Warning on link between processed foods and health risks

Author: Adrian O'Dowd
Warning on link between processed foods and health risks

Fresh warnings have been made in two large European studies published today by The BMJ that found possible links between consuming highly processed (ultra-processed) foods and risk of cardiovascular disease and death.

The researchers have called for more work to better understand these effects, and a direct (causal) link remains to be established, but they recommended policies that promote consumption of fresh or minimally processed foods rather than highly processed foods.

Ultra-processed foods include packaged baked goods and snacks, fizzy drinks, sugary cereals, ready meals containing food additives, dehydrated vegetable soups, and reconstituted meat and fish products.

These often contain high levels of added sugar, fat, and/or salt, but lack vitamins and fibre. They are thought to account for around 25-60% of daily energy intake in many countries.

Previous studies have linked ultra-processed foods to higher risks of obesity, hypertension, high cholesterol, and some cancers, but firm evidence is still scarce.

Therefore, in the first study*, researchers based in France and Brazil assessed potential associations between ultra-processed foods and risk of cardiovascular and cerebrovascular disease.

Their findings were based on 105,159 French adults (21% men; 79% women) with an average age of 43 who completed an average of six 24-hour dietary questionnaires to measure usual intake of 3,300 different food items, as part of the NutriNet-Santé study.

Foods were grouped according to degree of processing and rates of disease were measured over a maximum follow-up of 10 years between 2009 and 2018.

Results showed that an absolute 10% increase in the proportion of ultra-processed food in the diet was associated with significantly higher rates of overall cardiovascular disease, coronary heart disease, and cerebrovascular disease – an increase of 12%, 13%, and 11% respectively.

In contrast, the researchers found a significant association between unprocessed or minimally processed foods and lower risks of all reported diseases.

In the second study**, researchers based in Spain evaluated possible associations between ultra-processed food intake and risk of death from any cause.

Their findings were based on 19,899 Spanish university graduates (7,786 men and 12,113 women) with an average age of 38 who completed a 136-item dietary questionnaire as part of the Seguimiento Universidad de Navarra (SUN) study.

Foods were grouped according to degree of processing and deaths were measured over an average of 10 years.

Results showed that higher consumption of ultra-processed foods (more than four servings per day) was associated with a 62% increased risk of all-cause mortality compared with lower consumption (less than two servings per day).

For each additional daily serving of ultra-processed food, mortality risk relatively increased by 18%.

Both studies were observational so cannot establish causality and there is a possibility that some of the observed risks may be due to unmeasured confounding factors.

Nevertheless, both studies took account of well-known lifestyle risk factors and markers of dietary quality, and the findings back up other research linking highly processed food with poor health.

Both research teams said policies that limited the proportion of ultra-processed foods in the diet and promoted consumption of unprocessed or minimally processed foods were needed to improve global public health.

*Srour B, Fezeu L K, Kesse-Guyot E, et al. Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). BMJ 2019;365:l1451. DOI: 10.1136/bmj.l1451

**Rico-Campà A, Martínez-González M A, Alvarez-Alvarez I, et al. Association between consumption of ultra-processed foods and all-cause mortality: SUN prospective cohort study. BMJ 2019;365:l1949. DOI: 10.1136/bmj.l1949