Does size really matter when measuring disease risk?
If these studies are anything to go by, doctors should consider replacing their high-end tests with a simple old-style measuring tape.columns Updated: Apr 11, 2015 14:46 IST
Size does matter when it comes to measuring disease risk, which varies with how high or low you stand in your socks.
The shorter you are, the greater is your risk of heart disease, reported researchers in the New England Journal of Medicine this week. Heart disease, which includes heart attacks and heart failure, is the leading cause of death in the world, including in India.
For the study, researchers examined the genes that determine height and found that the markers that made people short also raised their levels of artery-blocking bad cholesterol and triglycerides, which trigger heart attacks.
* Small threat to the heart
Each additional 2.5 inches (6.4 cm) to height lowered heart risk by 13.5%, which makes the difference in heart risk between a five-foot tall and a six-foot tall person is around 64%. When compared to other risk factors like smoking that increases heart risk by 200-300%, the risk is small, said researchers, but it was large enough for shorter people to monitor their cholesterol and triglyceride levels closely.
This is not the first study linking size to heart disease. Shorter adults were 1.5 times more likely to develop heart disease and die from it than were tall people, concluded a large review of 52 scientific studies of more than 3 million (30 lakh) people in European Heart Journal some years ago.
The study defined short as height below 165.4 cm for men and below 153 cm for women, while tall for men was above 177.5 cm, and for women, over 166.4 cm.
* Out on a limb
Several studies have shown that early life environment plays a role in susceptibility to chronic disease such as heart disease, diabetes and cancers in later life. Using height, along with physical measures such as knee height and arm span, as biological indicators of early life deficits, such as poor nutrition, scientists are increasingly predicting individual health risks.
People with shorter arms and legs, for example, have a 1.5 times higher risk of dementia in old age as compared to people with longer arms and legs, reported a study in Neurology®, the medical journal of the American Academy of Neurology.
While long legs give both genders an edge against disease risk, leggy women have the added advantage of lower risk of Alzheimer’s and other forms of dementia. In women, every extra inch of leg lowered the risks of dementia and Alzheimer’s by 16%, found the study that followed 2,798 people for an average of five years.
Women with the shortest arms were 50% more likely to develop the disease than those with longer arms. In men, only arm length was linked to Alzheimer's, with every extra inch lowering risk by 6%.
* No tall claim
But being tall it is not all good news. Overall cancer risk increases by 10% to 15% per 4 inches (10cm) of added height in both men and women, reported a meta-analysis of prospective studies of height and total cancer risk in Lancet Oncology in 2011. The risk to height connection was consistent across race and countries.
Men’s taller stature is also used to explain why -- leaving aside cancers that are sex-specific, known lifestyle risk factors like alcohol intake, smoking, and occupational exposures to carcinogens -- women have a lower incidence of cancer than men in shared sites such as lungs, liver, kidney and brain, among others.
Yet, additional height remains a risk within gender. Compared to short women, taller ones are at greater risk of cancers of the breast, colon, thyroid, rectum, kidney, colorectum, ovary and skin, showed a study of 20,928 postmenopausal women published in Cancer Epidemiology, Biomarkers & Prevention .
The cause could be a complex interplay between hormones and growth factors that fuel both height and cancer cells. Or it may just be that height increases the surface area of the body’s organs, resulting in a greater number of overall cells and higher subsequent risk of untrammeled growth of cells and malignancy.
Animal studies also suggest a link between cancer and excess calories consumed during adolescence, which also leads to growth spurts. Then there are social reasons. It’s been suggested that taller women have a higher risk of skin cancer because they spend more time in the sun than short, stay-at-home women.
If these studies are anything to go by, doctors should consider replacing their high-end tests with a simple old-style measuring tape. It will not only make studying medicine a lot easier but will also save patients both time and money.