Nuts and seeds: nutrition, portions, storage, roasting, quality and differences between varieties.
Walnuts are by far the common nut with the most omega-3: a 1 oz (28 g) serving provides about 2.57 g of alpha-linolenic acid (ALA). Pecans, pistachios, almonds, hazelnuts, and cashews provide much smaller amounts. ALA is a plant omega-3 and is not nutritionally identical to the EPA and DHA found in fish.
Roasted nuts are not automatically less healthy than raw nuts. Roasting lowers moisture and can reduce some heat-sensitive compounds, but protein, minerals, and most of the fat profile change little. Added oil, salt, sugar, or coatings often matter more than roasting itself.
Chia stands out mainly for fiber and ALA omega-3. A 1 oz (28 g) serving provides about 138 calories, 4.7 g protein, 9.8 g fiber, and roughly 5 g ALA. It is nutrient-dense in a small portion, but it usually works better as a protein contributor than as the main protein source in a meal.
Chia and flax are nutritionally similar but not identical. Per 1 oz, chia provides about 9.8 g fiber and 5.0 g ALA; flax provides about 7.7 g fiber and 6.4 g ALA. Flax is best eaten ground so its nutrients are easier to access, while chia can be eaten whole.
Almonds are concentrated foods: 100 g provides about 579 calories, 21 g of protein, 12.5 g of fiber and 50 g of fat. A more realistic 1-ounce serving provides about 164 calories, 6 g of protein, 3.5 g of fiber and 14 g of fat, mostly monounsaturated. Almonds are also notable for vitamin E and magnesium.
A 1-ounce serving of walnuts provides about 185 calories, 4.3 g of protein, 1.9 g of fiber and 18.5 g of fat. Their distinctive feature among common nuts is ALA: roughly 2.5 g of this plant omega-3 per ounce. ALA is not the EPA or DHA found in fish, but it is an essential fatty acid the body cannot make.
In a 1-ounce serving, almonds provide about 164 calories, 6 g of protein and 3.5 g of fiber; walnuts provide about 185 calories, 4.3 g of protein and 1.9 g of fiber. Walnuts, however, provide roughly 2.5 g of ALA omega-3, while almonds are far richer in vitamin E. Neither wins every category.
A useful comparison is not 100 g versus 100 g: 100 g of avocado provides about 160 calories, while 1 ounce of almonds provides about 164. At similar calories, almonds supply more protein and concentrated fat; avocado provides much more water and volume and still delivers substantial fiber. Both are rich in unsaturated fats but play different roles.
Almonds lead many common nuts at about 12.5 g of fiber per 100 g, followed by pistachios and hazelnuts around 10 g. In a 1-ounce serving, that becomes roughly 3–3.5 g of fiber, which is useful but much less dramatic than the 100 g ranking suggests.
Chia provides about 34 g of fiber per 100 g and flax about 27 g, well ahead of sesame, sunflower, pumpkin and hulled hemp. In a 20 g portion, chia contributes roughly 6.8 g of fiber and flax about 5.4 g, so this ranking has a genuinely large practical gap.
Nuts are high in calories because they pack a lot of fat into very little water: a 1-ounce serving usually provides about 155–200 calories. That does not make them nutritionally poor; most of their fat is unsaturated, and the same handful also provides protein, fiber, vitamins and minerals.
Nuts are calorie-dense, but that does not mean they automatically cause weight gain. Controlled trials have not found a meaningful increase in body weight when nuts are added to eating patterns; the practical question is how much you eat and what the nuts replace.