By Dr. James A. Duke in The Green Pharmacy Guide to Healing Foods
I usually don't play favorites, but when it comes to foods, garlic tops my list of healers. Though a recent high-profile study called its cholesterol-lowering ability into question, it still has enough heart-protective benefits to rank high on my list. It has other great qualities as well, including immunity-boosting and antiseptic properties. Onions share many of the properties and healthful benefits of garlic, so they also deserve a mention here. And in my Farmacy, I grow a nice batch of ramps, members of the garlic/onion family that you won't find in many supermarkets (unless it's ramp festival time in West Virginia and Ohio). All of these plants contain the very important compound alliin, which converts to the super-medicinal allicin.
Nutrient Nuts and Bolts: When it comes to the heart, you can thank garlic's many sulfur compounds, including diallyl disulfide, which prevent clotting and allow for smooth blood flow. Of course, garlic also contains over a dozen immunity-boosting compounds that can fight off colds and other infections, maybe even more effectively than popular herbs like echinacea. Recent research has also shown that several compounds in garlic can prevent cellular changes within the body that lead to cancer.
Onions offer many of the same sulfur compounds as garlic, but they bring even more to the table with their high amounts of flavonoids, specifically quercetin. This flavonoid has been shown in studies to reduce platelet clumping and even prevent some forms of cancer. So far, there is no better food source of quercetin than onion skins.
How to Get More: The other advantage of garlic and onions is just how easy they are to incorporate into your menus. I add both to virtually all my soups and stews. And when it comes to salads, just about the only dressing you'll see me use is vinegar and oil mixed with fresh garlic and fresh diced onion, often with hot sauce or diced hot pepper. That mixture alone has hundreds of healthful compounds. Sometimes I even roast garlic and put it on toast for breakfast.
Making the Most of Them: Now I know what you're thinking: "But Dr. Duke, what about the smell?" Well, as much as it pains me to say it, studies have shown time and again that the more garlic stinks, the better it works.
That's why I often use it raw in salads or even eat whole cloves of the stuff if I don't have anything social going on that day.
This isn't to say that you can't get benefits from cooked garlic; you can. But you lose 40 percent of the original potency after garlic is cooked for 10 minutes, and you lose much more after 20 - but you never lose it all. So, if you're making a soup or stew, it might be a good idea to wait until near the end of the cooking time to add garlic. Green tea, parsley, and coriander all have a unique ability to partially quell the smell, so you may want to consider brewing green tea and garlic together or adding parsley to a garlicky salad. Or if you have a new potential client or lover or relative coming over, eat some parsley or coriander and drink some green tea quick!
Other Eating Tips: If you're going for full effect and eating whole cloves of garlic, it's important that you nick the surface of a clove first; that is, don't swallow it intact. I thought that was the way to go until my garlicologist, Larry Lawson, PhD, told me the skin should be broken before garlic enters the GI tract to get its benefits. This ensures that the medicinal compounds of the bulb are released and will begin working more quickly in the body.
Now back to onions for a minute. In one of the funny quirks of nature, most of the helpful flavonoids, such as quercetin, are found in the skin of the onion. That's why I always put the skins in a mesh bag and steep it in soups and stews when I'm making them. Just remove the bag before serving.