Most of the health benefits that are touted for garlic are more anecdotal than based on scientific studies. Below are the benefits observed in the studies (there have been a lot of them). I believe that a lot of the differences in studies observed have to do with the kind of garlic used, fresh or dried as used in supplements and food spices. The fresh garlic seems to have more of an effect.

1.) Garlic preparations may have small, positive, short-term effects on bloodstreatm lipids; it is not know if the effects are sustainable beyond 3 months.

2.) There is some promise of activity to help in the treatment of thromobosis, but there is not enough data for a definite conclusion.

3.) A possible decreased risk of laryngeal, gastric, colorectal, and endometrial cancers, and adenomatous colorectal polyps.

4.) Although there is not a consistent reduction in blood pressure across studies A meta-analysis of many studies supports that claim.

5.) A fresh chewed garlic study indicated that it reduces cholesterol, triglyceride, Malondialdehyde and blood pressure.

6.) A fresh paste has positive effects on oral yeast infection. It works as well as the antibiotic chlorhexidine.

7.) Infants breastfeeding time is reduced when mothers ingest garlic in their food.

Benefits not found in the studies included:

1.) Effects on glucose or insulin sensitivity

2.) Use of garlic supplements less than 3-5 years is not associated with decreased risks of breast, lung, gastric, colon or rectal cancer.

Garlic help in digestion of food, prevent gastric problem and reduces cholesterol if eaten raw in the morning. In India there is another type of garlic called Garlic Pearl which is genetically created garlic, looks just like a medium sized pearl but has no smell and is only used to eat as a medicine in morning.

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Allium sativum, commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, and chive. Garlic has been used throughout recorded history for both culinary and medicinal purposes. It has a characteristic pungent, spicy flavor that mellows and sweetens considerably with cooking.
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information obtain from http://en.wikipedia.org/wiki/Garlic

Health benefits are
1.Treat symptoms of acne
2.It can assist in the reduction of managing high cholesterol levels
3.Natural antibiotic
4.Healthy Antioxidant
5.It can help prevent colds
6. Help prevent Blood Clots

You can read the page on this links to see the benefits of garlic also the links have the information of the benefits mentioned.
http://www.garlic-central.com/garlic-health.html
http://naturalhealthremedies.org/what-are-the-health-benefits-of-garlic/

i dont know but fresh garlic is the best for cooking i use it on evreything.