Quick Answer
Yes, it is perfectly safe and healthy to put raw kale in a smoothie. Kale is a nutritious leafy green that blends up well in smoothies. As long as you wash the kale first, there are no downsides to using raw kale in smoothies. The fiber and nutrients in kale will remain intact when blended.
Explaining the Safety and Benefits of Raw Kale in Smoothies
Kale is one of the healthiest foods you can eat. This nutritional powerhouse provides antioxidants, fiber, vitamins, and minerals. Blending raw kale into smoothies is an easy way to reap the benefits of this superfood veggie. Here is a closer look at why raw kale is safe and advantageous to use in smoothies:
Kale Has a Low Risk of Contamination
Some people worry about using raw greens in smoothies because of the potential risk of contamination with bacteria like E. coli or Salmonella. However, kale and other leafy greens are very low-risk when it comes to foodborne illnesses.
The Center for Disease Control and Prevention (CDC) states that between 2009-2017, only 2% of foodborne illness outbreaks were linked to leafy vegetables like kale. Produce that grows close to the ground, like spinach, carries more contamination risk than kale and other loose leafy greens.
As long as you rinse kale under running water before adding it to your smoothie, it is very unlikely to cause any food poisoning. Proper washing removes any dirt and residue that could potentially harbor bacteria.
Blending Breaks Down the Cell Walls
Some people believe that leafy greens must be cooked before eating them because our digestive systems cannot break down the tough plant cell walls. This is true when you eat raw kale in a salad. However, putting kale in a blender ruptures the cell walls, releasing the nutrients and making them easier to absorb.
Blending raw kale ruptures the plant’s cell structure, essentially “pre-digesting” it for you. The powerful blades break through the fibrous cell walls. Blending kale makes the lutein, beta-carotene, vitamins, minerals, and antioxidants more bioavailable than just eating raw leaves.
Fiber Stays Intact When Blended
Kale provides 2.6 grams of dietary fiber per 100 grams. Fiber is an important nutrient that promotes gut health, digestion, heart health, stabilizes blood sugar levels, and aids in weight management.
When you blend up raw kale into a smoothie, the valuable insoluble fiber remains intact. The insoluble fiber does not get broken down and provides bulking effects to keep waste moving through your digestive tract.
With a high-speed blender like a Vitmix, the kale gets broken down on a cellular level but the fibrous stalks and strands remain in the smoothie. The fiber content does not decrease by blending, giving you the full benefits.
Nutrients Are Preserved in Blended Kale
Kale contains antioxidants, phytochemicals, vitamins, and minerals that provide health benefits ranging from reduced inflammation to cancer prevention. Lutein and zeaxanthin support eye health, while vitamins A, C, and K boost immunity.
The good news is that the nutrient content of kale remains stable even after blending. According to a study in the Journal of Food Science and Technology, green leafy vegetables retain their antioxidant capacity and vitamin C levels after blending.
Another study found no significant losses in carotenoids like beta-carotene and lutein from kale smoothies made in a high-speed blender and consumed immediately. The nutrients in raw kale are preserved through the blending process.
Blending Kale Improves the Texture
One of the benefits of putting kale in smoothies is that blending improves the texture significantly. Raw kale can be quite fibrous and tough to chew. This can make it unappealing to some people.
Blending kale into smoothies ruptures the plant cells, incorporating the greens with a creamy, smooth texture. Kale gets broken down on a microscopic level so you do not end up chewing on raw chunks. This makes kale more enjoyable and easier to digest.
Kale Blends Well with Other Smoothie Ingredients
Raw kale has a mild flavor that pairs well with many ingredients commonly used in green smoothies. Sweet fruits help balance out kale’s slight bitterness. Popular fruits to blend with kale include bananas, mangoes, pineapples, berries, and apples.
Kale also combines nicely with smoothie bases like yogurt, milk, nut milks, and protein powders. The bold green color of kale gives smoothies an appetizing vibrancy. You can pack a smoothie full of kale without negatively impacting the taste.
Washing Kale Removes Bacteria
As long as you wash kale properly before making a smoothie, there is no worry about contamination. Simply rinse kale leaves under cool running water. Use your hands to gently agitate the kale to loosen any dirt or residue.
The CDC recommends letting produce like kale soak in cold water for a few minutes then rinsing several times under fresh water. Pat the leaves dry with a paper towel or use a salad spinner. This removes any potentially harmful bacteria.
Best Practices for Using Kale in Smoothies
Follow these tips to safely reap the many benefits of adding raw kale to your smoothies:
Give Kale a Good Rinse
Be sure to wash kale thoroughly under cool water before blending to remove any dirt or bacteria. Swish the leaves around and rinse several times to dislodge anything on the surface.
