The power of food to change your child’s brain
With great power comes great responsibility.
Image by catalyststuff at Magnific.com
Eating a poor diet causes weight gain over time - no surprise there. More surprising is that before there is any noticeable change to the waistline there are noticeable changes to the structure of the BRAIN, and it happens in childhood. The effects of these changes go far beyond body shape, and this hot area of science is uncovering more all the time…
A recent study led by APC Microbiome Ireland [1], found that a high fat, sugar and salt diet (HFSS) early in life changes mice brains and how they go on to manage appetite and food choices into adulthood. While this is a study in mice, it’s a significant step forward in understanding. Let’s look at the science…
We now know that appetite is largely controlled via the gut-brain axis, with the gut calling the shots. The brain is very well protected from our general circulation by the blood brain barrier, which is hugely selective about what chemicals are let in. However, gut hormones that indicate hunger and fullness are permitted entry through the barrier. Ghrelin is the ‘hunger hormone’, and leptin and insulin signal when our hunger is satiated. Other gut hormones send messages to the brain via the vagus nerve with real-time data to control appetite and energy levels.
HFSS foods appear to disrupt the brain’s appetite centre, the hypothalamus, overriding this natural hunger and satiety signalling. Mice fed a HFSS diet during their juvenile development stages had a reduced ability to regulate consumption of those foods into adulthood. Even after their diet was ‘corrected’ and their weight returned to normal levels, when exposed to a choice of healthy or unhealthy food, they were less able to control their intake of the unhealthy foods than mice without early exposure to HFSS food. This will resonate with anyone who has faced lifelong struggles with their weight and painful yo-yo dieting.
This study also offered a beacon of hope: a specific strain of probiotic, healthy gut bacteria, and prebiotic fibre helped to reverse this damage. I will look out for more on this with some anticipation.
But food-related brain changes are not limited to the control of body weight and metabolism. Food choice appears to affect attention and mental health.
A brand-new study [2], has identified that even a modest increase in ultra-processed junk foods (UPFs) is associated with a clear and measurable drop in attention in adults. Even the equivalent of adding one packet of crisps into an otherwise healthy diet, was enough to see a measurable effect.
This study was designed to explore the effect of diet on dementia, not children’s attention and focus, but the findings are scary. For parents of children with conditions such as ADHD, further challenges with attention and focus are entirely unwelcome.
This study specifically links attention changes to those industrialised chemical ingredients and processes rather than high fat, salt and sugar content. The link between attention and UPF was found regardless of whether the rest of the diet was healthy or unhealthy.
Unhealthy diet patterns have also been correlated with the development of a smaller left hippocampus in humans [3] – an area of the brain associated with learning, memory and mood regulation. Reduced left hippocampus size is specifically implicated in both depression and dementia.
New science has also uncovered a link between our gut microbiome (and therefore our diets) and our ability to manage stress and maintain healthy circadian rhythms.
More amazing research coming out of the APC Microbiome research centre shows how the health of our gut shapes brain function and behaviour in relation to stress and our body’s circadian rhythms [4]. We have evolved with an internal body clock, the circadian rhythm, which helps us sleep at night and wake up in the morning. It helps govern alertness, metabolism and digestion through hormonal control. This system heavily overlaps with the stress pathway, bearing in mind that well controlled levels of stress hormones drive much of behaviour, like waking up in the morning, detecting hunger and seeking food.
This was another study conducted in mice, not humans, but they found that the gut microbiome changes in a rhythm throughout the day, affecting the brain’s circadian and corresponding stress responses. They identified that the gut was influencing the brain, rather than the other way round, by assessing differences between mice with a healthy gut microbiome and mice with a depleted microbiome.
This is a complex study, but it is furthering the scientific understanding of just how important the gut microbiome, and therefore diet, is in mediating brain and hormonal changes that affect so many aspects of behaviour.
So, what do we do with all these disturbing discoveries? Despite sharing these horror stories with you, I got into nutrition because I find it a very hopeful subject – we have the power to improve our lives with food.
All the negative impacts on metabolic health, attention, depression and stress are in what the boffins call a ‘dose-dependent relationship’ with food. This means that the more healthy choices and the fewer unhealthy ones we can make, the better. I do not aim for perfection, or anything close.
My main approach with my children’s eating is ‘crowding out’ the less healthy food with healthy food, not eliminating it altogether. A snack-plate with fruit, nuts, wholegrain toast and a few sweets is better than the whole bag of sweets. A few chocolate buttons on Greek yogurt and strawberries is better than just a bag of buttons. Keeping real, whole foods as a substantially bigger percentage of their diet is my happy medium.
If you’d like to discuss your child’s nutrition with me, get in touch using the contact details at www.cathlinbeaumont.com
References
[1] Cuesta-Marti, C., Ponce-España, E., Uhlig, F. et al.Bifidobacterium longum and prebiotic interventions restore early-life high-fat/high-sugar diet-induced alterations in feeding behavior in adult mice. Nat Commun17, 1653 (2026). https://doi.org/10.1038/s41467-026-68968-2
[2] Cardoso BR, Steele EM, Brayner B, et al. Ultra-processed food intake, cognitive function, and dementia risk: A cross-sectional study of middle-aged and older Australian adults. Alzheimer's Dement. 2026;18:e70335. https://doi.org/10.1002/dad2.70335
[3] Jacka, F.N., Cherbuin, N., Anstey, K.J. et al. Western diet is associated with a smaller hippocampus: a longitudinal investigation. BMC Med13, 215 (2015). https://doi.org/10.1186/s12916-015-0461-x
[4] Tofani, G.S., Leigh, S.J., Gheorghe, C.E., Bastiaanssen, T.F., Wilmes, L., Sen, P., Clarke, G. and Cryan, J.F., 2025. Gut microbiota regulates stress responsivity via the circadian system. Cell metabolism, 37(1), pp.138-153.