This post could also be entitled "Research: Kale and other brassica vegetables may protect against heart disease, too!"
A new study has shown that a compound called sulforaphane, from brassica vegetables like broccoli, cabbage, cauliflower, and kale, may protect arteries from disease by boosting a natural defense mechanism. (Arteriosclerosis Thrombosis and Vascular Biology, Sept 2009, “Activation of Nrf2 in Endothelial Cells Protects Arteries From Exhibiting a Pro-inflammatory State”, M. Zakkar, et al.)
Sulforaphane ia a compound most widely associated with broccoli. Highest levels of sulforaphane are found in commercially available broccoli sprouts, but are also present in all brassica vegetables. In this recently published research, sulforaphane as an individual molecule (not from a whole food), was shown to activate a protein called Nrf2 in arteries. While the protein is normally present and active in the inner lining of arteries, in areas of arteries that are susceptible to disease, i.e., the bends and branches of arteries, the researchers found that Nrf2 is inactive, which may explain why those areas are sights for inflammation, an early stage in the development of heart disease such as atherosclerosis.Both cell studies and animal studies showed that sulforaphane could reduce inflammation at these high risk areas by turning on the activity of the Nrf2 protein. The researchers next steps are to test whether eating a vegetable such as broccoli (or kale or other brassicas) will have the same protective effect for both prevention and reducing progression in already diseased arteries.
Cruciferous vegetables, like kale, broccoli, cauliflower, cabbage and Brussels sprouts, contain high levels of the active plant chemicals called glucosinolates (see one of my previous blog postings about glucosinolates). The glucosinlates are metabolized in our body into another group of molecules called isothiocyanates, which are known to be powerful anti-carcinogens. The main isothiocyanate from broccoli is sulforaphane.
Considerable previous research regarding the potential benefits of broccoli and sulforaphane have focused on the anti-cancer effects. Epidemiological (population data) and animal studies have shown that diets high in cruciferous vegetables result in fewer instances of certain cancers, especially lung, colon, breast, ovarian and bladder cancer.
This study clearly adds to growing research that including kale and other brassica vegetables in the diet on a frequent, even daily, basis may have multiple health benefits, however, the portion size needed to experience these benefits will likely be much larger than just nibbling around the edges of the decorative kale on your plate once in a while!
As a tip, in addition to all the other brassica vegetables I grow or purchase, I do enjoy eating broccoli sprouts by adding them in salads. I also use them in place of lettuce in sandwiches or wraps especially during the winter if I cannot find lettuce to purchase grown by our local farmers in their hoop houses, which permit nearly year-round production of fresh greens even as far north as Michigan. (Note: I highly recommend obtaining all the various healthful molecules available in our food (many of which have not yet been studied) instead of purchasing a bottle of just one molecule as a dietary supplement.)
Last night I made a stir-fry dish using three different types of brassica vegetables: red cabbage, baby bok choy, and yellow cauliflower. It was beautiful and tasty. I finished it for lunch today. I think that easy recipe might be called the Brassica Tri-fecta Stir-fry! I'll post that recipe and a photo separately.
Where kale is more than decoration on my plate!
Diana Dyer, MS, RD