foundation Foods. Full sources are at the end of the page.

Walnuts Nutrition Facts (per 28g serving — approximately 7 whole walnuts)

A 28g serving of 7 pieces provides 2.7g of plant-based omega-3 at 190 calories — the richest ALA contribution of any tree nut snack.

Vitamins in Walnuts (per 100g)

* From USDA’s SR Legacy data for raw walnuts. % Daily Values use the FDA’s current Daily Values.

Standout: Walnuts’ B6 content (39% DV) is the strongest individual vitamin figure — supporting neurotransmitter synthesis, protein metabolism, and homocysteine regulation. Folate at 25% DV and thiamine at 19% DV add meaningful B vitamin breadth — the folate figure is particularly notable and complementary to walnuts’ brain health research profile, given folate’s direct role in one-carbon metabolism and neurotransmitter production. Riboflavin at 12% DV and pantothenic acid at 11% DV round out a genuinely comprehensive B vitamin spread.

Minerals in Walnuts (per 100g)

Multiple standouts: Walnuts’ mineral profile is genuinely impressive. Copper (134% DV) and manganese (130% DV) both exceed the full daily value per 100g. Magnesium at 34% DV supports over 300 enzymatic reactions including ATP production, muscle function, and insulin sensitivity. Phosphorus at 29% DV serves as both a structural bone mineral and a component of every ATP molecule in the body. Zinc at 25% DV contributes to immune function and testosterone production, and iron at 12% DV (non-haem form) makes a useful contribution for plant-based eaters.

The Omega-3 Story: 9.7g of ALA and What It Actually Means

This is the defining nutritional fact about walnuts and deserves complete, honest treatment — covering what ALA does, what its relationship to EPA and DHA is, and why they are nonetheless a genuinely valuable omega-3 source.

The Three Forms of Omega-3

ALA (alpha-linolenic acid) is the plant-derived omega-3, found in walnuts, flaxseeds, chia seeds, and hemp seeds. It is an essential fatty acid — the body cannot synthesize it and must obtain it from food. ALA has its own direct biological roles, and it also serves as a precursor to EPA and DHA through a conversion process.

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the long-chain omega-3 fatty acids found in fatty fish and algae. These are the forms with the strongest and most direct evidence for cardiovascular, anti-inflammatory, and neurological benefits. Both are precursors to anti-inflammatory resolvins (DHA also to protectins), and DHA is the primary structural omega-3 of brain cell membranes and the retina.

The Conversion Efficiency Reality

The human body can convert ALA to EPA and then EPA to DHA, but conversion efficiency is limited:

• Approximately 5–15% of dietary ALA converts to EPA
• Approximately 0.5–5% of dietary ALA converts to DHA

This means a 28g handful of walnuts (2.7g of ALA) might yield roughly 0.14–0.4g of EPA and up to about 0.14g of DHA — useful, but well below what a serving of salmon (about 3.8g of EPA+DHA in a 180g fillet) or a can of sardines (about 0.9g) provides directly, with no conversion step.

Why This Doesn’t Make Walnuts Less Valuable

ALA has direct biological roles independent of its conversion to EPA and DHA:

Cardiovascular protection — higher ALA intake is associated with a modestly lower risk of heart disease in observational studies. The Lyon Diet Heart Study, one of the landmark Mediterranean diet trials, found a 50–70% reduction in repeat heart attacks with a Mediterranean-style diet deliberately rich in ALA — though because the whole diet changed, the effect can’t be attributed to ALA alone.

Anti-inflammatory effects — some trials find that ALA-rich diets lower inflammatory markers, though results are mixed.

The ratio matters as much as absolute amounts — walnuts’ ALA content helps correct the omega-6 to omega-3 imbalance in most modern diets (where the ratio is typically 15:1 or higher). While they also contain substantial omega-6 (39.6g per 100g), the ALA specifically works to shift the balance in a more favorable direction.

The Practical Position

For people who regularly eat fatty fish, walnuts’ ALA provides a complementary plant-based omega-3 contribution. For people who don’t eat fish, walnuts are one of the most practical whole-food ALA sources available, but algae-based DHA/EPA supplements or regular fatty fish remain important for the specific benefits of these long-chain forms. Walnuts and fatty fish are optimally complementary, not interchangeable.

The Omega-6 Consideration

Walnuts contain 39.6g of omega-6 linoleic acid per 100g alongside their 9.7g of ALA — a ratio of approximately 4:1 omega-6 to omega-3. This is meaningfully more balanced than most dietary fat sources (which run 10:1 to 20:1 or higher), making them one of the more omega-3-representative nut options. However, it’s meaningfully less balanced than flaxseed or chia seed, which are heavily omega-3 dominant.

The practical guidance is the same as applied to sunflower seeds — walnuts as a whole food, consumed at typical snack quantities (28g), provide valuable nutrition including their ALA alongside their omega-6, and the net effect on dietary omega balance is positive relative to most alternatives. Regular fatty fish consumption provides the EPA/DHA that walnuts cannot efficiently supply.

