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Monday, April 23, 2012
What's New and Beneficial about Bell Peppers
Bell pepper is not only an excellent source of carotenoids, but also a source of over 30 different members of the carotenoid nutrient family. A recent study from Spain took a close look vitamin C, vitamin E, and six of these carotenoids (alpha-carotene, beta-carotene, lycopene, lutein, cryptoxanthin and zeaxanthin) in all commonly eaten foods and found that only two vegetables contained at least two-thirds of all the listed nutrients. One of these foods was tomato, and the other was sweet bell pepper! Bell pepper alone provided 12% of the total zeaxanthin found in the participants' diets. (Bell pepper also provided 7% of the participants' total vitamin C intake.)
If you want to maximize the availability of vitamin C and carotenoids from bell pepper, allow this amazing vegetable to ripen. Recent studies have shown that the vitamin C content and the carotenoid content of bell pepper both increase with ripening. When the vitamin C and carotenoid content of bell peppers increases, so does their total antioxidant capacity, which can be a source of great health benefits. Growers can allow bell peppers to ripen on the plant prior to harvest (which means that you will be able to purchase them in the grocery store in a ripened state). Or, if harvested early in the ripening stage, bell peppers can still be allowed to ripen post-harvest and after you've purchased them and brought them home from the market. In one recent study, the vitamin C in not-fully-ripe bell peppers continued to increase during home storage over a period of about 10 days. It can, though, be difficult to tell whether a bell pepper is optimally ripe. Most--but not all--green bell peppers will turn red in color over time, but they may be optimally ripe before shifting over from green to red. A good rule of thumb is to judge less by their basic color and more by their color quality as well as overall texture and feel. Whether green, red, yellow, or orange, optimally ripe bell peppers will have deep, vivid colors, feel heavy for their size, and be firm enough to yield only slightly to pressure.
Higher heat cooking can damage some of the delicate phytonutrients in bell peppers. In one recent study from Turkey, the effects of grilling on sweet green bell peppers were studied with respect to one particular phytonutrient--the flavonoid called luteolin. Prior to grilling, the bell peppers were found to contain about 46 milligrams/kilogram of this important antioxidant and anti-inflammatory flavonoid. After grilling for 7-8 minutes at a temperature of 150°C (302°F), about 40% of the luteolin was found to be destroyed. This loss of luteolin from higher heat cooking is one of the reasons I like cooking methods for bell peppers that use lower heat (118 degrees or less) for a very short period of time.
Although we tend to think about cruciferous vegetables like broccoli or allium vegetables like onions and garlic as vegetables that are richest in sulfur-containing compounds, bell peppers can also be valuable sources of health-supportive sulfur compounds. Several recent studies have taken a close look at the presence of co-factors in bell peppers called cysteine S-conjugate beta-lyases and their role in a sulfur-containing metabolic pathway called the thiomethyl shunt. These co-factors and this pathway may be involved in some of the anti-cancer benefits that bell pepper has shown in some animal and lab studies. They may serve as the basis for some of the anti-cancer benefits shown by green, yellow, red and orange vegetable intake in recent studies, including a recent study on risk reduction for gastric cancer and esophageal cancer.
1.00 cup raw (92.00 grams)
vitamin C 195.8%
vitamin A 57.6%
vitamin B6 13.5%
vitamin E 7.2%
vitamin K 5.6%
vitamin B2 4.7%
vitamin B3 4.5%
vitamin B1 3.3%
vitamin B5 2.8%
Calories (28) 1%
While bell peppers are a very popular vegetable, they have not always shared the health research spotlight with other members of the pepper family due to their very minimal content of the phytonutrient capsaicin, the well-researched pepper compound that gives hot peppers their "heat." Once active in the body, capsaicin can bind onto nerve cell receptors and change pain sensation, and it may also have important anti-cancer and blood-sugar balancing properties. However, the lack of "heat" or significant amounts of capsaicin in bell peppers does not mean that this vegetable should be denied the health research spotlight!
