Corn 101: Nutrition Facts and Health Benefits
Also known as maize (Zea mays), corn is one of the most popular cereal grains in the world.
It is the seed (grain) of a plant from the grass family, native to Central America, but grown in countless varieties throughout the world.
Popcorn and sweet corn are commonly eaten varieties, but refined corn products are also widely consumed, frequently as ingredients in foods.
These include tortillas, tortilla chips, polenta, cornmeal, corn flour, corn syrup, and corn oil.
Whole-grain corn is as healthy as any cereal grain, rich in fiber and many vitamins, minerals, and antioxidants.
Corn is typically yellow, but comes in a variety of other colors, such as red, orange, purple, blue, white, and black.
Aside from containing varying amounts of water, corn is mainly composed of carbohydrates, and has small amounts of protein and fat.
The table below contains detailed information on all the nutrients in corn (1).
Like all cereal grains, corn is primarily composed of carbs.
Sweet corn, also known as sugar corn, is a special low-starch variety (28%) with a higher sugar content (18%), most of which is sucrose (1).
The glycemic index is a measure of how quickly carbs are digested. Foods that rank high on this index may cause an unhealthy spike in blood sugar.
Despite the sugar content of sweet corn, it is not a high-glycemic food, ranking low or medium on the glycemic index (3).
Bottom Line: Corn is mainly composed of carbs. It scores low to medium on the glycemic index, so whole corn should not cause large spikes in blood sugar.
Corn contains a fair amount of fiber.
One medium bag of popcorn from a cinema (112 g) contains approximately 16 grams of fiber.
The predominant types of fiber in corn are insoluble fibers, such as hemicellulose, cellulose, and lignin (2).
Bottom Line: Whole corn is fairly high in fiber. In fact, one bag of popcorn may contain a large proportion of the recommended daily intake.
Corn is a decent source of protein.
Overall, the protein quality of zeins is poor because they are lacking in some essential amino acids, mainly lysine and tryptophan (8).
Aside from their role in nutrition, zeins are quite unique and have been used in the production of adhesives, inks, and coatings for pills, candy, and nuts (7).
Bottom Line: Corn contains a decent amount of low-quality protein.
However, corn germ, an abundant side-product of corn milling, is rich in fat and used to make corn oil, commonly used for cooking.
Refined corn oil is mainly composed of linoleic acid, a polyunsaturated fatty acid, while monounsaturated and saturated fats make up the rest (9).
However, there are still a number of concerns with refined seed oils like corn oil. Whole corn is fine, but corn oil is not recommended.
Bottom Line: Whole corn is relatively low in fat. However, corn oil is sometimes processed from corn germ, a side product of corn milling.
Corn may contain a fair amount of several vitamins and minerals.
However, the amount is highly variable depending on the corn type.
In general, popcorn is rich in minerals, whereas sweet corn is higher in many vitamins.Popcorn:
- Manganese: An essential trace element, found in high amounts in whole grains, legumes, fruits and vegetables. Manganese is poorly absorbed from corn due to its phytic acid content (12).
- Phosphorus: Found in decent amounts in both popcorn and sweet corn, phosphorus is a mineral that plays an important role in the growth and maintenance of body tissues.
- Magnesium: An important dietary mineral. Poor magnesium status may increase the risk of many chronic diseases, such as heart disease (13, 14).
- Zinc: A trace element that has many essential functions in the body. Due to the presence of phytic acid in corn, its absorption may be poor (15, 16).
- Copper: An antioxidant trace element, generally low in the Western diet. Inadequate copper intake may have adverse effects on heart health (17, 18).
- Pantothenic acid: One of the B-vitamins, also called vitamin B5. It is found to some extent in nearly all foods and deficiency is therefore rare.
- Folate: Also known as vitamin B9 or folic acid, folate is an essential nutrient, especially important in pregnancy (19).
- Vitamin B6: A class of related vitamins, the most common of which is pyridoxine. It serves various functions in the body.
- Niacin: Also called vitamin B3, niacin in corn is not well absorbed. Cooking corn with lime can make it more available for absorption (2, 20).
- Potassium: An essential nutrient that is important for blood pressure control and may improve heart health (21).
Bottom Line: Corn is a good source of many vitamins and minerals. Popcorn tends to be higher in minerals, while sweet corn tends to be higher in vitamins.
Corn contains a number of bioactive plant compounds, some of which may have beneficial health effects.
- Ferulic acid: One of the main polyphenol antioxidants in corn, which contains higher amounts of it than other cereals, such as wheat, oats, and rice (22, 23).
- Anthocyanins: A family of antioxidant pigments responsible for the color of blue, purple, and red corn (23, 24).
- Zeaxanthin: Named after corn (Zea mays), zeaxanthin is one of the most common carotenoids found in plants. In humans, it has been linked with improved eye health (25, 26).
