The keto or ketogenic diet is not new, but
it is very popular
.
And just as it gains followers, this eating pattern that emphasizes the consumption of fats and restricts the consumption of carbohydrates, is also often dismissed by health professionals who warn that, for most people, the risks involved are greater than their benefits. .
Within this framework, a new study recently presented at the annual scientific session of the American College of Cardiology in conjunction with the World Congress of Cardiology, which observed that ketogenic diets can double the risk of cardiovascular disease, is
inscribed
.
Keto diet: what is it?
The keto diet was designed a century ago by the American physician Russel Wilder.
But it was not born with the aim of promoting weight loss, but as a strategy to help reduce difficult-to-control seizures in childhood.
Today, in fact, it continues to be indicated for this purpose in boys and girls with
refractory epilepsies
(that is, those that do not respond well to medications).
More recently, it has gained popularity as an alternative to treat various health conditions, including obesity and diabetes.
It is that adherence to the keto or ketogenic diet can be associated in the short term with
rapid weight loss
.
Ketogenic diets are based on limiting carbohydrate intake to 10% of total daily calories (for example: bread, pasta, rice and other cereals, potatoes, fruits and vegetables), protein to 20-30% and obtaining
60 to 80%
of daily calories from fat.
While those percentages can vary a bit, this is a high-fat, low-carb diet that aims to
achieve weight loss by burning fat
.
"For years we have known that by significantly reducing the intake of carbohydrates and replacing it with an exaggerated increase in fat, we can generate rapid
satiety
in the body on the one hand , and on the other hand, despite the high caloric content, a significant loss of adipose tissue,"
cardiologist Mario Boskis, a member of the Argentine Society of Cardiology (SAC),
explained to
Clarín .
"This occurs because fats are broken down, producing particles called
ketone bodies
, which are used as energy for the body to make up for the deficit in hydrates, which are the main fuel for metabolism," he said.
And he added that "any diet that
creates such an imbalance in the proportion of food eaten, it must be
thoroughly evaluated
for safety."
Keto diet and cardiovascular risk
That was the goal of the team led by Iulia Iatan, a doctor and researcher at the Center for Cardiopulmonary Innovation at the University of British Columbia (
The University of British Columbia
), in Canada.
"Our study found that regular consumption of a self-reported low-carbohydrate, high-fat diet was associated with higher levels of LDL, or 'bad,' cholesterol, and increased risk of heart disease," said Iatan, the paper's lead author. of which only preliminary results are known at the moment.
"To our knowledge, our study is
one of the first to examine the association
between this type of dietary pattern and cardiovascular outcomes," added the physician, who is also with the Providence Health St. Paul Hospital Heart Healthy Program. Care.
For the study, Iatan and his team defined a
modified ketogenic diet
, which consists of consuming no more than 25% of total daily calories from carbohydrates and more than 45% of total daily calories from fat.
They called it a "keto-like diet" because it is higher in carbohydrates than the traditional one.
The research team analyzed data from the UK Biobank, a large-scale database with health information on more than half a million people.
Upon enrolling in the biobank, the participants completed a questionnaire about the composition of their diet and had blood drawn to check their cholesterol levels.
The researchers identified 305 participants whose responses to the questionnaire indicated that their diet met the definition of being keto-like.
Those participants were matched by age and sex with 1,220 people who reported following a standard diet.
Three out of four were women and the
average age of the group was 54 years
.
Those on the low-carb diet had an average body mass index (BMI) of 27.7 and those on the standard diet 26.7.
(A BMI of 25 to 30 falls within the overweight range)
Keto is not a balanced diet.
Photo Shutterstock.
"Among participants on a low-carb diet, we found that those with the highest levels of LDL cholesterol had the highest risk of a cardiovascular event," Iatan said.
