My wife is 86 and has been experiencing constant stomach pain and an urge to go to the loo – especially at night – even though very little happens when she does. The GP has diagnosed irritable bowel syndrome and prescribed mebeverine to stop the cramping, but she’s no better.

Name and address supplied.

Dr Martin Scurr replies: Based on your description of your wife’s symptoms, it does sound like she has irritable bowel syndrome (IBS). It’s a very common condition – affecting up to one in five adults in the UK.

However, I am not convinced this is the root of her problem – in your longer letter, you describe how the pain and cramping wakes her every night in the early hours; and IBS pain does not usually occur at night, and nocturnal waking is, in my view, a symptom that needs investigating.

You also mention that, over the past two years, her weight has dropped from 8st (or just over 50kg) to just 7st (44kg) and that she has been taking Fortisip, a high-energy, milkshake-like supplement that is prescribed for malnutrition.

This weight loss amounts to more than 10 per cent of her body weight and is therefore a significant factor, especially if your wife has been consuming Fortisip due to loss of appetite.

It could point to some form of gastrointestinal inflammation and is worthy of further investigations to identify the cause.

However, it is reassuring that she has had abdominal scans already, presumably an ultrasound scan and a CT scan, which were clear, and that blood tests have also revealed nothing of clinical significance.

My view is that further investigations are called for, such as a colonoscopy – where a thin, flexible tube with a camera on the end is used to examine the lining of the bowel. This is done under sedation and takes 30 to 45 minutes. I suggest you discuss this with her GP, as well as the possibility of a referral to a gastroenterologist.

In the meantime, your wife should weigh herself on a weekly basis – as any further weight loss could underpin the need for more prompt investigations.

I add a sweetener called Truvia to my coffee but I’m concerned frequent use could be dangerous. Is it safe?

Norman Wanstall, Worcs.

Dr Martin Scurr replies: Truvia is a low-calorie substitute made from erythritol, a sugar alcohol derived from the leaf of stevia, a sunflower-type plant that’s 50 times sweeter than sugar but does not raise blood sugar levels in the same way.

The product has been researched and it is considered safe, even with long-term use.

Some users do report side-effects – mainly bloating, flatulence, loose stools and abdominal discomfort. But once you stop using it there’s no evidence of long-term damage.

More significantly, however, some studies have found high blood levels of erythritol are associated with an increased risk of heart attacks and strokes, possibly because it may affect the platelets – the cells in our blood that stick together to form clots.

Exactly how it does this is not clear – and it’s worth noting that opinion is divided on this research finding, as the evidence is mainly from lab studies on platelets, which doesn’t necessarily translate into the same effect in humans.

So more research is needed. However, if you’re already at risk of heart problems – i.e. you’ve been diagnosed with cardiovascular disease, or have type 2 diabetes or obesity – then regular, large doses are best avoided.

Otherwise, unless you have side-effects, I believe you are safe to continue as you are.

In my view... men must look after their bone health too 

A patient of mine – a dentist – recently consulted me after his thumb fractured while gripping a surgical instrument.

Tests confirmed while otherwise fit and healthy, he has osteoporosis, a condition more common in women but that also affects men.

The worry is that this is not widely known and, as a result, men are often diagnosed at a later stage than women.

The main risk factors for men are a family history of the condition, ageing (as bone strength weakens) and reduced physical activity (the bones need to be ‘stressed’ by weight-bearing activity to remain healthy).

Other causes include low testosterone, taking corticosteroids (usually prednisolone, widely used to treat conditions such as polymyalgia), and diseases that affect the absorption of food (e.g. coeliac disease).

As well as taking vitamin D and calcium, I have encouraged my dentist friend to take up a high-impact, weight-bearing exercise – swimming and cycling, his preferred activities, are now replaced by training for a half-marathon.

The message is that men, too, must not ignore their bone health.