Corn

Corn / Maize (Zea mays)

Corn (in Hebrew “תירס”) is one of the most important crops in human history, and it is also one of the hardest foods to talk about in general terms — because “corn” is really four different things: sweet corn, eaten as a vegetable; field corn, for industry and animal feed; popcorn (a separate variety with an especially hard hull); and processed derivatives such as starch and corn syrup.

The question “is corn healthy?” is meaningless without specifying which of them you mean. A boiled corn cob and a drink made with corn syrup are not the same food in any sense, even though both are “corn”.

And corn hides one of the most instructive stories in the history of nutrition: nixtamalization — the reason some cultures that lived on corn thrived, while others fell ill with a deadly deficiency disease.

Nutrition facts per 100 grams

A medium corn cob (about 90 grams of kernels) is about 77 calories — a small serving of carbohydrate, not a free vegetable.

Nixtamalization — the story worth knowing

Corn contains a reasonable amount of niacin (vitamin B3), but in a bound form — “niacytin” — that the body cannot absorb. Mesoamerican cultures discovered a process thousands of years ago that solves this: soaking the kernels in an alkaline solution (limewater or ash) and cooking them. The process is called nixtamalization, and it:

• releases the niacin into an absorbable form;
• improves the availability of lysine and tryptophan, and with it the protein quality;
• adds calcium from the lime itself;
• softens the hull and allows the kernel to be ground into a dough (masa) — the basis for tortillas and tamales.

When corn left the Americas in the 16th century, it was taken without the process. In regions of Europe, Africa and the southern US where corn became the almost exclusive staple food, pellagra broke out — a niacin-deficiency disease characterized by dermatitis, diarrhea, dementia and death. Tens of thousands of people died of it in the US alone in the early 20th century, until the dietary cause was identified.

The practical conclusion: a real Mexican tortilla made from masa is not nutritionally equivalent to regular cornmeal. And as long as corn is part of a varied diet rather than an exclusive staple food — pellagra is not a practical consideration today.

Lutein and zeaxanthin — a real distinction

Yellow corn is the only grain that contains a significant amount of lutein and zeaxanthin — carotenoids that accumulate in the macula at the center of the retina and filter blue light. In observational studies their intake is linked to a lower risk of age-related macular degeneration.

Like all carotenoids, they are fat-soluble: corn needs to be eaten with a source of fat — olive oil, avocado, a little butter — for them to be absorbed. White corn does not contain them at all.

Benefits

• Fiber in popcorn: 14.5 grams per 100 grams — one of the most fiber-rich snacks there is, when it is air-popped rather than popped in oil.
• Lutein and zeaxanthin — as detailed above.
• Vitamin B1 and folate in reasonable amounts.
• Gluten-free — suitable for celiac disease, subject to cross-contamination.
• Resistant starch: corn that has been cooked and cooled develops resistant starch, which serves as food for gut bacteria.
• Magnesium in popcorn: 144 mg per 100 grams — 34% of the daily value.
• Available, cheap and keeps well — frozen, canned or on the cob, all year round.

Downsides and considerations

• The processed derivatives are the problem, not the vegetable. High-fructose corn syrup is found in sweetened soft drinks, sweetened breakfast cereals and sweetened ketchup, and cornstarch is a basic ingredient in ultra-processed food. Confusing these with corn on the cob mainly serves the industry.
• A carbohydrate serving, not a free vegetable. 18.7 grams of carbohydrates per 100 grams — three times as much as cauliflower or broccoli. In a salad it counts as a carbohydrate.
• Sweetened canned corn. Many products contain added sugar and sodium (“Whole kernel corn, sweetened”). Look for “no added sugar or salt”, or rinse in a strainer.
• Movie theater and microwave popcorn. Air-popped popcorn is about 387 calories per 100 grams; popcorn with butter and oil reaches 500 and above, with high sodium. Microwave packs add fats and additives.
• Whole kernels in the stool. A common phenomenon that causes needless worry. The outer hull of the corn kernel is made of cellulose, which the body has no enzyme to break down. What’s inside — the starch, protein and fat — is digested and absorbed. Thorough chewing reduces the phenomenon, and it is not a sign of a digestive problem.
• GMO. Most of the world’s field corn is genetically engineered and used for animal feed and industry; sweet corn for direct consumption is mostly not engineered. The position of the major health bodies is that the approved varieties are safe to eat. Those who prefer to avoid them can choose organic products.
• Allergy and sensitivity to corn exist but are uncommon.

Practical use

• Eat it with fat. A little olive oil or butter on the cob is not a sin but a condition for absorbing the lutein.
• Roast rather than boil. Grilling or oven-roasting concentrates sugars and caramelizes them; long boiling draws water-soluble vitamins out into the water.
• Fresh corn — cook it quickly. As with peas, the sugars in corn start turning into starch right after harvest. A cob picked today is much sweeter than a two-day-old cob. Frozen corn, blanched and frozen close to harvest, is usually better than “fresh” corn that has traveled.
• Homemade stovetop popcorn: a tablespoon of oil, a lid, medium heat — about 100 calories for a large 30-gram serving. Much less than ready-made packs. Alternatively, amaranth popcorn provides more protein for the same volume.
• Count it as a carbohydrate on the plate, not as a vegetable.
• When buying canned: read the ingredients — corn, water, and maybe salt. Sugar on the list is a reason to choose something else.
• Rinse canned corn in a strainer — it removes a considerable part of the sodium and sugar in the liquid.

Summary

Corn itself — the cob, the frozen kernels, air-popped popcorn — is a reasonable to good food: fiber, B vitamins, and a unique status as the only grain source of lutein and zeaxanthin. What gave corn its bad reputation is what the industry makes from it: high-fructose syrup and refined starch. Two practical things to remember: eat it with fat so the carotenoids are absorbed, and count it as a carbohydrate, not a vegetable. And whole kernels in your stool? That is the cellulose hull, and it is completely normal.