The exact process by which garlic may be helping the body is not yet understood. Some of the substances found in garlic, such as sulfur-containing compounds, have been associated with specific health benefits and include the following:

Researchers continue to look for the specific sulfur–containing compounds that are responsible for reported health benefits.

In the context of heart health, garlic is often touted for the following benefits:

• Had similar effects to antioxidant vitamins (perhaps because it contains the antioxidants vitamin A, vitamin C and selenium). These effects included a reduction in plaque and prevention of further plaque buildup, which reduced the risk of atherosclerosis (hardening of the arteries).
  
  
• Improved circulation.
  
  
• Lowered blood pressure.
  
  
• Lowered levels of both cholesterol and blood fats (triglycerides), even when a very high-fat diet was consumed in short-term studies (1 to 3 months).
  
  
• Maintained elasticity (flexibility) of the major artery that pumps blood from the heart to the rest of the body (the aorta).
  
  
• Reduced the blood’s viscosity (stickiness), so it was less likely to clot.

While these results are impressive, they are contradicted by large analyses of previous studies, as well as at least one well-designed human study showing that there is insufficient data to draw any firm conclusions about garlic's effect on heart health. Most researchers agree that additional studies are necessary to determine if specific compounds in garlic can have beneficial health effects. Even though garlic may not significantly reduce cholesterol or blood pressure, it can be part of a healthy diet as it provides many heart-healthy antioxidants.