Tea contains compounds that may lower cancer risk, but don’t drink it too hot.
Although America is a nation that loves its coffee, there’s always been another option in the warm beverage category, and it’s one that has billions of devotees the world over: tea. Whether you take black tea the British way with a splash of milk or prefer a steaming mug of green tea, there’s something inherently soothing and energizing about sipping a warm beverage to start the day, keep it going or wind it down.
Hot tea is the beverage of choice in many cultures around the world, and there may be more to this staple than just a bit of internal warming. Many studies over the years have suggested that tea could help prevent cancer.
“Teas – like other plant foods, herbs and spices and vegetables and fruits – contain some natural components that may be beneficial in terms of immunity and cancer-fighting potential when looked at in terms of a healthy diet,” says Stacy Kennedy, senior clinical nutritionist at Dana-Farber Cancer Institute in Boston. And it’s believed that phytochemicals or phytonutrients are the source of these protective qualities. “Phyto is just the Greek work for plant. It’s an umbrella expression for all the different things” that make up a plant’s goodness including antioxidants, carotenoids, flavonoids, isoflavones, flavanols, catechins and polyphenols, among others.
The American Institute for Cancer Research reports that “thousands of phytochemicals have been identified so far, and scientists have only begun to investigate their promise,” but it’s believed that many of these compounds have health-boosting qualities, which is why they’re often cited in discussions of “superfoods.”
Jessica Swift, a registered dietitian and owner of Chef Jess, a meal delivery, catering and nutritional counseling service based in Washington, D.C., says that phytochemicals are “what protects the cells” from environmental damage that otherwise could result in mutations leading to cancer. “Cruciferous vegetables are really good” for providing the phytochemicals our bodies need to restore and repair themselves, Swift says. Other rich plant sources of these compounds include berries, leafy greens, garlic, nuts and seeds.
But tea – because it’s brewed by steeping leaves of certain plants in hot water – is also a great way to consume many of these compounds. “Specifically in green tea, there are some compounds that may have what we call antiangiogenics activity which is another way of saying ‘making it harder for [a cancer] tumor to make its own blood supply,’” Kennedy says.
Another benefit tea can offer is simple hydration. Swift says that side effects of some cancer treatments, including chemotherapy and other medications, can alter the way foods taste, making eating and drinking normally a challenge. “Especially during chemo you can get dehydrated.” Tea could be a solution for some patients who aren’t getting enough fluids. Kennedy recommends trying herbal teas “for dealing with the taste changes associated with chemotherapy. Sometimes [taste aversions are] a real barrier to getting the hydration that you need, so it can be a nice tool” to fend off dehydration.
Caution: Contents Hot
Although there’s lots of observational data that suggests tea may be helpful in preventing cancer, Kennedy cautions that we not get too excited about what it might be able to do until we know more about exactly how all those plant compounds work in the body. “When we talk about the research it’s so important to clarify for people that it’s very preliminary. The data is observational.” The studies have “not been randomized control trials. Some have been [conducted in] animals. Some of the research has been in test tubes and slides. When we’re isolating some of these compounds in a microscope,” how they interact with cancer cells could be quite different from how these compounds work inside the human body. She says more studies need to be conducted in humans to determine whether there’s a causal relationship between drinking tea and cancer prevention. “It’s just important to keep that in mind,” she says.
With this whole discussion of tea, it’s also important to note that we’re talking about hot tea made by pouring boiling water over a tea bag or loose leaves, not the plastic bottles of pre-packaged cold tea you might pick up at a convenience store. “With all the bottled beverages, just be mindful of added sugars, artificial sweeteners and other ingredients” that can turn what would have been a healthful beverage into a sugar- and calorie-bomb, Kennedy says. If you prefer iced tea, look for unsweetened varieties or make your own at home.
And when it comes to hot tea, don’t drink it too hot, especially if you also smoke and drink alcohol. A very large study published earlier this year in the journal Annals of Internal Medicine found that people who drank “burning hot” tea and also smoked and drank alcohol had a fivefold increased risk of developing esophageal cancer. (The study noted that participants who only drank burning-hot tea but did not smoke or drink did not appear to increase their cancer risk.) The theory behind why the three behaviors increased risk is that drinking beverages at very high temperatures could cause damage to the cells of the esophagus – that’s the tube that food and drink travels down to the stomach. In the presence of alcohol and tobacco smoke, cellular mutations could add up, leading to the development of cancer.
The study was conducted in China and relied on participants to self-report their tea drinking habits. Although it’s unclear exactly how hot “burning-hot” is, to be on the safe side, let your tea cool for a few minutes before you start sipping, especially if you drink alcohol or smoke cigarettes.
If you’re currently dealing with cancer, be sure to talk to your doctor before adding a whole lot of tea to your diet. “The bottom line advice is when you’re in treatment, run any questions by your physician, and ask your physician to refer you to a registered dietitian who specializes in oncology,” Kennedy says.
Although many patients might like to opt for a supplement to provide some of the benefits of these compounds, Kennedy says it’s always preferable to “look for food versions of all of these things versus supplements. And read the packages carefully. Sometimes they are blends of tea that may have an ingredient that you want to bring to the attention of your [oncology] team if you’re on a lot of medications.” Some patients who like green tea are advised not to drink it or take green tea supplement pills while undergoing chemotherapy treatment because it could disrupt the effectiveness of certain drugs. Tea also contains oxalates, which can increase risk for kidney stones in certain people, and some teas may have drug interactions, so read the labels and talk to your doctor.
As with everything related to diet and health, Kennedy says the focus should remain on achieving a balance. “In general, tea can absolutely be a healthy part of an overall, well-balanced diet, and we want to encourage people to focus on good nutrition, balanced eating, regular physical activity, and weight management. Enjoying a moment to sip a cup of tea can certainly be part of that approach, Kennedy says. “Taking a moment to just breathe and relax and sip a cup of tea and maybe have a little snack – that can be such a healthy behavior in so many ways.” She says this sort of “relaxed, mindful eating experience that you can make a regular part of your everyday” can be part of an overall wellness strategy whether you’re dealing with cancer or not.
