Corn

What food is more synonymous with summer than freshly picked corn on the cob? Corn grows in "ears," each of which is covered in rows of kernels that are then protected by the silk-like threads called "corn silk" and encased in a husk. Corn is known scientifically as Zea mays. This moniker reflects its traditional name, maize, by which it was known to the Native Americans as well as many other cultures throughout the world. Although we often associate corn with the color yellow, it actually comes in host of different varieties featuring an array of different colors, including red, pink, black, purple, and blue. Although corn is now available in markets year-round, it is the locally grown varieties that you can purchase during the summer months that not only tastes the best but are usually the least expensive.

What's New and Beneficial about Corn

• You can get health-supportive antioxidant benefits from all varieties of corn, including white, yellow, blue, purple and red corn. But recent research has shown the antioxidant benefits from different varieties of corn actually come from different combinations of phytonutrients. In the case of yellow corn, it's the antioxidant carotenoids leading the way, with especially high concentrations of lutein and zeaxanthin. In the case of blue corn, it's the anthocyanins. There's one particular hydroxybenzoic acid in purple corn—protocatechuic acid—that's also been recently linked to the strong antioxidant activity in this corn variety.
• In research on carotenoid antioxidants in food, there has been ongoing debate over the availability of all carotenoids in any particular food if one or two specific carotenoids are present in unusually high amounts. Because yellow corn is a high-carotenoid food that contains highly differing amounts of individual carotenoids, researchers have long wondered whether it is possible to get health benefits from all of the carotenoids in yellow corn when their concentrations are sometimes so different. In yellow cornmeal, the carotenoids lutein and zeaxanthin fall into the high concentration category and reach a level of 1,355 micrograms per 100 grams. That level is nearly 14 times as high as the level of beta-carotene (97 micrograms per 100 grams). But thanks to recent research, we now know that absorption of beta-carotene from yellow cornmeal is only mildly compromised by the high levels of lutein and zeaxanthin in the cornmeal. In other words, in terms of carotenoid nourishment, we appear to get health benefits from all of corn's diverse carotenoids!
• We correctly think about corn as a good source of fiber. Corn is a food that gives us plenty of chewing satisfaction, and its high ratio of insoluble-to-soluble fiber is partly the reason. Past researchers have not been clear, however, about the ability of corn fiber to nourish our lower digestive tract. When you look at foods as a whole, they contain many different types of fiber, and when certain types of fiber reach the lower part of our large intestine (especially certain types of soluble fiber) they can be metabolized by intestinal bacteria into short chain fatty acids (SCFAs). This process not only helps support healthy populations of friendly bacteria in our large intestine, but also provides a direct supply of energy (in the form of SCFAs) to the cells that line our large intestine. With this benefit of this extra SCFA energy supply, our intestinal cells can stay healthier and function at a lower risk of becoming cancerous. Recent research has shown that corn can support the growth of friendly bacteria in our large intestine and can also be transformed by these bacteria into SCFAs. These SCFAs can supply energy to our intestinal cells and thereby help lower our risk of colon cancer. The amount of corn fiber analyzed in recent studies has been relatively high at 12 grams per day. That's the same amount provided by about 2.5 cups of fresh corn. While that amount might be more than you would consume at a single meal, it's an amount that you might easily consume over the course of several days. We suspect that future research will demonstrate the risk-reducing effects of smaller amounts of corn consumed over a longer period of time.

Corn, yellow, cooked
1.00 each
(77.00 grams)

Calories: 74
GI: medium

NutrientDRI/DV

 pantothenic acid12.2%

 phosphorus8.4%

 vitamin B38.1%

 fiber7.4%

 manganese6.5%

 vitamin B66.4%

This chart graphically details the %DV that a serving of Corn 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 Corn can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Corn, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

• Health Benefits
• Description
• History
• How to Select and Store
• Tips for Preparing and Cooking
• How to Enjoy
• Individual Concerns
• Nutritional Profile
• References

Health Benefits

Corn has gathered a diverse reputation in the U.S. For some people, corn is a "staple" food that provides the foundation for tortillas, burritos, or polenta. For others, corn is a "snack" food that comes in the form of popcorn and corn chips. For still others, corn is a "special summertime food" that is essential at barbecues and cookouts. But regardless of its reputation, corn is seldom considered in the U.S. as a unique source of health benefits. Yet that's exactly what research results are telling us about this amazing grain.

