Researchers warn against demonizing entire food groups

Food scientists have suggested that lifestyle factors may have more negative health effects than the consumption of ultra-processed foods, challenging current public health recommendations.

perspective: Ultra-processed foods and health: Are we interpreting the available evidence correctly? Image credit: Rinma Bondarenko / Shutterstock

In a recent perspective article published in European Journal of Clinical Nutritionresearchers discussed epidemiological studies on the effects of ultra-processed food (UPF) consumption on human health.

They conclude that there is insufficient evidence that hyperprocessing specifically, rather than other confounders, is causing the observed adverse outcomes.

Confounders and surrogate actions

Several recent studies have found a link between UPF intake and negative health outcomes such as obesity, overweight, heart disease, type 2 diabetes, and increased risk of cancer. Researchers also found that those who consumed the most UPF may have a higher risk of death from all causes.

Research findings showing a correlation between UPF intake and poor health have often been interpreted as a causal relationship, that is, UPF intake causes poor health. However, because the study is primarily observational, causality cannot be inferred and confounding factors may be involved.

In these studies, researchers ensure that measurements of food intake are accurate and accurate, that the composition of the food is known and can be quantitatively characterized, and that the results are not affected by food storage, cooking, or cooking. We must also assume that. food.

A step in the right direction is recent research focusing on the contribution of emulsifiers, showing that some (but not all) emulsifiers are associated with the likelihood of developing some cancers and overall cancer risk. It turned out that. However, the researchers cautioned that it would be a mistake to extend these findings to all emulsifiers, as many emulsifiers are not associated with cancer risk.

Importance of subgroup analysis

One problem is that studies may combine different groups of UPF into one category, and many published papers do not explicitly mention subgroup analysis. However, even in a single study, different subgroups can have very different associations with health outcomes.

For example, some UPFs (including sauces, margarines, and foods containing ultra-processed fats) may be associated with a higher risk of diabetes, cancer, and heart disease, while foods such as cereals and ultra-processed breads There are indications that other UPFs are at higher risk. , may be protective.

Another study found that the relationship between heart disease and UPF consumption was driven by increased intake of ultra-processed sauces, condiments, and fats and decreased fiber intake. An analysis of the association between colorectal cancer deaths and UPF intake found that the consumption of ultra-processed ice cream and sorbet was the cause.

Similarly, a study linking mortality and UPF consumption found that the relationship was largely due to ultra-processed beverages. Breast cancer incidence is associated with sugary products, but not sugary drinks. So far, no studies have found a link between negative health effects and ultra-processed vegetables and fruits. The lack of subgroup analyzes in many studies may unfairly group some UPFs as posing more significant health risks, further complicating public health messaging. means.

Regional differences and UPF consumption

Therefore, experts say that people who ingest the highest amounts of UPF may face the most overall health risks, but this may be due to a small number of UPFs rather than ultra-processing itself. states. For example, it was established that certain animal-derived products were unhealthy long before the current UPF classification was established.

The observed relationship may be due to the fact that UPF consumption is often a surrogate for suboptimal lifestyle and dietary habits. This means that people who eat poorly are also more likely to engage in unhealthy habits, such as smoking.

Importantly, the findings also show significant regional heterogeneity. On average, people in Italy have a low intake of UPF. There, all-cause mortality is significantly increased in people whose UPF consumption contributes approximately 24% of their energy intake.

Findings differ in countries where people consume more UPF, such as the UK. Mortality increases only when UPF consumption exceeds 40% of total energy intake. This regional difference suggests that other factors, such as lifestyle and dietary patterns, may play a larger role than UPF consumption per se.

Notably, the study found no risk of increased mortality associated with UPF intake among low-income American populations that were highly dependent on ultra-processed foods. Because it is unlikely that the UPF in some countries is healthier than in others, this may mean that confounding factors such as broader dietary habits or socio-economic status are driving the observed differences. This further supports the idea that there is.

conclusion

To strengthen the current evidence, it is necessary to present results for all groups of UPFs and not lump them into one category. Research should also examine each step of the food preparation process and the specific compounds that may contribute to the observed adverse health effects.

If superprocessing is not the cause of poor health outcomes, public health recommendations seeking to limit UPF intake will not improve health outcomes. Rather, they may reduce access to nutrition for low-income populations who rely on these products.

The observational evidence from the current study can be strengthened by using an framework to investigate the mechanistic and causal basis of these relationships. More studies are needed to directly investigate the causal relationship between UPF intake and health outcomes, which cannot be established through observational studies alone. We should also focus on UPF, which is “nutritionally beneficial” and may protect against some diseases and adverse health outcomes.