You can increase the health benefits you receive from garlic by letting it sit after you've chopped it or crushed it. If you give your chopped/crushed garlic time to sit before changing its temperature (through cooking) or its pH (through the addition of an acidic food like lemon juice), it will give the alliinase enzymes in garlic an opportunity to work on behalf of your health. For example, in the absence of chopping or crushing, research has shown that just 60 seconds of immediate microwaving will cause garlic to lose some of its cancer-protective properties. Immediate boiling of whole, intact garlic will also lower these properties, as will immediate addition of a very low-acid ingredient like lemon juice.
Some of garlic's unique components are most durable in food (versus processed extract) form. Allicin-one of garlic's most highly valued sulfur compounds-stays intact for only 2-16 hours at room temperature when it is present in purified (extracted) form. But when it's still inside of crushed garlic, allicin will stay viable for 2-1/2 days.
Garlic may help improve your iron metabolism. That's because the diallyl sulfides in garlic can help increase production of a protein called ferroportin. (Ferroportin is a protein that runs across the cell membrane, and it forms a passageway that allows stored iron to leave the cells and become available where it is needed.)
In addition to being a good source of selenium, garlic may be a more reliable source as well. Garlic is what scientists call a "seleniferous" plant: it can uptake selenium from the soil even when soil concentrations do not favor this uptake.
The cardioprotective benefits of garlic may partly rest on the production of hydrogen sulfide (H2S) gas. Our red blood cells can take sulfur-containing molecules in garlic (called polysulfides) and use them to produce H2S. This H2S in turn can help our blood vessels expand and keep our blood pressure in check. Interestingly, some processed garlic extracts cannot be used by our red blood cells in the same way and do not seem to provide the same level of cardioprotection that is provided by garlic in food form.
While still in its very early stages, research suggests that garlic consumption may actually help to regulate the number of fat cells that get formed in our body. 1,2-DT (1,2-vinyldithiin) is one of the unique sulfur compounds in garlic that has long been recognized as having anti-inflammatory properties. But only recently have researchers discovered that some of our fibroblastic cells (called "preadipocytes") only evolve into full-fledged fat cells (called "adipocytes") under certain metabolic circumstances involving inflammatory system activity. 1,2-DT may be able to inhibit this conversion process. Since obesity is increasingly viewed by researchers as a chronic state of low-grade inflammation, the inflammation-related benefits of garlic's 1,2-DT may eventually be extended into the clinical area of obesity.