Cognitive health: Nutrition for the brain
Most of us realise how important it is to have a nutritious, balanced diet if we want to stay in good physical and mental health. But a good diet can help keep our brains and cognitive functioning healthy too. In fact today there’s an increasing amount of evidence to support a substantial link between diet and cognitive processes, which can collectively be described as information processing (eg. thinking, memory, problem solving, reasoning, perception and so on).
Find out more about cognitive health and what it means by reading our guide.
What is the Mediterranean diet?
Nutritionists typically recommend following a balanced diet with plenty of fruit and vegetables and low in saturated fats to keep your brain healthy. But lately researchers have become interested in specific types of diet and how they may affect brain health. And one of these diets – which has been shown to be have positive effects on brain health – is the Mediterranean diet.
For example, research by the charity Age UK found that people who ate a Mediterranean-type diet experienced a lower loss of total brain volume over three years than those who followed the diet less closely (i). The research scanned the brains of people at the age of 73 and then again at the age of 76 to find out how their brain volume had changed over time.
Researchers elsewhere have discovered that following a Mediterranean diet may reduce your risk of developing cognitive disorders by 21 per cent, as well as reducing your risk of Alzheimer’s disease by 41 per cent (ii). Others also suggest that those who follow the Mediterranean diet more strictly may benefit from 1.7 fewer years of cognitive ageing than those who follow it less strictly (iii).
A Mediterranean diet typically includes:
Lots of fruit and vegetables, cereals and legumes
Moderate amounts of alcohol (usually wine) and fish
Low-to-moderate amounts of dairy foods
Low amounts of red meat and poultry
Fats supplied by olive oil rather than saturated fats (animal-derived fats)
Indeed, according to Age UK, this type of diet may be associated with better cognitive functioning in old age as well as a lower risk of dementia (i).
What food is good for the brain?
As well as types of diet, many experts have investigated specific foods and how they may benefit cognitive health. For instance, researchers writing in the Journal of Alzheimer’s Disease have discovered certain foods – and perhaps not those you expect – may have a direct impact on our mental sharpness in later life (iv).
Using data from the UK Biobank database and research resource, the scientists discovered the following:
Out of all the foods studied, cheese was found to be the most protective food against age-related cognitive problems (however researchers elsewhere suggest eating too much saturated fat – found in high amounts in cheese – may accelerate cognitive decline in older people (v))
Drinking a little alcohol every day – particularly red wine – may improve cognitive function
Eating lamb but not other red meats once a week might improve long-term cognitive functioning
Eating too much salt may further increase your risk of Alzheimer’s if you already have a higher-than-normal risk for the disease
Other foods for the brain include:
Oily fish and Omega-3
The omega-3 fatty acids found in oily fish such as salmon, sardines, pilchards, herring, mackerel and fresh tuna are considered essential for a healthy brain. A growing number of studies are discovering a positive link between fish oils and cognitive health – in one example, researchers found a moderate intake of omega-3 fatty acids may postpone cognitive decline in older men (vi).
Experts recommend having at least two portions of fish each week, one of which should be oily (though women and girls shouldn’t have more than two portions of oily fish a week if they may become pregnant in the future or if they’re already pregnant or breastfeeding) (vii).
Like fish, nuts also contain omega fatty acids. Choose walnuts, pecans or pistachios, which have the highest levels of omega-3 fatty acids. Flaxseeds and chia seeds are also high in omega-3s. Nuts and seeds also contain vitamin E, which experts believe could help keep your brain healthy as you get older too (viii).
Foods rich in vitamin E are also worth adding to your diet, since research has found vitamin E may reduce cognitive decay when you’re older (ix). Other foods rich in vitamin E include nuts, olives, seeds, vegetable oils, wheatgerm and olives.
Colourful fruit such as blueberries, blackberries, raspberries, cherries and black currants contain antioxidants that may help increase blood flow to your brain and give your cognition a boost. Studies that support this idea include one that links eating blueberries with improved memory in older people (x).
Cocoa powder – which is found in higher amounts in dark chocolate than milk chocolate – contains lots of antioxidants called flavonoids (or cocoa flavanols). These compounds have been found to help boost cognitive functions such as memory and slow down age-related and disease-related cognitive decline, not just in animal studies but human studies too say scientists (xi). Some scientists believe this may happen because cocoa flavanols increase blood flow to the brain (xii). Dark chocolate is also a rich source of magnesium, which is also thought to be beneficial for brain health (see below).
Choose a chocolate that has a high percentage of cocoa solids (at least 70 per cent) as the more cocoa solids chocolate contains, the higher its flavonoid content.
