Green beans

Green Beans are Our Food of the Week

This week we celebrate green beans, one of only a few varieties of beans that can be eaten fresh. Picked when they are still immature and the inner bean is just beginning to form green beans are a great source of folate, fiber and vitamin K.

For more on the Food of the Week

What's New and Beneficial about Green Beans

Because of their rich green color, we don't always think about green beans as providing us with important amounts of colorful pigments like carotenoids. But they do! Recent studies have confirmed the presence of lutein, beta-carotene, violaxanthin, and neoxanthin in green beans. In some cases, the presence of these carotenoids in green beans is comparable to their presence in other carotenoid-rich vegetables like carrots and tomatoes. The only reason we don't see these carotenoids is because of the concentrated chlorophyll content of green beans and the amazing shades of green that it provides.
You can enjoy green beans while supporting food sustainability! Recent surveys have shown that 60% of all commercially grown green beans are produced in the United States, with large amounts of green bean acreage found in the states of Illinois, Michigan, New York, Oregon, and Wisconsin. Although countries like France, Mexico, Iraq, and Argentina are large-scale producers of green beans, there is plenty of this delicious vegetable available in our own backyard.
If you are unable to obtain fresh green beans, you can still get many valuable nutrients from green beans that have been frozen or canned. We like fresh greens the best! But we realize that access to them can sometimes be a problem. When first frozen and then cooked, retention of some B vitamins in green beans (like vitamins B6 and B2) can be as high as 90%. Recent studies have shown that canned green beans, on average, lose about one third of their phenolic compounds during the canning process. They lose B vitamins as well but in the case of some B vitamins like folic acid, as little as 10%.
Green beans (referred to as "string beans" by the study authors) have recently been shown to have impressive antioxidant capacity. Research comparing the overall antioxidant capacity of green beans to other foods in the pea and bean families (for example, snow peas or winged beans) has found green beans to come out on top, even though green beans are not always highest in their concentration of specific antioxidant nutrients like phenolic acids or vitamin C. It's not surprising to find recent studies highlighting the antioxidant capacity of green beans! Researchers now know that the list of antioxidant flavonoids found in green beans is not limited to quercetin and kaemferol but also includes flavonoids like catechins, epicatechins, and procyanidins. Researchers also know that the antioxidant carotenoids in this vegetable are diverse, and include lutein, beta-carotene, violaxanthin, and neoxanthin, as noted above.
Green beans may be a particularly helpful food for providing us with the mineral silicon. This mineral—while less well known that minerals like calcium and magnesium—is very important for bone health and for healthy formation of connective tissue. Green beans have recently been shown to stack up quite well against other commonly-eaten foods as a good source of absorbable silicon.

WHFoods Recommendations

To retain the maximum number of health-promoting phytonutrients and vitamins and minerals found in green beans, we recommend Healthy Steaming them for just 5 minutes. This also brings out their peak flavor and provides the moisture necessary to make them tender, and retain their beautifully bright green color. It is best to cook green beans whole to ensure even cooking. For more on the Healthiest Way of Cooking Green Beans, see below.

Green Beans, cooked
1.00 cup
(125.00 grams)

Calories: 44
GI: very low

NutrientDRI/DV

vitamin K22.2%

manganese18%

vitamin C16.1%

fiber16%

folate10.3%

vitamin B29.2%

copper7.7%

vitamin B17.5%

chromium5.8%

magnesium5.6%

calcium5.5%

potassium5.2%

phosphorus5.1%

choline4.9%

vitamin A4.8%

vitamin B34.8%

protein4.7%

omega-3 fats4.5%

iron4.5%

vitamin B64.1%

vitamin E3.7%

This chart graphically details the %DV that a serving of Green beans provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Green beans can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Green beans, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

Health Benefits

Antioxidant Support from Green Beans

Best studied from a research standpoint is the antioxidant content of green beans. In addition to conventional antioxidant nutrients like vitamin C and beta-carotene, green beans contain important amounts of the antioxidant mineral manganese. But the area of phytonutrients is where green beans really shine through in their antioxidant value. Green beans contain a wide variety of carotenoids (including lutein, beta-carotene, violaxanthin, and neoxanthin) and flavonoids (including quercetin, kaemferol, catechins, epicatechins, and procyanidins) that have all been shown to have health-supportive antioxidant properties. In addition, the overall antioxidant capacity of green beans has been measured in several research studies, and in one study, green beans have been shown to have greater overall antioxidant capacity than similar foods in the pea and bean families, for example, snow peas or winged beans.

Cardiovascular Benefits

Just as you might expect, the antioxidant support provided by green beans provides us with some direct cardiovascular benefits. While most of the cardio research on green beans involves animal studies on rats and nice, improvement in levels of blood fats and better protection of these fats from oxygen damage has been shown to result from green bean intake. Interestingly, the green bean pod (the main portion of the green beans that provides the covering for the beans inside) appears to be more closely related to these cardio benefits that the young, immature beans that are found inside.

