New study conducted in Brazil indicate connection between artificial sweeteners and faster cognitive decline, especially among diabetes under the age of 60.
People who consumed the highest amounts of certain artificial sweeteners, equivalent to one can of a diet drink per day, showed a significant decline in their ability to recall words compared to people who consumed the lowest amounts.
People who consumed the highest amounts of low or zero calorie sweeteners showed a 62 percent faster overall cognitive decline than those who consumed the least.
This is equivalent to 1.6 years of brain aging. The study was published in the journal Neurology and was conducted over eight years.
The researchers analyzed the diet and cognitive abilities of nearly 13,000 people aged 35 to 75. The average age of participants was 52.
Dietary information was collected at the beginning of the study using detailed questionnaires, and a series of cognitive tests was conducted three times throughout the period. The tests examined verbal fluency, working memory, word recall ability, and information processing speed.
In previous studies, higher consumption of ultra processed foods was linked to faster cognitive decline, and many of these foods contain artificial sweeteners.
The heaviest consumers of artificial sweeteners in this study consumed an average of 191 milligrams of artificial sweeteners per day, an amount equivalent to about half a teaspoon.
One can of a diet drink sweetened with aspartame contains between 200 and 300 milligrams, according to the World Health Organization.
The medium group consumed an average of 66 milligrams per day, while the lowest group consumed only 20 milligrams per day.
The results were dramatic. After adjusting for factors such as age, sex, high blood pressure, and cardiovascular disease, researchers found that people who consumed the most sweeteners showed a 62 percent faster decline in thinking and memory compared to the lowest group, equivalent to about 1.6 additional years of aging.
People in the highest sweetener consumption group experienced cognitive aging at a much faster rate than expected, which may increase the risk of earlier impairment later in life.
The medium group showed a 35 percent faster decline than the lowest group, equivalent to about 1.3 additional years of aging.
What Happens to the Brain
The researchers examined few types of sweeteners: aspartame, acesulfame saccharin, sorbitol, erythritol, xylitol and tagatose.
Interestingly, tagatose was the only sweetener not associated with cognitive decline.
Tagatose is a monosaccharide, or simple sugar, similar to fructose and glucose.
Because it occurs naturally in very few plants, it is considered a rare sugar, but it can be produced using complex chemical or enzymatic processes.
One of the most surprising findings was that the association between artificial sweeteners and cognitive decline was significant only among participants under the age of 60.
Exposure during midlife may be particularly harmful, since midlife is a critical period for determining the trajectory of brain health.
Cognitive decline and dementia develop decades before symptoms become noticeable, so exposures during midlife may accelerate these processes and have long term consequences.
Among diabetes participants they saw faster cognitive decline was stronger than without.
Diabetes is already a strong risk factor for cognitive decline associated with Alzheimer disease and vascular dementia, which likely makes the brain more vulnerable to harmful exposures.
Animal studies suggest that aspartame may lead to neuroinflammation, while erythritol and sorbitol may alter the gut microbiome and damage the blood brain barrier.
These mechanisms may make the brain more vulnerable over time, especially when exposure begins in midlife.
Artificial sweeteners have been in use since the early 20th century, when saccharin was the first artificial sweetener sold to consumers.
Since the 1970s, the American FDA has approved six sugar substitutes for use in food.
Previous studies have shown certain benefits of using sugar substitutes, including reduced increases in blood sugar levels for people with diabetes and protection against tooth decay.
However, in recent years, studies have been published showing potential health risks of sugar substitutes, such as possible negative effects on the gut microbiome.
Low calorie sweeteners have been linked to a higher risk of certain health conditions, including heart attack and stroke, metabolic syndrome, obesity, migraine, and cancer.
Two international bodies of the World Health Organization declared aspartame as a possible carcinogen, although consumption guidelines remain unchanged.
Recent studies have shown that consumption of erythritol and xylitol may increase the risk of blood clots that can lead to heart attack or stroke.
Association but Not Causation
The study adds to the understanding of how diet may affect long term brain health.
Although the finding that high consumption is associated with faster cognitive decline is thought provoking, it is essential to emphasize that this study shows an association, not causation.
It does not prove that sweeteners are responsible for cognitive decline.
Other lifestyle factors associated with high sweetener consumption may be involved.
Because the study was observational, more controlled research would be helpful to get closer to determining causality.
In addition, research is needed on the biological mechanisms and how these specific sweeteners may affect brain cells or vascular health.
Although further research is needed before making firm recommendations, it would be reasonable for people to reduce their consumption as much as possible and ideally avoid these products altogether.