Walnuts and pistachios are both nuts, but their nutrition profiles solve different problems. Pistachios are higher in protein and fiber; walnuts are dramatically higher in ALA, the main plant omega-3.
Per 100 grams
| Nutrient | Walnuts | Pistachios |
|---|---|---|
| Calories | ~654 | ~560 |
| Protein | ~15.2 g | ~20.2 g |
| Fat | ~65.2 g | ~45.3 g |
| Fiber | ~6.7 g | ~10.6 g |
| ALA | ~9.1 g | ~0.3 g |
Pistachios provide about 5 g more protein and 3.9 g more fiber per 100 g, with about 94 fewer calories. Walnuts provide roughly 8.8 g more ALA.
At a 30 g serving
Thirty grams of walnuts is about 196 calories, 4.6 g protein, 2.0 g fiber, and roughly 2.7 g ALA. The same weight of pistachios is about 168 calories, 6.1 g protein, 3.2 g fiber, and less than 0.1 g ALA.
That means pistachios save about 28 calories and add roughly 1.5 g protein, while walnuts add more than 2.5 g ALA.
Why walnuts are higher in calories
Fat is the main reason: roughly 65 g/100 g versus 45 g/100 g. That is about 20 g additional fat per 100 g, while the final calorie difference is around 94 calories because all macronutrients contribute to the full composition.
Walnut omega-3 is ALA
NIH lists 2.57 g ALA in 1 oz of English walnuts. That makes walnuts one of the most concentrated everyday ALA foods. It should not be read as 2.57 g EPA+DHA because conversion of ALA to the long-chain forms is limited.
Pistachios lead on protein, fiber, and potassium
At about 20.2 g protein and 10.6 g fiber per 100 g, pistachios are well above walnuts for both. They also provide substantially more potassium by equal weight.
Which one should you choose?
If ALA is the goal, walnuts have an enormous advantage. If you want more protein and fiber with somewhat fewer calories, pistachios fit those numbers better. Both are rich in unsaturated fat and can easily coexist in a varied diet.
Which nut fits better depends on what you are trying to get from the serving
A one-ounce serving makes the comparison more realistic than looking only at 100-gram tables. Walnuts and pistachios are both energy-dense because most of their calories come from fat, but the type of fat and the rest of the nutrient package differ. Walnuts stand out for alpha-linolenic acid, the plant omega-3 fatty acid usually abbreviated ALA. Pistachios generally provide more protein per ounce, along with a little more fiber and carbohydrate. Neither profile makes the other nut nutritionally redundant.
The omega-3 difference deserves context. ALA is an essential fatty acid, but the body converts only a limited proportion of it into the long-chain omega-3 fats EPA and DHA found in seafood. Walnuts are therefore a useful plant source of ALA, not a nutritional substitute that makes fish and algae-derived EPA or DHA identical. For people who do not eat seafood, the distinction is especially useful when planning the rest of the diet rather than assuming every “omega-3” label refers to the same molecules.
Pistachios have their own strengths. Their green and purple pigments include carotenoids and polyphenols, and they provide potassium, vitamin B6 and copper in useful amounts. They also tend to contain more protein than walnuts at the same serving size. That can make pistachios appealing in a snack where you want some protein and crunch, while walnuts may be especially useful in oatmeal, salads or baking when ALA is the nutrient you are trying to increase.
Preparation can change the practical comparison more than the raw nutrient table suggests. Salted pistachios may contribute much more sodium than unsalted walnuts, while honey-roasted or sugar-coated versions add ingredients that are not part of the plain nut. Oil-roasted products can also differ slightly from dry-roasted versions. When comparing packages, use the same serving basis and look at sodium, added sugars and ingredient lists instead of assuming the nut itself explains every difference.
Storage matters because both nuts contain unsaturated fats that can oxidize. Walnuts, with their high polyunsaturated-fat content, are particularly prone to developing stale or paint-like flavors if kept warm for too long. Refrigeration or freezing can extend quality, especially after opening or when buying large bags. Pistachios also benefit from a cool, airtight environment. A “healthy fat” is still susceptible to rancidity; the nutrition profile does not protect the food from oxygen, heat and time.
The useful takeaway
Walnuts and pistachios do not have the same nutritional specialty. Walnuts stand out for ALA; pistachios provide more protein and fiber for fewer calories at the same weight.
Sources
- USDA FoodData Central — Raw English walnut and raw pistachio composition per 100 g.
- NIH Office of Dietary Supplements — Omega-3 Fatty Acids — ALA in walnuts and distinction between ALA, EPA and DHA.