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Worldwide percentages of metabolic disorders have been sustained for decades. High blood pressure, high cholesterol, obesity and diabetes have all become very common since the mid -20th century. These metabolic disorders now influence More than one in three Americans, in what is described on a large scale as an epidemic. In turn, the risk of fatal heart conditions, strokes and certain cancers increases.
Although social, genetic and lifestyle factors all play an important role in this collective rising risk, another surprising variable can also influence our metabolic fate. The time of year and the weather that leads to the conception of an individual shifts how their bodies uses energy and ultimately their lifelong health, per a study Published on April 7 in the magazine Nature metabolism.
“The season in which a person was devised has a lasting impact on their metabolism,” lead study author Takeshi YoneshiroA molecular physiologist and metabolism researcher at the Tohoku University School of Medicine in Japan, says Popular science. “Our study suggests that the environment that parents have experienced, even before the pregnancy can later form the metabolic health of the child in life”
What is brown fat?
More specifically, Yoneshiro and his co-researchers discovered that those who were conceived during colder months have more brown fat, a kind of tissue with established health benefits.
The primary biological goal of brown fat is supposed to regulate body temperature. Compared to normal fat, which is usually passive energy storage, brown fat is much more active – burning by calories to create heat. “Calories-in, calorie-out” is a simplification, but it is true that excess weight and visceral fat that is particularly harmful fat that collects in the abdomen around organs are determined by the amount of energy that we consume and the amount we burn. The idea of ​​diets is to minimize calories (although often this is counterproductive). But brown fat helps on the other side of the comparison by using more energy that we take. It can also have more direct metabolic benefits by burning the harmful by -products of other cellular processes.
For those conceived during colder months, an increase in brown fat also seems to correlate with higher daily energy consumption, lower body mass index (BMI) and less fat accumulation around internal organs, compared to their summer or spring on the other hand.
[ Related: There are two types of fat cells. Here’s how to get more of the good stuff. ]
Conception season versus homesters
In the new study, the researchers assessed four separate cohorts, in total more than 500 people. They used the date of birth of each participant to calculate the estimated time of their conception with retroactive effect. That the estimate of the conception was linked to weather data, measurements of metabolic activity, energy consumption, BMI, belly fat and brown fat levels, to see if there were any trends.
While birth The season had no direct significant effect on the metabolic health of a subject or brown fat level, the timing of them conception did it according to the results. It may seem like a contradiction, but can be explained by the fact that human pregnancy is 9 months old. Someone can be conceived in a cold month, but born in a much warmer time and vice versa.
Moreover, the weather and the season during the Utero development showed no significant influence. This means that the prejudice period is the most critical time for determining future brown fat activity levels at offspring. Higher temperature variability (estimated as the difference between the registered cold and high temperature for a certain day) also showed a positive impact for the conception on brown fat.
Depending on the rated cohort, the difference in brown fat between the warm and cold season groups was between 11.9 and 14.6 percent. The daily energy consumption was approximately 5.8 percent higher in the Cold Conception Group.
The epigenetic factor
It can be difficult to believe – almost related to the pseudoscience of horoscopes – those seasonal trends before you are born can affect your health. Thanks to decades of research, however, scientists now know that how your genes are expressed can be changed by environmental signals, in a process known as epigenetic modification.
Due to epigenetics, the actual DNA sequence remains unchanged, but certain genes can be deactivated or intensified as molecules that bind and respond to certain pieces of DNA. A Study 2018 Mice discovered that epigenetic changes in sperm cells, in response to temperature, can influence the brown fat levels for offspring.
[ Related: Scientists can now tell if you had a ‘vanishing’ twin in the womb. ]
The same research from 2018, conducted by a non -committed group of scientists, found a small but significant correlation between conception month and BMI in a single human cohort in the same way. This new research builds on those findings by conducting additional tests from more people, assessing four independent groups and collecting data about the prevalence of brown fat, energy consumption and visceral fat measurements to connect the dots between BMI and birth season.
“We have done a little human work, but not nearly to that extent,” we say Christian WolfrumA co-author of the 2018 article and a molecular biologist at Eth Zurich, who was not involved in the new investigation. With the new “impressive” study, “we can now make a strong explanation about people,” adds Wolfrum.
‘We generally look for bad things’
However, this new study is still largely observational. Yoneshiro and his colleagues have proven no cause and effect, nor do they dig in the underlying mechanisms with which exposure to parental temperature and brown fat are linked. But the authors suggest that an epigenetic path, similar to what was found in the 2018 study in mice, is the most likely explanation in humans. In other words: paternal Cold exposure to the day of conception is a key factor in dictating the amount of brown fat activity of a child and ultimately metabolic health through life.
“If we look at parental programming, we generally look for bad things,” we say Raffaele TerperinoA development physiologist and epigeneticist at the Helmholtz Munich, a biomedical research center in Germany. Often, he says, identify epigenetics researchers changes that lead to diseases and reduced quality of life. Terperino was not involved in the new research, but wrote one accompanying then publish in addition to the study in Nature metabolism. One of the most interesting things in the study in his opinion is that “the authors report a provisional challenge that is actually beneficial for the next generation.” It is the rare case in which an epigenetic modification can offer a health benefit.
Eyes on paternal health
The findings, now repeated in two studies, have major implications for potential parents and for our understanding of human health. Firstly, the connection between temperature and brown fat can mean that climate change can continue to challenge our ability to stay healthy over generations, says Tepperino. The study offers a possible explanation for Differences in metabolic disease rates About longitudinal and climate gradients. Finally, it emphasizes that paternal health can form the future of a child in unexpected ways. “Paternal health has largely been overlooked … But the science shows that it is relevant,” he explains. “We have to re -balance responsibility for reproduction and offspring, so it’s not all on the mothers.”
[ Related: Unhealthy sperm can play a role in lost pregnancies. ]
But it is too early to know exactly if and how those who hope to think should integrate these findings into their lives, says Treperino. “I’m not sure if we have enough solid evidence to give instructions or recommendations.”
We do know that sperm production cycles last weeks, not hours, so a single cold shower will not do much to guarantee the health of future descendants. But otherwise more work, in more diverse populations is needed to understand whether or how we can consciously use the epigenetic benefits of cold, say both Teperino and Wolfrum. Maybe Sauna -cut off time Prior to pregnancy, a good idea is, suggests Terperino, but does not necessarily reach the ice bucket.