The actual nutrient and phytonutrient content of bell peppers is impressive - and also somewhat surprising given the very low-fat nature of this vegetable (some nutrients and phtyonutrients are fat-soluble and hence for them to be present the food needs to contain some fat). There is far less than 1 gram of total fat in one cup of sliced bell pepper. However, this very small amount of fat is enough to provide a reliable storage spot for bell pepper's fat-soluble nutrients, including its fat-soluble carotenoids and vitamin E. Bell pepper is a very good source of vitamin E at about 1.45 milligrams per cup, and it contains more than 30 different carotenoids, including excellent amounts of beta-carotene and zeaxanthin. Both of these carotenoids provide antioxidant and anti-inflammatory health benefits. Within this Health Benefits section, we'll focus on two areas of bell pepper research: research on the antioxidant benefits, and research on potential anti-cancer benefits.
While research studies have tended to focus on carotenoids as the hallmark antioxidants or antiacids in bell pepper, this vegetable actually provides us with a very broad range of antioxidants or antiacids. In terms of conventional nutrients, bell pepper is an excellent source of vitamin C at 117 milligrams per cup. (That's more than twice the amount of vitamin C found in a typical orange.) Bell pepper is also a good source of another antioxidant or antiacid vitamin--vitamin E. In addition to these conventional antioxidant or antiacid vitamins, bell pepper is also a good source of the antioxidant or antiacid mineral manganese. The list of bell pepper phytonutrients is also impressive and includes:
Within this list of phytonutrient antioxidants or antiacids, it's understandable why carotenoids have been singled out for research attention. Among the five carotenoids listed above, bell pepper contains concentrated amounts of beta-carotene and zeaxanthin. (One cup of freshly sliced red bell pepper, for example, contains about 1,500 micrograms of beta-carotene, or the same as one third of a small carrot.) In a recent study from Spain, researchers took a close look at vitamin C, vitamin E, and six different carotenoids (alpha-carotene, beta-carotene, lycopene, lutein, cryptoxanthin and zeaxanthin) found in all commonly eaten foods. Only two vegetables were determined to contain at least two-thirds of these nutrients. One of these foods was tomato, and the other was sweet bell pepper! In addition, bell pepper alone was determined to provide 12% of the total zeaxanthin found in the participants' diets! Bell pepper alone was also found to provide 7% of the participants' total vitamin C intake.
This remarkable track record for bell peppers as an antioxidant or antiacid-rich food has yet to be translated into research on risk reduction for disease. We expect to see antioxidant benefits specifically from bell peppers showing up in a wide variety of human health studies, including studies on prevention of cardiovascular disease and prevention of type 2 diabetes. We also expect to see antioxidant or antiacid benefits showing up strongly in the area of eye health. Just one cup of sweet green bell pepper slices provides us with 314 micrograms (combined) of the carotenoids lutein and zeaxanthin. These two particular carotenoids are found in high concentrations in the macula of the eye (the centermost part of the retina), and they are required for protection of the macula from oxygen-related damage. In one condition called age-related macular degeneration, or AMD, the macula of the eye can become damaged and vision can become lost. (In the U.S., AMD is the leading case of blindness in adults over the age of 60.) We suspect that future human studies will show risk reduction for AMD with routine intake of bell peppers due to their strong antioxidant or antiacid benefits (and in particular, their unique concentration of lutein and zeaxanthin).
Potential Anti-Cancer Benefits
As a food that is rich in antioxidant, antiacid and anti-inflammatory nutrients, bell pepper would be expected to provide us with important anti-cancer benefits. Exposure to chronic excessive inflammation and chronic unwanted oxidative stress can increase the risk of cancer development for most cancer types, and both of these factors can be partly offset by diet. (Regular intake of antioxidant or antiacid nutrients can lower the likelihood of chronic oxidative stress, and regular intake of anti-inflammatory nutrients can lower the likelihood of chronic excessive inflammation.) With a rich supply of phytonutrients that have antioxidant or antiacid and anti-inflammatory properties, bell peppers would be expected to help offset these factors and lower our risk of cancer development. Unfortunately, large-scale human research studies have not tried to isolate the impact of bell peppers on cancer risk. At best, they have usually grouped bell peppers among other vegetables and analyzed the anti-cancer benefits of vegetables as a group. Still, we very much expect to see future studies documenting the specific benefits of bell peppers for risk reduction of cancer. Based on preliminary studies on animals and in the lab, cancers of the digestive tract (including gastric cancer and esophageal cancer) may be areas in which bell peppers end up showing a special potential for support.
