As a member of the Allium family of vegetables, garlic shares some nutritional benefits with onions and leeks, which are also members of this Allium family. Other allium vegetables include chives, shallots, and scallions. At WHFoods, our minimum recommended daily intake level for allium vegetables is one-third serving per day. Our outstanding recommended intake is two-thirds serving per day. For onions and leeks, one-third serving would be one-third cup chopped and cooked. For garlic, one-third serving would be 2 cloves. To achieve outstanding daily intake, you would simply double these amounts. Our World' Healthiest Foods Meal Plan is a great place to start if you want to see how easy it is to incorporate garlic into your daily meals in a delicious and flavor-enhancing way.
While garlic ranks as an excellent source of manganese and vitamin B6, a very good source of vitamin C and copper, and a good source of selenium, phosphorus, vitamin B1, and calcium in our WHFoods rating system, it is the sulfur compounds in garlic that serve as its spotlight nutrients in terms of overall health benefits. The sulfur-containing compounds in this allium vegetable have been shown to provide us with health advantages in a wide variety of body systems, including: our cardiovascular system, immune system, inflammatory system, digestive system, endocrine system, and detoxification system. We'll start with a quick look at these unique sulfur-containing compounds.
The six categories of sulfur-containing compounds presented below will give you an initial look at the remarkable complexity of this allium vegetable. In terms of potential health benefits, each of these compounds has been studied fairly extensive. However, it is also worth noting here that the majority of studies have not focused on the presence of compounds in fresh garlic consumed as a food, but rather on garlic supplements, whether they be oils, tablets, powders, or other types of extracts.
While there are far more details here than can be covered in a summary food profile, we would like to point out two basic types of health benefits associated with these sulfur-compounds. First are the benefits associated with sulfur itself. Even though this mineral does not have public health recommendations associated with it and is not included as a DRI (Dietary Reference Intake) nutrient by the National Academy of Sciences, it is well-known to play a critical role in our health, especially in connection with cellular detoxification system, the health of our joints and connective tissue, and oxygen-related metabolism. It is important not to overlook this sulfur-richness of garlic since it is a property of garlic that is not found in most foods that we eat.
Second are the benefits associated with unique forms of sulfur in this food. At the top of the list here would be allicin and its breakdown products. As indicated above, allicin is a thiosulfinate. The most immediate breakdown products of this thiosulfinate are the diallyl sulfides and polysulfides (DAS, DADS, and DATS). But in the presence of other sulfur-containing groups called thiols, these sulfides can also release free hydrogen sulfide (H2S). This H2S may be involved in the cardiovascular benefits of garlic since it appears able to work synergistically with nitric oxide (NO) in optimizing blood vessel elasticity.
Garlic provides us with cardiovascular benefits in a variety of different ways. In fact, so diverse are these different pathways for cardiovascular support that new studies keep discovering new ways in which garlic helps protect this body system. By far the best researched of these pathways are the antioxidant and anti-inflammatory properties found in this allium vegetable. Chronic unwanted inflammation is, of course, a special risk within our blood vessels since it can contribute to damage of our blood vessel walls, formation of plaque, and eventual clogging of our blood vessels. The vinyldithiins, diallyl polysulfoxides, and a sulfur-containing compound called thiacremonone have been most closely associated with the anti-inflammatory activity of garlic in our cardiovascular system.
Right alongside of this anti-inflammatory support is the antioxidant support provided to our heart and blood vessels through consumption of garlic. In this antioxidant category, the many forms of cysteine found in garlic have received special research attention, as have the presence of glutathione and selenium. Of course, it is also important to remember that garlic is an excellent source of the antioxidant mineral, manganese, and a very good source of vitamin C, another key antioxidant nutrient. Finally, it has been interesting to see how the generation of pyruvate from sulfur-based interactions in garlic might be linked with the antioxidant health benefits provided by this vegetable. Researchers have long been aware of the capacity of pyruvate—a highly common organic acid present in many metabolic reactions throughout the body—to provide us with antioxidant support. However, a more recent research focus has involved the generation of pyruvate from garlic whenever the alliin in garlic gets converted into allicin. Each time that this conversion process occurs (with the help of the enzyme called alliinase), there is a potential for two molecules of pyruvate to be formed. Formation of pyruvate during this chemical reaction may be important in the provision of antioxidant benefits from this allium vegetable.
