Study Findings: Artificial Sweeteners and Cognitive Decline

A study published in the journal Neurology indicates a link between higher levels of artificial sweetener consumption and a faster rate of decline in thinking and memory skills. Researchers followed 12,772 adults, with an average age of 52, over approximately eight years. Participants provided dietary information and underwent cognitive tests at the beginning, middle, and end of the study period.

The study divided participants into three groups based on their daily artificial sweetener intake: a lowest group (average 20 milligrams), a highest group (average 191 milligrams, comparable to a can of diet soda), and a middle group.

Key Results

Individuals in the highest consumption group experienced a 62% faster decline in thinking and memory skills compared to the lowest consumption group. This effect was estimated to be equivalent to 1.6 years of aging. The middle group showed a 35% faster decline, equivalent to about 1.3 years of aging. A faster rate of decline in memory and cognition was also observed in participants with diabetes.

The study specifically linked six artificial sweeteners to cognitive decline:

Aspartame (found in diet drinks, dairy products)
Saccharin (e.g., Sweet 'N Low)
Acesulfame-K (found in beverages, candies, baked goods, e.g., Equal)
Erythritol (used in keto-friendly products, drinks, e.g., Truvia)
Sorbitol (often used in sweets)
Xylitol (found in gums, oral care items)

The researchers concluded that these findings “suggest the possibility of long-term harm” to cognitive function from the use of artificial sweeteners and sugar alcohols.

Expert Perspectives

Experts caution that this was an observational study, which identifies a link but does not prove causation. Factors such as physical activity, sleep, and overall diet quality, which can influence brain health, were not examined in this study.

Possible Mechanisms

Possible mechanisms for the observed link include:

Neuro-inflammation and Neuro-degeneration: Artificial sweeteners may trigger processes like neuro-inflammation, neuro-degeneration, or disruption of the gut–brain axis, based on animal models. Aspartame, for instance, has been suggested to cause brain inflammation.
Gut Microbiota Alteration: Sugar alcohols like erythritol and sorbitol may alter gut microbiota and compromise the blood–brain barrier.
Insufficient Brain Fuel: Artificial sweeteners do not provide glucose, which is essential for energy and normal brain function. A diet heavy in these sweeteners might deprive the brain of necessary fuel, potentially accelerating cognitive issues.

Diabetes and Cognitive Decline

The study indicated a stronger link between artificial sweetener use and cognitive decline in individuals with diabetes. This may be due to several factors:

Pre-existing Risk: People with diabetes are already at a higher risk for cognitive changes due to high blood sugar and insulin resistance affecting blood vessels and the brain.
Increased Exposure: Individuals with diabetes may consume artificial sweeteners more frequently as a sugar substitute, leading to higher overall exposure.
Metabolic Impact: Certain sweeteners, such as aspartame and acesulfame-K, may affect glucose metabolism and gut microbiota, potentially worsening metabolic control.
Brain Confusion: The brains of diabetic patients, which struggle to process natural sugars, might mistakenly attempt to break down artificial sugars, impacting cognition over time.

Recommendations

While experts do not universally advise completely avoiding artificial sweeteners, they suggest limiting consumption. It is recommended to reduce intake as much as possible, ideally avoiding daily use. Natural sugars from fruits are proposed as a healthier alternative.

To support cognitive health, a focus on whole foods, physical activity, and adequate sleep is recommended, alongside reduced artificial sweetener use.

Occasional use is generally not considered a concern for most individuals.