Boskis, who was present at the congress, commented to
Clarín
about the results that after almost 12 years of follow-up: "The researchers found that those who followed the keto diet not only significantly increased their levels of LDL cholesterol and apoB, a lipoprotein with ability to cause atherosclerosis, but also doubled the risk of heart attack, coronary angioplasty with stenting, or stroke compared with the control group who had followed a balanced diet" (9.8% vs 4.3%).
"Our findings suggest that people considering following a low-carb diet should be aware that doing so could
lead to an increase in their LDL cholesterol levels
," she said, suggesting consulting a health professional before starting. in a dietary pattern of these characteristics.
If followed, he recommended they monitor their cholesterol levels and try to address other risk factors for heart disease or stroke, such as diabetes, high blood pressure, physical inactivity and smoking.
"These results warn that finding high lipid levels while on a ketogenic diet is a
strong alarm signal
that we cannot dismiss," the Argentine doctor, who did not participate in the study, stressed along the same lines.
Not everyone responds the same to the keto diet
The study findings also suggest that not everyone responds in the same way to a low-carb diet.
Although on average cholesterol levels tend to increase on this diet, in some people they may remain
stable or decrease
.
"There are inter-individual differences in the way people respond to this dietary pattern that we don't yet fully understand. One of our next steps will be to try to identify specific traits or genetic markers that can predict how someone will respond to this type of diet
.
" advancement.
The ketogenic diet is high in fat and very low in carbohydrates.
Photo Shutterstock.
Study limitations
One limitation of the study is that the participants provided dietary information at a single point in time, at the beginning of the research, the author recalled.
And because the study was observational,
it can only show an association
between diet and increased risk of major cardiac events, not a cause (keto diet)-effect relationship (increased risk of cardiovascular disease).
"I would not say that it is inappropriate to follow this diet based on this study,"
lead author Liam Brunham said in a
Medscape Medical News article.
"This is just an observational study. It's not definitive. But if people want to follow this dietary pattern because they feel there will be some benefits, then they need to be aware
of the potential risks
and take steps to mitigate those risks," he added.
Consulted for that same article, lipid specialist Steven Nissen, from the Cleveland Clinic (in Ohio, United States), expressed some reservations about the impact of the work.
"We can't make decisions about what kind of diet to recommend to patients based on observational studies like this, which
lack a lot of subtlety
" and which he characterized as "hypothesis-generating."
However, he said that he does not usually suggest this type of diet and, instead, the Mediterranean diet.
Ranking: last place for the keto diet
While this study is new, the warnings about the potential cardiovascular risks of adhering to the keto diet are not new.
In fact, the classic US News Best Diet 2023 ranking, which analyzes 24 popular diets, places it
last
in the ranking of the best diets for the heart.
"Pregnant women, children without epilepsy, people with certain cancers, people with heart disease, and high-performance athletes should not try this diet," says an article accompanying the classification compiled on the advice of more
than 30 experts
(nutritionists, doctors and epidemiologists).
"The metabolic needs of these groups are such that they do not align with the macronutrient distribution of the ketogenic diet, which could be
potentially harmful or very dangerous
, especially if followed for a long period of time," he adds.
Is keto more effective than other diets?
A review of studies published in 2021 in
Frontiers in Nutrition
, suggests that the ketogenic diet may reduce body weight, but "not more effectively than other dietary approaches in the long term when combined with energy intake."
In addition, the researchers note that ketogenic diets have been linked to increased risk of chronic kidney disease, cardiovascular disease, cancer, diabetes, and Alzheimer's disease due to decreased intake
of "protective foods
," including vegetables, fruits, legumes and whole grains.
On the contrary, they contemplate a high consumption of red and processed meats and saturated fats, which are linked to a greater risk of developing these chronic diseases.
Very low-carbohydrate diets are associated with
marked risks
, the authors argue.
LDL cholesterol can rise "dramatically" in some cases, they said.
"Current evidence suggests that for most people,
the risks of such diets outweigh the benefits
," the review concludes.
***
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