Processed Foods Associated with Negative Health Outcomes, Study Finds

New research from an inter­na­tional team of sci­en­tists has high­lighted the haz­ards of ultra-processed foods (UPF) to human health, con­nect­ing high UPF expo­sure to more than 30 health issues.

The researchers car­ried out an umbrella review – a sys­tem­atic review of pre­vi­ous reviews – of 45 pooled meta-analy­ses from 14 pub­lished review arti­cles on the link between UPF and adverse health out­comes.

All the reviewed arti­cles were less than three years old and included research data from almost 10 mil­lion peo­ple.

Previous research has asso­ci­ated highly processed food with poor health; how­ever, no com­pre­hen­sive review has yet assessed the accu­mu­lated sci­en­tific evi­dence.

In their research paper, pub­lished in the Journal of the British Medical Association (BMJ),
they found that higher con­sump­tion of UPFs can lead to a higher risk of a range of health con­di­tions, includ­ing car­dio­vas­cu­lar dis­ease, men­tal dis­or­ders and even mor­tal­ity.

“Consistent evi­dence shows that higher expo­sure to ultra-processed foods is asso­ci­ated with an increased risk of 32 dam­ag­ing health out­comes includ­ing can­cer, major heart and lung con­di­tions, men­tal health dis­or­ders and early death,” Melissa Lane, the study’s lead author from Deakin University in Australia, told Olive Oil Times.

Some of the most com­mon ultra-processed foods are mass-pro­duced bread, sweet­ened cere­als, ice cream, soft drinks, bis­cuits, sausages and instant soups.

More specif­i­cally, the researchers graded their evi­dence as con­vinc­ing, highly sug­ges­tive, sug­ges­tive, weak, or no evi­dence if no asso­ci­a­tion is estab­lished between the con­sump­tion of UPF and health issues.

Their review showed there is con­vinc­ing evi­dence that higher UPF intake is directly asso­ci­ated with an almost 50 per­cent increased death risk due to car­dio­vas­cu­lar dis­ease and a 12 per­cent higher risk of type 2 dia­betes.

Higher UPF con­sump­tion was also linked to a 21 per­cent increased risk of death from any cause and a 22 per­cent higher risk of depres­sion, based on highly sug­ges­tive evi­dence.

The study also linked UPF to asthma and some types of can­cer, although it stated that the evi­dence for this con­nec­tion was lim­ited.

UPF is also gain­ing ground among con­sumers world­wide, though its pen­e­tra­tion is not ubiq­ui­tous in all coun­tries and regions exam­ined.

In some high-income coun­tries, such as the United States and Australia, UPFs account for up to 58 per­cent and 42 per­cent of the total daily energy intake (the calo­ries from avail­able food). At the same time, they have also infil­trated the diets of many low- and mid­dle-income coun­tries such as Colombia and Mexico.

“Over recent decades, the avail­abil­ity and vari­ety of ultra-processed prod­ucts sold have sub­stan­tially and rapidly increased in coun­tries across diverse eco­nomic devel­op­ment lev­els, but espe­cially in many highly pop­u­lated low- and mid­dle-income nations,” the authors wrote.

The study also shed some light on the mech­a­nism under­pin­ning the con­nec­tion between UPF dietary pat­terns and poor human health, which requires fur­ther inves­ti­ga­tion as the researchers stressed.

They explained, nev­er­the­less, that as ultra-processed foods dis­place more nutri­tious foods in diets such as fruits, veg­eta­bles, legumes and nuts, they reduce the intake of ben­e­fi­cial bioac­tive com­pounds, includ­ing polyphe­nols and phy­toe­stro­gens, which are estro­gen-like com­pounds derived from plants and plant-based foods.

The result­ing nutri­ent-defi­cient dietary pat­tern can lead to chronic dis­ease devel­op­ment through var­i­ous mech­a­nisms in the human body, includ­ing inflam­ma­tion.

“Ultra-processed foods, includ­ing pack­aged baked goods and snacks, fizzy drinks, sug­ary cere­als and ready-to-eat or heat prod­ucts, undergo mul­ti­ple indus­trial processes and often con­tain col­ors, emul­si­fiers, fla­vors and other addi­tives,” Lane said. ​“These prod­ucts also tend to be high in added sugar, fat and salt but low in vit­a­mins and fiber.”

Although some experts doubt whether the study estab­lishes a cause-and-effect rela­tion­ship between the con­sump­tion of UPF and poor health, oth­ers have sup­ported its find­ings.

According to Chris van Tulleken, asso­ciate pro­fes­sor at University College London and lead­ing expert on UPFs, who was not involved in the study, the find­ings are con­sis­tent with an ​‘enor­mous num­ber of inde­pen­dent stud­ies’ that link a diet high in UPFs to a wide range of dam­ag­ing health out­comes.

“We have a good under­stand­ing of the mech­a­nisms by which these foods drive harm,” van Tulleken told The Guardian. ​“This is partly because of their poor nutri­tional pro­file – they are often high in sat­u­rated fat, salt and free sugar.”

Scientists have also sug­gested that a prac­ti­cal way to iden­tify ultra-processed food is to review the ingre­di­ents list for con­stituents rarely or never used in a home kitchen, such as hydro­genated oils and high-fruc­tose syrup or addi­tives, such as fla­vor enhancers and arti­fi­cial col­ors, that make the food prod­uct more palat­able.

However, the com­mon denom­i­na­tor of all highly processed foods is that they are almost exclu­sively pro­duced on an indus­trial scale and con­tain sev­eral ingre­di­ents and sub­stances rather than the inten­sity of pro­cess­ing their ingre­di­ents undergo.

Fruit-fla­vored yogurt, for exam­ple, which is clas­si­fied as UPF, is hardly more processed than plain yogurt, except for the addi­tion of extra ingre­di­ents.

The study authors noted that their umbrella review has cer­tain lim­i­ta­tions and fur­ther ran­dom­ized con­trolled tri­als are required to estab­lish causal­ity.

They also said that their study’s find­ings are suf­fi­cient to urge gov­ern­ments and pub­lic author­i­ties to take action to reduce peo­ple’s expo­sure to UPF and pro­mote healthy eat­ing.

“We note the con­sis­tent trend link­ing ultra-processed foods to poor health out­comes is suf­fi­cient to war­rant the devel­op­ment and eval­u­a­tion of gov­ern­ment-led pol­icy and pub­lic health strate­gies aimed at tar­get­ing and reduc­ing dietary expo­sure to ultra-processed foods,” Lane said.

Nonetheless, in recent years, coun­tries world­wide have rec­og­nized the impor­tance of the wide­spread use of a healthy eat­ing pat­tern in the pop­u­la­tion, includ­ing foods such as fruits, veg­eta­bles, legumes and whole grains in the dietary guide­lines for their cit­i­zens.

Research has also indi­cated that a healthy eat­ing pat­tern like the Mediterranean diet can be more cost-effec­tive than other stan­dard diets while offer­ing higher nutri­tional value.

• The Guardian
• Euronews
• Future Learn