Animal protein amplifies the harmful effects of salt consumption
Although we have all heard that we need to avoid high salt intake, about 30-50% of us have a significant increase in blood pressure in response to high salt intake, percentages that are even higher and more impactful for people of color.
The two new studies by researchers at Georgia Medical College and Wisconsin Medical College provide more evidence that the gut microbiota, which contains trillions of microorganisms that help us digest food and plays a key role in regulating our immune system response, is also a player in the unhealthy response to salt consumption.
The findings provide more evidence of the “potential power” of nutritional intervention to improve the gut microbiota and, consequently, our long-term health, says Dr. David L. Mattson, president of the Department of Physiology MCG, Georgia Research Alliance Eminent Scholar in Hypertension and lead author in the two studies.
They result from the unexpected observation that the protection works even in the salt-sensitive rat called Dahl SS. This type of rodent is bred to develop high blood pressure and progressive kidney disease on a high-salt diet. In 2001, Wisconsin Medical College distributed their colony of Dahl SS rats, which were fed a milk-based protein diet. Once the rats arrived in the Charles River laboratories, based in Wilmington, Massachusetts, they switched to a grain-based diet. Both diets are relatively low in sodium, although the protein diet has a little more salt.
It was soon observed that when a high salt content was added to their diet, rodents that were switched to the plant diet developed significantly less blood pressure and associated kidney damage than the remaining rat colonies in Wisconsin on the protein diet.
More than a decade of research has documented these differences, write Mattson and colleagues at MCG and MCW, and now they have shown that the development of salt-sensitive hypertension is not just about sodium. “Animal protein has amplified the effects of salt,” says Mattson, a researcher with extensive experience in hypertension.
“Because the gut microbiota has been implicated in chronic diseases such as hypertension, we hypothesized that dietary changes change the microbiota to mediate the development of salt-sensitive hypertension and kidney disease,” the researchers wrote in the journal ACTA PHYSIOLOGICA.
“The gut microbiome is designed to metabolize what we eat, break it down and put it in a form that gives us nutrition, and this, of course, reflects what we eat,” says first author Abais-Battad. When the microbiomes from rats were analyzed, they noticed that they were different, but when they sequenced the genetic material of both colonies of rats, they found that they were “practically identical”, and the difference appeared in their different response to a high-salt diet.
Preeclampsia is a potentially fatal problem during pregnancy, when the mother’s blood pressure, which was usually normal before, increases, and organs such as the kidneys and liver show signs of damage. There is evidence that, even with a low-salt diet, Dahl’s salt-sensitive rats are prone to developing preeclampsia. To analyze the impact of the diet in this scenario, Dahl SS rats were kept on their herbal or animal protein diet, which was relatively salty, and both groups had three separate pregnancies and births.
Rats on the whole wheat diet were protected from preeclampsia, while about half of the rats on the animal-based casein diet developed this significant complication of pregnancy, says Dasinger, the first author of the preeclampsia study.
“This means that if the mother is careful about what she eats during pregnancy, this will help during pregnancy, but also with an impact on her long-term health and could provide protection for children,” say the researchers. This research shows that the essential difference between these diets is that the protein-based diet results in the production of more proinflammatory molecules, and the herbal diet seems to suppress these factors.
High blood pressure is the biggest modifiable risk factor for the development of cardiovascular disease and, according to the latest benchmarks from groups like the American Heart Association, who say that a systolic value or greater than 120+ is also increased when we have 130-139 we are already talking about stage one hypertension, almost half of us are hypertensive. Diet – including a high-salt diet – is one of the main modifiable risk factors for high blood pressure and cardiovascular disease, scientists say. It was found that both hypertensive people and animals with the same problem have an unbalanced intestinal microbiota and less diverse than those with normal blood pressure.
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