Eating large amounts of ultra-processed foods may increase the risk of obesity, heart disease, stroke, depression, and early death, according to a new systematic review and meta-analysis.
Key Facts:
- Ultra-processed foods are industrial formulations made with ingredients extracted from foods or synthesized in labs. Examples include chips, soft drinks, instant noodles, chicken nuggets, and frozen pizza.
- The analysis combined data from 23 studies involving over 290,000 people. It found that those who ate the most ultra-processed foods had a 39% higher risk of obesity, 29% higher risk of cardiovascular disease, 34% higher risk of stroke, 20% higher risk of depression, and 25% higher risk of early death compared to those who ate the least.
- While more research is needed, limiting ultra-processed foods and focusing on minimally processed whole foods may bring significant health benefits.
Source: Br J Nutr.
What are Ultra-Processed Foods?
Ultra-processed foods are formulated industrial products made largely or entirely from substances extracted from foods or synthesized in laboratories.
They typically contain little or no whole foods.
Examples of ultra-processed foods include:
- Savory snacks like chips, crackers, and cheesy puffs
- Sweet packaged snacks like cookies, cakes, and candy
- Sugary drinks like soda, energy drinks, and fruit yogurt drinks
- Ready-to-eat or heat meals like frozen pizza, microwaveable meals, chicken nuggets
- Breakfast cereals, instant noodles, pre-made sauces
- Distilled alcoholic drinks
These foods are highly manipulated and engineered to be convenient, affordable, highly palatable, and hyper-rewarding.
They are typically high in salt, refined carbs, unhealthy fats, and artificial flavors/colors while being low in fiber and nutrients.
Over the past several decades, ultra-processed foods have flooded food supplies and become staples in many people’s diets, displacing traditional whole foods.
Their low cost and convenience have made them popular. However, evidence increasingly links high ultra-processed food intake to poor health outcomes.
Review of 23 Studies on Ultra-Processed Foods and Health
To systematically analyze the relationship between ultra-processed food intake and health, researchers did a comprehensive review of all available observational studies through 2020.
The analysis included 23 high-quality studies involving over 290,000 adults from several countries including the US, France, Spain, and Brazil.
It included both cross-sectional studies that analyzed diet and health at a single point in time and prospective cohort studies that followed people’s diets and health outcomes for 3-19 years.
Across these diverse populations, studies consistently found that high ultra-processed food intake was linked to higher risks of chronic diseases and mortality.
Ultra-Processed Food Intake Linked to Obesity
Five cross-sectional studies with over 70,000 people found that those who ate the most ultra-processed foods had a 39% higher risk of being obese compared to those who ate the least.
Two large cohort studies with 29,000 participants also found a 23% higher risk of becoming overweight or obese over time in those with the highest ultra-processed food consumption.
Possible reasons for this strong link to weight gain include the high calorie density, fat, and sugar content in ultra-processed products.
Their addictive qualities also drive overeating.
And chemical exposures from packaging may play a role.
Higher Risks of Heart Disease and Stroke
Three major cohort studies with over 180,000 people followed for 5-20 years found that those who ate the most ultra-processed foods had a 29% higher risk of developing cardiovascular disease and a 34% higher risk of cerebrovascular disease (stroke) compared to those who ate the least.
Beyond just weight gain, this may be due to negative effects on blood pressure, cholesterol, triglycerides, and inflammation.
Toxins formed during processing may also play a role.
Increased Risk of Depression
Two cohort studies with approximately 30,000 adults found a 20% higher risk of developing depression among those with the highest ultra-processed food intake compared to the lowest intake group, after adjusting for confounders.
Reasons for this link are still unclear but may involve effects on the gut microbiome and metabolic pathways affecting mood.
More research is needed.
Higher Risk of Early Death
Five large cohort studies with over 110,000 people found that those who ate the greatest amounts of ultra-processed foods had a 25% higher risk of early death compared to those who ate the least.
This increased mortality risk may be due to the higher risks of obesity, heart disease, stroke, and depression linked to ultra-processed food consumption. However, more studies are needed to confirm this association.
Takeaway: Ultraprocessed Foods & Health Risks
This meta-analysis had some limitations including differences in how studies assessed ultra-processed food intake.
Also, few studies controlled for other unhealthy lifestyle factors that tend to correlate with poor diets.
However, it represents the most comprehensive analysis to date on this topic.
The consistent observations across diverse populations strengthen the conclusions that high ultra-processed food intake appears linked to higher risks of obesity, cardiovascular disease, cerebrovascular disease, depression, and early death.
While further research is still needed, limiting consumption of mass-produced snacks, sweets, ready meals and other ultra-processed products in favor of fresh, minimally processed whole foods may bring significant health benefits.
Moderating ultra-processed food intake wherever possible, along with an overall high-quality diet and active lifestyle, is advised for optimal health.
References
- Study: Consumption of ultra-processed foods and health status: a systematic review and meta-analysis
- Authors: G. Pagliai et al. (2021)
