Juice made from cooked greens like kale, spinach, and collard greens has become a popular health drink. Some claim that cooking greens before juicing releases more nutrients, making it more nutritious than raw vegetable juice. This article reviews whether juice from cooked greens is good for you.
Nutrients in raw vs cooked greens
Cooking greens before juicing breaks down plant cell walls, allowing some nutrients to be better absorbed. For example, cooking significantly increases the amount of lutein and zeaxanthin antioxidants your body absorbs from greens.
However, heat also destroys or alters some nutrients in greens. For example, vitamin C levels drop with prolonged cooking as heat sensitivity causes this vitamin to degrade. Here’s a comparison of select nutrients in raw vs cooked kale:
|Nutrient||Raw kale||Cooked kale|
|Vitamin C||120 mg (200% DV)||53 mg (89% DV)|
|Vitamin K||1084 mcg (904% DV)||1303 mcg (1086% DV)|
|Lutein and zeaxanthin||26 mg||35 mg|
As you can see, cooking kale into juice increases some nutrients like vitamin K and antioxidants but decreases heat-sensitive ones like vitamin C.
Benefits of drinking cooked greens juice
Here are some potential benefits of drinking juice made from cooked veggies like kale, spinach, and collard greens:
May be easier to digest
Cooking greens breaks down fiber and plant cell walls, which may make nutrients easier to absorb. This can be beneficial if you have difficulty digesting raw veggies.
Higher antioxidant absorption
Cooking boosts your absorption of antioxidants like lutein and zeaxanthin. In one study, adults absorbed over three times more lutein and zeaxanthin from cooked kale vs raw.
Inactivates compounds that can inhibit thyroid function
Raw brassica veggies like kale contain goitrogens, compounds that may suppress thyroid function by interfering with iodine uptake when consumed in excess. Cooking greens inactivates most goitrogens, reducing this risk.
More beta carotene
Beta carotene, a precursor to active vitamin A, increases with cooking. Your body converts this antioxidant into vitamin A as needed. Juice from cooked greens provides more beta carotene than raw juice.
Higher potassium content
Potassium often leaches into cooking water when greens are boiled or steamed. Drinking this nutrient-rich cooking liquid via juice gives you more potassium than consuming raw greens.
Downsides of drinking cooked greens juice
Drinking juice made from cooked greens also has some drawbacks:
Loss of heat-sensitive vitamins
Cooking degrades vitamin C and B vitamins like folate and thiamine. Juice from cooked greens will be lower in these vitamins than raw vegetable juice.
Potential acrylamide formation
Acrylamide, a potentially toxic compound, can form when certain foods are cooked at high temperatures. However, acrylamide levels remain low when boiling, steaming, or blanching greens.
Lower enzyme content
Cooking destroys the beneficial enzymes found naturally in raw fruits and vegetables. These enzymes help you digest nutrients. Juice from raw veggies retains more active enzymes.
Greens like spinach and kale contain nitrates that may boost heart health and exercise performance. Levels decrease significantly when greens are cooked.
Nutrition comparison of raw vs. cooked greens juice
This nutrition comparison shows key differences between 1 cup (240 ml) raw kale juice vs. juice made from cooked kale:
|Nutrient||Raw kale juice||Cooked kale juice|
|Protein||2 grams||3 grams|
|Vitamin C||120 mg (200% DV)||53 mg (89% DV)|
|Vitamin A||698 mcg (78% DV)||843 mcg (94% DV)|
|Vitamin K||1084 mcg (903% DV)||1303 mcg (1086% DV)|
|Potassium||299 mg (6% DV)||490 mg (10% DV)|
As shown, cooking greens prior to juicing increases some nutrients but decreases sensitive ones like vitamin C. It also provides more potassium from the released cooking water.
Should you drink juice made from cooked greens?
Drinking vegetable juice made by juicing cooked greens like kale, spinach, and collard greens can be very nutritious. The heat helps your body better absorb antioxidants like lutein while inactivating compounds that may impair thyroid function.
However, cooking also destroys heat-sensitive vitamins like C. Additionally, the lack of fiber from juicing greens rather than eating them whole increases your glycemic response.
For most people, the positives outweigh the negatives. Juice from cooked greens can be a healthy addition to your diet when consumed in moderation as part of an overall vegetable-rich eating pattern.
Aim for no more than 1 cup (240 ml) per day, and be sure to also eat plenty of raw fruits and veggies. Juice from cooked greens provides different benefits than raw vegetable juice, so rotating both into your diet gives you the best nutrient profile.
The bottom line
Juice made by juicing greens like kale, spinach, and collard greens after cooking can provide some nutritional benefits. The heat breaks down antioxidants and plant compounds, potentially increasing their absorption. However, it also degrades some nutrients, especially vitamin C. For the best nutrient profile, incorporate both raw and cooked greens juice as part of a healthy diet.