The Dark Side of Green Smoothies You Should Know

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The Dark Side of Green Smoothies You Should Know

The fashion of green smoothies has taken the world by storm, with everyone from die-hard vegans to paleo folks jumping on the cabbage-and-spinach-loaded drink bandwagon. Read on to learn about the health issues associated with overzealous consumption of green smoothies and why drinking these drinks regularly may not be as conducive to optimal health.

While green smoothies have earned a reputation for being extremely healthy, there is a dark side to these drinks that few people are aware of. This does not mean that you should leave them, but you should be aware of what this side implies that everything consumable (without balance) has.

Are green smoothies healthy?

In the health community, the green smoothie has become the poster child for healthy eating. If you’re a fan of green smoothies, your typical recipe probably looks something like this:

  • 1 apple, peeled, cored and chopped
  • 1 cup unsweetened almond milk
  • 2 cups de-stemmed and chopped spinach or kale
  • 1 cup of broccoli

This green smoothie is packed with veggies – spinach, kale, and broccoli – so it must be healthy, right? Well, not necessarily. While cruciferous vegetables and leafy greens certainly have health benefits, consuming large amounts of them in green smoothies may not be healthy in the long run, for several significant reasons.

Heavy metals in cruciferous

Cruciferous vegetables, such as kale, broccoli, cauliflower, and cabbage, have been found to contain high levels of a toxic heavy metal, thallium.

Cruciferous vegetables contain goitrogens, which are naturally occurring plant chemicals that inhibit the uptake of iodine by the thyroid gland and reduce the production of thyroid hormone, thus decreasing thyroid function.

Too much oxalate is not good

Many green leafy vegetables, such as spinach and kale, are high in oxalates. Oxalates are plant-based compounds that can promote kidney stone formation and inflammation when consumed in large amounts.

As you can see, it may be time to reconsider whether regularly drinking green smoothies is a good choice for our health.

Cruciferous vegetables and green leafy vegetables undoubtedly have many health benefits, but consuming large amounts of them in green smoothies may not be healthy in the long run.

Are there heavy metals in your kale?

The soil in which vegetables are grown has a significant impact on their micronutrient content. However, just as beneficial minerals are transferred from the soil to plants, so are toxic metals.

Unfortunately, research shows that the toxic heavy metal thallium, which is produced in the soil as a byproduct of smelting and burning coal, preferentially accumulates in cruciferous vegetables such as kale, broccoli, cauliflower, cabbage, Brussels sprouts and Chinese cabbage.

Thallium, toxic metal in green smoothies

This means that people who eat a lot of cruciferous vegetables, as most green smoothie fanscan be exposed to high levels of thallium.

In fact, an astute molecular biologist and alternative health practitioner named Ernie Hubbard found this to be the case among his health-conscious clients, who were experiencing many strange symptoms that did not fit any standard disease pattern.

After much research, he was finally able to trace his symptoms back to thallium toxicity as a result of his cruciferous green smoothie habits with lots of vegetables.

Unfortunately, when it comes to thallium, even low-level exposures can cause symptoms like nausea, diarrhea, stomach pain, hair loss, and peripheral neuropathy.

While some medical authorities have argued that toxic metals are present in our environment and we shouldn’t be concerned about trace levels in otherwise healthy vegetables, the problem remains that heavy metal exposures are additive. and synergistic.

Many heavy metals have similar adverse effects on the body, so continued consumption of thallium in vegetables, plus daily exposure to other sources of heavy metals, exponentially increases the body’s toxic load.

According to this evidence, if you regularly drink green smoothies and experiencing unusual health problems, it may be time to investigate your thallium level and reconsider your green smoothie habit.

Organic is the solution

If you’re not ready to ditch your green smoothies yet, at least consider using only organic cruciferous vegetables in your drink. Soils that are rich in carbon-based matter, such as the soil on organic farms, have been found to impede the transfer of thallium to plants.

This effect is less likely to occur in carbon-depleted soils used on conventional farms. This means that organic produce may contain lower levels of heavy metals, such as thallium, compared to conventionally raised produce, which could result in a healthier green smoothie.