Antioxidant Benefits

While it might sound surprising to some people who are used to thinking about corn as a plain, staple food, or a snack food, or a summertime party food, corn is actually a unique phytonutrient-rich food that provides us with well-documented antioxidant benefits. In terms of conventional antioxidant nutrients, corn is a good source of the mineral manganese. But it is corn's phytonutrients that have taken center stage in the antioxidant research on corn. When all varieties of corn are considered as a group, the list of corn's key antioxidant nutrients appears as follows:

Antioxidant Phytonutrients in Corn

• anthocyanins
• beta-carotene
• caffeic acid
• coumaric acid
• ferulic acid
• lutein
• syringic acid
• vanillic acid
• protocatechuic acid
• zeaxanthin

Different varieties of corn highlight different combinations of antioxidant phytonutrients. In the case of yellow corn, carotenoids lead the way and provide especially high concentrations of lutein and zeaxanthin. Blue corn is unique in its anthocyanin antioxidants. One particular hydroxybenzoic acid in purple corn—protocatechuic acid—has recently been linked to the strong antioxidant activity in this corn variety.

Most studies of disease and risk reduction from dietary antioxidant intake have not looked specifically at corn and its impressive combination of antioxidants. However, in several small-scale studies, corn has been directly mentioned as a food that was important in overall antioxidant protection and a contributing factor in the decreased risk of cardiovascular problems. Some of the mechanisms for decreased cardio risk may be related to other properties of corn's phytonutrients that go beyond their antioxidant properties. For example, some of the phytonutrients in corn may be able to inhibit angiotensin-I converting enzyme (ACE) and help lower risk of high blood pressure in this way. We suspect that future studies will further confirm the important role of corn's phytonutrients in reduction of risk for a variety of health problems, and that antioxidant and other properties will play a key role in this risk reduction.

One great piece of news about corn's antioxidants involves the practice of drying corn (still on the cob) or separated corn kernels. Research studies have shown that the drying of corn in temperature ranges as high as 150°-200°F (65°-93°C) does not significantly lower corn's antioxidant capacity. This research confirms the wisdom of many North American and Mesoamerican cultures which relied on naturally-dried corn in the preparation of meal foods, especially during the winter months.

Interestingly, recent research has determined that the percent of amylose starch found in corn may be related to its antioxidant capacity. Higher amylose corn varieties have shown higher antioxidant capacity in some preliminary studies. While the jury is out on the exact meaning of these findings, this research reminds us to keep an open mind about the potential importance of antioxidant health benefits from corn.

Digestive Benefits

Anyone who has eaten fresh corn-on-the-cob or freshly popped popcorn knows how satisfying this food can be to chew. Some of that satisfaction comes from corn's fiber content. At 4.6 grams of fiber per cup, corn is a good fiber source, and in research studies, corn intake is often associated with good overall fiber intake. For example, persons who eat popcorn tend to have 2-3 times more overall whole grain intake than persons who do not eat popcorn, and they also tend to have higher overall fiber intake as well.

Corn fiber is one of the keys to its well-documented digestive benefits. Recent research has shown that corn can support the growth of friendly bacteria in our large intestine and can also be transformed by these bacteria into short chain fatty acids, or SCFAs. These SCFAs can supply energy to our intestinal cells and thereby help lower our risk of intestinal problems, including our risk of colon cancer. The amount of corn fiber analyzed in recent studies has been relatively high at 12 grams per day. That's the same amount provided by about 2.5 cups of fresh corn. While that amount might be more than any person would consume in a single meal, it's an amount that a person might easily eat over the course of several days. We suspect that future research will demonstrate the risk-reducing effects of smaller amounts of corn consumed over a longer period of time.

