There are always people who manage to stay completely relaxed in the run up to exams while the rest of us stress and eat our weight in biscuits. But have you ever wondered why? The answer could be as seemingly random as a difference in blood group.
Last year, a group of scientists in East India, led by Arunima Chaudhuri, conducted a study to investigate the connection between blood group and stress. This involved 465 healthy, non-smoking medical college students of blood group O, B, A, and AB. These students all scored highly on a stress scale indicating they were at risk of experiencing ‘severe stress’.
The amount of stress the students were experiencing during their exam period was measured to look for differences in the ability to cope with stress between blood groups. The stress scores of students in blood group O were significantly higher than those in blood group A, indicating that group O was more susceptible to stress.
These findings were supported by similar research lead by a scientist named Neumann which found that people in blood group A reduced their cortisol levels faster in response to stress. Cortisol is a hormone that is released when an individual is stressed, so a quick reduction of the increased level of cortisol indicates a faster recovery from stress.
After finding differences in stress susceptibility between blood groups, the original team lead by Chaudhuri then attempted to understand the cause of the differences in stress; this is important because stress can result in serious negative health implications such as heart disease, stomach cancer and ulcers in an area of the small intestine called the duodenum.
In order to uncover why blood group O was more prone to stress, a measurement of the students’ lipid, or fat, profiles were taken whilst experiencing stress. People are usually familiar with the idea of ‘good fats’ and ‘bad fats’ from adverts for alternatives to butter which reduce the ‘bad fats’ in the blood. These ‘bad fats’, or cholesterols, are carried by low-density lipoproteins (LDLs) so LDL-C refers to cholesterol bound to LDL. The lipid profiles revealed that students in blood group O had more low-density lipoprotein-cholesterol (LDL-C) in their blood. Therefore increased stress correlates with increased LDL-C levels to which blood group O are particularly susceptible.
The reason stress is involved in the onset of a range of diseases is because of the elevated amounts of LDL-C. High blood levels of LDL-C due to high stress is a major factor underpinning the development of heart disease. Dyslipidemia refers to abnormal levels of lipids such as cholesterol in the blood, which can build up in the arteries eventually blocking them. Dyslipidemia has been shown to occur in stressed people, particularly those in blood group O. This demonstrates the causal influence of amplified LDL-C levels on a variety of diseases and how increased stress can exacerbate this problem.
This link between blood group, stress, and associated diseases offers some insight for the clinical treatment of stress. The discovery that people in blood group O experiencing stress have a larger increase in LDL-C suggests these individuals are more at risk of heart attacks and stroke. Blood group O should, therefore, be considered a risk factor for these diseases and more focused research should be conducted to reveal measures specific to blood group O that could be taken to reduce their LDL-C level and by default their stress.
Connecting blood groups to stress and its resulting diseases could help in their prevention through the knowledge of previously unknown risk factors. Currently, it may be difficult to clearly attribute a disease as caused by stress. Understanding blood group O as a risk factor, however, could greatly improve diagnosis in the future.
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