Western Mail Profiles: Dr Anna Croft, Bangor University

‘How a simple cup of tea can help battle problems of ageing’

Dr Anna Croft is a senior lecturer in the School of Chemistry at Bangor University.

Do you drink tea with milk? Perhaps with lemon? Or maybe you prefer your tea black?

If you don’t add anything to your tea, you might notice a rough feeling on your tongue – astringency.

This feeling is caused by polyphenols (sometimes known as tannins) in the tea – also found in wine, berries and edible seaweeds – interacting with proteins in your saliva.

When they interact, they bind together tightly and rasp along your tongue to cause the feeling of astringency. If you add milk to tea, the polyphenols stick to the milk protein instead, leading to a smoother brew.

I became interested in this phenomenon because of health-giving properties reportedly associated with tea and primarily attributed to the polyphenols.

Polyphenols are antioxidants, which work by trapping highly reactive free-radicals, preventing them from causing damage in the body.

Radical damage has been associated with many long-term diseases, including Alzheimer’s disease, heart disease and many problems associated with aging.

My group wanted to see if proteins played a role in preventing radicals escaping from the polyphenols but instead, we found just the shapes of the polyphenols and proteins were enough to keep them stuck together, without any radical intervention.

This has interesting implications for the creation of functional foods – foods enriched in natural products designed to have specific health benefits.

It means with the right combination of the right sort of proteins, we can make truly super-foods, loaded with additional polyphenols and tasty without being too astringent.

This wasn’t the path we originally started on – science is full of surprises.

So while we didn’t find a role for radicals in milky tea (yet), we’ve been using the knowledge gained to look at other free-radical systems – those where nature has managed to control the power of these reactive entities.

Not widely recognised, free-radicals are extremely critical to life, including in the biosynthesis of many vitamins, maintaining a healthy brain, and making the DNA building blocks of all living things.

They may also play a role in the new science of epigenetics – a way for exposure to environmental factors to be temporarily passed down the generations, rather than permanently through gene mutation.

Many bacteria use very specific free-radicals in their metabolism to keep themselves alive – very different from the analogous processes in humans. We predict these differences will provide a key to developing new antibiotics.

We are looking at very similar interactions to those we find in tea – between polyphenol-like molecules and SAM-radical proteins, which are primarily found in bacteria that can live anaerobically (without oxygen).

Some of these bacteria include Bacillus anthracis (anthrax), Mycobacterium tuberculosis (TB), MRSA and Clostridium difficile, both of which are major causes of death from hospital infections.

We’re hoping the lessons learned about tea will help us develop new molecules that will stick to the inside of these proteins, blocking them from further action and stopping bacterial growth.

So next time you sit down to a cup of tea, relax, and think how the patterns in nature can allow us to understand what seem like very different systems – hopefully those that will produce a healthy life for all.

To contact Anna email a.k.croft@bangor.ac.uk.

This article first  appeared in the Western Mail‘s Health Wales supplement on the 20th February 2012, as part of the Welsh Crucible series of research profiles.