Why does eating chocolate now make me sneeze?
Q WITHIN seconds of eating chocolate, I sneeze three or four times. I’m in my mid-80s and this has only just started. Is it an allergy and, if so, why has it taken so long to develop? Alan Gardner, Sheffield.
A I FIRST came across this phenomenon during my training, while working in the nose clinic at the Royal Brompton Hospital in London — since then, I have seen a surprising number of patients with the issue.
You’ll be relieved to hear that it is not believed to be an allergy — so you can still eat chocolate. That’s because the sneezing isn’t accompanied by any other symptoms of an allergic response, such as itching in or around the mouth or hives (and allergy tests carried out on my own patients with chocolate reactions confirmed this). Instead, it’s thought to be caused by a reflex — possibly a variant of the photic sneeze reflex, where sneezing is triggered by exposure to the sun or bright lights.
This genetic quirk, passed down through families, affects around one in five people and has long been a source of intrigue. In Ancient Greece, Aristotle asked why the sun provoked sneezing — and there are even tales of knights in armour sneezing when setting their eyes on pretty maidens.
It’s thought sunlight-induced sneezes are due to crossed wires in the trigeminal nerve. This large and complex nerve has three branches that transmit information to the brain from the eyes, nose and jaw.
It is believed that, sometimes, signals about sunlight cross over into the nose branch, which leads to them being mistaken for a tickle in the nose — and a sneeze is triggered.
Something similar may occur with chocolate.
It contains theobromine, a bitter-tasting compound known to suppress dry coughs by acting on the vagus nerve — another nerve that carries crucial information between the body and brain.
In this case, erroneous crosstalk between the vagus nerve and the trigeminal nerve may somehow set off a sneeze.
It is also possible flavonoids, antioxidants found in cocoa beans, may be involved — some stimulate the production of nitric oxide, a chemical that helps widen blood vessels. This prompts me to suggest that perhaps, in rare cases, chocolate fuels a brief rush of blood in the capillaries within the nasal lining — this is interpreted by the brain as a tickle, and a sneeze ensues.
Why this should become an issue at this point in your life is unclear, though it might depend upon chocolate type and purity. For example, the milk in milk chocolate may interfere with the absorption of some of the sneeze-inducing constituents.
If this is the case, then dark chocolate may be more likely to make you sneeze.
This is speculation but, if it tallies with your experience, eating milk chocolate — in moderation, of course — may make you less likely to sneeze.
Q IN YOUR opinion, how safe are mammograms and, in particular, the possible risks posed by radiation and trauma damage to the breasts caused by the crushing pressure? Paula Fielding, Newcastle upon Tyne.
A THIS is an area of concern for many women. However, the mammogram is the only breast imaging technology that is proven to reduce breast cancer-related deaths.
Mammograms are X-rays that can spot breast tumours too small to see or feel. In fact, they may detect cancer between one and four years before a lump is evident. They are offered to all women aged 50 to 70 every three years and to women who have symptoms that need investigation, such as a lump.
During the procedure, the breast is compressed between X-ray plates and images are taken from above and the side.
Your concern over radiation is understandable, but the typical dose is only 0.7 millisieverts (mSv), about the same amount you receive over three months from the radiation naturally present in our environment.
Furthermore, the compression — necessary for good-quality images — does not, despite the discomfort (which can be extreme), cause any damage.
The process is not without risk, however. As I see it, the greatest problems are false positives and overdiagnoses.
If a woman has a mammogram every three years from the age of 50, the chance of a false positive result — when healthy tissue is wrongly flagged up as being abnormal — is 20 per cent.
More than one in ten of these will go on to have the lump removed, only for it to turn out to be non-cancerous. This can cause unnecessary anxiety and undermine confidence in the healthcare system.
However, we can’t distinguish between women for whom the disease could prove fatal and women who have cancer that may never prove problematic, so the patient can be burdened with gruelling treatments.
Indeed, for every woman whose life is saved by screening, three more are offered treatment they did not need.
But it’s crucial to remember that screening can detect a cancer that, if not spotted early, could prove life-threatening.
On that basis, surely it does more good than harm.
WRITE TO DR SCURR
WRITE to Dr Scurr at Good Health, Scottish Daily Mail, 20 Waterloo Street, Glasgow G2 6DB or email drmartin@dailymail.co.uk — include your contact details. Dr Scurr cannot enter into personal correspondence. Replies should be taken in a general context and always consult your own GP with any health worries.