Flaxseed (linseed) is added to porridge, yogurt, smoothies and baking, usually ground, because whole seeds often pass through undigested. A 15 g serving has about 80 kcal and 4 g of fiber, part of it soluble mucilage, and is a good source of thiamin, copper, manganese and magnesium. Most of its fat is polyunsaturated, mainly the plant omega-3 fat ALA. Ground flaxseed goes rancid much faster than whole seeds, so grind it fresh or keep it cold.