Promote Lung Health
If you or someone you love is a smoker, or if you are frequently exposed to secondhand smoke, then making vitamin A-rich foods, such as collard greens, part of your healthy way of eating may save your life, suggests research conducted at Kansas State University.
While studying the relationship between vitamin A, lung inflammation, and emphysema, Richard Baybutt, associate professor of nutrition at Kansas State, made a surprising discovery: a common carcinogen in cigarette smoke, benzo(a)pyrene, induces vitamin A deficiency.
Baybutt's earlier research had shown that laboratory animals fed a vitamin A-deficient diet developed emphysema. His latest animal studies indicate that not only does the benzo(a)pyrene in cigarette smoke cause vitamin A deficiency, but that a diet rich in vitamin A can help counter this effect, thus greatly reducing emphysema.
Baybutt believes vitamin A's protective effects may help explain why some smokers do not develop emphysema. "There are a lot of people who live to be 90 years old and are smokers," he said. "Why? Probably because of their diet…The implications are that those who start smoking at an early age are more likely to become vitamin A deficient and develop complications associated with cancer and emphysema. And if they have a poor diet, forget it."
If you or someone you love smokes, or if your work necessitates exposure to second hand smoke, protect yourself by making sure that at least one of the World's Healthiest Foods that are rich in vitamin A, such as collard greens, is a daily part of your healthy way of eating.
Cardiovascular Protection
Collard greens are an excellent source of folate and a very good source of vitamin B6, both of which are needed to keep levels of homocysteine, a potentially dangerous molecule, low.
Vitamin B6 and folate are both involved in an important cellular process called methylation in which homocysteine is converted into other, benign molecules. Since homocysteine can directly damage blood vessel walls, high homocysteine levels are associated with an increased risk of heart attack and stroke-one risk you can lessen by eating foods rich in folate and B6, such as collard greens. In addition to these B vitamins, collard greens are a very good souce of riboflavin, another important B vitamin for cardiovascular health since it is necessary for the proper functioning of B6. Without riboflavin's assistance, vitamin B6 cannot change into its active form, the form in which it carries out its many beneficial activities, including the conversion of homocysteine.
But that's not the only reason riboflavin is of value for cardiovascular health. Riboflavin is also a cofactor in the reaction that regenerates glutathione, one of the body's most important antioxidants. Among its many beneficial activities, glutathione protects lipids like cholesterol from free radical attack. Only after cholesterol has been damaged by free radicals does this fat-containing molecule pose a threat to blood vessel walls.
Collard greens are also a good source of niacin. Yet another B vitamin with cardiovascular benefits, niacin has been used for years to safely and effectively lower high cholesterol levels, which is also important in atherosclerosis and diabetic heart disease.
In addition to their cardio-protective B vitamins, collard greens are a very good source of potassium and a good source of magnesium, two minerals that have both been shown to reduce high blood pressure, another risk factor for cardiovascular disease. Add to this the fiber that collards supply, which can help lower high cholesterol levels, and you have an exceptionally beneficial food for individuals with atherosclerosis or diabetic heart disease.
In a single cup of cooked collard greens is concentrated the cardiovascular benefits provided by 44.2% of the daily value for folate, 21.3% of the DV for dietary fiber, 18.5% of the DV for vitamin B6, 11.8% of the DV for riboflavin, 14.1% of the DV for potassium, 8.1% of the DV for magnesium, and 5.5% of the DV for niacin. All this for a cost of less than 50 calories!
Cholesterol-Lowering Benefits from Indole-3-Carbinol
Researchers from the University of Hawaii have shown that, at the tiny concentration of just 100 micromoles per liter, indole-3-carbinol (a metabolite of the glucosinolate phytonutrients found in collard greens and other ruciferous vegetables) lowers liver cells' secretion of the cholesterol transporter, apolipoproteinB-100 by 56%! Apolipoprotein B-100 (apoB) is the main carrier of LDL cholesterol to tissues, and high levels have been linked to plaque formation in the blood vessels.
When liver cells were treated with I-3-C, not only was apoB-100 secretion cut by more than half, but significant decreases also occurred in the synthesis of lipids (fats), including triglycerides and cholesterol esters. (Maiyoh GK, Kuh JE, et al., J Nutr.)
Vitamin E-rich Leafy Greens Slow Loss of Mental Function
Mental performance normally declines with age, but the results of Chicago Health and Aging Project (CHAP) suggest that eating just 3 servings of green leafy, yellow and cruciferous vegetables each day could slow this decline by 40%, suggests a study in the journal Neurology (Morris MC, Evans DA, et al.) Compared to people who consumed less than one serving of vegetables a day, people who ate at least 2.8 servings of vegetables a day saw their rate of cognitive decline slow by roughly 40%. This decrease is equivalent to about five years of younger age, said lead author Martha Clare Morris, ScD, with Rush University Medical Center in Chicago.
The prospective cohort study, funded by the National Institute of Aging, used dietary data from 3,718 participants (62% female, 60% African American, average age 74). Mental function was assessed with four different tests: the East Boston Tests of immediate memory and delayed recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test, taken at the start of the study and then again after 3 and 6 years.
After adjusting the results for potential confounders such as age, sex, race, education, and cardiovascular risk factors, the researchers found that consuming an average of 2.8 vegetable servings each day was associated with a 40% decrease in cognitive decline, compared to those who ate an average of less than one (0.9) serving a day. Of the different types of vegetables, green leafy vegetables had the strongest association, said Dr. Morris.
Surprisingly, no relationship was found between fruit consumption and cognitive decline.
Morris hypothesizes that this may be due to the fact that vegetables, but not fruits, contain high amounts of vitamin E, which helps lower the risk of cognitive decline. Also, vegetables, but not fruits, are typically consumed with a little fat, such as olive oil or salad dressing, which increases the body's ability to absorb vitamin E.
The Rush University researchers plan further research to understand why fruit appears to have little effect and to explore the effects of citrus fruit, specifically, on cognitive decline.
Practical Tip: If you remember to enjoy at least 3 servings of leafy greens each day, you are much more likely to remember other things as well!
History
Like kale, cauliflower and broccoli, collards are descendents of the wild cabbage, a plant thought to have been consumed as food since prehistoric times and to have originated in Asia Minor. From there it spread into Europe, being introduced by groups of Celtic wanderers around 600 B.C. Collards have been cultivated since the times of the ancient Greek and Roman civilizations. While collards may have been introduced into the United States before, the first mention of collard greens dates back to the late 17th century. Collards are an integral food in traditional southern American cuisine.
