2. Vitamin D
Vitamin D is also an important supplement when it comes to fighting the flu. You might be surprised just how much is affected by vitamin D within your body. The first thing you should know is that it is naturally produced by your body, but it is only triggered when you go out and get some sun.
In addition, vitamin D is responsible for regulating more than two thousand different genes within the body. Some of those genes belong to the immune system.
There has been a great deal of research over the past two years that has shown without a doubt that those with lower vitamin D levels than they should have are prone to much higher rates of respiratory infections, flu, and more occurrences of the common cold. While many health experts believe that 2000 IU per day is the recommended amount, some physicians believe that you should double that dose.