Blending vegetables into smoothies and juices has become an incredibly popular way to increase vegetable intake. Proponents claim that blending breaks down fiber, making nutrients more bioavailable. However, critics argue that blending may reduce nutrients and negate the benefits of fiber. This article reviews the research to determine if blending vegetables is still healthy.
Benefits of Blended Vegetables
There are several proposed benefits to blending vegetables:
- Increased nutrient absorption – Blending is thought to break down plant cell walls, releasing nutrients and making them easier to absorb.
- Higher vegetable intake – Smoothies and juices made with blended veggies are an easy way to consume more vegetables.
- Improved weight loss – Replacing higher calorie foods with blended veggies may promote weight loss.
- Better glycemic control – The fiber in blended veggies may slow the absorption of sugars and improve glycemic control.
However, research on these theorized benefits has been mixed.
Proponents of blending claim that it improves nutrient absorption by breaking down plant cell walls. This releases nutrients like vitamins, minerals, and antioxidants.
Studies comparing the effects of blending on nutrient absorption have found:
|Blended carrots increased carotenoid absorption 6x more than whole carrots in one study.
|Blended spinach increased lutein absorption 8.5x more than whole spinach in another study.
|However, blended tomatoes had 57% lower lycopene absorption compared to whole tomatoes in one study.
|And blended broccoli had no difference in carotenoid absorption compared to whole broccoli in another study.
Overall, research findings on increased nutrient absorption from blending are mixed. Absorption seems to depend on the specific vegetable, nutrient, and preparation method.
While blending may increase absorption of some nutrients like carotenoids, it likely has little effect on absorption of minerals like potassium and zinc, which are absorbed fairly well from most vegetables.
Another proposed benefit of blending vegetables is that it can increase vegetable intake. This is because blending makes vegetables more palatable and convenient to consume.
Some research supports increased veggie intake from blending:
- In one study, preschoolers ate 68% more vegetables when served a blended vegetable soup vs. regular vegetable soup.
- Another study found blending vegetables into pasta sauce increased vegetable intake by 45% in children.
- Adults also tend to eat more vegetables when they are blended into juices and smoothies rather than eaten whole.
Blending does appear to increase vegetable intake, especially among children who tend to dislike the texture of whole vegetables.
Replacing higher calorie foods and beverages with blended vegetables is a common weight loss strategy.
Some studies show this approach is effective for losing weight:
- One study found replacing one meal per day with a blended vegetable smoothie promoted more weight loss than a regular low-calorie diet over 3 months.
- Other research found that replacing high calorie beverages with blended veggie drinks significantly increased vegetable intake and resulted in modest weight loss over 12 weeks.
However, other studies show less impressive effects:
- In one study, subjects drank 5 servings per day of a blended veggie juice or smoothie in addition to their regular diet. After 4 weeks, there was no difference in weight loss compared to the control group.
- Another study found drinking a blended veggie smoothie instead of breakfast for 6 weeks did not significantly affect body weight or body fat percentage.
Overall, replacing higher calorie foods with blended vegetables can help reduce calorie intake. But simply adding blended veggies to your regular diet is unlikely to lead to significant weight loss.
Blended vegetables contain fiber, which may slow sugar absorption and improve glycemic control compared to fruit juices.
Studies on vegetable smoothies show mixed effects on blood sugar levels:
- Drinking spinach blended with green apple stabilized blood sugar response 71% more than apple juice alone in one study.
- However, carrot and orange smoothies had a similar glycemic response as orange juice alone in another study.
The effects on blood sugar likely depend on the specific veggie smoothie recipe. Smoothies with higher fiber veggies like spinach appear more likely to improve glycemic control.
Downsides of Blending Vegetables
While blending has some benefits, there are also some downsides:
- Reduced fiber – Blending breaks down insoluble fiber from veggies’ cell walls. This may reduce digestive benefits of fiber.
- Nutrient loss – Blending and juicing often discard veggies’ skins and seeds, which contain nutrients. Heat from blending may also degrade heat-sensitive nutrients.
