The truth about green tea – should we be stocking up or cutting down?

From weight loss to antioxidant capacity – what are the benefits?

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Qualified Nutritionist (BSc, MSc, RNutr)
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08 August 2018

An introduction to green tea – what’s all the fuss?

Green tea originated in parts of Indian and China which are well known as some of the healthiest cultures in the world. It is a staple of their diet and they drink it happily on a daily basis. In more recent years especially, this hearty brew has become more prominent in Western cultures – specifically amongst the more health-conscious of us!

Now, as part of a normal healthy regime fine, green tea may be all well and good but actually, could stocking up as a result of some of the questionable health claims out there be doing us more harm than good? Here I run through all you need to know and give my approach for including green tea in your diet going forward.

What are some of the proposed health benefits of green tea?

For one reason or another, you may have heard that green tea is a wondrous ingredient and we should be including more of it in our diet. Here I run through some of the top claims and help to determine how ‘healthy’ green tea really is. 

Claim 1 - Green tea can help improve mental alertness 

One of the softer claims out there, you may have heard that green tea could help to improve mental alertness. This may be particularly attractive for people who are feeling stressed, or are going through menopause, for example, as foggy heads may be more of a common occurrence!

What’s the reality...

Although research suggests that green tea may help to support our mental alertness right enough1, this may have something to do with the caffeine content rather than the type of tea itself. Yes, that’s right; green tea still contains caffeine, up to 50mg per cup. This is comparable to some black teas but not quite as strong as most coffees which average out at around 100mg per cup but still, it’s a decent amount. 

We know that caffeine can indeed help improve mental alertness in the short-term but remember, especially if you’re particularly caffeine-sensitive, other side effects can include heightened anxiety, digestive upset or adrenal fatigue in the long-term as it stimulates the stress response in your body.

Claim 2 - Green tea helps support the cardiovascular system

From lowering cholesterol to managing blood pressure, green tea has often been vouched to help keep your cardiovascular system in tip-top condition and see you through to old age without so much as a glitch.

What’s the reality...

The evidence surrounding the benefits of green tea on the cardiovascular system is quite mixed. Some larger-scale studies look promising for its protective effects2, but then many of these were conducted on Japanese subjects who let’s face it, have a very different lifestyle to many more Western regimes in the first place! Their diet and lifestyle differs to ours and for this reason, we can’t confidently ascertain whether green tea is the cause of cardiovascular wellness.

Claim 3 - Green tea melts fat and aids in weight loss

The phrase ‘melts belly fat’ may just be a tad far-fetched for my liking, but there are also claims of green tea helping to support or increase metabolism and support blood sugar regulation. These could be plausible mechanisms for supporting weight loss overall, especially as green tea is virtually a calorie-free beverage in itself.

What’s the reality...

When it comes to the truth on the effects of green tea on weight management, the outlook doesn’t look as promising as we might have hoped. There’s not really enough evidence to suggest that the effects of green tea on weight loss are significant. 

In a large scale review study including overweight or obese subjects, the effects of consuming green tea preparations for at least 12 weeks showed small but insignificant changes in body weight. These also weren’t maintained in the long-term3 – much like many other fad diet then!

The supposed mechanisms for this slight influence on body weight may be attributed to the antioxidant and/or caffeine content of this brew, but the evidence suggests the effects are minimal and green tea may not be an effective sole means of lose weight. However, in saying that, it certainly wouldn’t be a bad thing to add it to your regime if you were embarking on a weight loss journey.

Are there any side effects?

Before embarking on any new regime, people often ask if it’s safe and what the risks are. So, when it comes to green tea, it’s important to know what you’re dealing with. 

Firstly, it’s important to remember that drinking green tea is a long-held tradition therefore, the safety profile of it is pretty good, but for higher strength supplements, the evidence isn’t quite as clear cut. 

Also, it’s important to remember that most green teas still contain caffeine so if you’re caffeine sensitive you may still suffer some of the ill-effects of this. Read on for my tops tips help to ensure you’re approaching green tea in the correct way!

How should I approach my green tea intake going forward?

1 - Stick to tea rather than tablets 

As we have traditionally drunk green tea, my advice is to continue using it in this way if we’re trying to exert some of the same health benefits. Tablets or capsules containing green tea extracts can in some cases be the equivalent of up to 15 cups of the stuff so are quite strong, especially if we haven’t previously been used to having any in our diet! 

Some studies have shown a slight increase in liver enzymes with consuming high strength green tea extract supplements longer-term too – this is just something else that your liver has to process which may not be completely necessary. 

2 - Be wary of drinking it on an empty stomach

If you’re caffeine-sensitive like me, then drinking a strong green tea on an empty stomach may not be the best idea. Caffeine can contribute to stomach upset or feelings of anxiety as it ups your fight or flight response. My advice is to try out a cuppa of the green stuff after a meal (say 20-30 minutes afterwards so you don’t risk diluting your all-important digestive juices either) and don’t drink any more than 3-4 cups per day.

3 - Don’t go overboard

As above, the safety profile of green tea as a drink looks pretty good, but as green tea extract in tablet or capsule form hasn’t been so readily studied, my advice is not to go overboard. As there are no concrete health benefits, my advice is to add it to your regime as a healthier alternative to other drinks, knowing that you are adding some extra antioxidants that may not have been there before. I wouldn’t worry about trying to consume it in excess though.

4 - Step up your health habits elsewhere

We’re well aware of the benefits of having an antioxidant-rich diet but as always, my advice is to aim for variety – too much of anything isn’t necessarily a good thing! Boosting your diet with a wider variety of fruit and vegetables is one of the easiest ways to increase your antioxidant intake and when it comes to some of the supposed health benefits of green tea such as weight management, we know that sustainable changes to our diet or lifestyles are what counts, rather than any fad diets or supplement regimes. 

Aim to eat fresher, aim to reduce your caffeine or alcohol intake or aim to move more – small changes can make a big difference to how you look and feel and will give rise to longer lasting results – best of luck!


1.Park S, Jung A and Lee WK et al. A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study. Journal of medicinal food, 14(4);

2.Kuriyama S, Shimazu T and Ohmori K, et al. Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan The Ohsaki Study, JAMA, 2006; 296(10); 1255–1265

3.Jurgens, TM, Whelan AM and Killian L et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Review, 2012

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