green smoothie
Don't be fooled by its pseudo-delicious convenience - this smoothie poison!
Given that we're on the precipice of World War III, I figured it was important to address a topic that gets little attention in the mainstream media (certainly not an accident). Deadly smoothies.

A couple of paleo peeps around the interwebs have been drawing attention to a study about the case of 65-year-old woman who managed to achieve full kidney failure doing a 10-day "green smoothie cleanse". From the study, "She had normal kidney function before using the cleanse and developed acute kidney injury that progressed to end-stage renal disease."

Wow. I bet the hippies have their yoga pants in a twist over this one!

The whole thing does seem a bit counter-intuitive, though. Green smoothies are supposed to be healthy, after all.

From this random green smoothie page:
We believe you're meant to do amazing things in the world. Drinking a daily green smoothie will give you the kick start you need to feel your best physically, mentally, socially... and beyond!

Now, that's what we call "rawesome!"

At Simple Green Smoothies, we help by creating tasty green smoothie recipes to equip you along the wellness journey. We also help you go farther with our plant-based meal plans that can give you even more incredible results.
Oops, looks like I was wrong. Green smoothies aren't just healthy, they're necessary equipment for the wellness journey. And they're "rawsome". The same site makes claims they help with adrenal fatigue, belly bloat, inflammation, boosting immunity, Ebola, toxoplasmosis, etc. (OK, I added in those last ones). So the idea that the pinnacle of wellness journey equipment could be somehow damaging or in any way detrimental is very not-rawsome. How are you going to do amazing things in the world if you're no longer able to drink your daily green smoothie? Not-rawsome indeed.

So lets talk smoothies. It seems you can't really be considered healthy, or be considered someone who considers their health, if you aren't gulping down some sort of gooey concoction for at least one meal of the day. Think about it, anyone who's exercising and getting ripped at the gym has to be accompanied by an iconic plastic big-gulp cup containing some sort of viscous liquid concoction or they aren't going to get any 'gains'. Protein, bro. God forbid you'd actually want to get your protein from, oh I dunno, maybe a steak? No. Muscles need powder. It's science, bro. You can't expect to get a completely unnatural physique unless you feed it with completely unnatural protein isolates with completely unnatural flavourings (this one comes in Red Velvet Cake Batter flavour!!!). Without one of those cups, you're clearly not serious about your workouts. They're as integral as zebra-striped workout pants.

workout bro
Do you even lift, bro?
But what if you're not looking to get yuge, yet you still want to be considered as someone who considers their health? What if you've bought into the whole plant-based diet nonsense? Protein shakes just won't do. Enter the smoothie - the super-trendy staple of 'on-the-go-but-still-health-conscious' individuals who blend their breakfast on the way out the door, sipping it on the way to work instead of the traditional coffee and a cigarette. Somehow the 1950s' conception of the future was right on this one - food now consists of liquids or pills giving you your required nutrition and not much else. Who has time for tasty? Pass me the astronaut food, please.

That said, there's nothing inherently wrong with smoothies, although I have a feeling that in 50 years the smoothie is going to be an iconic image of our current time period which will be looked back on with a sense of kitsch (kinda like 1960s fondue parties). It makes sense that people who are pressed for time would want to forego the arduous process of preparing food (it's so hard!) and actually having to chew (who has time for chewing?), in favour of chucking everything in a blender and 'ingesting' it. Yes, ingesting. We can't really call this eating. If we could find a way to bypass the necessity of swallowing maybe we could save even more time. I'm picturing, maybe, a green smoothie patch?

green smoothie patch
Looks like someone beat me to it.
As long as you ignore the fact that smoothies don't really taste very good (no, @ultrasmoothiequeen73, they don't; you're deluding yourself) and that the texture is also kinda weird, they're not exactly "bad" for you, provided you're not talking about Weight Watchers meal replacement shakes. The main problem with smoothies is that they're generally a pretty poor substitute for an actual meal. It doesn't really matter how many "superfoods" from tropical countries you're throwing in there. You may be getting off-the-charts levels of antioxidants, but antioxidants aren't the only nutrients you should be getting from a meal. Animal proteins, animal fats, fat soluble vitamins - these are the real superfoods and they're what tend to be missing from smoothies (theoretically, you could throw some lard or beef jerky in your smoothie, although I haven't encountered such a thing). Your average workout bros are at least getting the animal protein part of the equation with whey or collagen, and they're also generally not replacing meals with their shakes. Bros: 2, hippies: 0.

