Tea has long been prized for its ability to protect against cancer, improve cardiovascular function and enhance mental health. The disadvantages of tea shouldn't be ignored, though. Despite its benefits, this popular drink can be toxic and even lethal under certain circumstances.
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Different tea varieties exist and each has distinctive properties and uses. Some are promoted for their calming effects, while others can relieve bloating and gas. What you may not know is that certain compounds in tea can interact with medications, affect digestion or cause toxicity, especially when consumed in large doses.
Risks and Disadvantages of Tea
Rich in antioxidants and phytochemicals, tea is a powerhouse of nutrition. Its health benefits are backed up by science. For example, a June 2014 review published in Current Pharmaceutical Design suggests that tea consumption may help prevent skin lung and esophageal cancers, reduce heart disease risk, improve blood lipids and slow the progression of neurodegenerative disorders. In a cohort study, green tea has been shown to lower the risk of diabetes by a staggering 42 percent.
Read more: 10 Everyday Ailments Soothed by Tea
Unfortunately, this healthful beverage has its drawbacks. Depending on the plants used, certain types of tea may cause organ damage or worsen existing conditions. Some can be lethal when ingested in high doses.
Senna tea, for example, is a popular home remedy for constipation. It's also promoted as a natural weight-loss aid. This beverage is made from senna leaves, which have laxative action.
According to a July 2017 review published by the European Medicines Agency, senna leaves may cause severe diarrhea, abdominal pain, electrolyte imbalances and toxic hepatitis, especially when consumed in excess. As the researchers note, senna may not be safe for children, pregnant women and individuals with inflammatory bowel disorders. Overdoses may cause multiple organ failure and even death.
Beware of Herbal Teas
Herbal teas carry the greatest risks. Plus, they are often misused or abused, which can further amplify their side effects.
A good example is comfrey tea. This beverage has been used as a natural cure for stomach ulcers, gastritis and joint pain for over 2,000 years. Clinical evidence indicates that echimidine, symphytine, lycopsamine and other pyrrolizidine alkaloids in comfrey may cause hepatotoxicity, as reported by the European Medicines Agency in May 2015. The National Institutes of Health warns that comfrey tea and supplements may lead to acute liver injury and liver failure.
If you're struggling with water weight, you might consider drinking nettle tea. This beverage exhibits diuretic properties, causing your body to flush excess water. The downside is that it may contribute to hypoglycemia, miscarriage and changes in the menstrual cycle, according to Penn State Health. Furthermore, it may affect blood clotting and digestive function.
Have trouble falling asleep? A cup of valerian tea can help you relax and get more shut-eye, as the Mayo Clinic points out. Just make sure you're aware of its potential risks. Indigestion, dizziness, nausea and headaches are all common side effects. In some cases, valerian tea may worsen insomnia and affect liver health.
As you see, many types of tea can have adverse reactions. Consult your doctor before including them in your diet, especially if you're pregnant or under medical treatment. The active compounds in tea may interact with medications or worsen your symptoms.
Tea and Heavy Metal Toxicity
A common problem associated with tea consumption is heavy metal toxicity. Health organizations report that tea may contain lead, aluminum and other contaminants.
The Journal of Toxicology discussed this issue in a September 2013 review. Researchers analyzed 30 types of tea and reported the following:
- 20 percent of brewed teas had dangerous aluminum concentrations
- 83 percent of teas brewed for 15 minutes and 73 percent of those brewed for three minutes were high in lead
- All tea varieties had detectable levels of cesium, tin, cadmium and arsenic
- Black tea contained unsafe levels of manganese
As the scientists point out, steeping tea for more than three minutes may increase the concentration of heavy metals by 10 to 50 percent. Tea origin matters, too. The brands sourced from China were the highest in contaminants. Additionally, the water used for brewing may contain heavy metals, too.
Lead, for example, accumulates in the body and may cause severe poisoning, warns the World Health Organization. Organ toxicity, impaired kidney function, high blood pressure, brain damage and convulsions are just a few of its side effects.
Aluminum is just as dangerous. When ingested in large amounts, it may lead to bone pain and deformities, confusion, anemia, mental disorders and respiratory problems.
Unfortunately, there is no way to eliminate these risks. However, you can reduce the disadvantages of tea by choosing an organic brand and avoiding those from contaminated regions, such as China. Also, don't let the leaves steep longer than three minutes. Enjoy this beverage in moderation and avoid using any herbs that you're not familiar with.
- Current Pharmaceutical Design: "Tea and Health: Studies in Humans"
- European Medicines Agency: "Assessment Report on Senna Alexandrina Mill. (Cassia Senna L.; Cassia Angustifolia Vahl), Folium and Fructus"
- Journal of Advances in Medical and Pharmaceutical Sciences: "Fatal Herb Senna: A Case Report"
- European Medicines Agency: "Assessment Report on Symphytum Officinale L., Radix"
- NIH: "Comfrey"
- Penn State Health: "Stinging Nettle"
- Mayo Clinic: "Valerian: A Safe and Effective Herbal Sleep Aid?"
- National Capital Poison Center: "Valerian: Benefits and Risks"
- Journal of Toxicology: "The Benefits and Risks of Consuming Brewed Tea: Beware of Toxic Element Contamination"
- WHO: "Lead Poisoning and Health"
- Winchester Hospital: "Aluminum Toxicity"