Our eating habits have an influence on our mental health.
According to a new American study, consuming ultra-processed food, which are rich in added sugars, saturated fats and salt, have an influence on our mood.
However, these products are widely available.
In the United States, they represent 70% of packaged foods, according to the study authors.
However, if you value your mental health, you should probably stay away from fast food and other ultra-processed foods.
At least that’s the conclusion of a study conducted by Florida Atlantic University and published in the journal Public Health Nutrition.
To carry out their research, the scientists used a large panel of participants, including 10,359 American adults who had never used drugs such as cocaine, methamphetamine or heroin.
During one month, the researchers measured “mild depression”, the number of “mental unhealthy days” and anxious days.
To do this, a questionnaire was filled out daily by the volunteers.
To measure the quality of food, the researchers used the classification system called NOVA, adopted by the United Nations’ Food and Agriculture Organization (UN FAO).
It differentiates food products into four categories: unprocessed or minimally-processed foods, processed culinary ingredients, processed foods and ultra-processed foods.
They found that people who eat the most ultra-processed foods show symptoms of poor mental health, compared to people who eat less.
Ultra-processed foods include packaged baked goods and snacks, fizzy drinks, sugary cereals, and ready-to-eat or -heat products, often containing high levels of added sugar, fat and/or salt, but lacking in vitamins and fibre.
There is little or no whole food in their composition, and they can also contain edible chemicals like flavours and dyes.
Once consumed, these foods are deleterious to the brain, and therefore, the mood.
“Poor diets dysregulate brain insulin, which affects mood, decreases neuronal levels of serotonin and dopamine, and increases neuroinflammation as measured by inflammatory cytokines,” explain the researchers.
Serotonin is known as the hormone of happiness; while dopamine is the hormone of immediate pleasure.
“Data from this study add important and relevant information to a growing body of evidence concerning the adverse effects of ultra-processed consumption on mental health symptoms,” said study co-author Dr Charles H. Hennekens in a press release.
Cancer and heart disease
Meanwhile, two other large studies published in The BMJ medical journal recently found links between high consumption of ultra-processed foods and increased risks of cardiovascular (heart) disease, colorectal (bowel) cancer and death.
The findings add further evidence in support of policies that limit ultra-processed foods, and instead, promote eating unprocessed or minimally-processed foods to improve public health worldwide.
They also reinforce the opportunity to reformulate dietary guidelines worldwide, by paying more attention to the degree of processing of foods along with nutrient- based recommendations.
Previous studies have linked ultra-processed foods to higher risks of obesity, high blood pressure, cholesterol and some cancers.
However, few studies have assessed the association between ultra-processed food intake and colorectal cancer risk, and those findings are mixed due to limitations in study design and sample sizes.
In the first study, researchers examined the association between consumption of ultra-processed foods and risk of colorectal cancer in American adults.
Their findings are based on 46,341 men and 159,907 women from three large studies of US health professionals whose dietary intake was assessed every four years using detailed food frequency questionnaires.
Foods were grouped by degree of processing and rates of colorectal cancer were measured over a period of 24-28 years, taking account of medical and lifestyle factors.
Results show that compared with those in the lowest fifth of ultra-processed food consumption, men in the highest fifth of consumption had a 29% higher risk of developing colorectal cancer.
This risk remained significant even after further adjustment for body mass index (BMI) or dietary quality.
No association was observed between overall ultra-processed food consumption and risk of colorectal cancer among women.
However, higher consumption of meat/poultry/seafood-based ready-to-eat products and sugar-sweetened beverages among men – and ready-to-eat/heat mixed dishes among women – was associated with an increased risk of colorectal cancer.
Processed to death
In the second study, researchers analysed two food classification systems in relation to mortality (death), i.e. the UK Food Standards Agency Nutrient Profiling System (FSAm-NPS), which is used to derive the colour-coded Nutri-Score front-of-pack label, and the NOVA scale.
Their findings are based on 22,895 Italian adults (average age 55 years; 48% men) from the Moli-sani Study, investigating genetic and environmental risk factors for heart diseases and cancer.
Both the quantity and quality of food and beverages consumed were assessed, and deaths were measured over a 14-year period (2005 to 2019), taking account of underlying medical conditions.
Results showed that those in the highest quarter of the FSAm-NPS index (least healthy diet), compared with the lowest quarter (healthiest diet), had a 19% higher risk of death from any cause and a 32% higher risk of death from cardiovascular disease.
Risks were similar when the two extreme categories of ultra-processed food intake on the NOVA scale were compared (19% and 27% higher for all-cause and cardiovascular death respectively).
A significant proportion of the excess risk of death associated with a poor diet was explained by a higher degree of food processing.
In contrast, ultra-processed food intake remained associated with mortality, even after the poor nutritional quality of the diet was accounted for.
Promote fresh foods
Both studies are observational so can’t establish cause, and limitations include the possibility that some of the risks may be due to other unmeasured (confounding) factors.
Nevertheless, both studies used reliable markers of dietary quality and took account of well-known risk factors, and the findings back up other research linking highly-processed food with poor health.
As such, both research teams say their findings support the public health importance of limiting certain types of ultra-processed foods for better health outcomes in the population.
Results from the Italian study also reinforce the opportunity to reformulate dietary guidelines worldwide, by paying more attention to the degree of processing of foods, along with nutrient-based recommendations.
In a linked editorial, Brazilian researchers argue that nobody sensible wants foods that cause illness.
The overall positive solution, they say, includes making supplies of fresh and minimally-processed foods available, attractive and affordable.
And sustaining national initiatives to promote and support freshly-prepared meals made with fresh and minimally-processed foods, using small amounts of processed culinary ingredients and processed foods.
“Enacted, this will promote public health. It will also nourish families, society, economies and the environment,” they conclude. – AFP Relaxnews and The BMJ