While not documented in the health research to date, we believe that the omega-3 fatty acid of content of green beans can also make an important contribution to their cardiovascular benefits. Most people do not even recognize green beans as a source of omega-3 fats! While there is a relatively small amount of the omega-3 fatty acid alpha-linolenic acid (ALA) in green beans, this amount can still be very important and is actually fairly large in comparison to the amount of calories in green beans. You get 1 milligram of ALA for every 4 calories of green beans that you eat. For every 4 calories of walnuts that you eat, you get 1.4 milligrams of ALA. So you can see that green beans—while not as concentrated in ALA as walnuts—are nevertheless an underrated source of this heart-protective nutrient.

Other Health Benefits

The strong carotenoid and flavonoid content of green beans also appears to give this vegetable some potentially unique anti-inflammatory benefits. For example, some very preliminary research in laboratory animals shows decreased activity of certain inflammation-related enzymes—lipoxygenases (LOX) and cyclooxygenases (COX)—following intake of bean extracts. Because type 2 diabetes is a health problem that is known to contain a basic component of chronic, unwanted inflammation, we are also not surprised to see some very preliminary research in the area of green bean intake, anti-inflammatory benefits, and prevention of type 2 diabetes. (The very good fiber content of green beans most likely adds to the potential of green beans to help prevent this common health problem.) We expect to see more research in both of these health benefit areas (anti-inflammatory benefits and prevention of type 2 diabetes).

Description

Commonly referred to as string beans, the string that once was their trademark (running lengthwise down the seam of the pod) can seldom be found in modern varieties. It's for this reason (the breeding out of the "string") that string beans are often referred to as "snap beans." Because they are picked at a younger, immature stage, "snap beans" can literally be snapped in half with a simple twist of the fingers. Although these bright green and crunchy beans are available at your local market throughout the year, they are in season from summer through early fall when they are at their best and the least expensive. You may also see them referred to as "haricot vert"—this term simply means "green bean" in French and is the common French term for this vegetable. This term can also refer to specific varieties of green beans that are popular in French cuisine because of their very thin shape and very tender texture

Green beans belong to the same family as shell beans, such as pinto beans, black beans, and kidney beans. In fact, all of these beans have the exact same genus/species name in science—Phaseolus vulgaris—and all can be referred to simply as "common beans." However, since green beans are usually picked while still immature and while the inner beans are just beginning to form in the pod, they are typically eaten in fresh (versus dried) form, pod and all. Green beans are often deep emerald green in color and come to a slight point at either end. Green bean varieties of this common bean family are usually selected for their great texture and flavor while still young and fresh on the vine. In contrast, dried bean varieties like pinto or black or kidney beans are usually selected for their ability to produce larger and more dense beans during the full time period when they mature on the vine. At full maturity, their pods are often too thick and fibrous to be readily enjoyed in fresh form, but the beans inside their pods are perfect for drying and storing.

History

Green beans and other beans, such are kidney beans, navy beans and black beans are all known scientifically as Phaseolus vulgaris. They are all referred to as "common beans," probably owing to the fact that they all derived from a common bean ancestor that originated in Peru. From there, they spread throughout South and Central America by migrating Indian tribes. They were introduced into Europe around the 16th century by Spanish explorers returning from their voyages to the New World, and subsequently were spread through many other parts of the world by Spanish and Portuguese traders. Today, the largest commercial producers of fresh green beans include Argentina, China, Egypt, France, Indonesia, India, Iraq, Italy, France, Mexico, the Netherlands, Spain, and the United States.

How to Select and Store

If possible, purchase green beans at a store or farmer's market that sells them loose so that you can sort through them to choose the beans of best quality. Purchase beans that have a smooth feel and a vibrant green color, and that are free from brown spots or bruises. They should have a firm texture and "snap" when broken.

Store unwashed fresh beans pods in a plastic bag kept in the refrigerator crisper. Whole beans stored this way should keep for about seven days.

Many people wonder about the possibility of freezing green beans, or purchasing green beans that have already been frozen. Both options can work—green beans are definitely a vegetable that can be frozen. We've seen several research studies on the nutritional consequences of freezing green beans, and most studies show the ability of green beans to retain valuable amounts of nutrients for 3-6 months after freezing. If you don't have fresh green beans available on a year-round basis, purchasing frozen green beans can definitely provide you with a nutritionally valuable option.

If you wish to freeze green beans we recommend that you steam the green beans for 2-3 minutes. Remove from heat and let them cool thoroughly before placing them in freezer bags and storing them in your freezer.

It is good to remember that the passage of time appears to lessen the concentration of multiple nutrients. There appears to be less nutrient loss at 3 months than at 6 months, and you may want to limit your freezer storage of green beans (whether frozen at home or pre-purchased in frozen form) to about 3 months for this reason.

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Thursday, March 27, 2014