Is blending fruit and vegetables healthy?
Blending fruit and vegetables into smoothies and juices has become an incredibly popular way to increase produce consumption. Proponents claim that blending breaks down fiber and makes nutrients more bioavailable. However, critics argue that blending strips away beneficial fiber and causes a rapid spike in blood sugar. So what’s the truth? Let’s take a comprehensive look at the health effects of blending fruit and vegetables.
Potential Benefits of Blending
Here are some of the touted benefits of blending fruits and veggies:
- Increases consumption of fruits and vegetables
- Makes nutrients more bioavailable
- Easier to digest
- Allows greater variety and combinations of produce
- More portable and convenient than whole produce
Blending does make it easier to consume more fruits and vegetables, which is linked to lower risks of chronic diseases like heart disease, diabetes, and cancer (1). The convenience of smoothies and juices may promote higher produce intake compared to eating whole fruits and veggies.
Some also claim that blending ruptures plant cell walls, releasing nutrients and making them more bioavailable for absorption. However, research on this is limited.
Blending may make produce easier to digest, especially for those with digestive issues like IBS. The mechanical breakdown may allow the nutrients to be absorbed more easily (2).
Additionally, blending enables unique combinations of fruits and veggies that would be difficult or impossible to eat whole. This allows greater diversity of nutrients.
Potential Downsides of Blending
Here are some potential cons associated with blending produce:
- Loss of fiber
- Rapid absorption and blood sugar spike
- Oxidation and loss of nutrients
- Not as satisfying as whole food
Blending liquefies the fiber in fruits and veggies. Fiber slows digestion and promotes fullness. Without fiber, the natural sugars in produce are absorbed very quickly, spiking blood sugar (3).
The mechanical force and heat generated during blending may destroy heat-sensitive nutrients like vitamin C. Exposure to oxygen may also degrade nutrients and antioxidants (4).
The liquid form of blended produce is not as satisfying as chewing whole fruits and vegetables. This could lead to overconsumption of calories (5).
Fiber Content
Fiber is an important nutrient that promotes gut health and satiety. Here is the fiber content of some blended fruits and vegetables compared to their whole food counterparts (6):
| Food | Serving | Fiber in Whole Food | Fiber in Blended Form |
|---|---|---|---|
| Apple | 1 medium (182g) | 4.4g | 1.5g |
| Banana | 1 medium (118g) | 3.1g | 1.3g |
| Blueberries | 1 cup (148g) | 3.6g | 1.5g |
| Broccoli | 1 cup chopped (91g) | 2.4g | 1.0g |
| Carrot | 1 medium (61g) | 2.3g | 0.9g |
| Kale | 1 cup chopped (67g) | 1.3g | 0.5g |
| Spinach | 1 cup (30g) | 0.7g | 0.3g |
| Strawberries | 1 cup whole (152g) | 3.3g | 1.4g |
As you can see, blending significantly reduces the fiber content of fruits and vegetables. The more thoroughly blended, the less fiber remains. Smoothies retain slightly more fiber than juices.
Blood Sugar Response
Blending produces rapid spikes in blood sugar compared to whole fruits and veggies. Here is the glycemic index (GI) for some blended items (7):
| Food | Glycemic Index |
|---|---|
| Apple juice | 41 |
| Banana smoothie | 59 |
| Carrot juice | 43 |
| Orange juice | 57 |
| Pineapple juice | 59 |
| Spinach smoothie | 15 |
| Strawberry smoothie | 40 |
| Tomato juice | 38 |
Higher GI foods cause faster and larger increases in blood sugar. As you can see, juices and smoothies generally have medium to high GI values, while whole fruits and vegetables are low GI.
Nutrient Retention
Studies comparing nutrient levels between blended and whole fruits and veggies have mixed results. In some cases blending reduces nutrients, while in others it makes no difference. Here is some of the research:
- In one study, antioxidant capacity was reduced by 24-53% in blended carrots, tomatoes, and broccoli compared to the whole vegetables (8).
- However, another study found no significant differences in antioxidant levels between blended and whole carrots and tomatoes (9).
- Vitamin C retention seems to be highly variable. One analysis found a nearly 3-fold greater loss of vitamin C in blended orange juice compared to whole oranges. However, losses were minimal when blending other fruits and veggies (10).
- Carotenoids like beta-carotene may become more bioavailable with blending due to the breakdown of tough cell walls (11).
- Heavy or prolonged blending can degrade B vitamins like folate and vitamin C, but light blending does not seem to cause much loss (12).
Overall, blending techniques and specific produce types greatly impact nutrient retention. Losses can be minimized by avoiding excessive heat generation, oxygen exposure, and blending duration.
Satiety
Evidence shows that solid foods are far more satiating than liquid forms:
- In one study, solid foods were 38% more filling than processed liquids with the same ingredients (13).
- Another trial found that solid carbohydrates were 47% more satiating than liquid versions (14).
- Participants consumed significantly fewer calories over the next day when they ate solid applesauce rather than drank apple juice, despite identical calorie counts (15).
- Overall, liquefied fruits and veggies do not appear to reduce hunger and calorie intake compared to whole produce (16).
The liquid texture of smoothies and juices makes them less satisfying. Without the chewing resistance of solid foods, it’s easier to quickly consume a large number of calories.
Bottom Line
So what’s the final verdict on blended fruits and vegetables? Here are some key takeaways:
- Blending makes it easier to consume more produce, but may significantly reduce fiber.
- The loss of fiber can cause quicker absorption and blood sugar spikes.
- Some nutrients are retained with blending, while others degrade.
- Blended produce is not as satiating pound-for-pound compared to whole fruits and veggies.
- Enjoy smoothies and juices in moderation as part of a diet high in minimally processed solid foods.
The bottom line is that blending likely provides some benefits, but is not nutritionally equivalent to eating whole fruits and vegetables. Smoothies and juices contain less fiber and may degrade heat-sensitive nutrients. However, they can be an effective way to increase your daily produce intake if you struggle to eat enough whole fruits and veggies.