Is it OK to put raw kale in a smoothie?

Adding raw kale to smoothies has become an incredibly popular health trend in recent years. Kale is chock full of vitamins, minerals and antioxidants that provide a wide range of health benefits. However, there are some potential downsides to putting raw kale in smoothies that are important to consider.

Benefits of Raw Kale in Smoothies

Here are some of the top benefits of adding raw kale to your smoothies:

  • Excellent source of vitamins and minerals – Raw kale is loaded with vitamins A, C, K, B6, manganese, calcium, copper, potassium and magnesium. Blending it into smoothies helps boost your daily nutrient intake.
  • Powerful antioxidants – Kale contains 45 different flavonoid antioxidants that can help fight inflammation and oxidative stress in the body. These include kaempferol and quercetin.
  • Aids digestion – The fiber in kale can help promote regularity and healthy digestion. Just 1 cup provides over 5 grams of dietary fiber.
  • Detoxification – Kale has compounds that support detoxification in the body. This includes indole-3-carbinol, which helps the liver neutralize toxins.
  • Anti-inflammatory effects – The omega-3 alpha-linolenic acid (ALA) in kale has anti-inflammatory properties that may help reduce chronic inflammation.
  • Heart health – The antioxidants, fiber, potassium, vitamin K and ALA in kale support heart health and may reduce heart disease risk.

Overall, adding kale to smoothies is an easy way to pump up your intake of essential vitamins, minerals and health-promoting plant compounds.

Potential Downsides of Raw Kale in Smoothies

Although kale smoothies certainly have some nutritional upside, there are also a few potential downsides to consider:

  • Thyroid effects – Kale contains goitrogens, compounds that may interfere with thyroid function by suppressing thyroid hormone synthesis in some people.
  • Digestive issues – For some, the fiber content of raw kale may contribute to gas, bloating or diarrhea, especially in large amounts.
  • Kidney stone risk – The oxalates found in kale can increase the risk of kidney stones in susceptible individuals when consumed in excess.
  • Nutrient absorption – The oxalates and phytic acid in kale can bind to some minerals like calcium, zinc and iron, reducing their absorption.
  • Unpleasant taste – Kale has a bitter, pungent flavor that some find unpalatable, especially when raw.
  • Gastrointestinal irritation – Isothiocyanates, compounds found in cruciferous veggies like kale, may irritate the GI tract in sensitive people.

For most people, having kale in smoothies should not pose any problems. However, those with thyroid issues, kidney problems, digestive disorders or who are taking certain medications may want to limit high intakes of raw kale.

Tips for Adding Kale to Smoothies

Here are some tips to keep in mind when using raw kale in smoothies:

  • Start small – Introduce kale gradually into your smoothies to allow your body time to adjust. Start with just a handful of leaves.
  • Blend thoroughly – This helps break down the fiber in kale for easier digestion and nutrient absorption.
  • Remove stems – Cut out the tough stems and ribs from kale leaves before adding to smoothies.
  • Pair with fruits – Adding fruits like bananas, mangoes and pineapple can help balance out kale’s bitterness.
  • Use baby kale – Baby kale tends to be milder in flavor with more tender leaves.
  • Don’t use exclusively – For variety, rotate kale with other leafy greens like spinach or romaine.
  • Watch thyroid medication – Separate ingestion of kale and thyroid medication by at least 4 hours to avoid negatively impacting absorption.

Following these tips can help you enjoy all of the nutrition of kale in smoothies without adverse effects.

Best Fruits and Vegetables to Blend With Kale

Certain fruits and veggies pair particularly well with kale in smoothies. Some top choices include:

  • Bananas – Bananas help provide creaminess and sweetness to balance out kale’s bitterness.
  • Pineapple – Pineapple contains bromelain, an enzyme that helps break down tough kale leaves.
  • Mango – Mango adds tropical flavor and helps mask the strong flavor of kale.
  • Blueberries – Blueberries provide a sweetness that complements the earthy flavors of kale.
  • Avocado – For a creamier texture, vitamin E and healthy fats.
  • Spinach – Spinach has a milder flavor that blends well with kale.
  • Apples – Apples add a touch of sweetness along with pectin fiber.
  • Cucumber – Cucumber provides hydration and a refreshing flavor.

