4. Sunlight
If you really want to support your immune system though, get some vitamin D in you! Vitamin D is a vitamin that is actually produced naturally in the body when we are exposed to sunlight. Many of us are deficient but to solve this problem, it is possible to get what you need from your diet.
Fish is a particularly great source of vitamin D – as are mushrooms as long as they’re grown in direct sunlight (rather than under a lamp).
The reason vitamin D is so important is again because it enforces the immune system. In one study, it was found that consuming vitamin D could be more effective than even some flu shots in preventing infections of influenza!