I began taking a garlic oil supplement or a small clove a day last summer. While I did notice a few side effects, the positives far outweighed the negative. POSITIVES first: improved mouth health - less aching, irritation, sensitivity. Vastly improved resistance to colds and/or sickness - I took garlic every day for at least four months, and noticed an increased immune response in times where I would normally already be sick - colds, coughs, anything. Cardiovascular health - greatly improved erections, ability to sustain longer periods of intense exercise. NEGATIVES - dry hair - for some reason my hair is more straw-like. I'm a guy and generally take good care of my hair, and I noticed this easily. Mood - I tend toward a little more grumpiness for some reason - I don't know why this is the case but it has been. I will try cutting down on my dosage to see if it helps. Headaches - this only happens when I take too much, which is caused by I assume to be too much thinning of the blood. All in all, for the the immune factor itself, I count this as a life-long food!