• Genetic tests may change the physiological response of our bodies.
  • Reading a DNA test is easy, interpreting them is very complicated.


They are in full swing. Some of them, are now being used for dealing with health issues such as breast cancer. They are said to serve women with information about certain mutations and family history. With other diseases such as Alzheimer’s, they are more delicate.

Most people use genetic tests for finding answers related to lifestyle, such as what are the capacities for the physical performance of a person and what is the best diet you can follow to maintain good health.

Some tests tell you if you are prone to suffering certain sports injuries, if you are better prepared genetically for strength or back exercises, if you are prone to gaining weight with certain foods and so on.

They look like innocuous tests, but they have an interesting psychological influence. The information they provide is so relevant to users that only knowing the verdict can turn them into better athletes or more restrained diners.

This is what concludes the research that a team of scientists from Stanford University, in the United States, published last December in the journal Nature Human Behavior.

Their results are the first ones that not only conclude that the placebo effect exists in the field of genetic tests but also that their results modifies the physiological response of the organism.

Researchers evaluated how more than 100 individuals responded to a report on their physical abilities and propensity for obesity.

First, they analyzed the CREB1 gene version of the subjects. Scientific studies indicate that there is a variety associated with a worse aerobic capacity, an increase in body temperature during exercise and less cardiovascular improvements when sports are practiced, while another version of the same gene eludes all those circumstances.

Scientists took note of how the volunteers’ bodies reacted on a treadmill, and gave them a genetic report that told them if they had a high-risk or a protective genotype.

The great thing about the experiment is that the information they gathered was true, but the information in the report was false.

A week later, the researchers did the stress test again and the results spoke for themselves.

The ability to take air and the resistance of people who had been told they had high-risk genes worsened, regardless of their actual genotype: they surrendered 22 seconds earlier than in the previous session, while those who thought they had the protective version took 47 seconds more to say that the test was beginning to be difficult for them.

Interestingly, the effect that the information had exerted on their organism was, on occasions, higher than what would be expected only as a consequence of having one or another version of the gene.

In a second experiment, the researchers did something similar with the FTO gene, the most studied genetic factor related to obesity.

A variant of this gene is associated with a worse capacity of the body to feel satiated and stronger neuronal responses towards food images, in brain regions involved in the regulation of appetite.

In this case, people who had been attributed a genotype of risk showed less control of satiety.

According to the scientists in their article, the explanation of this phenomenon could be in the mindset of the participants.

That is, the key for the placebo effect to appear is how the results are communicated to the clients of the analyzes.

In fact, the largest study that has been done with direct consumer tests, which was published in the New England Journal of Medicine in 2011, concluded that participants in this type of tests, in which there is not a professional in communicating the results, they had a high risk of having obesity associated with eating a less healthy diet and reducing the amount of exercise three months after receiving the results.

Three months. And then what? Nobody knows.

Genetic information significantly changes the behavior of people, what is not clear is how long its influence lasts.

How do DNA tests change outcomes?

If a person does not intake an excess of saturated fats, they do not have any problems, they will not be obese, but if the intake increases, it doubles the possibility of having health problems.

The personal exploration of their genome highlighted the reason why geneticists have always had problems with a metabolic marker that increases triglycerides, but now, thanks to new knowledge they know that people must follow a diet rich in omega 3. When not possible, they must use the supplements.

Only conclusions that are supported by sufficient research can be taken into account.

The gene is only a guide that indicates where to look, but that does not have to be determinant. There are diseases that are the inexorable result of a defective gene, but they are few and tend to debut in childhood.

That is, for a middle-aged person it is normal to receive a report of probabilities, not of certainty, and, on the other hand, the experience of the geneticist shows that it is absolutely necessary to complete the genetic information with complementary analyzes.

The objective of these analyses should not be to know what genes you have but to find a way to improve your health. It is also what companies that are dedicated to marketing them should aspire to, and where they think they will move to in the future.

Genetics may indicate that you may have a lot of risk but a metabolic marker can tell you that you are currently doing well because you exercise, you eat well and so on. In that case, genetics is not being expressed.

A person predisposed to have a heart attack should rely on markers that doctors know are related to cardiovascular health, that depend on their lifestyle and that do not appear in the genes, but in another type of analysis of the situation of your body at a specific moment.

On the other hand, the fact that no genetic analysis assigns risk to a disease does not always mean that you can not have it. And it is very important to bear in mind that genetic information can generate new problems.

For example, if an obese person is told that they have a greater genetic risk of obesity, it can even cause them to stop having a healthy life because they may think that, whatever they do, they will be obese throughout their lives, and that’s terrible.

Even if a person has genetic risk information, if they live a healthy life, if they eat well and exercise his genes will not have as much influence on weight and, therefore, it will not be fulfilled that he needs to be obese.

At the moment it is being discussed if it is positive or not to give this information directly to the consumer, without anyone mediating between the professional and the laboratory.

A very important detail obtained from the genetic study is that the probabilities can change, that is, although the DNA does not change, the probability that a variant of risk provides can change because it depends on the environment.

When a test indicates that someone is twice as likely to be obese, if you eat well, practice sports and develop healthy lifestyle habits, you may end up canceling that extra risk.

“I do not care about the risk of a disease, I do not care if it’s 90 percent, what can I do to reduce it by half?” That is the right question and the right attitude people should have.

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