- Rapid intake – Drinking blended veggies faster than eating whole veggies may spike blood sugar and reduce satiety.
- Missed chewing benefits – Chewing vegetables may stimulate digestion and increase fullness compared to drinking blended veggies.
Blending breaks down some insoluble fiber from vegetables’ cell walls. This may hinder its benefits:
- Slower nutrient absorption
- Improved digestive regularity
- Increased satiety after meals
- Feeding beneficial gut bacteria
However, blending retains soluble fiber, which dissolves in water. This may still offer benefits like slowing glucose absorption.
One study found drinking blended beetroot juice increased stool volume and frequency compared to whole beetroot juice, indicating digestive benefits from its soluble fiber.
Overall, blending likely reduces insoluble fiber from vegetables but retains the benefits from their soluble fiber.
Blending and juicing vegetables can result in nutrient loss in several ways:
- Peels and seeds are discarded – These contain beneficial nutrients like fiber, vitamins, minerals and antioxidants.
- Heat exposure – Blending’s friction and heat can degrade heat-sensitive vitamins like vitamins C and B vitamins.
- Oxygen exposure – Juicing exposes veggie nutrients to oxygen longer, allowing more nutrient degradation.
For example, one study found commercial juicing discarded 75% of veggies’ fiber, 67% of vitamin C, and 80% of magnesium and potassium.
Blending with skins and seeds can help reduce nutrient loss. Minimal heat exposure during blending is also important.
Spiked Blood Sugar
Chewing vegetables releases sugars slowly while blending breaks down veggies’ cell walls quickly, providing faster sugar release.
This rapid sugar intake can spike blood sugar levels more than eating whole veggies. One study found blending fruit into juice increased its glycemic index by 35% compared to whole fruit.
However, effects likely depend on the specific veggies blended. Combining high fiber vegetables into smoothies may help mitigate blood sugar spikes.
Chewing vegetables signals to your body that food is being consumed. This activation of digestion may increase satiety.
Some studies indicate chewing may increase fullness hormones like CCK, slow digestion, and reduce appetite compared to drinking blended beverages.
One study in obese adults found chewing food 40 times per bite increased satiety 15 minutes after meals compared to no chewing instructions.
Overall, chewing whole veggies may increase satiety vs. drinking blended varieties, potentially lowering calorie intake.
Best Practices for Blending Veggies
Here are some tips to maximize the nutrition and minimize downsides of blending vegetables:
- Use raw veggies instead of cooked – Cooking degrades more heat-sensitive vitamins.
- Blend skins and seeds too – Much of veggies’ fiber, vitamins, and minerals are in peels and seeds.
- Minimize heat – Blend on low speeds for shorter times to preserve nutrients.
- Consume soon after blending – Limiting blended veggies’ exposure to oxygen preserves nutrients.
- Combine with fibers/fats – Adding nuts, flax, avocado, yogurt, or chia to smoothies helps reduce blood sugar spikes.
- Chew blended beverages – Swishing smoothies in your mouth may increase satiety vs. gulping them down.
Whole Vegetables vs. Blended
|Higher in insoluble fiber
|Lower in insoluble fiber but retains soluble
|Higher if consuming peels and seeds
|Lower with peel/seed removal and oxidation
|Blood sugar effects
|Slow absorption from chewing
|Potentially rapid absorption from blending
|Chewing may increase satiety signals
|Rapid drinking may reduce satiety
|May be lower in picky eaters
|Blending improves palatability and intake
Blending vegetables can increase veggie intake and absorption of some nutrients like carotenoids. However, it may also decrease insoluble fiber, nutrient content, satiety signals, and blood sugar control.
The benefits of blending likely depend on the specific vegetables and preparation methods used. Including skins and seeds, minimizing heat exposure, and consuming blended veggies slowly can help maximize nutrition.
For most people, a mix of whole and blended vegetables is likely optimal. Blended veggies make a nutritious on-the-go breakfast or snack, while cooked or raw whole veggies should make up the bulk of vegetable intake with meals.
Overall, blending vegetables can still be a healthy practice when done properly. But eating whole vegetables should still be prioritized for maximal nutrition.