Blood Sugar Benefits

Given its good fiber content, its ability to provide many B-complex vitamins including vitamins B1, B5 and folic acid, and its notable protein content (about 5-6 grams per cup), corn is a food that would be expected to provide blood sugar benefits. Fiber and protein are key macronutrients for stabilizing the passage of food through our digestive tract. Sufficient fiber and protein content in a food helps prevent too rapid or too slow digestion of that food. By evening out the pace of digestion, protein and fiber also help prevent too rapid or too slow uptake of sugar from the digestive tract up into the bloodstream. Once the uptake of sugar is steadied, it is easier to avoid sudden spikes or drops in blood sugar.

Consumption of corn in ordinary amounts of 1-2 cups has been shown to be associated with better blood sugar control in both type 1 and type 2 diabetes. Fasting glucose and fasting insulin levels have been used to verify these blood sugar benefits. Interestingly, in elementary school-age and teenage youths already diagnosed with type 1 diabetes, whole grain cornbread has emerged in one study as the whole grain food with the highest acceptability among all whole grain foods. Youth participants in the study who consumed whole grain cornbread were also less likely to consume fast foods.

Other Benefits

In countries outside of the U.S., numerous studies have examined the ability of corn to improve overall nourishment, especially when combined with legumes. Researchers conducting these studies have been interested in absorption of minerals like zinc, calcium and iron, as well as overall energy and protein intake. Maize (corn)-bean meals (typically consumed in the form of porridge that combines these foods) have been shown to help improve overall nutrient status and to help provide outstanding nutrient richness in the diet.

One fascinating new area of research on corn involves its potential anti-HIV activity. Lectins are special proteins found in virtually all foods (and for that matter, in virtually all organisms) that can bind onto carbohydrates or onto carbohydrate receptors that are found on cell membranes. In the case of some micro-organisms (including the HIV virus), the binding of lectins onto sugars has been shown to help inhibit activity of the virus. One specific lectin found in corn (called GNAmaize) has preliminarily been shown to possess this HIV-inhibiting property. Of course, much more research is needed to determine the relationship between everyday consumption of corn as a whole food and HIV infection risk.

Description

While the kernels that we commonly call "corn" are technically the fruit of the plant Zea mays, corn is widely classified as a grain and is typically included in research studies of whole grain foods like wheat, oats, and barley. Throughout much of the world, corn is referred to as "maize." In many ways, "maize" is the best way of describing this plant since it was first domesticated in Mesoamerica over 8,000 years ago and was originally described using the Spanish word "maiz." This remarkable food took on sacred qualities for many Central American and South American cultures, as well as many Native American tribes in what is now the United States.

All types of corn come from the same genus and species of plant, Zea mays. However, within this genus and species, there are well over 100 subspecies and varieties. Many different subspecies are most familiar to consumers in terms of color. White, yellow, pink, red, blue, purple, and black corn are all varieties of Zea mays. Each of these varieties contains its own unique health-supportive combination of antioxidant phytonutrients. In the case of yellow corn, there's a greater concentration of carotenoids, especially lutein and zeaxanthin. With blue corn, there's a richer supply of anthocyanins. In purple corn, there's one particular hydroxybenzoic acid—protocatechuic acid—that's been recently linked to this variety's antioxidant capacity.

History

Perhaps no other food has been more closely identified with the Americas than corn. Both the Mayan and the Olmec civilizations that date back to 2000-1500 BC in what is now Mexico and Central America (commonly called Mesoamerica) had not only adopted maize as a staple food in the diet but had also developed a reverence for maize that was expressed in everyday rituals, religious ceremonies, and in the arts. The first domestication of maize in Mesoamerica actually dates back even further, to 9000-8000 BC. Corn was equally valued by Native American tribes living in North America, although tribal wisdom about corn was largely ignored by European colonists in the 15th and 16th centuries AD.

By the time Columbus and other explorers arrived in North America, corn was already an integral part of Native American cuisine. However, many colonists ignored Native American traditions related to corn—including the pot ash tradition—and later fell victim to the vitamin B3 deficiency disease called pellagra. (When cooking corn and cornmeal, Native Americans had developed a practice of incorporating ash from the fire into the food, and the mineral mix in this ash increased the bioavailability of vitamin B3 from the corn. The addition of lime in the form of calcium hydroxide to tortillas still serves this purpose today.)

