Introduction

Why is brain health important?

Maintaining a healthy brain is crucial for our overall health, well-being, and quality of life, as it is responsible for many of our daily functions, including thinking, moving, communicating and emotions. 

As the body’s critical control centre, our brain’s development and its health over our lifespan can be influenced by several factors. 

The World Health Organization (WHO) defines brain health as “the state of brain functioning across cognitive, sensory, social-emotional, behavioural and motor domains.” The WHO also identifies the main factors influencing brain health as being:¹

• Environment
• Safety and security
• Learning and social connection
• Access to quality services 
• Physical health (including nutrition) 

Importantly, adequate nutrition and healthy diets are crucial for brain health, especially in reducing the risk of developing conditions related to cognitive decline, such as dementia. 

Nutritional composition of mackerel

Mackerel is a highly nutritious oily fish and an excellent source of protein, omega-3 fatty acids, and essential vitamins and minerals, including vitamin D, vitamin B12 and selenium. The UK’s NHS recommends incorporating two portions of fish per week into your diet, one of which should be an oily fish. 

Omega-3 fatty acids (omega-3s) are polyunsaturated fatty acids (PUFAs), commonly referred to as ‘healthy’ fats because they help lower your risk of heart disease by helping to maintain healthy cholesterol levels. 

Omega-3s are known as essential fatty acids because our bodies cannot create them, so we must get them from our diet, and consuming them is important for good health.² The main omega-3s are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Although it is possible to convert a very small amount of ALA into EPA and then DHA, we must obtain EPA and DHA from foods and dietary supplements to maintain adequate levels.

Benefits of mackerel for brain health

Omega-3 fatty acids and cognitive function

Omega-3 fatty acids, EPA and DHA play a critical role in cognitive function and brain development.³ Almost 60% of our brains are composed of fatty acids, of which 35% is made up of omega-3s.⁴ 

Studies have found DHA is important for brain and nerve cell development.⁵ This is vital for the growth and function of infants’ brains, where research indicates diets deficient in DHA are associated with lower intelligence scores in children and learning deficits.^6,7 

Beyond childhood, omega-3s are important for maintaining brain health, with consumption related to mental performance benefits across age groups.⁴ DHA is abundant in the brain’s grey matter – a part of the brain that controls our movement, memory and emotions. For older adults, omega-3 consumption leads to improved blood circulation in the brain, which is beneficial for memory and reducing learning deficiencies related to ageing.⁴ 

Vitamin B12 and neurological health

Vitamin B12 (cobalamin) is essential for a healthy nervous system, red blood cell formation and DNA replication. 

Similar to omega-3s, your body cannot naturally produce vitamin B12. Instead, it can be sourced from animal foods like meat, fish, poultry, dairy and eggs. Although plant foods do not naturally contain vitamin B12, many breakfast cereals have been fortified with vitamin B12 that your body can absorb. 

Vitamin B12 has a special function in producing myelin – a protective fatty membrane that wraps around the nerves in your body.⁷ Myelin helps messages to travel quickly along nerves, myelin formation, and especially supports nerve regeneration - for example, after an injury.⁸ 

Being deficient in vitamin B12 can result in cognitive dysfunction and nerve damage, with very low levels potentially leading to health conditions like megaloblastic anaemia.⁹ Symptoms include confusion, tingling in your hands and feet, and memory loss, which contribute to peripheral neuropathy (nerve diseases). Because a lack of vitamin B12 can damage nerves (the myelin sheath that protects the nerve), this could lead to elevated levels of an amino acid called homocysteine, increasing your risk of developing Alzheimer’s disease and stroke.⁹ 

Protein and selenium for brain health

Amino acids are the building blocks of protein and are required by the brain to produce neurotransmitters - the body’s chemical messengers.¹⁰ 

Although there are 20 amino acids, there are just nine you need to consider, known as the essential amino acids. By eating enough protein and foods that contain essential amino acids, our body can convert these amino acids into neurotransmitters, such as serotonin, glutamate, and dopamine.¹⁰ 

Tryptophan is an amino acid that is the precursor for serotonin, found in oily fish, poultry, and plant foods, like oats. Serotonin is especially important for our mental health as it influences mood regulation, appetite, and sleep.¹⁰ Having low levels of serotonin can cause sleep issues, headaches and depression.¹⁰ 

Selenium is a trace mineral that is vital for brain health. Selenium has antioxidant properties that can help protect the brain from oxidative stress.¹¹ The brain is susceptible to oxidative stress because of its high oxygen consumption, resulting in an imbalance between free radicals and antioxidants.¹² Selenium is crucial in neutralising these free radicals, such as breaking down peroxides, which cause damage to DNA and brain tissue.¹³ 

Selenium may also protect the brain by reducing inflammation associated with neurodegenerative diseases and disorders, including Alzheimer’s disease and Parkinson’s disease.^{.12, 13}

What does the evidence say?