But back to the deadly smoothie cleanse. The sub-class of smoothie, known as the "green smoothie" is not just a clever descriptor of its appearance. Faced with the government recommendations of eating five servings of fruits and vegetables per day and quickly discovering that this was not realistic for most people, the idea of blending and drinking your greens was born. Raw spinach, kale, lettuce, that mulch that collects under your lawnmower - anything is fair game in a green smoothie, as long as it's green. But this is where things turn deadly (sort of).

Some green vegetables, particularly raw leafy ones, contain plant defense compounds called oxalates (aka. oxalic acid). Some berries do too, as do soy and nuts. So if you consider the number of people making their smoothie with soy milk, or some sort of nut milk, including berries and leafy greens, you've got yourself an oxalate cocktail. If the concentration of oxalates in our urine becomes too high, we run the risk of forming calcium oxalate kidney stones. Again, from the study, "Consumption of such juice cleanses increases oxalate absorption, causing hyperoxaluria and acute oxalate nephropathy in patients with predisposing risk factors."

And to be sure, the woman from the study had predisposing risk factors in spades. The study mentions she had undergone a particular type of gastric bypass, which interferes with fat absorption and is known to increase oxalate absorption. She had also recently undergone a prolonged course of antibiotics, which can kill off some of the oxalate degrading bacteria in the gut, leading to more oxalate absorption. So overall, this woman was at high risk for hyperoxaluria (excessive oxalate in the urine) and therefore kidney injury; much more so than your average smoothie drinker.

So despite the hyperbolic title of this piece you're reading, green smoothies aren't really deadly for most. But typical of health food fads, people tend to go overboard, or are simply ignorant of the possible risks. As Robb Wolf comments:
Folks love the idea of "cleanses" and all manner of pseudoscience gets wrapped into these things.

On one hand it's kinda compelling: Eat LOTS of greens! A quick fix to get back on track! Clean your body of "toxins!" If a little kale is good, a couple pounds is better, right?!
But it should be known that doing a green smoothie "cleanse", not being the best idea anyway, shouldn't be undertaken by individuals at high risk for oxalate absorption. But it's not known. Of the 9 million hits you get in a search for "green smoothie", 0.2% of them also mention oxalates (if my math is right, which is not necessarily a safe assumption).

This is little different from hundreds, if not thousands of cleanses, supplements and health trends that rely on half-truths or just stuff someone made up. The Master Cleanse, the brown rice cleanse, breatharianism, colon cleansing, the raw food diet, the vegan diet - all of these are based on misinformation that comes from assumptions or ideologies, with little to no understanding of how human physiology actually works. If you take a look at the original Master Cleanse book by Stanley Burroughs, it's so poorly written that you'll likely wonder how anyone ever takes it seriously (this coming from someone who actually did the Master Cleanse in days gone by. Twice).

It seems that the internet age has a certain Darwinian bent to it that really tests people's ability to discern. If you can't wade through the BS to find what actually works, but instead rely on self-proclaimed health gurus (or dietitians) for solutions to health issues, you're pretty much going to suffer for it, and a few people might actually die. Perspicacity is the virtue of our 'modern' age. And this goes far beyond the subject of health.

So while the average green smoothie drinker is probably not risking kidney failure, they might want to avoid putting a lot of raw green veggies, high in oxalates, into their smoothies, none the less. Or, conversely, maybe they could try eating an actual meal instead of looking for shortcuts. Cooking high-oxalate foods is generally a good way of neutralizing them, making greens actually better in their cooked form, despite what the raw foodists would have you believe. There's a reason humans started cooking their foods at certain stage of our evolution. Grandma didn't drink no smoothies.