Ultra-processed foods linked to greater risk of early death

Eating ultra-processed meat is linked to a higher risk of premature death, a 30-year Harvard study has found.

Scientists tracked more than 114,000 adults in one of the largest studies of the long-term consequences of modern diets.

The highest risks were associated with the most processed meats such as sausages and ham. Regular consumers of these products were 13% more likely to die during the 34 years of follow-up.

The study found that diets high in sugary and artificially sweetened beverages had a 9% increased risk.

Overall, those who ate diets with a high proportion of packaged foods and snacks were found to have a 4% higher risk of death during this period.

These foods have already been linked to obesity, heart disease, diabetes and bowel cancer.

However, few studies have followed participants for such a long time or examined overall deaths.

The Harvard study also went further than previous research to find out the potential impact of different types of ultra-processed foods.

Dairy desserts, such as cheesecake or fresh cheese, were linked to a 6% increased risk, while breads and breakfast cereals were linked to a 4% increase.

The study followed the participants for 34 years

In the main study, researchers tracked the long-term health of 74,563 female nurses and 39,501 male health professionals between 1984 and 2018.

Female participants were between 30 and 55 years old at the start of the research, while male participants were between 40 and 75 years old.

Every two years participants provided information about their health and lifestyle habits, with detailed food questionnaires completed every four years.

In the following years, researchers identified 48,193 deaths from cancer, cardiovascular, respiratory and neurodegenerative diseases.

The diets were analyzed and divided into four groups.

Overall, those with the highest intake of ultra-processed foods (an average of seven servings a day) had a four percent greater risk than those in the lowest group, who consumed an average of three servings a day.

The strongest links were found among ready-to-eat meat, poultry and seafood products such as sausages, ham, hot dogs, convenience meals and processed snacks. Sugary and artificially sweetened soft drinks followed, and then dairy-based desserts.

The findings “provide support for limiting consumption of certain types of ultra-processed foods for long-term health.”

“Our results suggest that prepared products based on meat, poultry and seafood and drinks sweetened with sugar and artificially sweetened are important factors that contribute to the harmful influence of ultra-processed foods on mortality,” explained researchers from the Departments of Harvard Epidemiology and Nutrition concluded.

They said the findings “provide support for limiting consumption of certain types of ultra-processed foods for long-term health.”

Ultra-processed foods include baked goods and packaged snacks, fizzy drinks, sugary cereals, and ready-to-eat or reheat foods.

They often contain colorings, emulsifiers, flavors and other additives and are usually high in energy, added sugar, saturated fat and salt, but lack vitamins and fibre.

However, there is no clear definition, with arguments over whether some products, such as wholemeal bread, should be classified as ultra-processed.

In the Harvard study, whole foods were not counted as ultra-processed, and the researchers said they were excluded because of their established benefits in reducing mortality.

The study was observational, meaning no firm conclusions about cause and effect could be drawn.

The research also found that the association was less pronounced after accounting for overall diet quality.

Mixed reaction to study results

Dr Duane Mellor, dietitian and spokesman for the British Dietetic Association, said the findings were interesting and in line with other studies highlighting the risks of processed meats and sugary and artificially sweetened drinks.

However, he said the findings suggested that the overall health of the diet was most important.

Dr Mellor said: “We also noticed that those who ate the most ultra-processed foods tended to eat fewer vegetables, fruit, legumes and whole grains. This seemed to suggest that it might not be as simple as those who ate the most ultra-processed foods were more likely to die earlier; it is quite possible that these foods could displace healthier foods in the diet.”

Professor Christine Williams, emeritus professor of human nutrition at the University of Reading, said the researchers' approach was more “nuanced” than many studies that tried to establish the risks of processed foods by separating different categories.

He said: “This new UPF study comes from the Harvard group, the world's leading group in the area of ​​nutritional epidemiology. This large study includes men and women followed by cause of death over 34 years with information of reference dating back to 1984 and 1986. They examined the relationship between UPF consumption levels and mortality risk (all diseases), as well as mortality from specific causes (cancer, cardiovascular, respiratory, neurodegenerative and others).

“The study showed a modest association with high UPF consumption in the 'All deaths' outcome category, which was 4% higher in the high UPF group.”

However, Professor Sir David Spiegelhalter, emeritus professor of statistics at Cambridge University, said this association was “weak”.

He said it was “surprising” that the researchers' findings focused on the risks of processing, given their recognition that overall diet quality had the biggest impact.

It comes after research found that people who followed a personalized nutrition program that avoids ultra-processed foods lost more weight and saw improvements in blood sugar control, compared to those following standard health guidelines .

This research, published in the journal Natural Medicine – Tracking adults following Zoe, a program that provides dietary recommendations after testing an individual's gut bacteria and response to fats and sugars, encouraging a plant-rich diet and avoiding ultra-processed foods.

The 18-week randomized control trial involving 347 adults in the US found that participants in the program lost an average of 2.5 kilograms more than those who followed the government's general advice.

Tests showed significant improvements in blood sugar control, more “good” gut bacteria and improved mood and sleep among those following the program, founded by Professor Tim Spector.

The Telegraph, London