Kale (Brassica oleracea), also known as leaf cabbage, is a nutrient-dense vegetable offering a variety of health-related benefits. Classified as a cruciferous plant, kale is most closely related to vegetables such as cauliflower, cabbage, brussels sprouts, and broccoli (1). Containing high levels of several vitamins and antioxidants, kale lives up to its reputation as a superfood.
Several different varieties of kale exist (baby, dinosaur, and red, to name a few) but the most common type is a dark green leafy plant known as curly kale (2). Kale is a simple plant to grow and harvest, and it can be found in nearly any climate worldwide. In fact, many people can successfully grow kale in their home gardens.
One cup of fresh kale contains only 7 calories, so this is a great vegetable to incorporate if you’re trying to lose weight or simply make more nutritious food choices (3). Despite its minuscule calorie count, fresh kale boasts an impressive vitamin (most namely vitamins C, K, several B vitamins, and the precursor to vitamin A) and mineral (manganese, calcium, copper, potassium, iron, phosphorus, and magnesium) profile. Kale also provides a modest amount of carbohydrates (about 1 gram/cup), almost entirely from dietary fibre, as well as minimal protein (0.6 g/cup) and fat (0.3 g/cup).
As kale does not have a strong flavour, it can easily be juiced or blended with a variety of other freshly-pressed vegetable and fruit juices. If you enjoy fresh juice for breakfast, adding kale to your recipe is an easy and refreshing way to pack in the nutrients and get your day started on the right foot!
Kale Juice & Iron Deficiency
If you suffer from iron deficiency, the chances are that you’ve been searching for an inexpensive and easy solution to your health woes. But wait… not so fast. Kale juice isn’t automatically a silver bullet here. Let’s talk science for a second.
Iron is one component of hemoglobin, which makes up a vital part of red blood cells (4). Hemoglobin is responsible for transporting oxygen through the bloodstream to wherever it is needed in the body (namely muscles and skin), then sends it back to the lungs to be exhaled as carbon dioxide.
If you don’t have enough iron in your diet, you may become deficient, and this may eventually progress to anemia. So, obviously, the easy answer is to consume more iron-rich foods. Most people can get plenty of dietary iron from heme (animal-based) iron sources, which are much more readily absorbed by the body – approximately 2 to 3 times more than plant sources (non-heme) (4).
However, for those of us who are vegetarian or vegan or simply do not consume much meat, this can pose a bit of a problem. Many plant foods contain moderate amounts of iron, including kale, but as noted before, the absorption of this iron is not nearly as effective. If you can consume a non-heme iron-containing food at the same meal as a food rich in vitamin C, the absorption tends to be greatly improved (4). However, you should avoid combining plant sources of iron with dairy foods, as they may inhibit the body’s uptake of iron.
So, if you are a vegetarian with iron deficiency, consider adding kale juice to your regimen – but remember to include a source of vitamin C. Kale and orange juices pair quite nicely in this respect!
Kale Juice & Coagulation
Kale juice contains impressive amounts of vitamin K1 (phylloquinone), a nutrient required by the body to activate proteins needed for coagulation (also known as blood clotting)(3). Coagulation can literally mean the difference between life and death – as clotting is required for something as simple as a scratch or cut (or as severe as trauma wounds or surgical incisions) to stop bleeding.
Kale Juice & Antioxidants
Similar to most other vegetables, kale contains high levels of several antioxidants, most notably vitamin C and beta-carotene (5). The primary function of antioxidants is to fight free radicals (reactive oxygen species), which are chemical compounds that can cause cell damage throughout the body as a result of oxidation reactions (6). The extent and location of cell damage can vary greatly, but the damage incurred by free radicals has been linked to the development of several chronic diseases, including cancer (7).
Kale Juice & Cancer Prevention
Endless amounts of research have concluded that cruciferous vegetables such as kale may help lower the risk of developing certain types of cancers – including prostate, colorectal, lung, and breast (8). While the link between colorectal health and this high-fibre vegetable is clear, how does it work for other types of cancer?
It all comes down to a few different compounds found in cruciferous vegetables such as kale. Glucosinolates are a naturally-occurring sulphur-containing compound formed from a chemical bound to glucose (9). During digestion, glucosinolates are broken down to active compounds that tend to prevent the development or spread of cancers of the gastrointestinal tract, lungs, and other tissues. These active compounds include thiocyanates, nitriles, indoles, and isothiocyanates, to name a few (8).
Of course, simply consuming enough kale juice isn’t a guarantee that you won’t develop cancer at some point in your life, but it can certainly improve your odds.
Kale Juice & Inflammation
Kale also possesses impressive anti-inflammatory effects. It is believed that these effects are owed to the presence of high levels of vitamin K, which helps decrease the presence of serum markers of inflammation (10).
Decreased inflammation can improve prognosis and/or quality of life for people afflicted with conditions such as chronic pain, infections, arthritis, and autoimmune disorders. Swelling and pain may be reduced significantly, and the incidence of infection owed to systemic inflammation can decrease.
Kale Juice & Eye Health
As we age, many people experience poor vision, and some even develop eye disorders such as cataracts and macular degeneration. While kale juice certainly cannot take you from legally blind to 20/20 vision, age-related vision deterioration can be minimised.
Two antioxidants in particular that are found in the carotenoid family (zeaxanthin and lutein) are abundant in kale (11). Several studies have concluded that these nutrients play a major role in the prevention of age-related vision disorders (11, 12).
Kale Juice & Heart Health
Kale has the ability to lower LDL (“bad”) cholesterol levels and increase HDL (“good”) levels. Kale contains bile acid sequestrants, which are chemicals that bind to bile acids in order to prevent them from being reabsorbed by the body (13). By preventing this action, cholesterol levels are lowered, as unused bile acids in the body are recycled for packaging into new cholesterol.
As you may already know, improved cholesterol levels are associated with a decreased risk of developing heart disease (13). That said, kale juice can be surprisingly effective in altering cholesterol numbers. One Korean study of otherwise healthy men with high cholesterol concluded that simply adding a daily 150 mL serving of kale juice was effective in decreasing LDL levels by 10% and increasing HDL by 27% (14).
A Word of Advice
As you’ve now seen, cold-pressed kale juice can be a great source of essential vitamins and minerals, and it can afford you a variety of health-related benefits. However, if you have any medical conditions (especially hypothyroidism or chronic kidney disease) or take any medications (most notable anticoagulants such as warfarin), you may want to exercise caution or discuss your intention with a doctor prior to adding large quantities of kale juice into your diet, as otherwise-beneficial nutrients may affect you differently.
Otherwise, go ahead and try kale juice to your heart’s content. Drink to your health. Cheers!