Is Kale a Superfood?

Kale, a leafy green vegetable from the Brassica family, has gained in popularity over the last decade, often being hailed as a superfood (Figure 1). But what exactly makes kale deserving of this title? To answer this, we'll delve into the nutritional profile of kale and its associated health benefits.

Kale is packed with essential nutrients, offering a high nutrient density in a low-calorie package. Here's a breakdown of its nutritional content per 100 grams (USDA):

Nutrient	Amount
Calories	35 kcal
Water	89.63 g
Protein	2.92 g
Total Fat	1.49 g
Carbohydrates	4.42 g
Fiber	4.1 g
Sugars	0.99 g
Vitamins
Vitamin A	6812 IU (136% DV)
Vitamin C	93.4 mg (155% DV)
Vitamin K	389.6 µg (487% DV)
Vitamin B6	0.147 mg (7% DV)
Folate	62 µg (15% DV)
Minerals
Calcium	254 mg (25% DV)
Iron	1.60 mg (9% DV)
Magnesium	33 mg (8% DV)
Potassium	348 mg (10% DV)
Manganese	0.774 mg (39% DV)

One cup of raw, chopped kale weighs around 67 grams, and so the 100g amount in the table is about 1.5 cups.

What stands out is that kale has very few calories (only 35 per 100g) and low in fat, but is high in fiber certain vitamins, and calcium. In particular kale has a lot of Vitamin K, which is necessary for the synthesis of certain proteins that are required for blood clotting. Also, the fiber amount is impressive given that recommended daily fiber intake for adults is 25 to 30 grams, while the average American adult only consumes about 15 grams of fiber per day.

Kale is also high in antioxidants, which includes beta-carotene, vitamin C, and flavonoids like quercetin and kaempferol, although the healthful benefits of anti-oxidants have not been well characterized. Generally speaking, antioxidants may help protect against oxidative stress which can contribute to various chronic diseases such as heart disease, cancer, and neurodegenerative disorders. Antioxidants can also act as anti-inflammation agent which can reduce the risk of inflammatory conditions such as arthritis and atherosclerosis.

Kale can be consumed raw (Figure 1) although you may want to add olive oil, lemon juice, or vinegar to soften its texture. Alternatively, one can lightly steam or sautée kale which can reduce its bitterness, soften it, while mostly preserving its nutrients.

While kale's nutritional profile is undoubtedly impressive, it's important to remember that no single food is a magic bullet for health. A balanced diet that includes a variety of fruits and vegetables is key for overall well-being.

In summary, kale can certainly be considered a valuable addition to a healthy diet. Its high nutrients to calorie/fat profile makes it a worthy contender for the "superfood" title. By incorporating kale into a balanced diet, you can reap the numerous benefits this leafy green has to offer.

Figure 1. Raw kale.