Vegetables

Asparagus

The fleshy green spears of asparagus are both succulent and tender and have been considered a delicacy since ancient times. This highly prized vegetable arrives with the coming of spring, when its shoots break through the soil and reach their 6-8 inch harvest length. In California the first crops are picked as early as February, however, their season generally is considered to run from April through May. The growing season in the Midwest and East extends through July.

What's New and Beneficial about Asparagus

• Recent research has underscored the value of careful storage and speedy consumption of fresh asparagus. The key scientific finding here involves respiration rate. Like all vegetables, asparagus doesn't instantly "die" when it is picked, but instead, continues to engage in metabolic activity. This metabolic activity includes intake of oxygen, the breaking down of starches and sugars, and the releasing of carbon dioxide. The speed at which these processes occur is typically referred to as "respiration rate." Compared to most other vegetables, asparagus has a very high respiration rate. At 60 milligrams of carbon dioxide release per hour per 100 grams of food (at a refrigerator temperature of 41°F), this rate is five times greater than the rate for onions and potatoes; three times greater than the rate for lettuce and tomato; and twice as great as the rate for cauliflower and avocado. Asparagus' very high respiration rate makes it more perishable than its fellow vegetables, and also much more likely to lose water, wrinkle, and harden. By wrapping the ends of the asparagus in a damp paper or cloth towel, you can help offset asparagus' very high respiration rate during refrigerator storage. Along with this helpful step, you will want to consume asparagus within approximately 48 hours of purchase.
• Wild asparagus (Asparagus racemosus) is a species of asparagus with a long history of use in India and other parts of Asia as a botanical medicine. Many medicinal qualities of wild asparagus have been associated with phytonutrients present in its roots, and especially one type of phytonutrients called saponins. Recent research has shown that the species of asparagus most commonly consumed in the U.S. (Asparagus officinalis) also contains saponins, not only in its root portion put also in its shoots. Saponins found in common, everyday asparagus include asparanin A, sarsasapogenin, and protodioscin. Asparagus even contains small amounts of the diosgenin - one of the best-studied saponins that is especially concentrated in yam. Saponins in food have repeatedly been shown to have anti-inflammatory and anti-cancer properties, and their intake has also been associated with improved blood pressure, improved blood sugar regulation, and better control of blood fat levels.
• You may have heard about two foods — chicory root and Jerusalem artichoke — that are widely recognized as providing health benefits for our digestive tract. These health benefits involve a special area of digestive support called "prebiotics" offered by a compound known as inulin. Both chicory root and Jerusalem artichoke contain rich concentrations of inulin, a unique type of carbohydrate called a polyfructan. Unlike most other carbs, inulin doesn't get broken down in the first segments of our digestive tract. It passes undigested all the way to our large intestine. Once it arrives at our large intestine, it becomes an ideal food source for certain types of bacteria (like Bifidobacteria and Lactobacilli) that are associated with better nutrient absorption, lower risk of allergy, and lower risk of colon cancer. Researchers now know that asparagus belongs among the list of foods that contain inulin. While approximately 5% lower in inulin than chicory root and Jerusalem artichoke, asparagus is a food that contains a valuable amount of unique carb and may provide our digestive tract with some equally unique health benefits.

Asparagus, cooked
1.00 cup
(180.00 grams)

Calories: 40
GI: very low

NutrientDRI/DV

 vitamin K101.2%

 folate67%

 copper33.3%

 vitamin B124.1%

 selenium19.9%

 vitamin B219.2%

 vitamin C18.4%

 vitamin E18%

 fiber14.4%

 manganese14%

 phosphorus13.8%

 vitamin B312.1%

 potassium11.5%

 choline11%

 vitamin A10%

 zinc9.8%

 iron9.1%

 protein8.6%

 vitamin B68.2%

 pantothenic acid8%

 magnesium6.3%

 calcium4.1%

Health Benefits

Anti-Inflammatory and Anti-Oxidant Benefits

It's not surprising to see asparagus being heralded as an anti-inflammatory food because it provides a truly unique combination of anti-inflammatory nutrients. Among these anti-inflammatory nutrients are asparagus saponins, including asparanin A, sarsasapogenin, protodioscin, and diosgenin. One of these saponins (sarsasapogenin) has been of special interest in relationship to amyotrophic lateral sclerosis (ALS), also known as "Lou Gehrig's Disease." Even though ALS is classified as a chronic, neurodegenerative disease and is not currently accepted as an autoimmune disorder, excessive, unwanted inflammation may play an important role in the death of certain nerve cells (motor neurons) in ALS. Other anti-inflammatory nutrients in asparagus include the flavonoids quercetin, rutin, kaempferol and isorhamnetin.