- Lutein: One of the main carotenoids in corn. Like zeaxanthin, it is found in the human eye (retina) where it serves as an antioxidant, protecting the eye from oxidative damage produced by blue light (25, 26).
- Phytic acid: An antioxidant that may impair the absorption of dietary minerals, such as zinc and iron (16).
Bottom Line: Corn contains higher amounts of antioxidants than many other cereal grains. It is especially rich in eye-healthy carotenoids.
Popcorn is a special variety of corn that pops when exposed to heat.
This happens when water, trapped in its center, turns to steam, creating internal pressure, which makes the kernels explode.
A highly popular snack, popcorn is one of the most common whole-grain foods in the US.
In fact, popcorn is one of the few common whole grains consumed as single foods. More frequently, whole grains are consumed as food ingredients, such as in breads and tortillas (27).
However, regular popcorn consumption has not been linked with improved heart health (27).
Even though popcorn may be healthy on its own, it is often associated with sugary soft drinks and is frequently loaded with added salt and high-calorie cooking oils, factors that may have adverse effects on health over time (30, 31, 32).
Bottom Line: Popcorn is a type of corn that pops when heated. It is a popular snack food, categorized as a whole-grain cereal.
Eating whole grain corn regularly may have a number of health benefits.
Macular degeneration and cataracts are among the world's most common visual impairments and major causes of blindness (33).
Infections and old age are among the main causes of these diseases, but nutrition may also play a significant role.
Commonly known as macular pigments, lutein and zeaxanthin are found in the human retina, the light-sensitive inner surface of the eye, where they protect against oxidative damage caused by blue light (38, 39, 40).
One study in 356 middle-aged and elderly people found a 43% reduction in the risk of macular degeneration among those with the highest intake of carotenoids, especially lutein and zeaxanthin, compared to those with the lowest intake (45).
Taken together, regular consumption of foods rich in lutein and zeaxanthin, such as yellow corn, may have beneficial effects on eye health.
Bottom Line: Being a good source of lutein and zeaxanthin, corn may contribute to the maintenance of eye health.
Prevention of Diverticular Disease
Diverticular disease (diverticulosis) is a condition characterized with pouches in the walls of the colon.
They main symptoms are cramps, flatulence, bloating, and less often, bleeding and infection.
Despite lack of evidence, avoiding popcorn and other high-fiber foods, such as nuts and seeds, has been recommended as a preventive strategy against diverticular disease (47).
However, one observational study, which followed 47,228 men for 18 years, does not support this recommendation.
In fact, popcorn consumption was found to be protective. Men who ate the most popcorn were 28% less likely to develop diverticular disease than those with the lowest intake (48).
Further studies are needed to confirm these results.
Bottom Line: Corn does not promote diverticular disease, as previously thought. On the contrary, it seems to be protective.
Eating corn is generally considered safe.
However, its consumption may be of concern for some people, especially in populations that depend on it as a dietary staple.
Antinutrients in Corn
Like all cereal grains, whole grain corn contains phytic acid (phytate).
Phytic acid impairs the absorption of dietary minerals, such as iron and zinc, from the same meal (16).
This is usually not a problem in well-balanced diets and for those who eat meat regularly, but may be a serious concern in developing countries where cereal grains and legumes are staple foods.
Bottom Line: Corn contains phytic acid, a plant compound that may reduce the absorption of minerals, such as iron and zinc.
Some cereal grains and legumes are susceptible to contamination by fungi.
The main classes of mycotoxins in corn are fumonisins, aflatoxins, and trichothecenes.
Fumonisins are particularly noteworthy.
They are found in stored cereals worldwide, but adverse health effects have mostly been linked with the consumption of corn and corn products, especially among people who depend on corn as their main dietary staple (53).
One observational study in South Africa indicates that regular consumption of corn meal may increase the risk of cancer in the esophagus, the tube that carries food from the mouth to the stomach (58).
Other mycotoxins in corn may also have adverse effects.
In April 2004 in Kenya, 125 people died from aflatoxin poisoning after eating home-grown corn that had been improperly stored (59).
Effective preventive strategies may include using fungicides and properly drying corn before storage.
In most developed countries, food safety authorities monitor the levels of mycotoxins in foods on the market, and all food production and storage is strictly regulated.
Generally, eating corn and corn products should not be a cause for concern.
However, in developing countries, and wherever corn is home-grown, the risk of adverse health effects may be higher.
Bottom Line: When corn is improperly stored, it can become contaminated with mycotoxins, which may have adverse health effects. This is generally not a cause for concern in developed countries.
Corn is one of the most widely consumed cereals grains.
Being a good source of antioxidant carotenoids, such as lutein and zeaxanthin, yellow (or colored) corn may promote eye health.
It is also a rich source of many vitamins and minerals.
For this reason, moderate consumption of whole-grain corn, such as popcorn or sweet corn, may well fit into a healthy diet.