Essential fatty acid Omega-3 just keeps coming back around in the ‘good foods’ guides – because it’s absolutely essential, and your body doesn’t produce it naturally.

Omega-3 contributes towards keeping cells healthy, and a deficiency has been associated with fatigue, mood swings, and depression.

Good sources include salmon, mackeral, or if you’re a vegetarian – chai seeds.

Salmon also contains Vitamin D, which many people who spend working days indoors are deficient in. It helps maintain a healthy immune system, when paired with calcium, and low vitamin D levels have been linked to depression.