How your height affects your health
I have an admission to make - I'm short. Not the kind of short where you can stand ramrod straight and fit in - even in heels, there are 10-year-olds I have to look up to. I've never minded that much - my mother constantly reminded me in my teens that tall women's options for boyfriends were much more limited than mine.
But a recent study suggesting my height might be putting me at higher risk of heart disease made me stop and think. I can live with the idea that my lifestyle - diet, smoking, exercise, weight - could boost or cut my risks, but there's nothing I can do to make myself taller.
So I did a bit of digging and found the news was mixed. For some conditions, being pocket-sized is a positive advantage, but for others every couple of inches could spell disaster.
Coronary heart disease
The most recent study suggested that someone like me, who just squeezes over the 5ft mark, has a 32% higher risk of heart disease than an equivalent woman of 5ft 6in. Apparently every two and a half inches you gain, cuts your risk of coronary heart disease (CHD) by about 13%. On the plus side, I'm not overweight, I don't have type 2 diabetes, high blood pressure or raised cholesterol and I don't smoke, so my risks were relatively low to start with.
Some scientists have suggested that being short means your coronary arteries are narrower, and so more prone to becoming blocked by fatty plaques. But other studies on identical twins suggest that if one twin is shorter, they're more likely to have a heart attack. This raises the possibility of 'nurture not nature' - since identical twins have identical DNA, their height is affected not by the genes they inherit but by factors in their environment, such as childhood illness or diet.
Interestingly, while heart disease often runs in families, a major study in the last decade has suggested that the vast majority of the risk of having a heart attack can be explained by lifestyle factors (smoking, waistline, exercise, diet, alcohol intake, etc) rather than heredity. So while this finding is interesting, it doesn't change the advice we give to patients.
Shorter people come off worse in the stroke stakes too, with every extra inch cutting your risk of stroke by 6.5%. Once again, scientists have pointed the finger at childhood nutrition, but inherited hormone differences may play a part.
On the plus side for those of us who are vertically challenged, most cancers connected with height seem to favour the smaller person. Taller women are at higher risk than their shorter counterparts of colon cancer, ovarian cancer, breast cancer, skin cancer and leukaemia. Men are at higher risk of prostate cancer if they're taller. The skin cancer/height link might be explained by taller women simply having more skin to become damaged by the sun, but bigger women don't necessarily have bigger breasts, and prostate gland size isn't linked to height.
Whatever the reasons, the best way to protect yourself against cancer is still a healthy lifestyle - the link between height and smoking-related cancers like lung cancer was much weaker.
Alzheimer's disease is another condition which seems to be more common in short than tall people. Your risk of the second most common form of dementia, vascular dementia, is closely linked to the same risk factors as heart disease, but studies haven't shown the same benefits in Alzheimer's disease from addressing your cardiovascular risks.
However, having a family history of Alzheimer's disease does increase your chance of getting it, so this may suggest a connection between genes affecting height and Alzheimer's disease.
Some diseases are the consequence rather than the cause of height differences. For instance, having Marfan syndrome, a connective tissue disease, means you're likely to be very tall, as well as more likely to have an aortic aneurysm, scoliosis, a detached retina and a collapsed lung.
People with Down's syndrome, by contrast, tend to be much shorter than average.
When I'm teaching other doctors and they're wondering what investigations to do or what advice to give, one of my most common questions to them is: "Will it change your management?" In the case of height and health, the answer is no. We can't change our stature, but we can certainly stack the odds in our favour with simple lifestyle changes. For now, that's good enough for me.