How to Have a Healthy Brain: The Best Diet at Every Stage of Life

While the foundations of brain structure and function are laid during pregnancy and early life, the brain is constantly being fuelled and shaped by the food and drink we consume daily. We should be thinking of brain health like a pension plan; it is best to start as early as possible so that you have more to draw from when you need it. That said, it is never too late to invest in your brain health. Here is how to use nutrition to aid the brain at each stage of life.

Research shows a correlation between diet quality and size of the hippocampus (the brain’s memory centre). So the greater the proportion of ultra-processed foods, the smaller this brain area.

Pregnancy

Most people know that you need to take folic acid to support a healthy pregnancy, but there is another lesser-known nutrient that is critical to brain development. Iodine is a trace mineral that is essential for the production of thyroid hormones. We know that thyroid hormones play a role in metabolism but they also determine the growth and development of the fetal brain during pregnancy. Consequently, the World Health Organization describes iodine deficiency as “the single most important preventable cause of brain damage" worldwide. A lack of iodine impairs thyroid hormone production during pregnancy, meaning a baby’s brain development will be unavoidably affected, with studies linking low maternal iodine with sub-optimal scores for verbal IQ at age eight.

Because adequate thyroid hormone is required from the moment of conception, women need to ensure sufficient iodine intake for several months before conceiving. This can typically be achieved by eating a balanced diet that includes a variety of dairy, fish and seafood. However, those who do not eat animal foods may need to consult a health professional about taking an iodine supplement. Too much can be a problem too, with an excess causing iodine poisoning or hyperthyroidism, so it is important to get the balance right.  Good things to eat during pregnancy are: fish and cooked seafood, preferably smaller species such sardines, salmon and mussels; and eggs. Seaweed is also recommended as a concentrated source of iodine.

Childhood

The brain continues its rapid growth and development during infancy and childhood. Omega-3 fatty acids, particularly one called DHA, make up a significant proportion of the membrane of brain cells. DHA is considered irreplaceable for brain development and evidence shows it may be especially important to ensure that children are getting sufficient amounts through regularly eating oily fish. A recent survey found that less than five per cent of UK children are meeting the fish consumption recommendations. On the other hand, children in the UK are eating more than the recommended levels of added sugar. The UK government advises that free sugars — sugars added to food or drinks and found naturally in honey, syrups and unsweetened fruit and vegetable juices, smoothies and purees — should not make up more than five per cent of the energy (or calories) you get from food and drink each day.

Children are eating, on average, eight sugar cube equivalents over the advised limit, largely in the form of sugar-sweetened beverages, and prepackaged cakes and biscuits, often eating over 11g of sugar at breakfast alone. Not only is added sugar a risk to teeth, the energy in sugar is easy to overconsume, increasing the risk of Type 2 diabetes. In turn, diabetes significantly increases the risk of cognitive decline and dementia, and the longer someone has the condition the greater the risk, so it is very worrying that rates of diagnosis in childhood are on the rise. Good things to eat during childhood are: oily fish such as salmon, mackerel, sardines, trout, anchovies, kippers; fresh fruit or cheese with oat crackers for snacks; and low- or no-sugar drinks.

Adulthood

Ultra-processed foods make up 55 per cent of the UK adult diet, the highest in Europe. Ultra-processed foods are sold ready-to-eat or ready-to-heat and produced using ingredients or processes for which there is no domestic equivalent. To improve palatability and shelf-life, these foods tend to be higher in added sugar, fat and salt, and contain less fibre than their homemade equivalents. So how might having a large proportion of these foods in our diets be affecting our brains?

Research indicates that it is causing us to miss out on brain-healthy nutrition. Research has shown a correlation between diet quality and size of the hippocampus (the brain’s memory centre). The greater the proportion of ultra-processed foods in the diet, the smaller this brain area — this is a concern because loss of brain volume is linked to poorer function. Indeed, a recent study found that just a few days on a high ultra-processed foods diet caused damage to the hippocampus that tracked with impairments in learning and memory. Though we are still in the early days of this research, evidence is showing that higher consumption of ultra-processed foods is linked to increased risk of depression and harmful changes in the regions of the brain linked to learning and memory. Good things to eat during adulthood are: leafy green vegetables (such as spinach, watercress, rocket, kale) on a daily basis; beans, legumes and wholegrains; and coffee or tea (preferably with little sugar or cream added).

Later in life

That dementia is currently the leading cause of death in the UK is not simply an artefact of longer life expectancy, because we know that other, longer-lived nations, such as Japan and Italy, have lower dementia rates. Revealingly, one study found that the Japanese Alzheimer’s disease rate had increased from 1 per cent in 1985 to 8 per cent in 2008 and cited the increased consumption of a western-style diet as the cause. What low-dementia rate nations have in common is moderate fish and seafood consumption, plenty of vegetables and beans, fermented foods eaten regularly, and tea and coffee. Good things to eat later in life are: oily fish; kimchi; sauerkraut; kefir or live yogurt; and berries such as strawberries, raspberries, blueberries, blackcurrants, blackberries, and cooked elderberries.   

Published in The Guardian on February 15, 2023. Reprinted with permission.