Effects of Nutrition on Cognitive Function in Adults with or without Cognitive Impairment: A Systematic Review of Randomized Controlled Clinical Trials

Abstract

New dietary approaches for the prevention of cognitive impairment are being investigated. However, evidence from dietary interventions is mainly from food and nutrient supplement interventions, with inconsistent results and high heterogeneity between trials. We conducted a comprehensive systematic search of randomized controlled trials (RCTs) published in MEDLINE-PubMed, from January 2018 to July 2021, investigating the impact of dietary counseling, as well as food-based and dietary supplement interventions on cognitive function in adults with or without cognitive impairment. Based on the search strategy, 197 eligible publications were used for data abstraction. Finally, 61 articles were included in the analysis. There was reasonable evidence that dietary patterns, as well as food and dietary supplements improved cognitive domains or measures of brain integrity. The Mediterranean diet showed promising results, whereas the role of the DASH diet was not clear. Healthy food consumption improved cognitive function, although the quality of these studies was relatively low. The role of dietary supplements was mixed, with strong evidence of the benefits of polyphenols and combinations of nutrients, but with low evidence for PUFAs, vitamin D, specific protein, amino acids, and other types of supplements. Further well-designed RCTs are needed to guide the development of dietary approaches for the prevention of cognitive impairment.

Vitamin D Status and Parkinson’s Disease

“…According to several investigations [ 49 , 50 , 51 ], vitamin D levels influence cognitive function [ 49 , 50 , 51 ]; however, to date, the impact of vitamin D on cognition in PD has been poorly explored. Underlying mechanisms include the influence of vitamin D on brain acetylcholine levels and the clearance of amyloid beta, both implicated in AD [ 51 ].…”

“…According to several investigations [ 49 , 50 , 51 ], vitamin D levels influence cognitive function [ 49 , 50 , 51 ]; however, to date, the impact of vitamin D on cognition in PD has been poorly explored. Underlying mechanisms include the influence of vitamin D on brain acetylcholine levels and the clearance of amyloid beta, both implicated in AD [ 51 ]. In CNS, cortical neurons and structures notably involved in processes of learning and memory, such as the hippocampus, are particularly rich in VDR and 24-hydroxylases, the enzyme responsible for catabolism of calcitriol [ 52 ].…”

The Potential Role of Gut Microbiota in Alzheimer’s Disease: From Diagnosis to Treatment

“…Diet is a rapid and direct way of modifying the gut microbiota composition and function, reducing inflammation, and helping in eubiosis maintenance [ 123 , 164 , 165 ]. Given the evidence of association between neuropsychiatric conditions and gut microbiota dysregulation, it is worth speculating that dietary interventions could represent effective candidates for preventing and delaying the pathogenesis and progression of AD [ 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 , 179 , 180 , 181 , 182 , 183 , 184 , 185 , 186 ] ( Table 2 ). Here, we present some of the most promising dietary therapies proposed in the literature, with a particular focus on Mediterranean and ketogenic diets.…”

“…So far, besides promising results for Medi diet, the role of DASH diet in AD prevention and therapy is still unveiled [ 168 ], and more studies should be carried out before driving any conclusion. Moreover, standard tools for assessing food intake and cognitive decline are needed to state which dietary pattern might be the most effective in protecting and delaying the onset of neurodegenerative diseases, and to ensure reproducibility [ 166 ].…”

Marital Age, Cigarette Exposure, Physical Activity, Sleep Duration, and Prenatal Depression

“…Observational studies indicate that a variety of nutritional components may be associated with depression. These include associations with nutrient deficiency, with vitamin D and omega-3 fatty acids being the most frequently studied [26]. Plasma riboflavin or vitamin B2 levels were significantly lower in the postpartum depression group (13.9%) than in the asymptomatic group [25].…”