Smoothie Science: Are Smoothies Good For You?

Everyone seems to love a good smoothie these days.

Everyone except me. I know I’m getting old because, more and more, I seem to be an outlier when it comes to popular opinion. Over 40–check. Opinionated–check. Crotchety–wait, no…I hope!

Nevertheless, I sometimes feel like I am the only person on the planet who doesn’t drink smoothies. Not even green ones or those with other real-food ingredients. I am just not a smoothie person. Never have been. Even if you call it a smoothie bowl (which is a smoothie in a bowl with toppings). But even I have to appreciate that clever rebranding!

I know I’m in the minority…a lot of people drinks smoothies, right?  That’s the idea I get from blogs, Pinterest and Instagram anyway, but please leave a comment and correct me if I’m wrong!

The thing I hate most about smoothies is that they often masquerade as health food when they are typically anything but. They are often full of sugar and calories, even if they have some redeeming qualities. And you know my thoughts about sugar; we all eat way too much! I just don’t think you need to eat something healthy–kale, for example–bad enough to load it into a smoothie with more sugar (natural or not) or calories than you should eat in one sitting. I’d rather have you learn to like kale–or frankly give yourself a break–and don’t eat kale, but choose other whole, real foods you do like.

Yes, you heard me! Kale is a nutrient-packed food, but you don’t have to eat kale unless you want to (preferably in a salad, soup or sauteed). That’s good news, isn’t it?

Well, maybe this is bad news, if you like to drink a lot of smoothies.

I know–you’re thinking your smoothies are healthier than most…and yes, there are healthier ways to make smoothies with real food ingredients. But even if you can keep the portion and amount of carbohydrates reasonable, the simple act of blending everything together may offer fewer benefits than the act of eating whole foods intact. Put simply, smoothies may cross the line into the “refined foods” category. Here’s why:

6 Good Reasons Not to Drink Smoothies:

Chewing, secreting saliva and other digestive “juices,” and movement (peristalsis) of the gut have important functions in digestion. I can’t bring myself to drink smoothies in part because pulverizing whole foods bypasses normal digestion processes.

  • First of all, when you drink smoothies, there’s no chewing, which is the first step in stimulating digestion. When you chew, enzymes are secreted in your saliva that begin to break down carbohydrate and fat in your mouth. Chewing also signals to the rest of your gut (and pancreas and brain) that food is on the way.
  • When food reaches your stomach, it causes the stomach to stretch. Liquids do not achieve the adequate stretching of the stomach that solids do. Every step in digestion, including stomach distention, results in a cascade of hormone secretions, some of which we understand well (insulin), some of which we have only begun to understand (ghrelin, leptin and GLP-1), but all of which are vital to optimal digestion and metabolism.
  • When fiber is no longer intact, and many servings of fruits and vegetables are blended into a high-carbohydrate beverage, the carbohydrates are more quickly absorbed and this results in a sharper increase in blood sugar. This affects insulin and hunger levels–and can be especially harmful in the short term (high blood sugar) and long term (obesity) for people with insulin resistance, prediabetes, and/or diabetes.
  • Research supports that when we blend fiber, its effects in the body are changed; how this matters is a little more difficult to determine. It’s difficult to study fibers’ effect on the gut because there are many types of fiber that occur in nature, and the gut is a complex organ. However, it is my belief that mechanically blending fiber probably does not offer the same prebiotic benefits that we are learning are beneficial to our microbiome (the natural bacteria in our gut).

Yes, there are ways some foods should be processed in order for us to eat them, such as cooking meats to avoid bacterial infection–so I’m not totally crazy to think we don’t need to process anything. However, we don’t need to blend foods into smoothies, so I really prefer to eat and chew my foods and let my body do the work of digesting them more slowly and fully.

Smoothies aren’t satiating and may make you eat more later.

