This month it's all about your immune system. For this first week of April we want you to focus on getting lots of vitamin D. Here are some sources:
Get D from the sun - it's free.
D as a supplement - take at least 5000 IU per day C as a supplement - take at least 2 grams per day and make sure your vitamin C contains "Flavonoids"
You can also get these essential vitamins from eating whole foods
This article talks about vitamin C and your immune system.