Kale Immunostimulatory And Anticancer EffectsSeptember 2014
By Michael Downey
For decades, scientists have known that the nutrients in cruciferous vegetables such as cabbage, broccoli, and kale offer unique protection against the type of DNA damage that too often results in malignancies. Kale, however, stands out. The total polyphenol content in kale has been found to be higher than in any other cruciferous vegetable.1
Powerhouse Immune Support
Kale provides a superior level of sulforaphane—a unique cancer-fighting compound.2
Sulforaphane boosts detoxification, the cleansing process by which the body eliminates harmful compounds, possibly by its induction of phase II detoxification enzymes, in addition to its boosting of antioxidant enzymes.2
As well as strongly enhancing natural detoxification mechanisms, sulforaphane also exerts chemoprotective effects through its demonstrated anti-bacterial and anti-inflammatory activity.3,4
Sulforaphane inhibits a group of enzymes that alter gene expression and produce proteins involved in initiating cancer.5
Critically, scientists recently learned that kale stimulates the body’s production of immunoglobulin (Ig), proteins used by the immune system to identify and neutralize foreign invaders.6
Surprisingly, it is not necessary to consume kale raw in order to secure these immunostimulatory benefits. In one recent study, a water-soluble fraction of kale that had been cooked for a long period of time—boiled continuously for half an hour—was even more effective than the raw kale fraction at producing immunoglobulin A (IgA).6
IgA is a principle antibody class that acts as an important first line of defense in the secretions that bathe the mucosal surfaces of the gastrointestinal, respiratory, and genitourinary tracts—the largest area of exposure of the body to external pathogens.7,8 IgA is believed to interfere with pathogen adherence to mucosal epithelial cells (“immune exclusion”) and, in the serum, to serve as a second line of defense by eliminating pathogens that have breached the mucosal surface.9,10
Thanks to these multiple modes of action, kale has been gaining a lot of attention from scientists primarily for its potent effects in combating cancer, as well as other health benefits.
Italian scientists found that individuals who ate cruciferous vegetables such as kale at least once a week lowered their risk of oral, colorectal, and breast cancers by 17%, and slashed the risk of esophagus and kidney cancers by 28 and 32%, respectively.11
However, kale may be superior to other cruciferous options in its cancer-prevention effects, owing to an especially rich source of glucosinolates, which are converted by the body into cancer-preventive compounds called isothiocyanates.12 These complex compounds are powerful inducers of both cancer-destroying enzymes and inhibitors of carcinogenesis.13,14
As a result of these various compounds, kale has been demonstrated to substantially reduce the risk of many cancers,15 including some of the deadliest forms, such as cancer of the pancreas,16 breast,17-20 colon,21 and esophagus.2
Although the exact anticancer mechanism for each of kale’s complex compounds is not known, the sulforaphane component alone has been shown to modulate cell death, cell cycle, angiogenesis, susceptibility to carcinogens, cancer invasion and metastasis, and anti-inflammatory activities.17,22,23
Other research reveals that sulforaphane helps support a healthy immune system, which is a key component in staving off cancer. It significantly enhances production of several chemicals involved in the immune response, such as interferon-gamma.24 And the water-soluble fraction of kale has been shown to stimulate production of immunoglobulin in human cells.6
Conspicuously, sulforaphane has been shown to selectively target precancerous and cancerous cells.17
Most compelling, several studies have reported that the isothiocyanates that result from the breakdown of kale’s glucosinolates affect epigenetic mechanisms—altering gene expression to trigger clearance of carcinogenic substances from the body more quickly.25-28
A study published in the American Journal of Clinical Nutrition reported that a high intake of cruciferous vegetables reduced the risk of dying from cardiovascular disease by as much as 22%.29 Yet the cardiovascular benefits of kale may be even stronger than other cruciferous vegetables.
Kale is especially abundant in the carotenoid lutein, which may help prevent atherosclerosis. An 18-month study from the University of Southern California found that in a group of 480 men and women aged 40 to 60 with no history of heart disease, those with the lowest serum lutein concentration had a five-fold greater increase in carotid artery thickness, a risk factor for heart disease, compared with those who had the highest serum lutein concentrations. This study also included an in vitro portion that compared tissue cultures of cells exposed to various combinations of lutein and low-density lipoprotein (LDL), which is known to promote atherosclerosis. The researchers found that pretreatment of cells with lutein dose-dependently protected the cells against inflammation associated with LDL plaque formation, further supporting a protective effort for lutein against atherosclerosis.30
Another cardiovascular benefit of kale relates to its high fiber content, which may have a protective effect against high levels of C-reactive protein (CRP), an inflammatory marker associated with predicting cardiovascular disease risk. Researchers examined the relationship between dietary fiber intake and CRP levels in more than 3,900 men and women aged 20 and older. After adjusting for confounding factors such as age, gender, physical activity, and body mass index (BMI), those with the highest fiber intake had a 51% lower risk for elevated CRP levels compared with those with the lowest intakes.31
Kale’s high-fiber content may also protect cardiovascular health by lowering cholesterol. Your liver uses cholesterol to make bile acids, specialized molecules that emulsify fat to aid in its digestion and absorption. When you eat a fat-containing meal, bile acids are released from your gallbladder into the intestine where they help ready the fat for interaction with enzymes and eventual absorption into the body.32 Fiber-related nutrients in kale bind together with some of the bile acids in your intestine in such a way that they remain in the intestine and pass out of the body in a bowel movement instead of getting absorbed along with the fat they have emulsified. When this happens, your liver replaces the lost bile acids by drawing on your existing cholesterol supply—lowering your body’s cholesterol level.32
A study demonstrated that the bile acid-binding—and therefore, cholesterol-lowering—ability of kale is greater than that of the other cruciferous vegetables, with the exception of collard greens, which proved only slightly more effective. The same study indicated that the fiber-related components in kale do a much better job of binding together with bile acids in your digestive tract when they’ve been consumed steamed instead of raw.32
Kale is also especially noteworthy for its high content of vitamin K, a fat-soluble vitamin that plays an important role in blood clotting.33,34
Kale is especially rich in lutein and zeaxanthin, two carotenoids known to absorb blue light. They act like sunglass filters to prevent eye damage from excessive exposure to ultraviolet light. In several studies, people with a history of eating lutein-rich foods such as kale had up to 22% lower risk for cataracts.35,36 Also, one cup of kale provides over 200% of the daily recommended intake of vitamin A, an important nutrient for vision.
Because it is high in fiber and contains protein, kale may help balance blood sugar. Fiber helps slow the rise of blood sugar and protein helps anchor blood sugar.
Anthocyanins , which are antioxidant superstars, are abundantly found in kale. These potent compounds may help combat obesity and weight gain by preventing fat cells from expanding. One study reported that, “anthocyanin-treated mice showed a 24% decrease in weight gain,” compared to those not given anthocyanins.37 Also, kale is incredibly low in calories, contains no trans fat, is low in sugar (in the form of vegetable carbohydrates), is practically fat free, and promotes satiety through its naturally occurring fiber and protein.38
Aside from its many exceptional compounds, kale delivers an abundance of vitamins and minerals. It is particularly rich in vitamins A, C, and K, as well as being a good source of calcium, manganese, copper, and potassium.38
Those who find it difficult to consume enough kale or other cruciferous vegetables in their daily diet can obtain standardized potencies of sulforaphane, zeaxanthin, and lutein in low-cost dietary supplements.
If you have any questions on the scientific content of this article, please call a Life Extension® Health Advisor at 1-866-864-3027.
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