Also packed with antioxidants, broccoli is a good source of vitamin K, a fat-soluble vitamin used to make a type of fat found in brain cells. Studies also link high vitamin K intake to improved memory in older people, and have found that those who are low in vitamin K are more likely to have memory problems (xiii). Other sources of vitamin K include green leafy veg such as spinach, as well as vegetable oils and cereal grains.
Eggs haven’t been directly linked to brain health. However they are among the most concentrated sources of a nutrient called choline, which is needed by the body to create a neurotransmitter (brain chemical) called acetylcholine that helps regulate memory (xiv). They also contain several B vitamins, including B6, B12 and folate (see B complex, below).
Supplements for brain health
Taking dietary supplements is another option you may want to consider if you’re interested in supporting your cognitive health. Brain health supplements – often called nootropics – are becoming increasingly popular, and are thought to play a positive role in cognition. Here’s a quick rundown of some of the main nutritional supplements that could help keep your thinking, memory and other cognitive functions sharp.
Eating oily fish may be good for your brain, but if you don’t like eating fish then you could try taking a good-quality fish oil supplement.
Fish oils contain omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with most fish oil supplements containing a mixture of the two. Some studies have found that taking omega-3 supplements may benefit cognition, including in people who don’t eat much fish.
One small-scale study, for instance, found people aged 50 - 75 taking four daily fish oil capsules over six months enjoyed improvements in certain cognitive skills such as verbal fluency and reading ability by 26 per cent on average, and that the structure and volume of tissue in several areas of their brains improved too (xv).
Another study discovered healthy young adults with diets low in omega-3s achieved better memory performance after six months of taking a fish oil supplement rich in DHA (xvi). On the other hand some scientists believe EPA is beneficial for cognitive performance too, with one trial finding volunteers brains worked less hard but achieved better cognition when they took EPA-rich supplements than when they didn’t take any supplements (xvii).
Elsewhere scientists working again with healthy young adults found the volunteers’ cognitive test scores improved after six months of taking a supplement containing both EPA and DHA. However the biggest improvements were among those who had previously had the lowest DHA levels (xviii).
Known best as a curry spice, the active ingredient in turmeric – called curcumin – has been shown to have some beneficial effects for some aspects of cognitive health in trials, with some scientists suggesting it may have properties that could prevent or improve processes underlying age-related cognitive decline and dementia.
One study, which involved 40 older adults with normal cognition or mild cognitive impairment, found taking a curcumin supplement twice a day for 18 months improved short-term memory, verbal memory and attention modestly when compared with a placebo (xix).
Another study in healthy adults aged 60 - 85 found that some – but not all – cognitive function test scores improved by 16 per cent an hour after they took a curcumin supplement. After four weeks of taking the same supplement, the volunteers’ scores had improved by 17 per cent (xx).
Some of the same scientists carried out further tests, and found that curcumin may be associated with better working memory performance if taken for 12 weeks, suggesting that their study’s results may hold promise for reducing cognitive decline in some people (xxi).
Often used by natural health practitioners to help prevent or treat memory problems, ginkgo biloba has also been widely used to increase cognitive function in older people as well as to help delay the progression of Alzheimer’s disease.
One overview of 10 reviews on the use of ginkgo found that it may improve cognition, but most convincingly when a higher dose was used. The scientists involved in the study concluded that there’s clear evidence to support gingko as a satisfactory treatment for mild cognitive impairment and dementia, but they could not confirm its effectiveness in preventing cognitive decline (xxii).
Other researchers have come to a similar conclusion, stating that gingko extract may improve the cognitive function of people with mild dementia if given for more than 24 weeks (xxiii).
B vitamins – including B1, B2, B3, B5, B6, biotin, folate (or folic acid) and B12 – are essential for health, but because our bodies can’t make them we must get a good supply through our diet, including from supplements. Each B vitamin has a variety of functions – for instance, many are involved in turning food into energy – but some may also help to slow down cognitive decline.
For instance, a study that involved 675 middle-aged people from the TwinsUK study found those who say they took vitamins regularly particularly B vitamins – scored higher on tests of cognitive performance (specifically relating to visuospatial and verbal memory) than those who didn’t regularly take vitamins (xxiv).
Meanwhile a two-year study of people aged 70 and older with mild cognitive impairment has also found a combination of folic acid, vitamin B12 and vitamin B6 helped to slow cognitive decline (xxv). Another study, this time in adults aged 60 - 74 who had depression, found taking folic acid and vitamin B12 for two years helped improve short and long-term memory (xxvi).
Scientists have also found that people with low vitamin B6 levels experience three-and-a-half times more cognitive decline than those with normal levels, and suggest that vitamin B6 may be an important protective factor in helping to maintain cognitive health in ageing (xxvii).