Green Smoothies and the Thyroid Gland

Regarding green smoothies, they can also have adverse effects on the thyroid gland. The thyroid gland requires the mineral iodine to make thyroid hormones.

Cruciferous vegetables, common ingredients in green smoothies, contain compounds called glucosinolates, which inhibit iodine uptake by the thyroid. This can result in a reduced ability of the thyroid gland to produce hormones, leading to reduced function and potentially a thyroid disorder.

Also, the risk of a high intake of cruciferous vegetables impairing thyroid function is higher in people with iodine deficiency. Iodine deficiency is not uncommon in people following a diet Paleoas the main available dietary sources of iodine are sea vegetables, iodized salt, dairy, and fortified foods, which are often excluded from a Paleo or raw diet.

While large amounts of raw cruciferous vegetables pose a problem for the thyroid gland, cooked cruciferous vegetables appear to be much safer. Cooking cruciferous vegetables stimulates the production of an enzyme called myrosinase that helps deactivate goitrogenic glucosinolates.

Choosing to eat cruciferous vegetables in their whole-food (unground) form is another way to reap the health benefits of these vegetables without taking a heavy hit from goitrogens; it is much more difficult to overeat vegetables when they are in their whole form compared to juiced or blended into a green smoothie.

Oxalates in green smoothies

Other major problem with green smoothies is that they are often high in oxalate, a type of natural plant compound that promotes kidney stone formation and inflammation in certain people when eaten in excess.

Oxalate occurs in high amounts in spinach, Swiss chard, dandelion greens, beets, kale, berries, broccoli, cabbage, and carrots. In some people, oxalates build up in body tissues and cause inflammation.

In fact, oxalate buildup has been associated with chronic pain, nephrolithiasis (also known as kidney stones), neurological symptoms, vulvar pain, and fibromyalgia pain.

Currently, a high oxalate intake is defined as consuming 250 mg of oxalate per day. For reference, one cup of raw spinach contains about 656 mg of oxalate.

As you can see, it would be quite easy to go overboard on oxalates if you regularly drink green smoothies, which often contain a cup or more of spinach.

Research has confirmed that green juices made from common vegetables contain high levels of soluble oxalates and that consumption of these beverages can precipitate the formation of oxalate kidney stones.

Including a variety of vegetables is part of the solution

Some green smoothie advocates They recommend that “swivel” vegetables include low-oxalate options like mustard greens, watercress and lettuce; this can help prevent green smoothie-induced oxalate overload.

Certain genetic variants, such as the SLC26A1 variant, and pre-existing intestinal problems, such as Crohn’s disease and dysbiosis, can increase an individual’s susceptibility to the harmful effects of dietary oxalates.

For these people, reducing dietary oxalate intake can significantly relieve symptoms.

Replenishing the gut with beneficial bacteria from probiotics and fermented foods can also aid in oxalate degradation, as several probiotic species, including Lactobacillus rhamnosus, Bifidobacterium animalis subsp. lactis BI07 and Oxalobacter formigenes have been found to degrade dietary oxalate.

Final Notes on Green Smoothies

Unfortunately, green smoothies are not as healthy as we have been led to believe, due to their thallium, goiter, and oxalate content. Instead of relying on green smoothies as your main source of vegetables, it is recommended to eat vegetables in their whole food form and cook cruciferous vegetables to reduce their goitrogen content.

If you’re not ready to give up green smoothies altogether, choose organic vegetables, which may be lower in heavy metals; rotate your greens to regularly include low-oxalate options like mustard greens and watercress; and consider supplementation with oxalate-degrading probiotics like Lactobacilli and Bifidobacteria.


Felker, P., Bunch, R., and Leung, AM (2016). Thiocyanate and goitrin concentrations in human plasma, their precursor concentrations in brassica vegetables, and the associated potential risk of hypothyroidism. nutrition reviews , 74 (4), 248–258.

McMillan, M., Spinks, EA, and Fenwick, GR (1986). Preliminary observations on the effect of dietary Brussels sprouts on thyroid function. human toxicology , 5 (1), 15-19.

Liebman, M. and Al-Wahsh, I.A. (2011). Probiotics and other key determinants of dietary oxalate absorption. Advances in Nutrition (Bethesda, Md.) , two (3), 254–260.

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