Finally, it would be important to include the anti-platelet activity of garlic's ajoene molecules in this summary of its cardiovascular health benefits. Platelets are one type of blood cell, just like red blood cells or white blood cells. On average, however, platelets are about five times smaller than red blood cells, and one of their key functions is to prevent excessive bleeding by helping seal off cuts and wounds. Under certain circumstances, however, the platelets can begin to clump together in a way that can eventually present us with health problems in the form of an unwanted blood clot. Researchers have demonstrated the ability of garlic's ajoenes to decrease our risk of unwanted clotting due to excessive platelet clumping (called platelet aggregation).
All types of health benefits from garlic described above combine together to make this allium vegetable helpful in reducing our risk of numerous cardiovascular diseases. Including in this list are: heart attack (myocardial infarct), coronary artery disease (CAD), high blood pressure (hypertension), and atherosclerosis. In addition, it is worth noting that the everyday flexibility of our blood vessels has been shown to improve with intake of garlic.
No area of garlic health benefits has gotten more publicity than its potential for reducing our risk of cancer. However, as an overall observation, we would describe the garlic-cancer studies are providing mixed findings, with some studies showing significantly reduced risk and other failing to show those results. From our perspective, one missing component in the cancer research on garlic is a focus on garlic in its food form. Too many studies exclusively investigate supplement forms of garlic including softgels contain garlic oil or capsules/tablets containing garlic powder extracts.
The most consistent cancer prevention results from intake of garlic involve cancers of the digestive tract. However, there seems to be a division here in the research between cancers of the upper versus lower digestive system. The sulfur compounds in garlic seem consistently helpful in lowering our risk of squamous cell carcinoma (one type of cancer) throughout our upper aero-digestive tract (UADT). Included in this region is our mouth, pharynx, larynx, and esophagus. In some situations, scientists have been able to identify not only contributing causes to cancer development (like chronic cigarette smoking) but also compounds in garlic that inhibit this cancer development process (like diallyl disulfides, or DADs). After risk reduction for cancers of the UADT, risk reduction for stomach cancer (also called gastric cancer) is the next strongest link in recent studies on garlic and cancer prevention. However, intestinal-site cancers—especially colorectal cancers in our lower (large) intestine—do not seem consistently reduced in incidence following consumption of garlic. In fact, we've seen one recent meta-analysis of 14 studies in this area that showed no statistical reduction in colorectal cancer risk following garlic intake. These results do not mean that consumption of garlic is bad for your lower digestive tract! However, they do raise questions about the ways in which garlic might help prevent occurrence of digestive tract cancers and why studies would show better protection occurring in the upper versus lower digestive tract.
For other cancer sites through the body, there just isn't enough large-scale human research available to draw reliable conclusions. However, two key issues that need to be carefully addressed in future studies are (1) the role of garlic compounds in helping lower toxin-related damage to our cells through support of our cellular detoxification systems and (2) the role of garlic compounds in helping reduce risk of infection through antibacterial, antiviral, and antifungal properties. Poor detoxification of contaminants in our body and excessive presence of potentially infectious agents are processes known to be involved with risk of certain cancers. Equally well known is the ability of garlic compounds to influence our detox processes as well as our infection risks.
As mentioned in the section above, sulfur-containing compounds in garlic have been shown to support our body's detox processes, especially processes involving sulfur or the role of glutathione-S-transferase (GST) enzymes. Also of special interest in this detox area has been the potential role of garlic's allyl sulfides.
The antibacterial, antiviral, and antifungal properties of garlic are fairly well studied, although not necessarily within the context of human diseases and their development. And like the cancer studies on garlic, most of these antimicrobial studies have involved the use of garlic supplements rather than its food form. Due to the strong research interest in garlic and gastric cancer, several studies have examined the potential for garlic compounds to help prevent overgrowth of the bacterium Helicobacter pylori in the stomach or overadherence of this bacterium to the stomach wall. However, results in this area have been mixed. In several studies, the ajoenes present in garlic have been successfully used to help prevent infections with the yeast Candida albicans. We have also see a study showing the ability of crushed fresh garlic to help prevent infection by the bacterium Pseudomonas aeruginosa in burn patients.
One exciting new area of research involves the potential role of garlic to support bone health. As mentioned earlier in this article, the diallyl disulfides (DADS) in garlic have been identified as the garlic compounds that help protect our cardiovascular system from damage by cigarette smoke. With respect to bone health, studies have shown that cigarette smoking increases our risk of osteoporosis, inadequate bone mineral density, and inability to heal from bone fractures. Conversely, intake of garlic may be able to reduce risk of these problems by offsetting some of the potential damage caused by chronic exposure to cigarette smoke. Especially interesting in this context is the potential of garlic to help protect osteoblast cells from damage. Osteoblasts are bone cells that help produce new bone matrix. If garlic intake can help protect these cells from potential damage by cigarette smoke, it may be able to help support formation of new bone matrix and maintenance of existing bone structure.