Combining kale with sweeter, hydrating fruits and veggies can lead to smoothies that are more balanced and enjoyable.

Sample Kale Smoothie Recipes

Here are a few tasty and nutritious sample recipes for kale smoothies:

Berry Banana Kale Smoothie

  • 1 cup kale leaves, stems removed
  • 1 frozen banana, cut into chunks
  • 1 cup frozen mixed berries
  • 1 cup unsweetened almond milk
  • 2 tbsp ground flaxseed
  • 1 tbsp almond butter
  • Ice as needed

Mean Green Smoothie

  • 1 cup kale leaves, stems removed
  • 1 peeled kiwi, cut into chunks
  • 1/2 cup pineapple chunks
  • 1 tbsp fresh lime juice
  • 1/4 avocado
  • 1 cup coconut water
  • 1/4 cup fresh mint leaves
  • Ice as needed

Chocolate Peanut Butter Kale Smoothie

  • 1 cup kale leaves, stems removed
  • 1 frozen banana, cut into chunks
  • 2 tbsp cocoa powder
  • 2 tbsp peanut butter
  • 1 cup unsweetened almond milk
  • 1 scoop unsweetened pea protein powder
  • 1 tsp vanilla extract
  • Ice as needed

Storing Kale Smoothies

To maintain flavor and nutrient content, it’s best to drink kale smoothies immediately after making them. However, you can store them in an airtight container in the refrigerator for 1-2 days.

For longer storage, smoothies can be frozen in individual servings. They will keep for 3-4 months in the freezer before quality starts to degrade. Thaw overnight in the fridge or for a few minutes at room temperature before drinking.

Some separation may occur when storing kale smoothies, so make sure to shake or stir them before drinking to recombine.

Possible Smoothie Add-Ins

In addition to fruits and veggies, there are many nutritional add-ins that can be incorporated into kale smoothies:

Add-In Benefits
Chia seeds Fiber, omega-3s, protein
Flaxseeds Fiber, omega-3s
Hemp seeds Protein, magnesium, iron
Nut butter Healthy fats, protein
Yogurt Probiotics, calcium, protein
Oats Fiber, manganese
Cinnamon Antioxidants, reduces bitterness
Ginger Anti-inflammatory
Turmeric Anti-inflammatory, antioxidants

These supplements can help further boost the nutritional value of kale smoothies and add interesting new flavors.

Potential Side Effects of Too Much Kale

Eating large amounts of raw kale smoothies on a regular basis may cause some potential side effects for certain people, including:

  • Thyroid problems – Very high intakes of kale may impact thyroid function over time due to goitrogens.
  • Kidney stones – Excess oxalates from high kale intake could increase kidney stone risk.
  • Digestive issues – Too much raw kale and its fiber may lead to constipation, gas or bloating.
  • Nutrient deficiencies – The compounds in kale can interfere with absorption of some nutrients.
  • Anemia – Kale contains oxalic acid that may inhibit iron absorption needed to make healthy red blood cells.

To avoid potential problems, limit consumption of kale smoothies to no more than 2 cups of raw kale per day as part of a varied diet. Also, monitor thyroid function and digestive symptoms when regularly consuming kale smoothies.


Putting raw kale in smoothies can certainly be healthy as part of a balanced diet and active lifestyle. Kale provides a powerhouse of important vitamins, minerals and antioxidants. However, overdoing kale smoothies may cause issues for some people.

When used in moderation alongside a variety of other fruits and veggies, kale can be a nutritious addition to smoothies. Start slow when adding kale to smoothies and be mindful of any effects. Trying out different ingredient combinations and recipes can also help make kale smoothies more enjoyable.

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