Kale Powder vs Fresh Kale

Fresh kale is readily available in grocery stores and farmers' markets, while kale powder is typically sold in resealable pouches or small tubs in health food stores. In this article, we compare the nutritional value of kale powder vs fresh kale. We will also provide information about the possible side effects of eating too much kale, as well as tips on how to store and use kale powder and its fresh counterpart.

Nutritional Value

Often touted as a superfood, kale is a nutritional heavyweight that is on par with powerhouse foods like moringa and spinach in terms of nutritional value. Whether you go for fresh or frozen kale, you will be providing your body with plenty of folate, vitamin C, vitamin K, beta-carotene, riboflavin, vitamin B6, vitamin E, and a slew of minerals. But how does kale powder fare against fresh kale in terms of nutritional value?

While some nutrition is always lost when green vegetables are turned into superfood powders because of the exposure to air during the drying and grinding processes, kale powder is still an excellent source of nutrients and health-protecting phytochemicals. In fact, weight for weight, kale powder is a better source of many nutrients than fresh kale because removing water during the dehydration process concentrates what's left, essentially jamming more fiber and air-resistant nutrients and phytochemicals into a smaller space.

Indeed, a study published in the peer-reviewed Journal of Food Processing and Preservation found that air-dried kale contained a whopping 158 milligrams of carotenoids and 646 milligrams of chlorophyll per 100 grams, while fresh kale contained 28.1 milligrams of carotenoids and 121 milligrams of chlorophyll. And, freeze-dried kale powder was found to contain even more of these health-giving compounds (1).

Like fresh kale, freeze-dried kale powder also contains glucosinolates which can be converted into cancer-fighting isothiocyanates in the presence of an enzyme called myrosinase (2). That said, the glucosinolate content of freeze-dried kale powder can vary greatly depending on the type of kale that was used to make the powder, with black kale (lacinato) generally beating curly kale in this regard (3).

Side Effects of Too Much Kale Powder or Fresh Kale

We have all heard the saying, "too much of a good thing can be harmful", and that applies to kale, too. Especially kale powder can be problematic because it is such as concentrated source of all sorts of compounds, so it is very easy to go overboard.

In particular, people who have an increased risk of thyroid problems or have an existing health problem should talk to a qualified health care professional before adding kale powder (or fresh kale) to their diet. That's because Brassica vegetables like kale and cabbage have goitrogenic properties, especially when consumed raw, which means that they may interfere with normal thyroid activity and cause conditions like hypothyroidism.

As kale is supercharged with vitamin K, also people who take blood thinning medications should take extra caution and ask their doctor about how much kale they can safely consume because high doses of vitamin K can block the effects of blood thinners like warfarin.

What's more, kale contains nitrates, though its nitrate content is generally nowhere near as high as that of arugula or spinach. Abundant in many green leafy vegetables, nitrates are controversial compounds that initially earned a bad reputation because they can be converted into nitrites and further into carcinogenic nitrosamines.

However, a meta-analysis published in the journal Nutrients could not find a positive correlation between a high intake of plant-based nitrates and risk of gastric cancer, probably because the health benefits of eating green leafy vegetables outweigh the disadvantages (4, 5).

Nevertheless, experts have been recommending measures to keep the nitrate levels in vegetables in check in order to maximize the health benefits of vegetables. These measures include storing vegetables properly and removing the stem and midrib from certain green leafy vegetables. (6)

Culinary Uses

We all love homemade kale chips, but that's just one of the many wonderful things you can do with kale. You can use fresh kale, for example, to add nutrients, flavor and texture to stir-fries, risottos, omelettes and pizza toppings. Or, whip up a tasty kale smoothie by puréeing some young kale leaves with your favorite fruits in a high-powered blender.

If you have a masticating juicer designed to handle greens like kale or spinach, you can also try making some nutrient-packed kale juice. While pure kale juice is not particularly tasty, it's wonderful when mixed with sweeter juices such as apple juice.

While fresh kale can add texture to dishes, kale powder is primarily used to add color, flavor and nutrients to dishes. Popular ways to use kale powder include blending it into green smoothies and puréed soups, adding it to sauces, dips and salad dressings, incorporating it into egg-based dishes such as omelettes and scrambled eggs, and sprinkling it on salads.

Storage

One of the most important differences between kale powder and fresh kale is that properly stored kale powder has a relatively long shelf life, whereas fresh kale should be eaten within days of being purchased. What's more, kale powder should be stored in an airtight container in a cool, dry place such as a kitchen cabinet, while fresh kale is best stored in a sealable plastic bag in the crisper drawer of your fridge.

If you think you won't be able to use up all the fresh kale in your fridge before it starts to wilt, you can also freeze it for later use. Before freezing kale, it is best to blanch it first by putting the trimmed and rinsed leaves into boiling water for two minutes and then submerging the blanched leaves in a bowl of ice water to stop the cooking process. Blanching vegetables before freezing helps destroy enzymes and bacteria that cause spoilage.

Sources

1. A. Korus (2013). Effect of preliminary and technological treatments on the content of chlorophylls and carotenoids in kale (Brassica oleracea L. var. acephala). Journal of Food Processing and Preservation, 37(4)
2. Isothiocyanates. Micronutrient Information Center, Linus Pauling Institute, Oregon State University.
3. M. Kim et al (2017). Glucosinolates, Carotenoids, and Vitamins E and K Variation from Selected Kale and Collard Cultivars. Journal of Food Quality, volume 2017, Article ID 5123572.
4. 4 P. Song et al (2015). Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis. Nutrients, 7(12): 9872-9895.
5. Marina Cavaiuolo and Antonio Ferrante (2014). Nitrates and Glucosinolates as Strong Determinants of the Nutritional Quality in Rocket Leafy Salads. Nutrients, 6(4): 1519-1538.
6. T. Chan (2011). Vegetable-borne nitrate and nitrite and the risk of methaemoglobinaemia. Toxicology Letters, 200(1-2), 107-108.