In recent years, green juices have become the poster child for the wellness movement. From casual health-conscious consumers to fitness buffs, everyone seems to be jumping on the green juice bandwagon. If you’re a green juice fan, your recipe probably includes a combination of green leafy vegetables, cruciferous vegetables, and grasses, among other ingredients. Those who prefer speed and convenience can find a diverse array of green powders to mix into water or other liquids. So you might be thinking — these are all healthy ingredients, so green juice must be healthy, right? Well, not necessarily. Some of the star superfoods in green drinks, like kale and broccoli, maybe hiding a dangerous secret: high levels of heavy metals, particularly thallium.
What is Thallium?
Thallium is a soft, malleable heavy metal discovered by Sir William Crookes in 1861. It is colorless, tasteless, and water-soluble; thus, it was once a favored homicidal poison.
Historically, thallium was once commonly used as a rodent or ant killer, but its use has been banned in the United States and many other countries due to accidental poisoning. Small amounts of thallium are still used industrially, for purposes such as:
- Optical lenses
- Green-colored fireworks
- Low-temperature thermometers
- Imitation jewelry
Thallium can also be found naturally in the environment, although usually at low concentrations.
However, emissions from natural or human causes can lead to increased levels of the heavy metal in the environment, where it can eventually pose a major threat to terrestrial, aerial, and aquatic systems.
High concentrations of thallium in soil poses a unique threat due to possible uptake and storage by plants. As a result, thallium can enter the food chain and accumulate in our bodies, causing severe health problems and even death. Of particular concern is that high thallium concentrations have been found in drinking water and many green vegetables, some of which include those we’ve come to know as “superfoods,” such as:
- Green cabbage1
- Collard greens
- Brussels sprouts
- Turnip (greens and roots)
The average human diet contains approximately 2 ppb thallium3, most of which is secreted in urine and feces. However, eating and juicing massive amount of kale day in and day out could contribute to thallium toxicity. This means that if you drink the same green juice or smoothie daily, you may want to reconsider your habit.
Symptoms of Thallium Poisoning
Needless to say, thallium is highly toxic. Its toxicity is known to be even higher than mercury, cadmium, and lead. Unfortunately, victims of thallium poisoning usually are not aware that they have consumed or have been exposed to the heavy metal. Furthermore, thallium poisoning is rare and published data is limited, which means it is often misdiagnosed until it is confirmed by urinary and blood tests, resulting in delay of treatment.4
What we do know is that thallium is quickly and almost completely absorbed via several pathways, including eyes, ingestion, inhalation, and skin exposure. Upon absorption, thallium spreads widely to multiple organs in a distribution pattern similar to that of potassium ions. Therefore, thallium deposition occurs in all tissues and is most highly concentrated in neuronal, heart, liver, kidney, and dermal tissues.5
Due to multiorgan involvement, the symptoms of thallium intoxication are nonspecific and variable, depending on the dose and route of exposure. Thallium poisoning commonly occurs in three stages.
Thallium and its salts are corrosive to the gastrointestinal mucosa, leading to the following symptoms:
- Severe abdominal pain
- Diarrhea, followed by constipation
This gastrointestinal phase may begin immediately after ingesting a large dose of thallium or 24 to 48 hours after smaller ingestions. These symptoms can last for 12 to 96 hours, and diarrhea is usually followed by several days of constipation. In some cases of chronic thallium poisoning, patients may experience few or no gastrointestinal symptoms.
This phase is characterized by painful, rapidly ascending sensory neuropathy. It may be accompanied by motor neuropathy. Patients commonly complain of the following:
- Severe pain
- Burning feet
- Difficulty walking
- Skeletal muscle cramps
- “Stocking-glove” numbness and tingling
- Vision changes due to dysfunction of cranial nerves
- Nystagmus (involuntary eye movement in which the eyes move rapidly from side to side, causing reduced vision and depth perception)
- Ataxia (impaired coordination)
- Altered mental status
- Short-term memory and cognitive deficits
The neurological phase may begin 2 to 5 days after ingestion, although it may occur sooner after a massive exposure.
Alopecia, or hair loss, is a hallmark of thallium poisoning and can occur 2 to 3 weeks after the other symptoms begin. Complete hair loss can occur within a month of exposure.
Other Symptoms of Thallium Poisoning
While alopecia and neuropathy may be the only symptoms present in some patients, others may also experience the following:
- Acute respiratory distress syndrome (ARDS)
- Pulmonary edema
- Respiratory depression
- High blood pressure
- Abnormal heart rhythm
- Rapid heart rate
- Loss of appetite
- Dry and crusty scaling of skin
- Inflammation of the mouth, lips, and gums
Severe cases of thallium poisoning can cause death in 5 to 7 days following exposure. The lethal dose of thallium in humans is reported to be 10 to 15 mg/kg, but deaths have been known to occur in adults with doses as low as 8 mg/kg.6,7
5 Ways to Minimize Thallium Exposure
- Diversify your diet: The fact is, there is no “magic bullet” that prevents diseases and/or aging. Instead of sticking to just 2 or 3 vegetables, try to add some variety to your vegetable consumption.
- Switch to stems and roots: The highest levels of thallium are found in plant leaves and seeds, while stems and roots have shown much lower levels. Switch out your kale and cabbage for radishes and wasabi (root) to minimize your thallium exposure.
- Use soil rich in potassium: Heavy metals and nutrient minerals compete with one another for absorption. Therefore, if you grow your own vegetables, adding potassium to the soil can suppress uptake of thallium.8
- Prioritize soil ecology: Potassium must first be solubilized before it can be taken up by plants, i.e., no amount of potassium supplementation will increase the uptake of the mineral without help. Potassium solubilizing microorganisms (KSMs) can help convert insoluble potassium to its soluble version.
- Supplement your diet: Potassium supplementation has been shown to mobilize thallium from tissues in cases of severe thallium intoxication.9 If you feel that you are experiencing symptoms of thallium intoxication, talk to your doctor about adding a dietary potassium supplement. Selenium has also been shown to counteract the toxicity of heavy metals like thallium.10
Should You Stop Drinking Green Juice?
With that being said, should you stop drinking green juice? Green juices may not be as healthy as we may have believed, and I would not recommend anyone rely on them as the primary source of vegetables. Still, I think the bigger concern here is that too many Americans still don’t eat enough green leafy vegetables. Rotate and diversify your green superfoods, and you’ll be able to continue enjoying their health benefits.
Now it’s time to hear from you. Have you experienced any odd symptoms after consuming green juices or smoothies? Are you surprised by the presence of heavy metals in kale and other superfoods? Share your stories or thoughts in the comments below!