I chew a clove of garlic and wash it down with water. If you peel a
clove and let it sit or even refrigerate it, it begins to lose the allicin
within about 10 minutes and if it sits over night the allicin is gone. The
allicin is what is believed to give garlic it health benefits. Do not mix
garlic and oil and store it that way because if there is any fungus on the
garlic, it can grow while in the oil and create enough poison to kill you (and
has done so).
Heating and cooking garlic also causes it to loose its allicin, so raw is
best. However, the Japanese have done a lot of university level research
regarding the health benefits of garlic and have produced a super garlic that
they age and encapsulate in a product called Kyolic. It is expensive for
what you get, but supposedly has lots of benefits. There are also other
high allicin garlics such as Pur-Gar and there are arguments for both
kinds. I prefer mine raw, though I do include it in cooking when I can.