Nutrition plays a vital role in maintaining brain health throughout life. In this section we focus on brain ageing and the role of omega-3s and micronutrients in preventing structural deterioration, reducing risk factors such as homocysteine and optimising cognitive function, brain cell communication and reducing oxidative stress.
Dementia is a serious cognitive disorder and affects brain functions such as memory, attention, speech and problem solving. Dementia is, in fact, an umbrella term for any condition characterised by gradual decline in cognitive function and nervous system-related mental health symptoms (neuropsychiatric illness). The most well known form of dementia is Alzheimer’s, but numerous other brain diseases also cause dementia as the brain becomes increasingly damaged. These include vascular dementia, frontotemporal dementia, Lewy body dementia, Korsakoff’s syndrome, Huntington’s disease and Parkinson’s disease.
Dementia is common among the geriatric population and approximately 750,000 people in the UK suffer with the condition. Risk of onset increases with age, but damage to the brain resulting in dementia begins many years before symptoms appear. Despite the high incidence of dementia in the older population, the condition is not an inevitable part of the ageing process and research increasingly supports the need for long-term prevention strategies.
Mild cognitive impairment, whereby memory and thinking are affected on a lesser scale, is not dementia, but those suffering with symptoms such as poor day-to-day memory may be at greater risk of developing dementia later in life. Poor memory and concentration may, however, be a sign of high stress or other mental health conditions and are not necessarily related to cognitive decline, even when experienced in older age. Seeking advice from your healthcare practitioner and monitoring symptoms is important, as early identification can help prevent speed of progression and reduce severity.
Dementia can affect everyone differently. Symptoms to look out for in yourself and loved ones include:
- Loss of short term memory, despite easily recalling events in the past
- Difficulty following conversations or television programmes
- Forgetting names of friends or objects
- Repeating yourself or losing the thread of what you are saying
- Problems with thinking and reasoning
- Feeling anxious, depressed or angry towards your forgetfulness
- Others commenting on your forgetfulness
- Feelings of confusion even in a familiar place
The brain is a complex organ made up of billions of cells that form various structures, all performing different functions. Neurones are the collection of cells responsible for the communication of information between different parts of the brain, as well as between the brain and the various organs, muscles and cells of the body. There are almost 100 billion neurones in the brain, which require oxygen and various nutrients to pass messages within cells via tiny electrical impulses, and between cells via chemical signals.
“Damage to cells in the brain can also be caused, or worsened, by high levels of inflammation, which results in reduced function and cell death.”
The brain structure is made up of cells, collectively termed glial cells, which provide structure and supply nutrients to the neurones. Each cell produces thousands of tiny proteins each day and these proteins form the chemical messengers needed for the brain to function correctly. During production, malfunctions can occur – resulting in too much, too little or an altered structure of these proteins. Most forms of dementia are associated with accumulation of too many of one type of protein that leads to damage, significantly reducing the ability of the cell to function and, in some cases, to cell death. Damage to cells in the brain can also be caused, or worsened, by high levels of inflammation, which results in reduced function and cell death. Unlike the majority of cells in the body, when a neurone cell dies it cannot be replaced. The different types of dementia arise as a result of different areas of the brain being damaged.
Risk factors that increase risk for cognitive decline and dementia include several aspects of lifestyle, including:
- Inactivity (regular physical exercise at all ages is associated with lower risk)
- Excessive alcohol use
- Elevated homocysteine levels
- High blood pressure
- Elevated cholesterol
Factors that increase brain function throughout life can actually reduce risk of dementia. These include:
- High mental stimulation through education, occupation or leisure
- High social interaction in later life
Genetics have been linked to increased risk of dementia and although specific expressions of several genes can increase your chances of developing the condition, the contribution of genetics to dementia risk is very small. Nevertheless, prevention strategies are important for anyone with a family history of dementia, as an inherited gene slightly increases the chance of developing the condition.
