Some things in life cause harm to your immune system and if you indulge in these then you need to stop. Smoking and drinking alcohol are high on the list here which will probably not surprise you. But there are other things that you need to avoid as well that we cover in detail.
The right diet will provide the nutrients and vitamins that your immune system needs to stay in tip top condition and work hard for you. Changing your diet is a big step to take, but if you are eating the wrong things then you need to do this for the sake of your immune system.