by Recent research has found a link between a higher intake of certain dietary nutrients and a lower risk of cognitive impairment in older adults. This large-scale study, involving thousands of participants, suggests that what we eat may play a critical role in maintaining our cognitive health as we age. The results were published in the journal Alzheimer’s & Dementia.
The impetus behind the study arose from growing concerns about dementia and cognitive decline, particularly as the world’s population ages. Dementia, including the most common form, Alzheimer’s disease, poses significant challenges not only to those affected but also to healthcare systems and healthcare societies in general. Recognizing that approximately one-third of Alzheimer’s disease cases may be linked to modifiable risk factors, the researchers focused on diet as a critical, modifiable factor.
As explained by Tiarnán Keenan, lead author of the study and Stadtman Tenure Investigator at the National Eye Institute: “In Western medicine, we are beginning to rediscover the enormous impact that diet can have on health: ‘I food can be excellent medicine. got ; in food, a bad cure can be found’ (Hippocrates, De Alimento). In fact, nutrition is a vital part of public health: ‘La destinée des nations depends on the manière dont elles se nourrissent’ (Brillat-Savarin, Physiologie du Goût). This may be particularly true for chronic diseases of ageing, such as dementia and age-related macular degeneration.”
“We have previously shown very strong links between a healthy diet and a reduction in the risk of age-related macular degeneration. The next natural step was to examine the same question regarding cognitive impairment and dementia, given that we had two excellent data sets with the unusual combination of comprehensive testing of cognitive function and detailed nutritional information in a large population of participants. studies for at least five years.”
The study analyzed data from two landmark research projects conducted in the United States (called the Age-Related Eye Disease Studies). The first project enrolled 4,757 participants aged 55 to 80, while the second involved 4,203 people aged 50 to 85. Initially these participants were part of research focusing on eye health but detailed cognitive function testing was also carried out. Researchers looked closely at the participants’ diets, using comprehensive questionnaires to assess the intake of various nutrients. They then explored how these dietary patterns related to participants’ cognitive ability.
The researchers found that certain nutrients were linked to a lower risk of cognitive impairment. These included several vitamins, minerals, and specific types of fats found in fish (DHA and EPA). On the flip side, some dietary components appeared to increase the risk. In particular, diets high in saturated fats and foods that cause high blood sugar levels (high glycemic index/load) were associated with a greater risk of cognitive decline.
“The main message is that there is a very strong association between a diet of nutrient-rich foods and a reduced risk of cognitive impairment and therefore likely dementia,” Keenan told PsyPost. “Nutrients with these protective associations include vitamins (eg, A, B, C, and E), minerals (eg, copper, magnesium, selenium, and zinc), carotenoids (eg ., lutein, zeaxanthin, beta-carotene, and lycopene. ), lipids (eg, omega-3 fatty acids), and fiber.”
“In contrast, a diet of foods with high levels of specific fats (eg, monounsaturated and saturated fatty acids) and diets with a high glycemic index are strongly associated with an increased risk of cognitive impairment.”
“Overall, this supports the idea that a Mediterranean-like dietary pattern is strongly associated with a reduced risk of cognitive impairment and dementia,” Keenan said. “Important aspects of the Mediterranean dietary pattern include frequent consumption of plant-based foods and infrequent consumption of saturated/monounsaturated fats (eg, red meat) or foods with a high glycemic index (eg, refined sugars). These nutrients may maximize cognitive reserve against impairment and dementia and may be suitable candidates for randomized trials.”
Although certain dietary choices appeared to affect the risk of cognitive impairment at one point in time, they did not significantly change the rate of cognitive decline over time. But this lack of longitudinal relationship may be the result of methodological limitations.
“Despite the significant findings regarding the risk of cognitive impairment in many cases, we did not observe slower levels of decline in cognitive function for any of these nutrients,” explained Keenan. “The distinction between significant results for cross-sectional but not longitudinal differences may be surprising. However, this is likely due to insufficient power to detect longitudinal differences or true discrimination.”
Although the study provides valuable insights, it is important to note that the results are based on observational data, which means that they can show associations but not cause and effect relationships.
“The pitfalls of this study include the possibility of residual confounding, ie. that the observed associations may be partially related to factors other than the dietary intake of each nutrient itself,” said Keenan. “However, we took every possible step to minimize confounding (eg, by adjusting for total caloric intake, body mass index, smoking status, and other factors). Likewise, since these are observational data, it is not possible to know with certainty that nutrient intake is causally linked to altered risk of cognitive impairment. Ultimately, the highest level of evidence would come from a randomized controlled trial.”
However, the study provides an important step forward in our understanding of the role of diet in cognitive health. It highlights the potential of certain nutrients for maintaining cognitive function and highlights the need for more research in this critical area of public health.
The study, “Dietary nutrient intake and cognitive function in Age-Related Eye Disease Studies 1 and 2,” was authored by Tiarnan DL Keenan, Elvira Agrón, Emily Y. Chew, and the AREDS and AREDS2 Research Groups.
