Intriguing research raises questions about risk for cancer, Alzheimer’s and more.
Common disease risk factors, such as family history, smoking, obesity and not getting enough exercise, are well-known. But researchers are now investigating another—and somewhat mysterious—risk factor that could be playing a role in a variety of chronic illnesses.
In both men and women, studies are increasingly linking stature to a number of very serious diseases. What scientists do not know is why.
To learn more, Bottom Line/Health spoke with Tim Byers, MD, MPH, professor emeritus at Colorado School of Public Health who has examined the relationship between height and disease.
What chronic illnesses are now being linked to height? Cancer is one. A number of studies have shown that tall people are more likely to get certain types of cancer, including malignancies of the colon, kidney and breast, than shorter people.
For example, when scientists recently analyzed data on more than 20,000 postmenopausal women, they discovered that for every four-inch increase in height above 5′ 1″, there was a 13% to 29% increased risk for 19 types of cancer.
Although this study involved only women, previous research has shown that height is associated with pancreatic and colorectal cancers among men.
Conversely, people of smaller stature are more likely to suffer from stroke and cardiovascular disease.
And with Alzheimer’s disease, one study found that men who were taller than 5′ 10″ were 59% less likely to develop the disease than men who were shorter than 5′ 6″.
How important is height believed to be in the development of these diseases? There is no question that height is somehow associated with risk for chronic diseases. Both the duration and degree, however, depend on the disease.
When researchers combined the data from previous scientific studies involving a total of more than 3 million people, they found that individuals of smaller stature (defined as 5′ 3″ or shorter) were 50% more likely to develop serious heart disease than taller people. This analysis was published in the European Heart Journal.
Stroke is another example. A study published in the journal Stroke, which looked at more than 10,000 men, discovered that those who were shorter (5′ 3″ or less) were 54% more likely to have a fatal stroke than those who were taller.
With regard to cancer, the risk for a tall person can be significant. For example, a woman who is 6′ tall has about a 16% higher risk of getting cancer (such as colorectal, breast or ovarian) than a woman who is four inches shorter, according to research published in The Lancet.
Does this mean that height (tall or short) causes disease? No, that has not been proven. In all previous research, height is associated with certain diseases.
It might be more accurate to say that height is a risk factor for disease. There could be other factors that influence both your height and your risk for certain diseases.
The scientific studies that have linked height and disease are primarily observational. In this type of study, scientists collect information—frequently from surveys or medical records—in order to identify common factors that influence health. Observational studies generate provocative ideas, but they cannot prove cause and effect.
So even though we know from these studies that a tall person is more likely to get cancer than someone who is short and that a short person has a higher risk for heart disease, we don’t know that height itself is the reason.
What factors are likely to influence both disease and height? Genetics is an obvious one. It’s possible that some of the same genetic factors that make you tall or short also could produce changes in the body that increase the risk for certain diseases.
It’s also likely that lifestyle factors, particularly those that occur early in life, are involved. Suppose that a child gets inadequate amounts of certain nutrients. He/she might not grow as tall as a child who eats greater amounts of nutritious foods. The same nutritional shortfalls could potentially lead to diseases later in life.
Meanwhile, high levels of insulin-like growth factor (a protein made by the body that stimulates the growth of many types of cells)—caused by such factors as diet, obesity and exercise habits—could trigger cell changes that eventually could lead to cancer.
Additionally, taller individuals tend to have larger organs and larger skin surface areas—this, of course, potentially increases the number of cells that could become malignant.
What should tall/short people do differently? You shouldn’t be particularly nervous about your disease risk if you’re tall or short. In either case, you should be following the same prevention and screening recommendations as everyone else.
Your doctor will continue to focus on the risk factors that are known to cause disease, such as high blood pressure, elevated cholesterol, smoking and so on.
It is important to keep this research in perspective. For now, it’s mainly of interest to scientists, who will use the association between height and health to gain a better understanding of the underlying causes of disease and the time in life when those causes might be acting.
In the future, doctors could potentially take height into consideration when assessing disease risk and giving health advice. The best advice, of course, is for everyone, tall or short, to do everything he/she can to stay healthy.