The Power of Kale to Detoxify

Green Leafy Vegetables (GLVs) are well known for being incredibly rich in micronutrients and phytonutrients, or plant-based nutrients. Some of these nutrients include, but are not limited to: iron, antioxidants (i.e. Vitamin A and Vitamin C) and polyphenols[i] (plant-based compounds). In fact, more recent research is suggesting that GLVs are an effective functional food in combating several conditions, including age-related macular degeneration[ii] and Cardiovascular Disease (CVD).[iii]

In a 2016 meta-analysis study, consumption of GLVs (including cruciferous vegetables) demonstrated a significant reduction in risk factors for various types of CVD.[iv] These findings beg the question: “Is there a superior GLV that is most beneficial to consume?”. In my opinion, there does seem to be one GLV that stands out amongst the rest: kale.

Kale is a GLV and a member of the Brassica family (Brassica oleracea acephala). It is commonly grown and consumed in North America and Europe and has more recently been cultivated and consumed in Asia (i.e. China and Korea).[v] Its nutrient profile is impressive, containing dietary fiber, minerals, vitamins, carotenoids, anthocyanins, coumarins, flavonoids and sulfur-containing glucosinolates (GLS).

GLS are probably the most interesting and promising phytonutrient found in kale, as GLS and their metabolic byproducts (i.e. isothiocyanates [ITC] and indoles), possess therapeutic properties for influencing both cancer and CVD.[vi] The metabolic byproduct of GLS to ITC provides an enzymatic mechanism for an important family of enzymes to get switched on within the pathways of Phase I and Phase II of liver detoxification – the Glutathione S-transferase (GST) family of enzymes.[vii]

A six-week study evaluating the effect of kale juice supplementation on subclinical hypertension (high blood pressure) found some promising results.[viii] In this study, the team of researchers evaluated the capacity of polymorphic (genetic-based) variations of the GST genotype to influence biomarkers after supplementing with kale juice.[ix] What they found was remarkable: a decrease in systolic and diastolic blood pressure, a decrease in serum LDL cholesterol, as well as improvements in blood glucose regulation. These results varied, depending on the specific combination of polymorphisms of the GST genotype of the research participant at hand. Nonetheless, the research suggested that kale is effective at helping to manage CVD.

Other research has demonstrated a significant reduction of serum LDL cholesterol in hypercholesterolemic men after supplementing with kale juice.[x] It seems that kale is truly a contender as the most superior of the GLVs.

ENDNOTES

[i] Tarwadi, K., & Agte, V. (2003). Potential of commonly consumed green leafy vegetables for their antioxidant capacity and its linkage with the micronutrient profile. International Journal Of Food Sciences & Nutrition, 54(6), 417.

[ii] Eisenhauer, B., Natoli, S., Liew, G., & Flood, V. M. (2017). Lutein and Zeaxanthin-Food Sources, Bioavailability and Dietary Variety in Age-Related Macular Degeneration Protection. Nutrients, 9(2), doi:10.3390/nu9020120

[iii] Pollock, R. L. (2016). The effect of green leafy and cruciferous vegetable intake on the incidence of cardiovascular disease: A meta-analysis. JRSM Cardiovascular Disease, 52048004016661435. doi:10.1177/2048004016661435

[iv] Pollock, R. L. (2016). The effect of green leafy and cruciferous vegetable intake on the incidence of cardiovascular disease: A meta-analysis. JRSM Cardiovascular Disease, 52048004016661435. doi:10.1177/2048004016661435

[v] Han, J., Lee, H., Kim, T., & Kang, M. (2015). The effect of glutathione S-transferase M1 and T1 polymorphisms on blood pressure, blood glucose, and lipid profiles following the supplementation of kale (Brassica oleracea acephala) juice in South Korean subclinical hypertensive patients. Nutrition Research And Practice, 9(1), 49-56. doi:10.4162/nrp.2015.9.1.49

[vi] Park, Y., Lee, H., Shin, M., Arasu, M. V., Chung, D. Y., Al-Dhabi, N. A., & Kim, S. (2018). Effect of different proportion of sulphur treatments on the contents of glucosinolate in kale (Brassica oleracea var. acephala) commonly consumed in Republic of Korea. Saudi Journal Of Biological Sciences, 25(2), 349-353. doi:10.1016/j.sjbs.2017.04.012

[vii] Han, J., Lee, H., Kim, T., & Kang, M. (2015). The effect of glutathione S-transferase M1 and T1 polymorphisms on blood pressure, blood glucose, and lipid profiles following the supplementation of kale (Brassica oleracea acephala) juice in South Korean subclinical hypertensive patients. Nutrition Research And Practice, 9(1), 49-56. doi:10.4162/nrp.2015.9.1.49

[viii] Han, J., Lee, H., Kim, T., & Kang, M. (2015). The effect of glutathione S-transferase M1 and T1 polymorphisms on blood pressure, blood glucose, and lipid profiles following the supplementation of kale (Brassica oleracea acephala) juice in South Korean subclinical hypertensive patients. Nutrition Research And Practice, 9(1), 49-56. doi:10.4162/nrp.2015.9.1.49

[ix] Han, J., Lee, H., Kim, T., & Kang, M. (2015). The effect of glutathione S-transferase M1 and T1 polymorphisms on blood pressure, blood glucose, and lipid profiles following the supplementation of kale (Brassica oleracea acephala) juice in South Korean subclinical hypertensive patients. Nutrition Research And Practice, 9(1), 49-56. doi:10.4162/nrp.2015.9.1.49

[x] Kim, S. Y., Yoon, S., Kwon, S. M., Park, K. S., & Lee-Kim, Y. C. (2008). Kale Juice Improves Coronary Artery Disease Risk Factors in Hypercholesterolemic Men11This research was supported by the Brain Korea 21 Project from the Korea Research Foundation. Biomedical And Environmental Sciences, 2191-97. doi:10.1016/S0895-3988(08)60012-4

Travis Cox