Alongside of these anti-inflammatory phytonutrients, asparagus provides a wide variety of antioxidant nutrients, including vitamin C, beta-carotene, vitamin E, and the minerals zinc, manganese, and selenium. In addition to the antioxidant nutrients above, this much-loved vegetable may also contain a valuable amount of the antioxidant glutathione (GSH). GSH is one of the body's best-studied antioxidants; it consists of three amino acids — glutamic acid, glycine, and cysteine — combined into one molecule. At least one published study has estimated the amount of GSH in fresh asparagus to average 28 milligrams per 3.5 ounces. Several studies have compared the overall antioxidant capacity of asparagus to the antioxidant capacity of other vegetables, and the results for asparagus have been impressive. Asparagus compares favorably with many of the cruciferous vegetables like cabbage and cauliflower, and while it ranks lower than some of the green leafy vegetables like spinach, it is still very high on the list of antioxidant foods.

Anti-inflammatory and antioxidant nutrients are some of the best risk reducers we know for common chronic health problems including type 2 diabetes and heart disease. These nutrients are also special risk reducers in the case of certain cancer — a special area of asparagus health benefits that is covered in the following section.

Digestive Support

As described earlier in our "What's New and Beneficial about Asparagus" section, asparagus is unusual as a digestive support food. One key factor in this regard is its inulin content. Like chicory root and Jerusalem artichoke, asparagus contains significant amounts of the nutrient inulin. Inulin is a unique type of carbohydrate called a polyfructan, and in practical terms, healthcare practitioners often refer to it as a "prebiotic." Unlike most other carbs, inulin doesn't get broken down in the first segments of our digestive tract. It passes undigested all the way to our large intestine. Once it arrives at our large intestine, it becomes an ideal food source for certain types of bacteria (like Bifidobacteriaand Lactobacilli) that are associated with better nutrient absorption, lower risk of allergy, and lower risk of colon cancer. While approximately 5% lower in inulin than chicory root and Jerusalem artichoke, asparagus is a food that contains a valuable amount of this unique carb and can help support our digestive health in this unique way.

Alongside of its unusual inulin content, asparagus is rich in fiber (about 3 grams per cup, including about 2 grams of insoluble fiber and 1 gram of soluble fiber) and also contains a noteworthy amount of protein (about 4-5 grams per cup). Both fiber and protein help stabilize our digestion and keep food moving through us at the desirable rate. (By contrast, too much fat can slow down our digestion rate more than desired, and too much sugar or simple starch can speed it up more than desired. We're not surprised to see species of asparagus like Asparagus racemosus (commonly known as Shatavari) having a long history of use in treatment of digestive problems in certain healthcare traditions (like ayurvedic medicine), and it makes sense to us that asparagus be considered as a great food for improving digestive support in most diets.

Heart Health and Blood Sugar Regulation

While we have yet to see large-scale dietary studies that examine chronic diseases in humans and asparagus intake, we would expect asparagus intake to show reduced chronic disease risk in two particular areas, namely, heart disease and type 2 diabetes. While there is some preliminary research in both areas, both areas need more attention from asparagus researchers. Our desire to see more research in these areas is based on several factors.

First is the amazing B-vitamin content of asparagus. In our food rating system, asparagus emerges as an excellent source of folic acid, vitamin B1, and vitamin B2 as well as a very good source of niacin, choline, vitamin B6, and pantothenic acid. Because B vitamins play a key role in the metabolism of sugars and starches, they are critical for healthy blood sugar management. And because they play a key role in regulation of homocysteine, they are critical in heart health has well. (Homocysteine is an amino acid, and when it reaches excessive levels in our blood, it is a strong risk factor for heart disease.)

Second, along with its impressive list of B vitamins, asparagus provides us with about 3 grams of dietary fiber per cup, including more than 1 gram of soluble fiber. Intake of soluble fiber has repeatedly been shown to lower our risk of heart disease, and our risk of type 2 diabetes can be significantly lowered as our intake of dietary fiber increases.

Finally, there is the anti-inflammatory/antioxidant factor. Heart disease and type 2 diabetes are both considered chronic diseases that evolve in relationship to chronic, excessive inflammation and oxidative stress. The outstanding antioxidant and anti-inflammatory nutrient composition of asparagus would seem to make it a no-brainer for inclusion as a risk reducer in both of these chronic disease areas. We expect future studies to establish asparagus as a standout for lowering our risk of cardiovascular and blood sugar problems.

Anti-Cancer Benefits

As a result of its very strong anti-inflammatory and antioxidant nutrient composition, we would definitely expect to see a food like asparagus showing up as a risk reducer for certain cancers. Chronic, excessive inflammation and chronic oxidative stress are risk factors for a variety of cancer types, and both unwanted phenomena are related to deficient dietary intake of anti-inflammatory and antioxidant nutrients—exactly the kind of nutrients that are especially plentiful in asparagus. Most of the studies we've seen on the anti-cancer benefits of asparagus have been studies on rats and mice, or studies on specific types of cancer cells. For this reason, we would describe asparagus cancer research as preliminary, and not yet validated by large-scale studies involving humans and dietary intake. But the trends in animal studies and cell studies are clear - asparagus and asparagus extracts can change the metabolic activity of cancer cell types, and these changes are protective in nature and related to better regulation of inflammation and oxidative stress. Cancer cells from the liver are best-studied in this regard.

