Eating a diverse range of plants helps our gut bacteria (and our brains) to thrive. Photo / DepostiPhotos
What we eat can have a significant impact on our brain – here are the six best foods, according to dietitians and neuroscientists.
You’ve heard before that the Mediterranean diet is an all-round superhero for our health – and particularly our brains – but now a new study shines a light on exactly why.
The diet’s brain-boosting benefits may be a result of how it changes the balance of bacteria in the gut, according to the study by researchers at Tulane University in the United States. Rats fed the Med diet’s mix of olive oil, fish and fibre showed increases in four beneficial types of gut bacteria, compared to rats eating a high-fat diet.
These bacterial changes were linked to improvements in memory tasks, learning and ‘cognitive flexibility’: the ability to adapt to new information. The study also found some slight improvements in the rat’s spatial memory.
“Spatial memory is important because getting lost is one of the first signs of Alzheimer’s and we know from large population studies that people who eat a Med diet have a reduced incidence of dementia,” says Dr Faye Begeti, a neurology doctor and neuroscientist at Oxford University Hospitals.
More research in humans is needed but its findings add to increasingly compelling evidence of the importance of the complex links between the gut and the brain.
So how can we cultivate a healthy gut that will also help to boost our brain’s cognitive skills? Here are seven things to try, based on the latest research and what the experts advise.
Granny was right to emphasise the importance of eating up your dark, leafy greens.
In a US study of men and women aged between 58 and 99 years old, eating one to two servings of green leafy vegetables daily was associated with slower cognitive decline, with the group who ate their green veg having brains that were cognitively 11 years younger than those who didn’t eat regular greens. The greens that were eaten included spinach, kale, collards and lettuce.
The diversity of plant foods also matters for our gut/brain health. “The more types of fibre and polyphenols we consume, the better our gut microbes can thrive – this is why eating a variety of plant-based foods (rather than just focusing on one or two specific ones) is so important,” says Dr Caitlin Hall, a neuroscientist and dietitian.
In a study by King’s College London last year, researchers found that adults aged over 60 who were given a prebiotic supplement rich in inulin performed better in memory tests used to capture early signs of Alzheimer’s.
We can’t digest prebiotic fibres ourselves, but they feed our gut microbes, helping them to produce beneficial short-chain fatty acids.
“In the UK we’re missing about 35 per cent of the fibre we should be eating, and prebiotic fibres are particularly useful for our guts. In studies, we tend to use supplements as it’s easier to isolate that ingredient, but ideally, we want to look at a food-first approach. Inulin, for example, is found in asparagus, leeks, onions and garlic,” says Dr Emily Leeming, a dietitian, scientist and author of Genius Gut: The Life-Changing Science of Eating for your Second Brain.
Legumes such as chickpeas, lentils and beans are also a good source of brain-boosting prebiotics.
Two interesting studies have shown that drinking kefir, a fermented milk, is beneficial for brain health.
In the first study, adults who drank the milk for four weeks improved their “relational memory”. “This is the type of memory that helps you to remember where your keys are and people’s faces and names,” Leeming explains.
In the second study, researchers did brain scans on women who drank kefir twice daily for four weeks and then showed them negative and positive images.
“The researchers were looking at their emotional reactions, and they discovered that those drinking kefir had less of an emotional reaction to the negative images, which suggests that the fermented drink was making them more emotionally resilient. Mouse studies have also shown that consuming kefir grains seems to boost the neurotransmitters involved in reducing stress and anxiety,” Leeming explains.
Kefir is readily available to buy, although Leeming suggests making it yourself, as not all commercial brands contain traditional grains. “You can easily buy the kefir grains, add them to milk, leave them for a day or so, and then strain,” she says. You can try kefir as a drink, have it with cereal, add it to your yoghurt, or use it to make a creamy, tangy salad dressing.
Berries are rich in polyphenols and flavonoids are good for focus, fatigue and your brain’s processing speed, studies have shown.
A berry smoothie at 9am could help your brain stay sharp throughout the day, one study suggests. In the research, one group had a smoothie with berries blended in, and the other had a placebo. By 3pm, the placebo group were experiencing the traditional afternoon energy slump, but the group who drank the berry smoothie maintained their energy, focus and mental performance.
Another study analysed how polyphenols impact cognition and found that they improved “visual information processing speed” which is how fast your brain can take in and interpret what your eyes see.
Polyphenols are also found in dark chocolate, extra virgin olive oil, coffee, tea and many fruits and vegetables.
Our brain is our most energy-hungry organ in our body, consuming 20% of our energy daily, so it’s important not to skip a meal.
“Multiple studies have shown that adults who skip breakfast tend to have a lower mood and eat less fibre, which is already a problem. Even having something small is going to be a supporting start to our day, and good for our microbes,” says Dr Leeming.
Aim for a balance of protein and healthy fats for stable blood sugar.
Research shows eating fish supports brain structure and reduces inflammation, thanks to DHA, a type of omega-3 found in high levels in fish. Yet in the UK we have low levels of omega-3s.
“Omega-3s have a direct influence on the cell membranes of our brains, but they’re also recognised as a potential prebiotic, having a similar effect to fibre in terms of feeding our gut microbes,” says Dr Leeming.
Omega-3 is also found in walnuts and chia seeds, but this form is harder for our bodies to absorb than the DHA found in fish.
Non-vegetarians should aim for two portions of fish a week and if you’re a vegetarian, look into an omega-3 supplement.
Your gut and brain health isn’t just about what’s on your plate. “Because the gut and brain are so interconnected via the gut-brain axis, stress can also alter the gut microbiome, reducing the production of short-chain fatty acids (SCFAs), which help protect against inflammation in the brain. Managing stress through movement and mindfulness doesn’t just improve digestion – it actively supports memory, focus, and long-term brain health,” says Dr Hall.
So find stress relief that works for you. That might be breathwork, yoga or even just regular five-minute screen breaks.
Exercise is also a proven stress reliever. Strength training boosts short-chain fatty acid production in your gut, and lower-impact movements such as yoga, Pilates and walking help alleviate stress and encourage problem-solving.
A good night’s sleep is also vital for stress management and all-round health. “Your gut microbiome follows a daily rhythm, just like you do, and poor sleep can throw it off – leading to poor cognition and brain fog,” says Dr Hall.
She recommends getting natural light within an hour of waking and ensuring a proper wind-down routine.