A recent study from the American Journal of Public Health found that a diet high in ultraprocessed foods like processed meats and pre-packaged snacks shows a significant increase in risk for developing dementia or cognitive impairment.
The study, which included more than 5,300 adults over 50 and took into account other risk factors, noted that those who ate the highest amount of ultra-processed food every day had a 58% increased risk of developing dementia and a 46% increased risk for cognitive impairment compared to people who ate the lowest amount of daily ultra-processed food. Participants who consumed minimally processed foods like whole grains, fruits, and veggies had lower risks for cognitive decline overall. Study authors concluded that even moderate consumption of processed foods carries a risk for cognitive impairment.
Another recent meta-study concluded that regularly consuming processed meat, sugary drinks, and trans fats, even in small amounts, can lead to major health conditions like type 2 diabetes, heart disease, and colorectal cancer.
“This study found evidence — under a conservative interpretation of the available data — to justify robust efforts and policies to promote the reduced consumption of processed meat, sugar-sweetened beverages (SSBs) and trans fatty acids (TFAs), particularly industrially produced TFAs, to reduce the risk of chronic diseases,” the study authors wrote. “Our observation that the greatest increases in disease risk occurred at low intake levels suggests that even lower levels of habitual consumption of these dietary risk factors are not safe.”
Four Always, Four to Avoid
In our research of the centenarians from the blue zones, we distilled more than 150 dietary surveys of the world’s longest-lived people to discover the secrets of a longevity diet. They eat beans regularly, consume very little meat (or none at all in cases of Loma Linda’s Seventh-Day Adventists), limit dairy products, and eat a plant-based diet highlighted with locally grown, in-season produce. Not because they were trying to eat a certain way, but because they ate what was available throughout the year. Although the blue zones regions were in very different parts of the world, they had similar eating patterns and lifestyles. We call these Four Always and Four to Avoid foods that the blue zones all had in common, and help to simplify the Blue Zones food guidelines: Favor beans, greens, root vegetables, fruit, whole grains, nuts, and seeds. And, in alignment with these recent studies, avoid processed meats, salty snacks, sugar-sweetened beverages, and packaged sweets.
Four Always and Four to Avoid foods that the blue zones all had in common and help to simplify the Blue Zones food guidelines: Favor beans, greens, root vegetables, fruit, whole grains, nuts, and seeds. Share on XBreaking Down the Numbers
The meta-study from the Institute for Health Metrics and Evaluation (IHME), published in 2025 in the journal Nature Medicine, examined more than 70 previously published studies — collectively involving more than 6.5 million participants – and accounted for variances in quality and findings between each. The meta-study employed Burden of Proof methodology to provide a more precise, rigorous, and conservative risk assessment.
Researchers found that daily consumption of up to 2 ounces of processed meat (defined as any meat preserved by smoking, curing, salting, or addition of chemical preservatives) elevates the risk of type 2 diabetes by 11% and colorectal cancer by 7%, compared to diets without these foods. Health risks appeared to increase steadily with higher intake; the researchers did not find a portion size small enough to be considered safe.
Sugary beverages — including sodas, energy drinks, and fruit drinks, but excluding 100% fruit and vegetable juices — can lead to an 8% average increase in type 2 diabetes risk and at least a 2% increase in heart disease risk. The study findings were premised on drinking the equivalent of one 12-ounce soda daily.
Regular consumption of industrially produced trans fatty acids increased the risk of ischemic heart disease by 3% on average, according to the IHME study.
In analyzing these recent figures, it is worth noting that a separate 2021 study found that, worldwide, processed meats and sugary drinks posed the greatest health threats in North America, and caused the least harm in South Asia and sub-Saharan Africa, respectively.
Policy Implications and Future Studies
The more recent IHME study figures may not seem as dramatic as some might have suspected. In fact, the findings were awarded at most two stars on the Burden of Proof system’s five-star scale, with one star showing weak evidence of risk and five stars showing the strongest evidence.
But the researchers attributed the modest risk estimates to the high variance of findings included in the meta-study. “The balance of evidence still points to adverse health outcomes associated with these foods,” the researchers wrote. “Policymakers should continue advocating for measures that reduce intake of processed meat, SSBs and TFAs as these food items are consumed widely and are associated with diseases that are highly prevalent.”
They also noted that low star ratings, combined with high disease prevalence, strongly suggests the need for more research into the health effects of these foods.
“Policymakers should continue advocating for measures that reduce intake of processed meat, SSBs and TFAs as these food items are consumed widely and are associated with diseases that are highly prevalent.” -Researchers Share on X