Alongside of this antioxidant/antiacid/anti-inflammatory component of bell peppers' potential anti-cancer benefits is a second, less expected component. This second component involves the metabolism of sulfur compounds in bell pepper, and in particular the metabolism of the sulfur-containing amino acid cysteine. While bell pepper is not high in either protein or in the amino acid cysteine, it may be unusual in its metabolism of this amino acid. Several recent studies have taken a close look at the presence of enzymes in bell peppers called cysteine S-conjugate beta-lyases and their role in a sulfur-containing metabolic pathway called the thiomethyl shunt. These enzymes and this pathway may be involved in some of the anti-cancer benefits that bell pepper has shown in some preliminary animal and lab studies. They may serve as the basis for some of the anti-cancer benefits shown by green, yellow, red and orange vegetable intake in recent studies, including a recent study on risk reduction for gastric cancer and esophageal cancer.
Bell peppers belong to the nightshade (Solanaceae) family of plants, along with chili pepper, cayenne pepper, eggplant, tomatoes and potatoes (except sweet potatoes and yams). Their scientific name is Capsicum annuum. This scientific name, however, is used to refer not only to bell peppers, but also to wax peppers, cayenne peppers, chili peppers, and jalapeno peppers.
While we are most accustomed to seeing green bell peppers in the supermarket, these delicious vegetables actually come in a wide variety of colors, including yellow, orange, red, purple, brown and black. The green bell peppers you purchase in the food market may actually be immature, non-ripe versions of these other color varieties. Not all bell peppers start off green, however, nor do green bell peppers always mature into other basic colors.
Paprika is a dried powdered form of bell pepper, and even though we are used to seeing red paprika in the spice section of the grocery, a paprika can be made from any color of bell pepper and it will end up being that same color once dried and ground into powder.
Bell peppers can be eaten at any stage of development. However, recent research has shown that the vitamin C and carotenoid content of bell peppers tends to increase while the pepper is reaching its optimal ripeness. Bell peppers are also typically more flavorful when optimally ripe.
Bell peppers have been cultivated for more than 9000 years, with the earliest cultivation having taken place in South and Central America. While the name "pepper" was given to this food by European colonizers of North America who first came across it in the 1500-1600's and then transported it back to Europe, the original name for this food in Spanish was pimiento.
Because bell peppers can be grown in a variety of climates and are popular in cuisines throughout the world, they can frequently be found on small farms in North America, Central America, South America, Europe, Africa, the Middle East, and parts of Asia. In terms of commercial production, however, China has become by far the largest producer of bell peppers and produced 14 million metric tons in 2007. At about 2 million metric tons, Mexico is the second largest commercial producer, followed by the United States at approximately 1 million metric tons.
Within the U.S., California and Florida are the largest bell pepper-producing states. (In terms of chili pepper production, however, New Mexico currently stands in first place.) . The average U.S. adult consumes about 16 pounds of peppers per year, including almost 9.5 pounds of bell peppers.
How to Select and Store
Choose peppers that have deep vivid colors, taut skin, and that are free of soft spots, blemishes and darkened areas. Their stems should be green and fresh looking. Peppers should be heavy for their size (reflecting their thick, well-formed and well-hydrated walls) and firm enough so that they will only yield slightly to a small amount of pressure. Avoid those that have signs of decay including injuries to the skin or water-soaked areas. The shape of the pepper does not generally affect the quality, although it may result in excessive waste or not be suitable to certain recipe preparations. Peppers are available throughout the year but are usually in greater abundance during the summer and early fall months.
