Doctor Q&A: Can hot tea increase your risk of cancer? Dr Renee Hoenderkamp answers your questions

If you cannot make head or tail of what you read online, you're not alone.

Your correspondent often finds the internet to be confusing, distracting and simply too big to comprehend.

Getting at what's true is even harder when it comes to health information as studies often produce conflicting results.

This concern is palpable in the questions submitted to Doctor Renée Hoenderkamp via health@gbnews.uk this week.

Doctor Hoenderkamp delivers her verdict on reports that hot tea increases the risk of oesophageal cancer, whether the shingles vaccine causes shingles and how to tell if you have taken too much vitamin D.

Last week, our resident doc addressed concerns about the symptoms of high cholesterol and B12 deficiency, and the hype surrounding the 'Mona Lisa' laser.

It's important to remember that the advice given below is general and not individual and you should always seek individualised health care from a doctor.

With those caveats aside, see below Doctor Hoenderkamp's answer's to GB News members' burning questions.

Can drinking hot tea increase your risk of oesophageal cancer? I have seen studies suggesting it does.   I am probably being paranoid but could you advise on this please. 

This is a really interesting question because every few years we get a really alarming headline saying that drinking hot drinks causes oesophageal cancer (OC) – one of the most devastating cancers one can get.

So what is the truth?

Firstly, there is certainly evidence that drinking very hot drinks, be that tea or water with lemon, can increase your risk of OC. These studies generally ask people about their hot drink habits and then revisit them years later and see how many have OC.

Whilst these studies certainly do seem to show an association, the question is how hot is hot? So drinks that put you at risk are above 60C (140F) and it is important to know that 60C is usually a lot hotter than most cups of tea.

Before you panic, it is always sensible to look at what we call confounders - other things at play in these studies that may be contributing to the outcome of OC. Most of these studies didn’t look at these. The studies often do look at whether people had ever smoked or were current smokers and there does seem to be a link between tea drinking and smoking increasing the risk. But even this is not clear as they did not look at how much people smoked, or for how long. There also has not been a detailed comparison of eating habits combined with hot drink habits, and as I detailed in a previous answer on here, some foods can definitely raise the risk of OC, such as pickled foods.

And not to forget that the natural ingredients in tea itself are associated with a lower risk of OC, green tea is rich in polyphenols, which have been reported as a cancer preventive agent. Epigallocatechin gallate (EGCG) - an abundant and active compound in tea - has been associated with being protective against cancer progression. So it would seem the temperature of the tea (and 60C is very hot) is the key.

It's worth noting that oesophageal cancer is less common in the UK, accounting for three in 100 new cases of cancer. The studies have generally been carried out in countries where cases of OC are much higher than the UK suggesting that other things are contributing. So even if very hot drinks might increase someone’s risk of oesophageal cancer, the chances of them developing OC are still low, because it isn’t very common in the UK.

So my advice would be to not drink VERY hot drinks but to carry on enjoying your tea, let them cool and always in moderation.

Can the shingles vaccine cause shingles? 

The shingles vaccine is being offered to people above 60 years old, in a phased programme, starting with older people first. By 2028, all people above 60 in the UK will be offered it. People with a previous history of shingles can have it, but not if they currently have shingles.

Many people ask if the vaccine can give you shingles and this is not an unreasonable question especially as it is a live vaccine.

So the major answer is no, it can cause an immune reaction which can include a chicken pox like rash although the rash is rare (one in 10,000) and the most commonly seen side effects (one in 10) include site of injection (such as pain, redness and swelling), chills, fever, muscle pain, tiredness, headache and side effects of the digestive system such as nausea, vomiting, diarrhoea and stomach pain. The manufacturer suggests that these will resolve within two to three days normally.

None of the public health sites or manufacturers' sites mention shingles, but I did find one case study here. This was an immunosuppressed patient who developed shingles after the vaccination and it was treated with a five-day course of anti-viral. The fact that it is a case study demonstrates how rare this is, but it does mean the answer to your question is ‘yes, but so rare the data cannot be collated into a risk profile’.

So the textbook answer is no. The absolute answer is that it's very unlikely but it has been seen.

I hope that this helps.

How do I know if I have taken too much vitamin D?I recently read a report on vitamin D toxicity and it's freaked me out. 

I love this question because we are rarely thinking about someone having too much vitamin D, just too little. This is because everyone living in the UK needs additional vitamin D due to insufficient exposure to sunlight, we are outside and it's very hard to get enough from diet, even if you love pickled herrings!

Vitamin D is an essential vitamin (a prohormone) and is used by your body to support bone development and maintenance. Vitamin D also plays a role in your nervous system, musculoskeletal and immune systems. Your body converts the vitamin D that you consume into the active form of vitamin D which helps calcium absorption.

Most adults in the UK should take 1000IU of vitamin D a day and that would be a safe level. However sometimes, when someone is deficient in vitamin D, that means that their blood test result is under 25, then a GP may give a super dose to give them a head start before they then buy and take vitamin D over the counter. This super dose could be 25,000IU three times a week for eight to 12 weeks. Now this is fine when you are deficient and need to get levels over 50. The problems may arise when this super dose is continued inadvertently and people are taking 75,000IU+ a week.

The symptoms one may get include confusion, nausea, weakness apathy, recurrent vomiting, abdominal pain, passing urine more frequently, thirst and drinking more, and dehydration. In fact, if left untreated this can lead to too much calcium in the bloodstream which can then go on to affect your kidneys and heart and lead to death. However, this is very rare and so much so that I couldn’t find any commonality of estimates in the UK.

I am including a case study which shows a case but demonstrates how high the dose has to be to be this serious (130,000IU a day).

A quick visit to toxbase (the database used by doctors when dealing with overdose), details 3000IU a day as the safe upper limit.

Truly, the chances of overdosing are low, everyone should take it, it is an important vitamin and if you are worried, ask your GP for a vitamin D blood test (although we are told not to do them to check for deficiency as it doesn’t change the advice; take vitamin D every day).

And how to take it? With K2 and if possible as a spray under the tongue. I do it this way and use BetterYou Vitamin D with K2.