ASK THE DOC

Surgeon and lecturer Dr Sarah Rayne weighs in on the link between chickenpox, shingles and cold sores, late-night snacking and whether to take a daily probiotic for gut health.

Q: Can the shingles vaccine help prevent cold sores?

A: Unfortunately not – to explain why, you need to understand the herpes virus family that causes cold sores. One side of the family is the varicella-zoster virus, which causes chickenpox in children. After infection, it hides in the body, tucked away in the nerves. As an adult, it can reactivate, presenting as a rash of painful blisters called shingles that can last for about six weeks. It’s often called the ‘belt of roses’ due to the red colour and the pain, which feels like you’re being pricked by 100 thorns. (Last year I had shingles on my tummy and can attest to that!) Before children were vaccinated, they may have come into contact with chickenpox more often, which would have boosted their immunity to prevent shingles. But because this doesn’t often happen nowadays, the varicella vaccine helps to avoid shingles in people over 50.

The other side of the family is the herpes simplex virus, which consists of two siblings: HSV-1, which causes cold sores – about 60% of the world’s population is infected with HSV-1 – and HSV-2, which causes genital ulcers. Neither have a vaccine. For the moment, if you notice the start of a cold sore (that trademark tingling), consult your doctor for medication – while it won’t stop the cold sore from forming, it will shorten its stay.

Q: I’m 48 and have developed a habit of snacking just before bed as it helps me sleep. But I’m putting on weight – yet if I don’t have a snack, I don’t sleep well. Which is worse in the long-term: late-night snacking or not sleeping?

A: The key to this question is in the first sentence – you’ve developed a habit. In researching this question, I discovered a whole new area of medical research called chrono-nutrition: the study of the effect that the time of day has on eating and obesity.

Unfortunately, you’ve discovered exactly what studies show: that eating later in the day increases your risk of obesity and ill health. This happens because it’s most common to have unhealthy snacks late at night, and if you’re eating in front of the TV or computer, you may not notice that instead of one treat, you’ve finished the entire packet of biscuits.

Also, eating late increases the hormones related to diabetes as well as your cholesterol levels. The hormone ghrelin resets at night, when we are not eating (about 12 hours), so that we’re appropriately hungry the following day. Eating late affects this process and may actually cause you to feel hungrier, which creates a cycle of overeating and weight gain.

Try to break the habit by preparing a small, healthy snack, perhaps with a hot drink, and eating it a few minutes earlier every night. Hopefully it won’t affect your sleep and will help you combat that weight gain.

Q: Would you recommend taking a probiotic every day? I hate the idea of daily medication, but is this a good thing?

A: Our gut houses millions of bacteria of at least 500 different species. It usually works well, and in a healthy adult, there’s little scientific evidence to show that taking probiotics improves your health more than a varied, healthy diet.

Probiotics are good and really help in the case of some illnesses like infected diarrhoea, inflammatory bowel disease and sometimes even irritable bowel syndrome. They may be useful in preventing diarrhoea if you’re taking antibiotics, but they reduce the risk by only 10%. They do work in avoiding traveller’s diarrhoea, so it might be worth taking along probiotics if you’re going on holiday.

If you use one, make sure it’s from a reputable company so you know what you’re taking. If you want a more natural alternative, I suggest live yoghurt as an effective, delicious way to introduce healthy bacteria into your gut.