A naturally occurring antioxidant sourced from a freshwater algae called Haematococcus pluvialis, astaxanthin is the red pigment in the algae that gives the fish and seafood that eat it their red/pink colour. It’s one of the most powerful antioxidant substances we know about, with researchers believing it to have 100 times more antioxidant power than vitamin E (xxviii).
Antioxidants may be useful in the prevention of cognitive decline, as there is some evidence that having low levels of antioxidants may be an early sign of age-related cognitive impairment (xxix). One study suggests taking astaxanthin supplements for three months may improve memory, mental quickness and multitasking in older people who are experiencing age-related forgetfulness (xxx). Another trial, which also gave volunteers astaxanthin extracts to people with age-related forgetfulness for 12 weeks, produced positive conclusions too (xxxi).
You can get more astaxanthin in your diet by eating plenty of fish and seafood such as salmon, lobster, crab and crawfish. However it may be difficult for you to get a large enough dose to see any health benefits through diet alone. That’s because researchers are typically using daily doses of around 4 - 16mg in their studies, whereas a portion of wild salmon contains less than 4mg. The easiest way to get a good amount of astaxanthin may therefore be to take a quality supplement (it’s also a good solution for those who don’t like eating fish or seafood).
Iodine is perhaps most well known as a nutrient essential for the production of thyroid hormones and for regulating the thyroid gland. However having an underactive thyroid gland (hypothyroidism) or being deficient in iodine are also associated with mild cognitive problems such as poor memory and an inability to concentrate.
Other signs of an underactive thyroid or iodine deficiency include feeling constantly tired, feeling cold all the time, constipation, dry skin and unexpected or unusual weight gain. However making sure you get a decent amount of iodine in your diet may help avoid cognitive problems (xxxii).
The richest dietary sources of iodine are fish, eggs, milk and other dairy products. You can also find it in many nutritional supplements, including multivitamin and mineral products. Find out more about this mineral in our guide to iodine.
In ancient Greece and Rome, rosemary was often used to boost memory (xxxiii). Even Shakespeare mentioned that rosemary was for remembrance in Hamlet (act 4, scene 5). Far more recently, scientists have concluded that the scent of rosemary may improve your memory.
In one study, 150 people aged 65 and older were put in rooms scented with rosemary and lavender essential oils, or no oils. After doing memory tests, those in the rosemary room had scores 15 per cent higher than those in the no-scent room. Those in the lavender room, on the other hand, were more calm and contented – but their memories were worse than the other two groups (xxxiv).
The smell of rosemary essential oil may also be helpful to students taking exams, say researchers writing in the Egyptian Journal of Basic and Applied Sciences, who found the smell significantly increased secondary school students’ memory (xxxv).
Researchers elsewhere have investigated compounds in rosemary called diterpenes, suggesting that they may have potential therapeutic benefit for Alzheimer’s disease (xxxvi). While admitting that further research is needed, the researchers claimed the effect of rosemary diterpenes on Alzheimer’s disease is very promising.
As well as adding rosemary as a herb to your food, you can find it in a range of nutritional supplements and as an aromatherapy essential oil.
Iron may not be the first thing you think of when it comes to cognitive health, but it is an essential nutrient that’s vital for blood flow, including blood flow to the brain. Some studies suggest iron may be important for cognition, especially in those who are deficient in the mineral.
For instance one trial suggests iron supplements may improve verbal learning and memory in adolescent girls – a population group that is often found to be lacking in iron (xxxvii). A review of studies also concludes that there’s some evidence that iron supplements improve attention, concentration and IQ, not only in older children but in adults too (xxxviii).
A compound found in several foods including meat, fish, egg yolks and soya beans, phosphatidyl serine is an important component of human cells and is often marketed as a brain health nutritional supplement.
One study has found a supplement containing phosphatidyl serine has a positive influence on memory, mood and cognition in elderly people, and that it may even help with things like daily functioning and emotional wellbeing in people with Alzheimer’s disease (xxxix). There’s also some evidence it may help improve cognitive performance in older people who are experiencing memory problems have not been diagnosed with dementia (xxxx).
Zinc – an essential nutrient found in foods such as meat, dairy products and nuts – is found in high levels in the brain and is needed for a healthy immune system. Experts believe that zinc may be linked with memory impairment, though it’s as yet unclear how this happens (xxxxi). Others suggest there’s evidence that a deficiency of zinc may increase your risk of developing a neurological disorder such as Alzheimer’s disease (xxxxii).
If your diet is low in zinc, taking a nutritional supplement – one that contains just zinc or a multivitamin and mineral with good zinc levels – may be helpful, not just for your immune health but your cognitive health too.
