Moments of truth

1st February 2013

Lynne Garton, consultant nutritionist and dietician dispels some enduring misconceptions about the nation's favourite beverage.

Tea is the UK's favourite drink. As a nation, we consume a staggering 165 million cups a day. Yet many misconceptions still surround the camellia sinensis plant - despite being such a prominent feature of our every day lives.

Perhaps one of the most common myths about tea is that it acts as a diuretic. This is not the case. Both the Food Standards Agency and the British Dietetic Association both advise that tea can help meet daily fluid requirements. So, where did the myth come from?

"The original studies showed that caffeine does have a diuretic effect but subjects were given caffeine pills with extremely high amounts - doses that do not translate into everyday use," says consultant nutritionist and dietician Lynne Garton.

"You'd have to drink more than six cups of tea in one sitting for tea to have a diuretic effect," she explains. It's an amount not even the most ardent of tea drinkers could sustain.

"In fact, a very recent study showed that water and tea are absolutely equal in their hydrating effects," she says.

So, it's official. Drinking tea will not make you dehydrated, nor will it have you dashing for the toilet every two minutes. But will it whip you up into a frenzied, hyped-up mess?

The answer again is no. It is sometimes said that tea contains as much caffeine as coffee. Yes, they are comparable if the leaves and beans are compared weight for weight. But practically, the amount of tea needed to brew a cup is far less. Ipso facto, there's less caffeine in a typical cup of tea than there is in a typical cup of coffee.

"According to the Food Standards Agency, a standard cup of tea contains approximately 35-50mg of caffeine," says Lynne, "whereas a cup of filter coffee can contain up to 111mg."

"Certainly, studies show that tea can be beneficial to drink because the caffeine increases alertness, reduces fatigue and improves concentration," she says. "But we are beginning to understand that the stimulating effects of the caffeine is balanced out by the presence of L-theanine, a amino acid that is almost unique to tea. L-theanine has a relaxing effect on the brain and emerging research suggests that it works in synergy with the caffeine so that you get the alertness but the relaxation as well."

Another subject area infused with confusion is how tea affects the body's ability to absorb iron.

Again, Lynne is quite clear on the subject.

"The Tea Advisory Panel (TAP) advises that drinking tea will not result in iron deficiency in people who have a normal, healthy diet. It is important to understand that there are two types of iron," she goes on to explains, "haem which is found meat and fish, and non-haem, which is found in fortified breakfast cereals, vegetables and fruit. Some studies suggest that polyphenols in tea could interfere with the absorption of the non-haem, which isn't as readily absorbed by the body. But there is certainly no evidence to suggest that healthy individuals who drink tea will develop anaemia."

The solution for people who are at risk of developing anaemia is equally straightforward. "Just wait an hour or so after your meal before having a cup of tea," she says.

Lynne has one final misconception to address.

"There are so many different varieties of tea on the market now that I've found people make the mistake of thinking that herbal teas contain what we call tea. They usually don't and are herbal infusions made with different plants, not camellia senensis."

"Shoppers need to look at the box carefully to make sure that they are buying the correct product. They won't feel the benefits otherwise!" she adds.

-----

Lynne Garton BSc (Hons), RD is a qualified nutritionist and dietician with over 19 years experience in food, diet and health. She has a first class degree in Nutrition and a Postgraduate Diploma in Dietetics from King's College, London and has worked within the NHS and in industry. She now runs her own nutrition practice, providing consultancy to various organisations and associations and to the media, and running programmes for corporate clients.