Summarize:

Nut butter, like cashew, almond, or peanut, add thickness and protein to any smoothie. They also provide a creamy, nutty flavor that adds another layer to your drink. Add a tablespoon or more in addition to ingredients like milk and banana. Chia seeds absorb tons of liquid, so this is a surefire way to thicken your smoothie. They are also full of fiber and fatty acids, so they make a nutritious addition to any recipe. Try mixing blueberries, chia seeds, almond milk, and cinnamon. Oats not only add a thickness to your smoothie, they also help keep you full for hours. Choose from instant, rolled, or steel-cut oats, all of which have the same nutritional value. Combine them with banana, berries, and coconut milk for a delicious drink. Flax seeds have a sweet and nutty flavor, and also add fiber and Omega-3s. Use a coffee grinder to break up the flax seeds before blending them into your smoothie. They taste great when mixed with yogurt, peanut butter, honey, and bananas.
Add a scoop of nut butter for added protein. Put in a scoop of chia seeds to increase the fiber. Toss in some oats to keep you full. Use flax seeds to sweeten your smoothie.