Grown originally in India and Nepal and often referred to as Indian ginseng, ashwagandha is one of the main herbs in Ayurvedic medicine (Ayurveda is the natural medicine system that has been used for more than 3,000 years in India). Besides other potential benefits, ashwagandha has been shown to improve cognitive performance in a small number of preliminary studies, thanks to the action of active compounds called withanolides found in its roots.
One study suggests taking ashwagandha extract for just 12 days may improve cognitive performance and reaction times in healthy people compared to a placebo (xxxxiii). Another, which this time centred on people with mild cognitive impairment, found taking ashwagandha for eight weeks may boost memory as well as other aspects of cognition compared to a placebo (xxxxiv).
Ashwagandha is widely found in supplement form – look for a product that contains good amounts of withanolides (no less than 1.5 per cent).
Found in a wide range of fruit and vegetables, vitamin C is classed as an essential vitamin, since we can’t make it in our bodies. And despite the fact that it is widely available, some people are thought to be vitamin C deficient or marginally deficient (though the deficiency disease scurvy is relatively rare in Western populations). Indeed, one report from 2013 has estimated that up to 30 per cent of elderly people may be deficient in vitamin C (xxxxv).
Vitamin C is needed for a variety of essential functions in the body, including several central nervous system functions. Some researchers also believe low vitamin C levels may be linked with lower cognitive performance (xxxxvi). In tests, they found volunteers with adequate vitamin C levels performed better in tests that involved attention, focus, working memory, decision speed, delayed and total recall, and recognition.
Vitamin C is available as a single supplement and also as a component of other supplements such as multivitamin and mineral formulations. It comes in tablet and capsule form, as well as in powdered form.
An essential mineral, magnesium is needed for the proper functioning of your metabolism and your nervous system, and also helps to maintain heart health. Like vitamin C it is easily found in a normal diet, yet despite this many people may not be getting adequate amounts.
Meanwhile there’s evidence that magnesium may help boost cognitive function as well as reduce the risk of developing dementia. In one US-based study, increasing magnesium intake for 12 weeks was found to improve cognitive function by more than nine per cent among 65-year-olds (though the study looked specifically at those who had a high calcium intake compared with their magnesium intake) (xxxxvii). The study’s findings, say the authors, may have significant implications for the prevention of cognitive ageing and Alzheimer’s disease.
Another US-based study, which followed more than 6,000 older women, found those who had the highest intakes of magnesium from foods and supplements had a 37 per cent lower risk of developing mild cognitive impairment compared with those who had the lowest intakes (xxxxviii).
Study participants aged 50 and older in Taiwan, on the other hand, were found to be 48 per cent less likely to develop dementia over a 10-year period if they took magnesium laxatives as a treatment for constipation compared to those who didn’t take the laxatives (xxxxix).
Magnesium can be found in foods such as dark chocolate, nuts, seeds, legumes, tofu, yoghurt, milk, oily fish, chicken, beef, bananas and leafy green vegetables.
Most people realise calcium is necessary for healthy bones and teeth, but what about the brain?
Research into calcium and cognitive function is in its infancy, with most studies to date being carried out on animal subjects. However Indian researchers have discovered that a lack of calcium – along with magnesium – may be associated with cognitive impairment in older people (l).
Calcium is available in supplement form, either on its own or as part of a multivitamin and mineral formulation. You can boost your intake of calcium-rich foods by eating more dairy foods, dark leafy greens and fortified foods such as breakfast cereals, breads and soya milk.
Humans have been drinking green tea for thousands of years, and many claims have been made for its effect on health, including how it affects the brain.
A review of 21 studies on green tea and its effect on the brain suggests it may well have an impact on cognition as well as brain function. As to the compound in green tea that causes this effect, the researchers believe it may be a combination of caffeine and l-theanine (li).
Another study suggests green tea may be useful as a therapy in the treatment of cognitive impairment (lii), while researchers from the National University of Singapore suggest regular drinkers of tea – whether green, oolong or black – may have better organised brain regions than non-tea drinkers, suggesting that they have healthier cognitive function (liii).
If you don’t like drinking green tea you can still benefit from its health properties by taking a green tea supplement.
There’s lots more information about cognitive health, including some of the main conditions that affect it and how your lifestyle can help keep it in good shape, in our health library.
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Keri Filtness has worked in the Nutrition Industry for 19 years. She is regularly called upon for her professional comments on health and nutrition related news. Her opinions have been featured by BBC3, Prima, Vitality, The Mirror, Woman’s Own and Cycling Weekly, amongst others. She has also worked one to one with journalists, analysing their diets and health concerns and recommending changes and additions, where appropriate.