A new study found that if people think they have a genetic predisposition to certain health characteristics, such as low exercise capacity or a tendency to eat, their bodies are starting to act like this. Even if your DNA does not really have those genetic variants.
The study raises questions about how many genes affect our physical well-being or whether, under certain circumstances, what we think about our bodies, their abilities and limits, could have a greater influence.
It is currently fashionable to obtain DNA tests. The services to be tested, with or without a prescription, promise to reveal something about our health heritage, for example, if we are predisposed to weigh, if we respond well to exercise, if we can effectively metabolize the different food and if we have more or less the risk of contracting a wide variety of diseases.
However, the veracity of many of these statements remains doubtful. Most scientists studying genetics believe that the effects of several specific gene variants are generally mild and little is known about them.
But even less is known about the psychological impact of knowing the existence of a high or low genetic probability for certain health problems and the way in which the attitudes we assume can play a role in our physiology.
So for the new study, which was published in December in Nature Nature Behavior, Researchers at Stanford University had the task of cheating a large group of men and women with lies about their genes, at least temporarily.
They started by advertising at the local level in search of participants interested in knowing which diets or exercise programs were most suitable for them, depending on their genotype. More than 200 healthy men and women responded and were accepted into the study.
Everyone gave a sample of saliva for genotype tests, then started the experiment, although the real purpose was hidden by the participants.
They divided men and women into two groups. One of them did a test on a treadmill, which is to run as quickly as possible using a mask that measures their oxygen consumption and lung capacity while telling the researchers how they felt..
The other group focused on diets and eating behaviors. The participants were given a 480 calorie liquid mass and asked to finish it and then describe how they felt they were coming. Researchers have taken blood to examine the levels of certain hormones that are known to contribute to the feeling of fullness in humans.
In a later visit to the lab, the volunteers saw the expected results of their genetic tests. Some of those who were part of the exercise group were informed that they had a genetic variant that made people less resistant and had difficulty in prolonged exercise. This genetic variant exists and is associated with a low response to resistance formation, however, most participants who were told to have been carriers of this gene were not.
Similarly, the researchers told people in the diet group, fake, that they had a genetic variant that could make them feel less saturated than they were in fact, and thus would be prone to overeating . ; others have been told that their gene variant will make them feel very saturated and therefore they are less susceptible to obesity.
Subsequently, men and women repeated the session on the treadmills or on liquid foods.
The results of each session were very revealing. Those in the exercises group, which they were told – almost never been true – that their genes made them badly responsible for exercise, they got tired faster than their previous time, and their pulmonary capacity and consumption of oxygen were much lower.
In the diet group, those who mistakenly believe they have the protective gene appetite gene feel more full than in the past after drinking the liquid, and their bodies have produced more of a hormone that increases saturation.
In both cases, psychological beliefs about their genetic biases have altered physiological responses to medical tests.
Perhaps the most interesting thing is that, later, the researchers compared the physical effects of the existence of the genetic variant against believing you wrongly.
For this, in the first round of testing – before people knew about their genetic tendencies – they reported how much oxygen consumption and lung capacity were lower if they had the unwanted genetic variation and how much the saturation and excretion of hormones appetite were higher if they had the most desirable alternative to appetite.
In both cases, the variant had the expected impact on human bodies, although the effect was lower.
In fact, it was found that physical effects on resistance and satiety were often more substantial among volunteers who thought they had the genetic variant and not those who did it.
These findings suggest that "people tend to attribute more power to the genes than they should," says Bradley Turnwald, a Stanford doctoral student who led the study with lead author Alia Crum and others.
Our attitudes or mental expectations of ourselves seem to play an equally important role or more than DNA in shaping our body's reactions to diet and exercise, Turnwald concludes.
But he adds that much more research is needed to understand the relationship between genes, beliefs and health, to help people better interpret the results they receive from genetic testing, says Turnwald.
As for volunteers in the study, Turnwald said that, in the end, everything was explained to them and given the real results of genetic testing.
Copyright: c.2019 New York Times Press Service