📊 Full nutrition facts — per 100g
| Nutrient | Amount | % Daily value | Level |
|---|---|---|---|
| Calories | 654 kcal | 33% | |
| Total fat | 65.2g | 100% | |
| Omega-3 ALA | 9.08g | — | |
| Protein | 15.2g | 30% | |
| Dietary fibre | 6.7g | 24% | |
| Manganese | 3.41mg | 148% | |
| Copper | 1.59mg | 177% | |
| Magnesium | 158mg | 38% | |
| Vitamin B6 | 0.54mg | 32% | |
| Folate | 98µg | 25% | |
| Ellagitannins | high | — | |
| Melatonin | present | — |
Based on Australian NRV. Source: FSANZ Australian Food Composition Database.
📈 Glycaemic index (GI)
💊 Key vitamins & minerals
✅ Health benefits
Walnuts uniquely contain omega-3 ALA, polyphenols and melatonin all in one food. They are the most extensively studied nut for cognitive function — regular consumption is associated with significantly better memory and processing speed.
Omega-3 ALA, arginine and polyphenols work together to reduce LDL cholesterol, improve endothelial function and lower inflammation markers. The PREDIMED trial found walnuts reduced cardiovascular events by 28%.
Walnut consumption consistently increases Lactobacillus, Bifidobacterium and Roseburia bacteria — associated with reduced inflammation, improved immunity and better mental health.
Ellagitannins in walnuts are converted by gut bacteria into urolithins — compounds with documented anti-proliferative effects against prostate, breast and colon cancer cells in multiple studies.
⚠️ Who should limit or avoid this food
Walnuts are a common tree nut allergen. Reactions range from mild oral allergy syndrome to severe anaphylaxis. Strict avoidance required if diagnosed.
At 654 kcal/100g, walnuts are one of the most calorie-dense common foods. Standard serving is 28–30g (7 whole walnuts) ≈ 185 calories.
Omega-3 ALA has mild antiplatelet effects. Walnuts may also delay absorption of levothyroxine — take thyroid medication at least 4 hours from walnuts.
Walnuts have very high polyunsaturated fat content which oxidises quickly. Rancid walnuts (bitter taste) contain harmful oxidised lipids. Always store refrigerated and discard if bitter.
🔬 Possible side effects or risks
High fat and fibre content can cause bloating, gas or loose stools in large quantities.
Very high polyunsaturated fat content oxidises quickly at room temperature or in light. Rancid walnuts taste bitter and contain harmful oxidised lipids.
May reduce absorption of levothyroxine when consumed close together.
🛒 How to select & buy fresh walnut
Fresh walnuts have a mild, sweet, slightly woody aroma. A sharp, bitter, paint-like smell means rancidity — do not eat them and discard immediately.
Inspect shelled walnuts carefully. Any mould, dark discolouration or shrivelled kernels indicate poor storage or age.
Whole walnuts in their shell have a significantly longer shelf life. The shell protects the fat-rich kernel from light and oxygen oxidation.
🧊 Storage tips & shelf life
High polyunsaturated fat goes rancid quickly at room temperature and in light. Seal well.
Best everyday storage. Cold dramatically slows oxidation of omega-3 fats.
Ideal for bulk buying. Walnuts thaw in minutes and quality is fully preserved.
📖 About walnut — complete guide
Walnuts hold a unique position in nutritional science as the only tree nut with significant omega-3 fatty acid content — providing 9.08g of ALA per 100g, the highest of any common nut. Their omega-3 content, combined with exceptional levels of copper, manganese, folate and B6, contributes to their remarkable anti-inflammatory and cardiovascular protective properties documented in decades of research.
Research on walnuts and the gut microbiome represents one of the most exciting recent developments in food science. A 2020 clinical trial found that eating two servings of walnuts daily for just three weeks significantly increased the abundance of beneficial gut bacteria — particularly Lactobacillus, Bifidobacterium and Roseburia. These bacteria are associated with reduced systemic inflammation, improved immune function and better mental health outcomes. The mechanism is thought to involve the ellagitannins in walnuts, which gut bacteria convert to the anti-inflammatory compounds called urolithins.