  • Research has shown that participants who consume liquid calories (beverages) consume more calories overall than participants who consume solid calories (food).
  • This study showed that eating a piece of whole fruit before a meal makes you feel more satiated than the same fruit in pureed or juice form and eating the whole fruit before the meal makes you eat fewer calories during the meal.
  • Part of the reason some research shows liquids aren’t as satiating may be the speed at which liquid calories are consumed and absorbed. Usually smoothies are downed quickly, sometimes while doing other activities on-the-go, such as driving or working. In addition, liquids result in less stomach distention–the actual stretching of the stomach with food–which is an important cue for the body to detect fullness.
  • But more recently, it has become clear that the GI tract, the largest endocrine organ in the body, plays a very complicated role in the secretion of many hormones to regulate processes such as satiety and food intake. Liquids and solids appear to affect these hormones differently. For example, ghrelin, the “hunger hormone,” is produced in the GI tract when the stomach is empty. It stimulates hunger, gastric acid secretion, and gut motility to move food through the GI tract. When food stretches the stomach, ghrelin secretion is stopped. When liquids are consumed, the stomach is not adequately stretched and may contribute to feelings of hunger even with adequate nutrient intake.

Smoothies (and juices) can contain more calories and carbohydrates than could typically be eaten in the same amount of time if eaten in whole food form.

  • In the same amount of time as it takes to slurp a smoothie down, you wouldn’t eat 5+ servings of fruit. A 20-oz. serving of orange juice, as a reference, contains 65 grams of carbohydate–the amount of carbohydrate 4 1/3 oranges. Your stomach would feel too full, due in large part to the fiber, which is an important part of satiety. But a smoothie (or juice) allows you to tolerate that much fruit at once, which jacks up the carbohydrate content significantly.
  • While nutrients are important for health and most people don’t eat enough fruits and vegetables, our bodies can indeed be overwhelmed by too much carbohydrate. 
  • Rather, research shows it is more beneficial when you eat a solid meal with whole foods, because it takes more time to eat and contains fewer calories.

Smoothies often contain protein powders to increase the protein enough to balance out the carbohydrates and fat content.

  • To make smoothies a balanced source of nutrients, protein powders are often used, which are also processed and further increase calories.  It is not difficult to get enough protein in your diet when you eat a variety of whole foods.
  • Chewing whole foods requires more time, which is helpful for proper digestion and satiety–and provides added social benefits. We generally eat smoothies on the go rather than taking the time to sit down and enjoy the food, preferably in the company of other people.

I choose to model eating whole fruits and vegetables to my children.

  • I do not agree with sneaking fruits and vegetables into my children’s diets unbeknownst to them. I want them to learn to like whole fruits and vegetables, not to just get the nutrients from them. I am shaping their mindset and this is one of the greatest gifts that will keep on giving long after they leave “the nest”!
  • So, I repeatedly offer them fruits and vegetables in raw and cooked form and they learn to like them over time, some more than others. That’s normal and to be expected. The important thing is that you don’t give up eating them and continue to offer them to your kids.
  • My kids sometimes have smoothies, but these are considered a treat.

It’s simply a pain to clean the blender.

  • A lot of people eat smoothies daily as a meal replacement because they say they are aiming for simplicy.
  • But frankly, it’s a lot easier to wash a piece of whole fruit and go. Or even slice up some peppers and cucumbers and start chomping while I rinse the knife quickly. Or boil or scramble some eggs and portion them in reheatable containers for the week.
  • Smoothies are really not easier when you have to figure out what to put in them, make them, and then clean the blender–every day.

Bottom Line:

What to do if you like smoothies?  Enjoy a small portion of a homemade smoothie with real-food ingredients infrequently as a healthier treat. Stick with fruits, vegetables, water, and full-fat yogurt or milk, or your unsweetened milk of choice as main ingredients.

As for your non-smoothie days, work on expanding your horizons with whole real foods, such as: 

  • set a goal to eat one fruit and one vegetable serving at each meal (or more if desired), OR
  • add a salad every day to your dinner, OR
  • try preparing a new vegetable (or a familiar vegetable in a new way) each week, OR 
  • join a delivery service or Community Support Agriculture (CSA) program through a local farm to have produce delivered right to your door.

References:

https://jamanetwork.com/journals/jama/fullarticle/199317

2 thoughts on “Smoothie Science: Are Smoothies Good For You?

  1. Vince December 4, 2017 / 4:26 pm

    For myself, I find relatively few cases where are smoothie works. They are great in the height of summer when you don’t even feel like eating, let alone cooking. But yes, as a general rule, they’re nowhere near as powerful as healthy meals. It is also far too easy to overconsume on calories, without even realizing.

    Like

    • thewanderingrd December 4, 2017 / 5:00 pm

      Thanks for sharing your comments! Indeed…I don’t want to deny anyone a refeshing occasional smoothie in the summer!

      Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s