The study, published in the journal Age and Ageing, examined the association between dietary fibre and cognitive decline in older adults and assessed the influence of genetic, lifestyle and clinical characteristics in this association.
Researchers studied the diet, cognitive state and other health parameters of 848 volunteers every three years for fifteen years. The participants were living in Chianti in the Tuscany region of Italy and were aged over 65, with an average age of 74 (56% were women).
Fibre intake was not associated with cognitive decline during the 15-years follow-up. However, in participants with APOE4, the gene that carries an elevated risk for disease development, a daily increase in 5g of fibre was significantly associated with a 30% lower risk for cognitive decline.
“This shows that an acceptable increase in the daily fibre intake can have an impact,” said Professor Cristina Andrés-Lacueva from the Institute on Nutrition and Food Safety Research at the University of Barcelona (INSA-UB) who led the study.
“These results show that old people with the ApoE ε4 haplotype could benefit from a higher fibre intake, and it opens the door to study the interaction between the ApoE genotype and consumption, which has not been characterized to date,” added the UB-INSA researcher Andrea Unión, first author of the study.
No association was observed in participants with APOE2 and APOE3 variants. However, according to Stanford Medicine researchers, the most common variant, APOE3, neither increases nor decreases one's chance for Alzheimer's, while APOE2 is protective. According to Alzheimer’s Research UK, meanwhile, people who inherit one copy of APOE4 (roughly one in four people) are around three times more likely to develop Alzheimer’s disease. About one in fifty people inherit two copies of APOE4 – one from each parent. They may be more than eight times more likely to develop Alzheimer’s. However, due to other contributing factors, such as age and lifestyle, people who inherit APOE4 still may never develop the disease.
“Cognitive decline, precursor of the development of dementia in old people, is currently a public health problem without treatment,” noted Tomàs Meroño. “This is why it is crucial to detect modifiable risk factors that allow us to develop prevention strategies, among which the diet has proved to be one of the most efficient. Evidence shows that healthy diets, characterized by a high consumption of fibre-rich foods, have a positive impact on cognition, but the specific role of fibre intake plays on the cognitive function is still unknown.”
The study was unable to distinguish the type of fibre that was being consumed by the participants, he told FoodNavigator. Neither was it able to separate the effect of fibre from that the Mediterranean diet, which itself is often linked with improved cognitive health and decreased risk of dementia.
“Dietary fibre is highly hetereogenous and we could not differentiate between soluble and insoluble fibre from our dietary analyses,” he told us. “However, regarding dietary sources of total fibre intake, major contributors in our study were fruits and cereals (43 and 35%, respectively), followed by vegetables (16%), legumes (5%) and nuts (0.4%). The mean intake of dietary fibre was 20 +- 6 g/day.” By way of comparison, most countries recommend a daily intake of dietary fibre of 25-35 g for adults. Fibre intake in most European countries is below the recommended levels. “We cannot be confident in saying that the fibre effect is independent of the overall dietary pattern,” he added.
Apolipoprotein E gene variants shape the association between dietary fibre intake and cognitive decline risk in community-dwelling older adults
Age and Ageing