Link to depression, dementia
A recent report on UPF consumption and mental well-being among nearly 300,000 people across 70 countries showed that 53% of those who consumed UPFs several times a day were distressed or were struggling with their mental well-being, compared with 18% of those who rarely or never consumed UPFs.
Part of the Global Mind Project run by the nonprofit Sapien Labs in Arlington, Va., the report also showed that individuals with the highest rates of UPF consumption reported higher levels of confusion, slowed thinking, unwanted or obsessive thoughts, irritability, and feelings of sadness.
“There seems to be a much broader effect than just depression symptoms,” Tara Thiagarajan, PhD, founder and chief scientist of Sapien Labs and coauthor of the report, said in an interview.
The report, which has not been peer reviewed, comes on the heels of several other studies, including one from the Nurses Health Study II that showed that participants who consumed more than eight servings of UPFs daily had about a 50% higher depression risk, compared with those who consumed half that much.
“We found that UPFs in general, and artificial sweeteners and beverages in particular, were associated with increased risk,” said lead investigator Andrew T. Chan, MD, MPH, professor of medicine at Harvard Medical School and chief of the clinical and translational epidemiology unit, Massachusetts General Hospital, both in Boston.
“This was an interesting finding that correlates with data from animal studies that artificial sweeteners may trigger the transmission of particular signaling molecules in the brain that are important for mood,” he told this news organization.
Cognition may also be affected. An analysis of more than 72,000 people in the UK Biobank showed that those who consumed a high levels of UPFs were 50% more likely to develop dementia than those who consumed fewer processed foods. For every 10% increase in UPF consumption, the odds of developing any kind of dementia increased by 25%.
Another study of nearly 11,000 people showed that higher UPF consumption was associated with a significantly faster decline in executive and global cognitive function.
Epigenetic changes
While these and other studies suggest a link between UPF consumption and brain health, they are designed to demonstrate correlation. To date, no human study has proven that eating highly processed foods directly causes a decline in mental health or cognition.
Animal studies could provide that causal link. Earlier this year, researchers at Florida State University in Tallahassee reported learning and memory deficits in two groups of male mice that completed a maze test after being fed water mixed with aspartame for about 20% of their adult lives, compared with a group of mice that drank water only. Animals that ingested aspartame could finish the test, but it took them longer, and they needed help.
The amount of aspartame used in the study was just 7% and 15% of the FDA’s recommended maximum intake of aspartame (equivalent to two to four 8-ounce diet sodas daily).
Most intriguing was that offspring of the mice in the aspartame groups demonstrated the same levels of cognitive decline and anxiety as their fathers, even though they had never ingested the artificial sweetener. Researchers theorize that in addition to changes in brain gene expression, aspartame also caused epigenetic changes in germ cells.
“Epigenetic changes in germ cells due to environmental exposures are both good and bad,” lead investigator Pradeep G. Bhide, PhD, professor of developmental neuroscience and director of the Center for Brain Repair at FSU, told this news organization. “They are bad because the next generation is affected. But they’re good because as long as the exposure no longer occurs, 2 or 3 generations later, that’s gone.”
The mice, which lacked taste receptors for aspartame, were the same age and weight in all three groups. Because the only difference was exposure to the artificial sweetener, Dr. Bhide says it suggests a causal link.
“Extrapolation of data from well-controlled laboratory experiments in mice to humans is always risky,” Dr. Bhide said. “The extrapolations give us insights into what could happen rather than what will happen.”