A final promising area of research on the potential health benefits of garlic involves blood sugar regulation. One focus in this area involves a hormone released by our fat cells called adiponectin. When there is too little adiponectin in our blood, our risk of type 2 diabetes and certain cardiovascular problems gets increased. In what we would describe as preliminary studies, 12 weeks of garlic consumption has been shown to increase blood levels of adiponectin in human participants. Researchers believe that this process may be closely connected with simultaneous production of another key regulatory molecule called nitric oxide. While more follow-up studies are needed, these initial results show a potential for garlic intake to lower our risk of type 2 diabetes through what would be called hormone-related pathways. We have also seen a recent research showing significant decreases in fasting blood sugar levels following garlic intake. The authors of this research actually combined results together from seven previous studies to do a more robust analysis of the garlic-fasting blood sugar relationship. In their conclusions, these researchers suggested further confirmation of blood sugar impacts by examining other markers of blood sugar regulation including PPG (postprandial glucose, i.e., the amount of sugar in our blood following a meal) and hemoglobin A1C (the percent of red blood cells to which sugar becomes attached).
Garlic—together with onions—are among the best known of all "allium vegetables." Both of these plants (garlic and onions) belong to the same genus of plants called the Allium genus. "Allium" is actually the Latin word for garlic! Other commonly enjoyed foods that belong to this Allium genus are leeks, chives, scallions, and shallots.
Unlike this genus grouping for garlic which is very straightforward, the food family for garlic can be confusing. The correct placement for garlic is within the very broad amaryllis family (Amaryllidaceae) that includes the very popular flower by that same name. The Allioideae are a subfamily within the amaryllis family and garlic (Allium sativum) is a member of this Allioideae subfamily, along with onions, leeks, chives, scallions, and shallots.
The reason for some confusion here is two-fold. First, there was a time when garlic and other allium vegetables were assigned to their own family of plants called the Alliaceae family. Second, there was also a time when garlic and the other allium vegetables were assigned to the Lillaceae plant family. As scientists have learned more about the history of plant genetics, they have found it necessary to juggle these classification categories to best fit the newly discovered genetic relationships. Of course, none of these shifts in family classification makes garlic any less reliable as a nutrient-rich, health-supportive food.
Garlic is arranged in a head, called a "bulb," which averages about 2 inches in height and diameter and consists of numerous small separate cloves. Both the cloves and the entire bulb are encased in paper-like sheathes that can be white, off-white, or have a pink/purple hue. Although garlic cloves have a firm texture, they can be easily cut or crushed. The taste of garlic is like no other—it hits the palate with a hot pungency that is shadowed by a very subtle background sweetness.
Most producers of garlic divide its varieties into four types: hardneck, softneck, black, and Creole. Hardneck garlic, like the name suggests, has a central stalk that is hard and woody. Purple Stripe is a popular variety of hardneck garlic, as are Rocambole and Porcelain. In the case of Purple Stripe and other hardneck varieties, you will typically find a light purplish or rosy tint to small portions of the cloves and skins. Hardneck varieties of garlic typically have more "bite" than softnecked varieties. Allium sativum subspecies ophioscorodon is usually the subspecies name to refer to hardneck garlics.
Softneck varieties of garlic are the most common types that you will find in the grocery store. They typically have less "bite" than hardneck varieties. Formidable, Western Rose, Artichoke, and Silverskin are popular varieties of softneck garlic. Allium sativum subspecies sativum is usually the subspecies name to refer to softneck garlics. Softneck varieties of garlic are also typically the types that you find braided in the supermarket.
You will find a good bit of agricultural information on garlic that treats "Creole garlic" as a type of softneck. However, there is also some genetic evidence to suggest that Creole garlic be treated as its own type of garlic, separate from softneck. Creole garlic is usually recognizable by from the rosy/purplish color of the entire garlic bulb (and not just intermittent rosy hues as can be present in hardneck varieties). You are less likely to come across this variety of garlic in the grocery store. Worldwide, however, well-known varieties of Creole garlic include Burgundy, Ajo Rojo, Cuban Purple, and Creole Red.
Heat treatment, high humidity, and aging are typically the processes used to create black garlic. Particularly when the aging process is allowed to continue not only over the course of several days but over the course of several weeks (or even longer), the color of the garlic cloves can turn into a rich black. This variety of garlic has a special history of popularity in parts of Korean, Japan, and Thailand. Although you will often hear the term "fermented garlic" being used to describe black garlic, the use of this term is a matter of some controversy since microorganisms (like bacteria) are not typically added during the garlic aging process to help produce black garlic. (In the world of food, "fermentation" is usually understood to involve the use of bacteria or yeasts in development of a "fermented food.")
