It can be found in some animal-based foods in its pre-made form, or found in plants in the form of beta-carotene -- a compound your body digests to form two vitamin A molecules. Yellow and dark green vegetables and fruits are good sources of the carotenes, including beta-carotene.
With the flu, you may feel very weak and fatigued for up to two or three weeks. You'll have muscle aches and periods of chills and sweats as fever comes and goes. You may also have a stuffy or runny nose, headache, and sore throat.
Symptoms of the flu usually develop suddenly, about three days after being exposed to the virus. It depends on the type of virus you were exposed to, but typically it takes 12 to 72 hours, or up to 3 days, before you start feeling sick.