Tea and Health: What do you need to know?
Is tea good for you or bad for you? Many people give up coffee and tea when they go on a health kick but is this really the way to go? Although too much might interfere with how your body absorbs iron, there does seem to be more benefit than harm from having a nice, hot, brew.
What's In Tea?
Tea has been cultivated for millennia – there is evidence that humans have been brewing tea for almost 5000 years. Tea is one of the world’s most popular drinks with almost 3 billion kilograms (over 6 billion pounds) of tea produced and consumed every year. Potential health benefits from tea come from special compounds found in tea called polyphenols. These are a range of natural substances that seem to have many health benefits. These include catechins, found in large amounts in green tea and theaflavins, found in large amounts in black tea.
Tea also contains caffeine – the levels vary due to processing and the particular variety. The amount in the final cup of tea also depends on how long you like to let your tea brew. The average cup of tea has around 20mg of caffeine per cup. Compared this to coffee which can have 40 to 180mg of caffeine per cup.
Green tea is made from tea leaves that have been gently steamed to stop fermentation and then dried. Black tea is made from tea leaves that have been fermented to produce the black colour and a different, often stronger, flavour.
What are the benefits?
Polyphenols from tea are known to be antioxidants. People who drink tea regularly do have higher levels of antioxidants in their bodies and these may help to protect the body from day-to-day damage.
Heat disease is where tea really seems to shine. Many studies have shown that people who drink tea regularly seem to have a lower risk of developing heart disease. Studies have shown benefits in reducing blood pressure as well as having a beneficial effect on some types of cholesterol. This doesn’t mean that you can eat all the cream cakes you want and have tea manage your cholesterol! But, as part of a healthy diet, tea seems to give you an extra edge when it comes to looking after your heart.
The same benefits that tea has for your heart seem to ring true for stroke as well. Alongside reducing risk of heart disease, drinking tea (green or black) seems to help reduce the risk of stroke.
Green tea has been shown to reduce the risk of liver cancer and other digestive cancers in studies in Japan and China. In Italy, studies have found that tea may protect against cancers of the mouth and throat. Other studies have shown a protective benefit of tea against prostate, stomach and breast cancer. However, most of these studies have looked at green tea and drinking tea will not make you cancer-proof! The people who had the best benefits in the studies also drank less alcohol and didn’t smoke.
Recent studies have shown that drinking tea may also help protect against developing Type 2 Diabetes. Benefits have been seen for both green and black tea on blood glucose levels and blood lipid levels. Tea may also help weight management which could have an effect on development of Type 2 Diabetes.
Tea may also help look after bones – women who drink tea have stronger bones (higher bone mineral density) compared to women who never drink tea.
Drinking tea, especially green tea, is linked with having a longer life. This may be due to reductions in cancer and heart disease. However, the benefits were seen in people drinking a lot of tea – more than 10 cups of green tea per day!
While polyphenols in tea may help protect against heart disease and cancer, they can also affect how well your body absorbs iron. As low iron can be a particular problem for people with coeliac disease, it is important to keep an eye on when and how much tea you drink.
When it comes to iron and tea, it is worth knowing that tea does not affect iron that comes from animal foods – known as “haem iron”. So drinking tea just after eating a nice steak or a lamb chop won’t affect your iron. Tea really has an effect on iron from plant foods – “non-haem” iron. This is the type of iron found in foods like spinach, wholegrains and nuts. If you are eating these foods, then studies show it is best to wait one hour after eating before you have your cup of tea.
Caffeine does affect you sleep – even if you think it doesn’t! Having caffeine after about 4pm can mean it takes longer to fall asleep and have a poorer quality of sleep. Have tea (or coffee!) earlier in the day and stick to herbal teas in the evening.
Too much caffein during pregnancy can affect how well the baby grows. Dietitians recommend that women who are pregnant limit their caffeine to less than 200mg per day.