The Brain Shape Coincidence: History and Actual Science

The observation that walnut kernels look remarkably like a human brain — two wrinkled hemispheres connected by a corpus callosum-like bridge — has been noted for centuries. European herbalists of the 16th and 17th centuries, following the “doctrine of signatures” (the idea that a plant’s appearance signals its medicinal use), recommended walnuts for ailments of the head because of this resemblance.

This is historically interesting but scientifically coincidental — the walnut’s shape reflects the development of the nut within its shell, not any special relationship to the brain.

What is genuinely supported by science is a plausible relationship between walnut consumption and brain health through well-understood mechanisms:

DHA availability — while conversion from ALA is inefficient, any EPA/DHA produced from walnuts’ substantial ALA contributes to the DHA that constitutes approximately 40% of the brain’s structural polyunsaturated fat.

Polyphenol content — walnuts contain ellagitannins including ellagic acid, which gut bacteria convert to urolithins, a class of compounds with anti-inflammatory and neuroprotective properties in research.

Vitamin B6 and folate — both support neurotransmitter synthesis and help keep homocysteine in check; high homocysteine is associated with cognitive decline.

Clinical research — some shorter trials and observational studies have linked regular walnut eating to better memory and cognitive performance. The largest trial so far, WAHA (Walnuts And Healthy Aging), gave around 700 healthy older adults 30–60g of walnuts a day for two years. Overall it found little effect on cognitive function, though brain imaging and analyses of subgroups hinted at slower decline in people at higher risk, such as former heavy smokers and those with lower starting scores. The researchers called these results encouraging but inconclusive.

The brain-shaped nut really does have brain-relevant compounds — just not because of its shape.

Ellagitannins and Juglone: Walnuts’ Distinctive Bioactive Compounds

Ellagitannins

The papery skin (pellicle) coating walnut halves contains the highest concentration of ellagitannins — polyphenol compounds that are converted by gut bacteria to urolithins. Urolithins have demonstrated:

• Anti-inflammatory properties through NF-κB inhibition
• Mitophagy activation — the cellular process that clears damaged mitochondria, associated with anti-aging effects
• Potential cancer cell growth inhibition in laboratory research

The bitter taste that makes some people remove the skin before eating is precisely this ellagitannin concentration — removing it sacrifices most of the polyphenol content. The skin is nutritionally the most valuable part.

Juglone

Juglone (5-hydroxy-1,4-naphthoquinone) is a compound found in walnut husks, roots, and leaves that has been studied for antifungal, antibacterial, and anticancer properties in laboratory research. The amounts in walnut kernels themselves are small and not considered meaningful for human health at dietary intake levels — juglone is more relevant as the allelopathic compound that prevents many plants from growing near walnut trees (walnut trees release juglone through their roots, inhibiting competing vegetation).

Health Benefits of Walnuts

The Most Studied Nut for Cardiovascular Health

They have one of the most extensive clinical research bases of any individual food for cardiovascular risk factors. Meta-analyses pooling dozens of randomized controlled trials (typically 30–60g per day) have found that walnut-enriched diets:

• Significantly reduce total and LDL cholesterol
• Reduce triglycerides and apolipoprotein B
• Improve endothelial function (blood vessel flexibility) in some trials

Effects on blood pressure and on inflammation markers such as C-reactive protein, however, have not held up when the trials are pooled. The combination of ALA omega-3, polyphenols, magnesium, and fiber provides several plausible mechanisms for the cholesterol-lowering effect, which is among the most consistent findings in nut research.

Useful Magnesium and Phosphorus

At 34% DV magnesium and 29% DV phosphorus per 100g, walnuts provide two of the most important minerals for energy production and bone health. Magnesium is involved in over 300 enzymatic reactions and is one of the most commonly deficient minerals in modern diets; phosphorus is a structural bone mineral and a component of every ATP molecule. A 28g serving covers 9% and 8% DV respectively — useful contributions from a snack.

Brain Health Support

As discussed above, the combination of ALA, ellagitannins, folate, B6, and the emerging urolithin research provides mechanistically plausible support for cognitive health — though controlled trial evidence so far is limited and mixed.

Meaningful Iron and Zinc for Plant-Based Eaters

At 12% DV iron and 25% DV zinc per 100g, walnuts make genuinely useful contributions to these trace minerals for people eating primarily or exclusively plant foods, where haem iron and highly bioavailable zinc from animal sources are absent.

Gut Health Through Fiber and Polyphenols

At 5.2g fiber per 100g (1.5g per serving) alongside ellagitannins that are fermented by gut bacteria to produce urolithins, walnuts support microbiome diversity through both direct prebiotic feeding and the production of bioactive compounds that influence gut bacterial populations.