Studies supporting the benefits of mackerel for brain health

Evidence shows the consumption of oily fish, like mackerel, has beneficial effects on cognitive abilities. 

Studies have identified cognitive improvements among children related to the consumption of fish oil and fish in their diets. A study in Thailand found that the consumption of fish oil enhances attention and cognitive processing capabilities.¹⁴ In Norway, a study of preschool children (aged 4-6 years) compared the consumption of fatty fish (herring and mackerel) to meat to investigate the impact on cognition.¹⁵ The children who were given fatty fish scored higher on cognition tests.¹⁵ 

Similar findings have been noted in studies looking at older adults. The Hordaland Health Study looked at those aged between 70-74 years old.¹⁶ Researchers found that the habitual consumption of fatty and lean fish (including mackerel) was associated with significantly better mean scores across cognitive testing.¹⁶ Importantly, groups who consumed fish performed better compared to those who only consumed fish oils.¹⁶ 

Interestingly, the beneficial effects of oily fish are not confined to early childhood and the elderly. A recent study of over 2,000 healthy adults found higher omega-3 concentrations related to better cognitive function and brain structure in middle-aged adults.¹⁷ 

Fish consumption may reduce the risk of developing neurodegenerative diseases; however, the evidence is unclear. 

Observational studies have found that people who have a higher intake of fish in their diets (around three servings per week) have a lower incidence of developing dementia, specifically relating to Alzheimer's disease.¹⁸ For example, a meta-analysis (a type of statistical analysis that combines the results from several studies) in China found that people who consumed a high amount of fish benefited from a 20% risk reduction of developing dementia compared to those who consumed little or no fish.¹⁹ 

In comparison, an observational study that followed over 5,000 participants for almost 10 years found that fish intake was unrelated to long-term dementia risk.²⁰ 

Whilst the existing research shows fish intake may reduce the development of neurodegenerative conditions such as Alzheimer’s disease, the studies do not prove that consuming fish prevents such disorders. 

How can mackerel be incorporated into your diet to support brain health?

Tips for including mackerel in meals

Whilst the research may not be definitive regarding mackerel’s effectiveness in preventing disorders, the evidence is clear that we should incorporate oily fish like mackerel into our diets. The NHS recommends eating at least one portion (around 140 grams) of oily fish per week. 

Fortunately, mackerel is an easy fish to include in meals and snacks. You can choose between fresh mackerel from the fish counter or tinned mackerel. Tinned fish is likely cheaper and more convenient as it has a longer shelf-life and is already cooked. Be selective when choosing tinned fish, and opt for mackerel in water or olive oil. 

Recipe ideas and cooking methods

If you buy fresh mackerel, the healthiest way to prepare it is to grill the fish. You can also bake or fry mackerel. Here are some recipe ideas for adding mackerel to your meals: 

• Grilled mackerel with roasted vegetables: for a quick and healthy midweek meal, marinate mackerel fillets with herbs (dried or fresh), lemon juice, and olive oil and grill until cooked through 
• Mackerel salad: add a can of mackerel to fresh salad greens, cucumber, cherry tomatoes, and avocado for a flavourful and nutritious meal
• Mackerel sandwich: Try elevating your lunchtime sandwich by adding canned mackerel to bread or a wrap, as well as onion, hummus and lettuce for a protein-rich lunch 

Considerations for individuals with dietary restrictions or allergies

Although mackerel has plentiful health benefits, it is important to remember that oily fish typically contain higher levels of pollutants than other seafood. For this reason, certain population groups have recommended consumption limits. 

The NHS advises that all people assigned female at birth (AFAB) who have not yet been through menopause, including those who are planning pregnancies, or who are pregnant or breastfeeding, should not consume more than two portions of mackerel or other oily fish per week. 

If you have dietary restrictions or allergies or do not wish to eat fish for ethical reasons, you may want to try fish oil supplements.

Summary

Omega-3 fatty acids, particularly EPA and DHA found in mackerel, are crucial for cognitive function and brain development. Vitamin B12 is crucial for a healthy nervous system and myelin production. 

Protein provides the amino acids needed for neurotransmitter production, while selenium acts as an antioxidant, protecting the brain from oxidative stress and inflammation associated with neurodegenerative diseases like Alzheimer's and Parkinson's. 

Overall, including mackerel and these nutrients in the diet supports brain health at different life stages.

Mackerel can be enjoyed as part of a healthy and balanced diet. It’s advised to try different types of oily fish to support sustainability so we can continue to benefit from these highly nutritious fish.  

While eating mackerel and other oily fish has many health benefits, always consult with a healthcare professional before making changes to your lifestyle and for personalised dietary advice.