It can be difficult to tell whether a bell pepper is optimally ripe, but from a nutritional and health standpoint, it is definitely worth paying attention to the degree of ripeness in your bell peppers. You don't want them to be overly ripe to the point of getting too soft, wrinkly, or blemished. In fact, if bell peppers are optimally ripe at the time of purchase, they can lose up to 15% of their vitamin C content over the course of 10-day storage in the refrigerator and up to 25% of their vitamin C over 20-days of refrigerator storage time. However, if not optimally ripe at the time of purchase, the vitamin C and carotenoids in bell peppers will actually increase with refrigerator storage over the next 10 days. So as you can see, there is a delicate balance in terms of optimal ripeness! I encourage you not to worry about eating bell peppers that are not yet optimally ripe, because they can still provide you with outstanding health benefits. But for optimal vitamin C and carotenoid benefits, you may want to experiment a little and see if you can develop a skill for evaluating ripeness in this vegetable. Unfortunately, you cannot use basic color as your primary guideline. Most - but not all - green bell peppers will turn red in color over time, but they may be optimally ripe before shifting over from green to red. (There are also some varieties of bell peppers which never start out green.) A good rule of thumb is to judge not by the color itself but by the color quality and overall texture and feel. Whether green, red, yellow, or orange, optimally ripe bell peppers will have deep, vivid colors, will feel heavy for their size, and will be firm enough to yield only slightly to pressure.
Unwashed sweet peppers stored in the vegetable compartment of the refrigerator will keep for approximately 7-10 days. . Because bell peppers need to still well hydrated and are very sensitive to moisture loss, we further recommend that you include a damp cloth or paper towel in the vegetable compartment to help the peppers retain their moisture. Do not cut out the bell pepper stem prior to storage in the refrigerator. Bell peppers are especially sensitive to moisture loss through this stem (calyx) portion and are more susceptible to chilling injury if the stem is removed. Sweet peppers can be frozen without first being blanched. It is better to freeze them whole since there will be less exposure to air which can degrade both their nutrient content and flavor.
Although most people would not consider washing bell peppers under hot water, I want to be clear about the disadvantages of doing so. A recent study has shown that bell peppers retain more of their total antioxidant or antiacid capacity when washed under cold versus hot water.
Finally, if you are going to consume your bell peppers within a day or two and suspect that they are not fully ripe, you may want to consider storing them without refrigeration. We've seen one recent study showing that room temperature storage of 20°C (68°F) can improve the availability of fat-soluble carotenoids in bell peppers that are not yet optimally ripe.
Tips for Preparing and Cooking
Tips for Preparing Bell Peppers
Before coring and/or cutting the pepper, wash it under cold running water. If the pepper has been waxed, you should also scrub it gently but thoroughly with a natural bristle brush.
Use a paring knife to cut around the stem and then gently remove it. Peppers can be cut into various shapes and sizes. To easily chop, dice or cut the peppers into strips, first cut the pepper in half lengthwise, clean out the core and seeds, and then, after placing the skin side down on the cutting surface, cut into the desired size and shape. Peppers can also be cut horizontally into rings or left whole for stuffed peppers. The pulpy white inner cavity of the bell pepper is rich in flavonoids and can be eaten, even though some people have a personal preference for removing this section.
The Healthiest Way of Cooking Bell Peppers
Of all of the cooking methods we tried when cooking bell peppers, my favorite is Healthy Sauté. We think that it provides the greatest flavor and is also a method that allows for concentrated nutrient retention.
To Healthy Sauté bell peppers, heat 3 TBS of broth (vegetable) or alkaline water in a stainless steel skillet. Once bubbles begin to form add sliced red bell peppers, cover, and Healthy Sauté for 3 minutes on medium heat. After 3 minutes add 2 TBS broth, then cook uncovered on low heat for another 4 minutes, stirring constantly. Transfer to a bowl and toss with our extra virgin olive oil and fresh lemon.
Bell peppers are an outstanding source of antioxidant/antiacid and anti-inflammatory phytonutrients. These phytonutrients include flavonoids (luteolin, quercetin, hesperidin) and hydroxycinnamic acids (especially ferulic and cinnamic acids). But the hallmark phytonutrient group found in bell peppers is the carotenoid family, with more than 30 different carotenoids being provided by this vegetable. Included in bell pepper carotenoids are alpha-carotene, beta-carotene, cryptoxanthin, lutein, and zeaxanthin. Bell peppers are an excellent source of antioxidants or antiacids vitamin A and nerve-supportive vitamin B6. Bell peppers are a very good source of heart-healthy fiber, vitamin E, folate, potassium, and vitamin K as well as the enzyme-supportive molybdenum. They are a good source of bone-building manganese and magnesium, energy-producing vitamins B1, B2, B3 and B5.
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