One confusing area of research on asparagus and cancer involves leukemia. And while this arena has focused upon enzymes related to an amino acid in asparagus, rather than asparagus itself, we thought to include information on it here to clarify this arena for you in case you had come across information on this topic.

Leukemia is a type of cancer involving the bone marrow and its production of white blood cells. In leukemia, white blood cells are not produced in a normal way and do not behave in a normal way, and for these reasons are called leukemia cells. One unusual aspect of leukemia cells is their need to obtain a specific amino acid called asparagine from other cells or from the fluid portion of the blood. If leukemia cells can be prevented from obtaining asparagine, they can sometimes have difficulty surviving. In the mid-1950's and 1960's, researchers discovered that the injection of an enzyme called asparaginase into persons diagnosed with leukemia could sometimes result in decreased levels of blood asparagine in the blood and selective destruction of leukemia cells through asparagine deprivation. Prescription injection of asparaginase enzymes is still used in treatment of acute lymphoblastic leukemia (ALL). Asparagus has become entangled in this fascinating set of events involving leukemia because the name of the amino acid "asparagine" and the name of the enzyme "asparaginase" clearly imply a connection with asparagus. Both the amino acid and the enzyme are present in asparagus, just as their names imply. However, we are not aware of any research showing a treatment connection between leukemia and dietary intake of asparagus. The only research we've seen involves injection of the purified, prescription enzyme medication. In addition, we know that pharmaceutical companies do not use asparagus as a source of the asparaginase enzyme, but rather, rely on bacteria as their enzyme production source.

Description

Asparagus is a perennial garden plant belonging to the Lily family (Liliaceae). While approximately 300 varieties of asparagus have been noted, only 20 are edible.

Asparagus, its fleshy spears topped with bud-like compact heads, is often thought of as a luxury vegetable, prized for its succulent taste and tender texture. It is harvested in the spring when it is 6 to 8 inches tall. While the most common variety of asparagus is green in color, two other edible varieties are available. White asparagus, with its more delicate flavor and tender texture, is grown underground to inhibit its development of chlorophyll content, therefore creating its distinctive white coloring. It is generally found canned, although you may find it fresh in some select gourmet shops, and it is generally more expensive than the green variety since its production is more labor intensive. The other edible variety of asparagus is purple in color. It is much smaller than the green or white variety (usually just 2 to 3 inches tall) and features a fruitier flavor. It also provides benefits from phytonutrients called anthocyanins that give it its purple color. With prolonged cooking, the purple color may disappear.

History

Asparagus has been prized as an epicurean delight and for its medicinal properties for almost 2000 years. Its presence across most continents is partly due to its many different species. Some of these species — like Asparagus officinalis — are widely cultivated and consumed as staple foods. Other species - like Asparagus racemosus, widely found in India and the Himilayas - have been used in a more medicinal context. In the case ofAsparagus racemosus, also known as Shatavari, there is a long history of use in Ayurvedic medicine, especially in relationship to digestive problems. Various species of asparagus were cultivated by Egyptian cultures beginning as early as 3000 B.C., and by European cultures including early Greek and Roman cultures. Asparagus also became particularly popular in France during the 18th century during the rule of Louis XIV. In terms of commercial production, China (587,500 tons) and Peru (186,000 tons) are currently the world's largest producers and exporters of asparagus. Next in line as commercial producers are the United States (102,780 tons) and Mexico (67,247 tons).

How to Select and Store

Since asparagus varieties most commonly available in the U.S. are green in color, you are most likely to find these green-colored varieties in your grocery store. However, asparagus growers are able to take these same varieties of asparagus, pile dirt on top of the shoots when they start to poke through the ground, and then allow the shoots to continue growing beneath the dirt. This process prevents sunlight from falling on the shoots and results in asparagus shoots that are white in color. While you are most likely to find white asparagus in canned form, you can also find it fresh in some select gourmet shops, and it is generally more expensive than the green variety. Other varieties of asparagus can be purple in color. These varieties typically have a higher sugar content than green and white varieties and for this reason have a sweeter taste. (Of course, even with this higher sugar content, asparagus is anything but a high-sugar food. We're talking about 3 grams of total sugar per cup of fresh asparagus — less than half of the amount in an extra small apple.)

Asparagus stalks should be rounded, and neither fat nor twisted. Look for firm, thin stems with deep green or purplish closed tips. The cut ends should not be too woody, although a little woodiness at the base prevents the stalk from drying out. Once trimmed and cooked, asparagus loses about half its total weight. Use asparagus within a day or two after purchasing for best flavor and texture. Store in the refrigerator with the ends wrapped in a damp paper towel.

Tips for Preparing and Cooking