Fatty nutrients are tricky. On the one hand, essential fats such as EFAs, Vitamin D, E, A and K, in addition to plant nutrients, are super-important. They’re particularly significant for long-term kinds of biological process such as building muscle and bone, for fertility, baby building and even stress management. On the other hand, they’re complex and sticky molecules that are difficult for the digestive system to process and require a lot of energy to be extracted from foods.