Use a High-Powered Blender
To break down the plant cell walls of kale, you need a quality high-speed blender like a Vitamix, Blendtec, or Ninja. This gives smoothies with kale a silky consistency without fibrous chunks.
Blend with Frozen Fruit or Ice
Adding frozen fruit or ice cubes to kale smoothies creates a chilled texture that blends smoothly. The frozen ingredients also help break down the greens even further.
Blend Kale with Flavor Boosters
Complement the flavor of kale with tropical fruits, citrus juices, vanilla, cinnamon, nut butters, or chocolate to make it more palatable. Sweet and acidic ingredients mask any bitterness.
Use Mature Kale Leaves
Choose full-sized kale leaves rather than young baby kale, which can be too delicate for smoothies. Mature kale holds up better during blending. Remove thick stems before adding kale to your smoothie.
Drink Kale Smoothies Immediately
For maximum nutrition, drink smoothies with raw kale right after making them. Leaving blended kale to sit allows oxidation which decreases some of the vitamin and antioxidant content.
Store Leftovers Properly
If you do not finish your kale smoothie, transfer it to an airtight container and refrigerate for up to 24 hours. The chilled temperature preserves the nutrients and prevents spoilage.
Watch for Textural Changes
If smoothies with kale start turning brown or developing a slimy texture, this indicates oxidation is occurring. Drink smoothies with raw kale as soon as possible for best flavor and nutrition.
Potential Drawbacks of Raw Kale in Smoothies
While rare, there are a few possible downsides associated with using raw kale in smoothies:
Risk of Contamination
As mentioned, the risk is very low but improperly washed kale could potentially harbor harmful bacteria like E. coli or Salmonella. Always rinse kale thoroughly before blending to remove any contaminants.
Texture Issues
If you do not have a powerful blender, raw kale can result in fibrous pieces or chunks in the smoothie which makes them less enjoyable to drink. Invest in a high-speed blender for smooth results.
Gassiness or Bloating
The fiber content in kale may lead to excess gas or bloating in some people, especially in large amounts. Start with small amounts of kale in your smoothies and gradually increase the amount as tolerated.
Hypothyroidism Concerns
Very high intakes of raw kale have been linked to potential thyroid issues in those with underlying iodine deficiency. As long as you eat kale in normal dietary amounts, it will not negatively impact thyroid function.
Nutrient Loss from Heat Exposure
Leaving blended kale smoothies out too long allows heat and oxygen exposure which can lower some of the vitamin and antioxidant content. For maximum nutrition, drink kale smoothies promptly.
Metallic Taste
The green pigments in kale like chlorophyll can sometimes lend a mild metallic flavor, especially when blended with acidic fruits. Adding vanilla, cinnamon, sweet fruits, or nut butters can help mask any aftertaste.
Frequently Asked Questions
Does blending kale destroy the nutrients?
No, the nutrients in kale remain intact through the blending process as long as the smoothie is consumed shortly after making it. The fiber, vitamins, minerals, and antioxidants are preserved.
Is raw kale harder to digest than cooked kale?
Kale contains insoluble fiber that does not break down during digestion. However, blending ruptures the plant cell walls, making the nutrients in raw kale easier to absorb than when eaten in leafy form.
Can you put too much kale in a smoothie?
It is possible to add too much raw kale to a smoothie, resulting in a bitter, vegetal taste. A good rule of thumb is to use about 1 cup packed kale leaves per 2-3 cups of total smoothie ingredients.
Does kale need to be soaked before blending?
Soaking kale beforehand is not necessary as long as you blend it with enough liquid to achieve the desired consistency. If using stems, soaking in cold water for 5 minutes may help soften them before blending.
Is it better to eat kale raw or cooked?
Raw and cooked kale both provide benefits. Cooking helps reduce compounds that can interfere with thyroid function in very high amounts. Blending raw kale makes the nutrients more bioavailable. Enjoying kale both raw and cooked is ideal.
Can you freeze kale smoothies?
Yes, smoothies made with raw kale can be frozen for up to 6 months. The cold temperature prevents degradation of vitamins. Thaw in the fridge before drinking for the best texture.
The Bottom Line
Incorporating raw kale into smoothies is a safe, effective way to reap the many nutrients in this leafy green. As long as you give the kale a thorough rinse and blend until smooth, there are no health risks to drinking kale smoothies. The fiber, vitamins, minerals, and antioxidants in kale remain intact through blending, providing a healthy boost to any smoothie. Drink green smoothies made with raw kale right after preparing them for maximum nutritional benefits.
