Few carbohydrates and many proteins in diet: danger for the cardiovascular system

Few carbohydrates and many proteins lead to a significant increase of atherosclerosis with a consequent increase of risk for cardiovascular diseases, especially heart attack. A consequence of this diet is an impairmant of the body´s ability to revasculate tissues deprived of blood flow due to the infarction.

That´s what was found by a team of researchers at Beth Israel Deaconess Medical Center (BIDMC) - a teaching hospital of Harvard Medical School, which led a study published in the journal PNAS.

This research comes originally from the observations of Shi Yin Foo, cardiologist in  the laboratory of Rosenzweig at BIDMC, who noted a number of cardiovascular problems by patients who followed a diet low in carbohydrates.

Researchers have therefore begun to investigate atherosclerosis in a mouse model subjecting three groups of mice to a diet low in carbohydrates and high in proteins for 12 weeks.
These mice "ApoE" were divided into 3 groups according to the diet:

1. Standard diet (65% carbohydrate, 15% fat, 20% protein)
2. "Western diet" (43% carbohydrate, 42% fat, 15% protein and 0.15% cholesterol)
3. Diet low in carbohydrates and high in proteins (12% carbohydrate, 43% fat, 45% protein and 0.15% cholesterol).

Tests were performed after 6 and after 12 weeks of the diet.

Just like observed in humans, mice fed with food low in carbohydrates and high in proteins gained weight by 28% less than the group fed with the "Western diet". The analysis, however, detected that the first group had a high degree of atherosclerosis, measured by the accumulation of cholesterol plaques: 15.3% for the diet low in carbohydrates and rich in proteins compared to 8, 8% for the "Western diet".

As expected, the standard diet group showed minimal evidence of atherosclerosis compared to the high levels shown in the other two groups.

"It 's very difficult to evaluate how and how much a diet can affect the cardiovascular system, for this reason we rely on serum markers. Our research suggests that, at least in animal models, a diet low in carbohydrates and rich in proteins can have unfavorable effects on the cardiovascular system. These effects, however, are not brought up by simple serum markers," said Anthony Rosenzweig, director of cardiovascular research at the Cardiovascular Institute at BIDMC and professor at Harvard Medical School.

In fact, the researchers analyzed the levels of cholesterol, triglycerides, oxidative stress, insulin and glucose as well as certain cytokines and found that the standard markers of cardiovascular risk weren´t changed in the group with "Western diet" compared to a diet low in carbohydrates and high in proteins, although there is clear evidence of increased risk for atherosclerosis and therefore the cardiovascular system.

Rosenzweig and his colleagues have therefore concentrated their attention on the vascular progenitor cells (EPCs) and found that the growth of plaques in blood vessels and impaired ability to form new vessels are associated with a reduction of EPC cells. They come from bone marrow and could play an important role in the growth and regenerative capacity of the blood vessels.

"We observed a 40% reduction of EPC cells in the bone marrow of mice which were on a diet low in carbohydrates and rich in proteins," says Rosenzweig.

"Although the role of these cells has not been fully investigated yet, these findings support the idea that these damaging events may be compensated by the body's ability to repair itself. The impairment of this capacity could be the cause of adverse events that occurred in the cardiovascular system of mice subjected to the diet low in carbohydrates and high in proteins," says Rosenzweig.

The findings highlight that there may be a separation between the loss of weight and serum markers and cardiovascular health. In particular the last one may be influenced not only by fat and cholesterol, but also from other macronutrients such as proteins and carbohydrates.

"Understanding the mechanisms underlying these processes as well as the regenerative ability of the cell that could contrast cardiovascular diseases would help physicians to improve the conditions of many patients, especially in light of the increasing prevalence of obesity and associated diseases," says Rosenzweig.

A healthy and balanced diet, such as the Mediterranean, and healthy lifestyle that includes regular physical activity are the best way to maintain a healthy body.

Zdroj: http://www.scienzenews.it/

Autor: Cristina Gandola

Překlad: Pavla Čermáková