Does Green Tea Protect Against Gastrointestinal Cancers?
Green tea extract is commonly taken as a natural remedy for IBS (irritable bowel syndrome), vomiting, diarrhea, and bowel disorders, including a range of GI (gastrointestinal) cancers. But, does consuming green tea protect you from GI cancers? And, if so, can you get these health benefits from drinking green tea or do you need to take a supplement? We’ve investigated!
The scientific name for green tea is Camellia sinensis. The dried leaves and leaf buds from the Camellia sinensis plant are steamed, pan-fried, and dried to create the loose leaves that we identify as green tea.
Tea is one of the most popular drinks around the world — particularly in countries such as China and Japan. It’s been around since the 17th century (Chacko et al., 2010). It’s estimated that 20% of all tea consumed is green!
Are green tea-lovers inadvertently protecting themselves against GI cancers?
In 2008, a team of researchers hunted through several scientific databases, extracting all of the research on green tea and cancer that had been published within the past 4 decades (Liu, Xing, and Fei, 2008). Study participants were either healthy individuals, pre-cancer patients, or cancer patients. Eventually, the team compiled a collection of 48 studies and began their analysis.
What did the researchers find?
Well over half of the studies suggested that green tea really does protect against GI cancers when consumed regularly (Liu, Xing, and Fei, 2008). In particular, the research suggests that drinking green tea can help to safeguard you from:
- bowel and rectal cancer (colorectal cancer),
- throat cancer (esophageal cancer),
- stomach cancer (gastric cancer), and
- mouth cancer (oral cancer).
Now, we can’t say for sure that drinking green tea reduces the risk of GI cancers. Some studies haven’t found any difference in the incidence of such cancers between tea-lovers and haters.
However, in this situation, we must weigh up the potential benefits against the potential risks of drinking green tea on a regular basis when it comes to GI health.
If you’re drinking 5–6 litres of green tea every day, you’re highly likely to make your IBS worse — mostly because of its caffeine content (Natural Medicines Database, 2017). Drinking green tea in this quantity can result in symptoms of:
- nausea,
- vomiting,
- abdominal bloating,
- abdominal pain,
- indigestion,
- flatulence, and
- diarrhea.
If, like most people, you’re only drinking 3–9 cups of green tea per day, it’s unlikely to do you any harm. So, you may as well up your green tea intake in the hope that it protects you from getting GI cancer. You’ve got nothing to lose!
The only time that you do need to be wary of drinking green tea at lower quantities is if:
- you’re allergic or highly sensitive to caffeine or tannins,
- you have a heart condition, or
- you’re pregnant or breastfeeding.
If any of these apply to you, it’s a good idea to limit your green tea intake to 2 cups per day and avoid taking nutritional supplements containing Camellia sinensis (Fujiki et al., 1999).
So, what is it about green tea that seems to protect us against GI cancers?
The polyphenols in green tea seem to be what gives these leaves their anti-cancer properties (Mukhtar et al., 1992).
Why? Polyphenols are powerful antioxidants. This means that they “soak up” harmful oxidizing agents in your body before they have the chance to promote cancer. Specifically, the polyphenols in green tea interact with one of the main enzymes in your liver, hepatic cytochrome P450 (Mukhtar et al., 1992). This interaction helps your liver “neutralize” oxidizing agents more effectively, thus protecting you from cancer. Pretty cool, huh?
Some of the cancer-protective polyphenols in green tea include:
- epicatechin (EC),
- epicatechin-3-gallate (ECG),
- epigallocatechin (EGC),
- epigallocate-chin-3-gallate (EGCG),
- cholorogenic acid,
- quinic acids,
- carotenoids,
- trigalloylglucose,
- chlorophyll, and
- methylxanthines.
What if you don’t like drinking green tea? And, how does the Camellia sinensis quantity in supplements compare to that of a drink made from the leaves themselves?
Typically, nutritional supplements contain 1.5 to 3 grams of green tea extract — the equivalent of drinking one cup of green tea (Natural Medicines Database, 2017). Therefore, you’d need to take a whopping 3–9 green tea extract supplements every day in the hope of protecting yourself against GI cancers.
Not only would this be costly and require a huge amount of dedication, it’s also never a good idea to take large quantities of supplements. Why? You never truly know how something man-made is going to influence your body — especially after years of continued use, and even if the active ingredient is naturally-derived.
One suggestion, if drinking 3–9 cups of green tea per day is too much to bear, is to take a supplement that contains a wide range of polyphenols and antioxidants in much smaller quantities. That way, you’re much more likely to experience health benefits without the unwanted side-effects.
A great option is Genuine Health’s Vegan Greens+ O. It contains just 15mg of Camellia sinensis but a whole host of other green superfoods to give you a powerful antioxidant boost in every scoop! It’s a great way to support your digestive system while you uncover the root cause of your IBS and start to heal your gut.
LET US HELP YOU GET RID OF YOUR IBS
Kiki from Mindfully Edible has created a delicious recipe using the original flavour of Vegan Greens+ O. Check out her Pomegranate Chocolatey Bark if you need some inspiration.
So, there you have it. Drinking 3–9 cups of green tea every day does seem to protect you from GI cancers! And, if you’re not a tea-lover, you can always get some cancer-fighting antioxidants into your diet using a diverse, allergen-free supplement like Genuine Health’s Vegan Greens+ O. Enjoy!
Sophie Ash, BSc (Hons), DipION, NNCP is a Nutritional Therapist in downtown Toronto. She has a background in nutrition, medicine, genetics, and research. Before establishing On Your Plate Inc., Sophie worked in hospitals throughout the UK as a Dietitian.