Anti-Inflammatory Properties

Walnuts’ ALA omega-3, ellagitannin-derived polyphenols, magnesium, and gamma-tocopherol (the main form of vitamin E in walnuts, which doesn’t count toward the vitamin E daily value) all show anti-inflammatory activity in research. In trials, though, walnuts’ effects on inflammatory markers such as C-reactive protein have been inconsistent.

Walnuts for Athletes and Active People

The Only Tree Nut With Significant Omega-3

For athletes seeking a plant-based omega-3 contribution from whole food snacks, walnuts are the definitive choice — 2.7g of ALA per 28g serving, with no other commonly eaten tree nut coming close.

Magnesium for Training Recovery

At 34% DV per 100g (9% per 28g serving), walnuts contribute to the magnesium intake that athletes deplete through sweat, supporting the ATP production and muscle contraction/relaxation cycle that training demands.

Anti-Inflammatory Recovery Support

The ALA, polyphenols, and ellagitannins may provide anti-inflammatory support that complements the EPA/DHA from fish sources, working through overlapping and complementary mechanisms.

Brain Health for Cognitive Performance

The cognitive research on walnuts is relevant beyond general wellness — athletes depend on pattern recognition, reaction time, and decision-making as much as physical capacity, and the folate, B6, and polyphenol content of walnuts contributes to the neural substrate that cognitive performance depends on.

Calorie-Dense Snack for Bulking Phases

At 679 kcal per 100g with 14.6g protein and the most omega-3-beneficial fat profile of any tree nut, walnuts are a practical, nutritionally complete calorie-dense addition to a deliberate caloric surplus.

Walnuts vs Other Common Nuts for Omega-3

† Polyunsaturated fat minus omega-3: in nuts, virtually all polyunsaturated fat is one or the other. Ratios are calculated from the rounded values above, so treat the larger ones as approximate.

The gap between walnuts and every other tree nut on omega-3 content is not marginal — it is categorical. Walnuts contain nearly 10 times more ALA than pecans (the second-highest), and over 100 times more than almonds, cashews, and hazelnuts. For tree nuts specifically, walnuts are in a class of their own as an omega-3 source.

Practical Ways to Include Walnuts in Your Diet

As a daily snack — about 14 walnut halves (7 whole pieces, 28g) provide a meaningful ALA contribution, useful magnesium and copper, and strong satiety at 190 calories.

On oatmeal or yogurt — adds crunch, omega 3, and minerals to breakfast with minimal preparation.

In salads — a tablespoon of walnuts adds texture and nutritional density to any salad, pairing particularly well with leafy greens, blue cheese, and dried fruit.

In baking — walnut banana bread, walnut brownies, and walnut cakes distribute the nut’s omega-3 and polyphenol content throughout a baked product. The heat of baking may oxidize some polyunsaturated fat, so raw walnuts provide more intact ALA — but baked walnuts still retain meaningful micronutrients.

Walnut pesto — blended with basil, garlic, lemon, and olive oil as an ALA-rich pasta sauce alternative to pine-nut-based traditional pesto.

Chopped over grain bowls — a tablespoon of chopped walnuts over any grain bowl adds omega-3 and minerals with minimal additional preparation.

In trail mix — combined with dark chocolate and dried fruit (raisins, cranberries), walnuts create a nutritionally balanced portable snack combining omega 3, polyphenols, copper, and natural sugar energy.

Potential Considerations

Calorie density — at 679 kcal per 100g, portion awareness matters for anyone managing total calorie intake; a 28g handful is a practical daily serving that delivers the benefits without significant caloric burden.

Omega-6 content — at 39.6g per 100g, walnuts are high in linoleic acid omega-6. For people already consuming significant omega-6 from seed oils, being mindful of total intake is sensible, though walnuts’ 4.1:1 omega-6:omega-3 ratio is far more balanced than most dietary fat sources.

Rancidity — walnuts’ high polyunsaturated fat content makes them more prone to oxidative rancidity than nuts with more saturated or monounsaturated fat. Store shelled walnuts in the refrigerator or freezer in an airtight container; the characteristic bitter, paint-like off-flavor of rancid walnuts is both unpleasant and a sign of significant oxidative degradation of the beneficial fats.

Tree nut allergy — walnut allergy is one of the more common tree nut allergies and can cause severe reactions.

Keep the skin — the bitter pellicle coating walnut halves contains most of the polyphenols. While the bitterness is real, eating the whole walnut including the papery skin maximizes the antioxidant and anti-inflammatory benefit.

Walnuts and Key Nutrients on This Site

• Calcium — 7% DV per 100 g
• Iron — 12% DV per 100 g in non-haem form

Nutrient data: USDA FoodData Central, Foundation Foods (FDC ID 2346394); values marked * from SR Legacy (FDC ID 170187), with the fat breakdown scaled to the Foundation Foods total. % Daily Values use the FDA’s current Daily Values.