A tree nut is the edible seed of a tree — almonds, walnuts, pecans, cashews, pistachios, hazelnuts, Brazil nuts, and macadamias are the main culinary examples. Peanuts are not tree nuts but legumes, though the distinction matters little to allergy sufferers. Nutritionally, tree nuts are dense in unsaturated fats, protein, fibre, vitamin E, and minerals, and regular modest consumption is linked to better heart health. They are also one of the major food allergens: tree nut allergy can cause severe anaphylaxis, which is why nuts are a mandatory allergen declaration on food labels in most jurisdictions and why nut-free policies are common in schools. Cross-contact in factories is carefully controlled.