Diet is an important determinant of general health. The structure, function and health of the brain are also heavily impacted by what we eat. A healthy diet throughout life and as we age is vital to prevent numerous health conditions, including dementia. A varied diet high in vitamins, minerals and essential fats is key for supporting brain health and reducing brain cell damage.
Much of the research into diet and dementia has focused on the Mediterranean diet, with those adhering closest to this type of diet having the greatest health outcomes and lowest risk for cognitive decline.
The key features of the Mediterranean diet include:
- High consumption of unrefined olive oil, legumes & unrefined cereals
- Very high seasonal fruit and vegetable consumption
- Moderate to high consumption of fish
- Moderate consumption of dairy products (mostly as cheese and yoghurt)
- Moderate wine consumption
- Low consumption of meat and meat products
Many of the benefits of following this type of diet have been attributed to the high consumption of fish, healthy fats and vegetables in relation to a typical Western diet. Together, these foods provide high levels of antioxidants, essential fats and important functional proteins. In addition, the Mediterranean diet consists predominantly of natural foods; almost no manmade or processed foods are consumed, thus conferring significant further health benefits.
To optimise brain function and prevent cognitive decline later in life, there are a number of specific nutrients that should be consumed regularly if you are concerned about dementia risk or existing symptoms.
The brain is predominantly made up of fatty acids. Each structure differs in its fat content, with the myelin cells being especially rich in fatty acids. Having the correct levels of specific fats in the various regions and cells of the brain is essential for healthy function and communication. The omega-3 family of fatty acids are particularly important for the brain, with high levels shown to protect against the formation of plaques and tangles. The two omega-3 fats considered most important for the brain are docosahexaenoic acid (DHA), a major structural fat essential for growth and function of the nervous system, and eicosapentaenoic acid (EPA), which contributes significantly to neurotransmitter production, brain signalling pathways, reducing the activity of the enzyme phospholipase A2 and reducing inflammation.
With DHA being the predominant structural fat in the brain, it has until recently been considered by the scientific community to be the most important omega-3 fatty acid for cognitive function and behavioural performance. With studies moving on from researching total omega-3 levels to the individual components EPA and DHA, however, scientists have investigated the effects of supplementation with high levels of DHA on cognitive function, and the onset and progression of cognitive conditions. These studies have shown disappointing – and potentially negative – effects for DHA on cognitive function, while EPA has come into the spotlight for its ability to increase brain cell communication and regulate neurotransmitters.
“EPA, despite being found at low levels in the brain, is now understood to be an important influencer of risk of cognitive decline, as well as moderating numerous brain functions that regulate cognition.”
The most crucial time for ensuring high intake of DHA is from conception up until a child is aged 5-6 years. At this point the brain is almost fully formed and DHA levels plateau. Supplementing with high DHA after this time, unless an individual is deficient, has been shown to have either no effect or potentially even negative effects on cognition and learning. Studies investigating DHA supplementation in dementia have also found that pure or high strength DHA oils, compared with a placebo, do not slow the rate of cognitive and functional decline in people with mild to moderate Alzheimer’s disease.
EPA, despite being found at low levels in the brain, is now understood to be an important influencer of risk of cognitive decline, as well as moderating numerous brain functions that regulate cognition. As detailed above, EPA’s two key roles are reduction of inflammation and reduced phospholipase A2 activity. Inflammation is a major contributor to dementia and increased cognitive decline risk; reducing inflammation directly prevents damage to the cells of the brain, thereby reducing the risk of developing dementia and slowing the rate of progression of cognitive illness. Phospholipase A2 is responsible for releasing structural fatty acids from cell membranes (depleting important structural fats in the process). Since EPA reduces phospholipase A2 activity, it directly protects against the loss of structural brain tissue. High EPA levels have a protective role against neurone damage and are directly linked to reduced risk of developing neurone dysfunction. High levels of EPA therefore offer considerable protection against the development and progression of dementia. Indeed, studies have directly shown that patients with pre-dementia syndrome have low levels of EPA, but not other fatty acids.
