A new study involving almost a half a million people has found that low carbohydrate diets are unsafe and should be avoided.

"We found that people who consumed a low carbohydrate diet were at greater risk of premature death. Risks were also increased for individual causes of death including coronary heart disease, stroke, and cancer. These diets should be avoided," commented the study's author, Prof Maciej Banach, of the Medical University of Lodz in Poland.

As obesity is a major public health issue and is known to raise the risk of a number of chronic conditions, such as high blood pressure and type 2 diabetes, many different diets have been suggested for weight loss.

However, the long-term safety of these diets is unclear, and in some cases, controversial. The reseachers decided to look specifically into the impact of low-carbohydrate diets on all causes of death, as well as deaths specifically from cancer and cardiovascular disease.

They looked at 24,825 people and found that compared to those who consumed the highest amount of carbohydrates, those with the lowest intake had a 32% higher risk of death from all causes over a six-year follow-up period.

The risk of death from coronary heart disease during the same period was 51% higher, while the risk from cancer was 35% higher.

These results were confirmed in a further analyisis of seven other studies involving more than 447,000 people who were followed up for an average of 15 years.

These studies suggested a 15% increased risk of death from all causes, a 13% increased risk of death from cardiovascular disease and an 8% increased risk of death from cancer.

"Low carbohydrate diets might be useful in the short-term to lose weight, lower blood pressure, and improve blood glucose control, but our study suggests that in the long-term they are linked with an increased risk of death from any cause, and deaths due to cardiovascular disease, cerebrovascular disease, such as stroke, and cancer," Prof Banach said.

Commenting on why this link may exist, he pointed out that animal protein, especially red and processed meat, has already been linked to an increased risk of cancer.

"The reduced intake of fibre and fruits and increased intake of animal protein, cholesterol, and saturated fat with these diets may play a role. Differences in minerals, vitamins and phytochemicals might also be involved," he suggested.

He said that this study indicates ‘an unfavourable association between low carbohydrate diets and total and cause-specific death, based on individual data and pooled results of previous studies'.

"The findings suggest that low carbohydrate diets are unsafe and should not be recommended," Prof Banach added.

Details of these findings were presented at the ESC (European Society of Cardiology) Congress 2018 in Munich.