Potassium in bananas and avocados helps to reduce blood pressure.
Soybeans and dark leafy greens such as spinach, kale, and chard contain magnesium, which can help to combat headaches & fatigue (which can either be direct result of stress, or can make stress worse).
The Omega-3 fatty acid contained in flax seeds can actually help to keep stress hormone levels low.
Healthy doses of Vitamin C will keep your immune system strong and allow you to cope better with stress. This smoothies packs a Vitamin C punch with dark leafy greens and strawberries.