Collard greens, long a staple of down-home Southern cooking, are largely overlooked by chefs and consumers outside the South. Considering the nutritional riches contained in collards’ dark green leaves, it’s unfortunate that more Americans aren’t consuming them on a regular basis. Collards are part of the cruciferous vegetable family, which also includes broccoli, cabbage, cauliflower, kale and Brussels sprouts. More significantly, collards outstrip many of their fellow cruciferous veggies in terms of nutritional value.
Collard greens are loaded with healthful vitamins and minerals, offering one of the richest plant-food sources of calcium. A cup of cooked collards contains 266 grams of calcium, roughly the same amount of calcium as a cup of milk, according to “Foods & Nutrition Encyclopedia.” The Harvard School of Public Health also recommends collards as a source of calcium for those who are lactose intolerant or simply dislike milk. The oxalate -- a salt of oxalic acid -- in raw collards can impede the absorption of this calcium, but boiling the greens for at least six minutes overcomes the absorbability problem, allowing diners to get the benefit of all of the vegetable's calcium content. Collards are also rich in a wide array of phytochemicals -- plant compounds with reputed medicinal properties -- including alpha-carotene.
A cup of chopped, cooked collards contains 4 grams of protein, 9.3 grams of carbohydrates, 0.68 grams of fat and 5.3 grams of dietary fiber, according to the USDA’s National Nutrient Database for Standard Reference. Other minerals in a cup of collards include 220 grams of potassium, 57 grams of phosphorus, 38 grams of magnesium, 30 grams of sodium and 2.2 grams of iron. Collards are also rich in several key vitamins, with 15,417 International units of vitamin A per cup, 36 milligrams of vitamin C, 177 micrograms of folate and 836 micrograms of vitamin K. If you’re watching your caloric intake, you’ll be happy to learn that a cup of collards has only 49 calories.
Help Fight Cancer
In a follow-up study to the National Health and Nutrition Examination Survey III, or NHANES III, a team of U.S. researchers analyzed mortality data to determine what, if any, link could be found between eating foods high in alpha-carotene and the risk of lung cancer. In a report in the March 2011 issue of “Archives of Internal Medicine,” researchers reported that study subjects who ate large quantities of yellow-orange and dark green vegetables, all high in alpha-carotene, had a significantly lower risk of lung cancer. Collards are one of the richest sources of alpha-carotene.
The ongoing Black Women’s Health Study has uncovered further evidence of collards’ anticancer benefits, according to a Reuters news report. Data from the study indicate that a diet rich in carrots and cruciferous vegetables, including collards, may significantly reduce the risk of breast cancer, particularly an aggressive form of the disease commonly found in African-American women.
Lower Glaucoma Risk
A team of international ophthalmology researchers explored the relationship between the consumption of various fruits and vegetables and the incidence of glaucoma in a study group made up of 1,155 older women. Researchers found that the risk of glaucoma was 69 percent lower in women who ate at least one serving of collards or kale per month, compared with those who ate the vegetables less often. In an article in the June 2008 issue of “The American Journal of Ophthalmology,” researchers said that their findings support the need for additional research to investigate the mechanisms involved.
A Note of Caution
Despite their high level of nutrients, collard greens aren’t for everybody. Certified nutritional consultant Phyllis A. Balch, author of "Prescription for Dietary Wellness," says people with a history of kidney stones should minimize their consumption of collards and other oxalate-containing cruciferous vegetables. Oxalate can contribute to the formation of kidney stones, says Balch.
- Greens Glorious Greens; Johnna Albi and Catherine Walthers
- Foods & Nutrition Encyclopedia, Vol. 1; Audrey H. Ensminger
- National Nutrient Database for Standard Reference: Collards, Cooked, Boiled, Drained, Without Salt
- Harvard School of Public Health: The Nutrition Source: Calcium and Milk: What's Best for Your Bones and Health?
- Archives of Internal Medicine: Serum Alpha-Carotene Concentrations and Risk of Death Among U.S. Adults
- Reuters: Collards and Carrots May Ward Off Breast Cancer
- American Journal of Ophthalmology: Glaucoma Risk and the Consumption of Fruits and Vegetables Among Older Women in the Study of Osteoporotic Fractures
- Prescription for Dietary Wellness; Phyllis A. Balch