While the average U.S. adult does not share the reverence for corn that characterized the practices of Native Americans and indigenous peoples of Mesoamerica, there is still an amazing influence of corn on the U.S. diet. Forty percent of all processed, pre-packaged foods sold in U.S. groceries currently contain some processed component of corn, although this component is most often high fructose corn syrup (HFCS). Per capita consumption of corn in all forms is approximately 160 pounds in the U.S. (and approximately 60-65 pounds come in the form of HFCS). U.S. farmers grow about 40% of all corn produced worldwide. An important region of the U.S. is still identified as the "Corn Belt." This region is typically defined as including Iowa, Illinois, the eastern parts of Nebraska and Kansas as well as North and South Dakota, the southern part of Minnesota, and parts of northern Missouri as well as Ohio and Indiana. However, Iowa, Illinois, Nebraska and Minnesota remain the top producers of corn in the U.S. and provide over 50% of all U.S. corn crops.

An increasing trend in U.S. production of corn has been cultivation for non-food purposes. Addition of ethanol to gasoline and biofuel production have been two important factors in the shift away from food-based cultivation of corn. The cultivation of corn for ethanol production has also led to an increased supply of ethanol by-products that have found their way into the marketplace. An example here is distillers dried grains, or DDGs. DDGs have already become an important part of livestock feed, along with other corn components.

Along with the United States, other important commercial producers of corn currently include China, Brazil, Mexico, Russia, Ukraine, Romania, and South Africa.

How to Select and Store

From a food safety standpoint, we recommend selection of corn that has not been exposed to any substantial amount of heat. Exposure to excess heat can increase the susceptibility of fresh corn to microbial contamination. If you are shopping in the grocery store, your safest bet is corn that is being displayed in a refrigerated produce bin. Next safest would be corn that, while not refrigerated, is still being displayed in a cool store location, out of direct sun and not near a heat source. These same recommendations apply for corn in a farmer's market or roadside stand. Here display of corn in the shade and out of direct sunlight can be important from a food safety standpoint.

Look for corn whose husks are fresh and green and not dried out. They should envelope the ear and not fit too loosely around it. To examine the kernels, gently pull back on part of the husk. The kernels should be plump and tightly arranged in rows. Due to changes that have occurred over time in commercial corn production, corn has become a food where quality is especially important. Over 70% of all corn found in U.S. grocery stores has been genetically modified in the form of herbicide-tolerant, or HT corn, or the form of insect-resistant, or Bt corn. (Bt corn gets its name from the transfer of a gene from the soil bacterium, Bacillus thuringiensis, into the corn. A protein toxin produced by this bacterium helps to kill certain insects that might otherwise eat the corn.) While there is no large scale human research on GE corn and its health impact, we share the concern of many researchers about the introduction of novel proteins into food and their potential for increasing risk of adverse reactions, including food allergies. One way to avoid these potential GE risks is to select certified organic corn, since GE modifications are not allowed in certified organic food.

While not a "Dirty Dozen" food in terms of pesticide residues as evaluated by the U.S. Environmental Working Group (EWG), non-organic, conventionally grown corn has repeatedly been shown to contain organochlorine pesticide residues. In one study, 19 different pesticide residues were found on samples of conventionally grown corn. Like potential GE risks, potential pesticide risks can be avoided through selection of certified organic corn.

Traditionally to enjoy the optimal sweetness of fresh corn, it was recommended to eat it the day of purchase. New varieties allow you 3 days to still enjoy its full flavor. Store corn in an air-tight container or tightly wrapped plastic bag in the refrigerator if you do not intend to cook it on the day of purchase. Do not remove its husk since this will protect its flavor. Fresh corn freezes well if placed in heavy-duty freezer bags. To prepare whole ears for freezing, blanch them first for five minutes depending. If you just want to freeze the kernels, first blanch the ears and then cut the kernels off the cob at about three-quarters of their depths. Frozen whole corn on the cob will keep for up to one year, while the kernels can be frozen for two to three months.