Elephant garlic (Allium ampeloprasum) is an unusual type of garlic because it is actually more closely related to leeks (Allium porrum) than to garlic (Allium sativum). When you see elephant garlic growing, its tall flower stalk and large purplish flower head make it seem like an extremely large version of normal garlic—and thus the name. Unlike leeks, however, elephant garlic does form a bulb, and this bulb usually consists of very large cloves that are few in number. (Elephant garlic bulbs may sometimes have only three to four cloves per bulb.)
Two other terms that are important to include in any description of garlic are scapes and ramps. Scapes is a term that is used to refer to the stalks that grow in the middle of hardneck garlic varieties and hold the flowers of the garlic plants. In other words, we are talking about the "greens" of hardneck garlic (versus the root bulb). Ramps (often called wild leeks, wild onions, or spring onions) are a unique species of garlic (Allium tricoccum) that scientists view as a very close relative of wild garlic (Allium vineale). The flavor of ramps is like a blend of pungent garlic and sweet onion. In terms of appearance, ramps look a good bit like scallions. Both scapes and ramps can be enjoyed in a food plan!
Few foods have been enjoyed for such a long period of time and in so many different parts of the world as garlic. There is evidence that garlic originally grew wild in locations as diverse as China, India, Egypt, and what is now Ukraine. At the present time, because wild garlic only grows prolifically in the area represented by Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan, this region is considered by some to be the "center of origin" for this remarkable food. Regardless of its center of origin, however, garlic has been cultivated for thousands of years in diverse regions of the world and has become a staple in cuisines across many continents.
China is by far the world's largest commercial producer of garlic, with 20 million tons of production in 2014. In that same year, India was the second largest producer with about 1.25 million tons, and South Korea, Egypt, and Russia rounded out the top five countries for garlic production. Between 50-75% of all garlic consumed in the U.S. is currently grown in China. Mexico and Argentina are also important sources for garlic imports into the U.S. At present, the U.S. serves as the number one import market for fresh garlic worldwide. This demand for fresh garlic in the U.S. is clearly reflected in our increased history of use: on a per capita basis, U.S. adults average about 2 pounds of garlic per year, as compared with less than ½ pound per year in the early 1970's.
Within the United States, 80-90% of all garlic comes from California. Two regions of the state are especially important for garlic production: the western San Joaquin Valley and the area west of the Diablo mountain range. Much smaller amounts of garlic are grown commercially in Oregon, Nevada, and Arizona.
For maximum flavor and nutritional benefits, always purchase fresh garlic. Although garlic in flake, powder, or paste form may be more convenient, you will derive less culinary and health benefits from these forms.
Purchase garlic that is plump and has unbroken skin. Gently squeeze the garlic bulb between your fingers to check that it feels firm and is not damp.
Avoid garlic that is soft, shriveled, and moldy or that has begun to sprout. These may be indications of decay that will cause inferior flavor and texture. Size is often not an indication of quality. If your recipe calls for a large amount of garlic, remember that it is always easier to peel and chop a few larger cloves than many smaller ones.
Fresh garlic is available in the market throughout the year.
At WHFoods, we encourage the purchase of certified organically grown foods, and garlic is no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including garlic. In many cases, you may be able to find a local organic grower who sells garlic but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown garlic is very likely to be garlic that displays the USDA organic logo.
Store fresh garlic in either an uncovered or a loosely covered container in a cool, dark place away from exposure to heat and sunlight. This will help maintain its maximum freshness and help prevent sprouting, which reduces its flavor and causes excess waste. It is not necessary to refrigerate garlic. Some people freeze peeled garlic; however, this process reduces its flavor profile and changes its texture.
Depending upon its age and variety, whole garlic bulbs will keep fresh for about a month if stored properly. Inspect the bulb frequently and remove any cloves that appear to be dried out or moldy. Once you break the head of garlic, it greatly reduces its shelf life to just a few days.
We actually include garlic as an ingredient in so many of our recipes. To find these just go to the Recipe Assistant on the Recipes page and click on "garlic" in the "Food to Include" box.
If you'd like even more recipes and ways to prepare garlic the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.
|vitamin B6||0.22 mg||13||8.7||excellent|
|vitamin C||5.62 mg||7||5.0||very good|
|copper||0.05 mg||6||3.7||very good|
|vitamin B1||0.04 mg||3||2.2||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%