<qa>  What is the maximum dose and duration of the benefits of garlic?This study will seek to identify the compounds in garlic that is are responsible for its ability to prevent the formation of blood clots prevent platelet aggregation and to determine the maximally effective dose and duration of the benefits. This study will also determine whether cooked garlic garlic powder added to boiling water, no allicin present is as effective as fresh garlic garlic powder added to ambient water, high allicin present and, if more than one compound is involved, and whether their combined effects are more significant than the effects of each compound alone. 