Tea fans may want to pay more attention to the quality of their teabags, as new research has suggested that cheaper bags contain high levels of fluoride and are potentially damaging to your health.
In the UK, tea drinking is one of the few edible pleasures we have left that isn't unhealthy or fattening, but it seems that the humble teabag could be hiding a dark secret.
Researchers at Derby University measured the levels of fluoride in supermarket own-brand teabags by looking at the amount found in a litre of tea, the equivalent of four cups a day. It's the amount the average Briton drinks a day. (And we don't know about your office, but around here four cups would be the bare minimum to get us through the day.)
On average, the level of fluoride in own-brand teabags was 6mg. The recommended daily amount (taken from US recommendations as there a recurrently none in the UK for fluoride) is just 4mg. Only Waitrose's own brand teabags were below this, with 3.6mg of fluoride per litre found.
And while green tea is touted for its health benefits, after standard black tea it was found to have the highest fluoride levels. Slightly pricier tea brands such as PG Tips and Twinings contained less fluoride than both of these.
Fluoride splits experts because it has some health benefits, which has led it to be added to the water in some US states. But many are concerned that it affects the body in more ways than we realise. It has been linked to osteoporosis and brittle bones and teeth, kidney damage and cancer and some specialists believe it affects the thyroid, which has a vital role in our hormonal systems and metabolism.
It's important to remember that fluoride is also found in other food and drink such as wine and seafood, plus toothpastes and mouthwash.
Fluoride is not a problem in coffee, fruit or herbal teas. Black, green and oolong teas all come from the same plant, which naturally absorbs fluoride. But purer, more expensive blends such as Darjeeling and Assam were lower in fluoride, as was oolong.
Researcher Laura Chan explains: "The tea plant, Camellia sinensis, is a fluoride accumulator, with mature leaves accumulating most of the fluoride.
"When tea is harvested, these older leaves may be used to produce lower quality, stronger teas such as economy teas.Whereas the bud and newer top leaves are used in the manufacture of higher grade and speciality tea products.
"People may be drinking excessive volumes of tea in addition to other dietary sources of fluoride and may not realise these potential health implications."
We might have to take that old argument that cheap teabags 'taste just the same' to a new level. Tell us your favourite tea on Twitter.
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