A lifelong combination of low-fat diet plus calorie restriction was found to prevent the activation of specialised immune cells found in the brain and spinal cord known as microglia during ageing, said the team writing in Frontiers in Molecular Neuroscience.
When activated microglia control inflammatory responses in the brain. Higher levels of activated microglia are part of the ageing-related inflammatory process, explained the researchers from the University of Groningen.
At age 24 months, both high-fat diet (HFD) and low-fat diet (LFD) mice showed increased levels of microglia activation, compared with younger mice. However, mice that had followed a LFD diet since weaning, which restricted calorie intake by 40%, showed no such increase, said the authors.
Restriction of calories in HFD mice had little effect, indicating that it is the combination of LFD and calorie restriction is critical to prevent the ageing-related inflammatory process.
"Ageing-induced inflammatory activation of microglia could only be prevented when mice were fed a low-fat diet in combination with limited caloric intake," commented lead author of the study Professor Bart Eggen, from the University Medical Centre Groningen. "A low-fat diet per se was not sufficient to prevent these changes."
"Nevertheless, these data do show that, in mice, the fat content of a diet is an important parameter in terms of the detrimental effects of aging on the brain, as well as caloric intake," he added.
The researchers also found that exercise was significantly less effective in preventing ageing-related microglial activation than caloric restriction. This was the case in both LFD and HFD mice. However, the researchers emphasised that human studies have shown a protective effect of exercise against cognitive decline.
Previous research has shown benefits of caloric restriction in slowing the ageing process, mitigating cognitive decline, reducing oxidative damage in the brain and helping to maintain the process of neurotransmission.
The findings of this study help may shed light on a possible mechanism underlying some of these effects, suggested the researchers.
“In conclusion, LFD resulted in reduced activation of microglia, which might be an underlying mechanism for the protective role of caloric restriction during ageing-associated decline.”
Source: Frontiers in Molecular Neuroscience
Published online 12 March 2018, doi: 10.3389/fnmol.2018.00065
“Low-Fat Diet With Caloric Restriction Reduces White Matter Microglia Activation During Aging”
Authors: Zhuoran Yin, Bart J.L. Eggen et al