In addition to the importance of EPA in reducing dementia risk, much attention has been paid to the brain-boosting benefits of coconut oil, which is a rich source of medium chain triglycerides (MCTs) – a specific type of fatty acid molecule that is particularly useful to the brain. These MCTs provide a rich source of easy-to-use fuel for the brain. Some research suggests that they may contribute to helping restore and repair neurons and nerve function in your brain, even after damage has begun. Whilst trials are yet to confirm and determine the exact benefits of using coconut oil in dementia, numerous early anecdotal reports indicate considerable benefits when several teaspoons are consumed daily.
A well-established nutritional intervention to prevent and slow dementia is through the addition of B-vitamins to the diet – in particular, B12, B6 and folate. These three B-vitamins play a fundamental role in preventing the accumulation of homocysteine.
Homocysteine is a by-product of the methylation cycle, a process required for a wide range of processes that affect:
- normal cell division and DNA repair
- numerous reactions and metabolic processes required for detoxification by the liver
- reactions involved in the synthesis of substances including antioxidants, components of cell membranes and myelin proteins
- metabolism of the neurotransmitters dopamine and serotonin and transmission of cell signals
- accelerated cell ageing.
High levels of homocysteine indicate that the methylation cycle is essentially ‘stuck’, which can be due either to an insufficient supply of methyl groups necessary to the process, or to a deficiency of the nutrients (specifically folate, vitamin B6 and B12) needed to ‘recycle’ homocysteine into its functional products. High homocysteine levels are directly linked with cellular damage, caused by an increase in oxidative stress that arises due to lower production of antioxidants.
High plasma homocysteine, and low levels or deficiency of vitamins B12, B6 and folate (the body-ready form of folic acid), have been found both to be present in, and increase the risk of, cognitive impairment, Alzheimer’s disease and vascular dementia. Increased oxidative stress, caused by high homocysteine levels, has also been implicated in the production of harmful plaques in the brain.
Levels of homocysteine in the blood are directly inﬂuenced by levels of the B-complex vitamins, so supplementation with these key nutrients offers preventive strategies for a number of conditions related to high homocysteine. Studies confirm that supplementing with B6, B12 and folate is a successful strategy to lower homocysteine.
Although currently studies are unable to show that taking B-vitamins can ‘treat’ existing dementia symptoms, there is ample research supporting the use of B6, B12 and folate supplementation in protecting cognitive function and preventing dementia. Benefits are seen when taken as a preventative measure from mid-life onwards and, in particular, for those with an elevated homocysteine status. Research has also found that lowering homocysteine levels via B-vitamin supplementation can slow disease progression in those with mild cognitive impairment.
The recommended doses of these vitamins to control homocysteine and protect against brain-related illness are well in excess of the RDA and are unlikely to be provided in general multivitamin formulas. It is advisable to take a supplement that has been specifically formulated to target homocysteine, offering the correct doses of these nutrients for preventing cognitive decline.
Dementia is heavily linked with increased oxidative stress, which can cause considerable damage in the brain. Levels of oxidative stress increase with age, adding strain to the systems that naturally produce antioxidants in the body. By increasing antioxidant levels through diet and supplementation we can directly reduce the damage caused by oxidative stress and protect all cells, including those in the brain. The following antioxidants are particularly useful in preventing cognitive damage:
- Alpha lipoic acid
- Vitamin E
- Vitamin C
- Coenzyme Q10 (CoQ10)
Of the above, both CoQ10 and carnosine have been directly shown to help protect against dementia. CoQ10’s ability to quench free radicals helps to maintain the structural integrity and stability of cell membranes and studies have found that supplementation with CoQ10 benefits neurodegenerative diseases, including Alzheimer’s. A possible explanation for this is that CoQ10 is neuroprotective and, together with carnosine, can reduce the accumulation of proteins in the brain, thereby inhibiting the formation brain of ‘plaques’ and ‘tangles’.
Copper, zinc, manganese & selenium are important for the production of Superoxide dismutase (SOD), whilst vitamin B6 and cysteine are needed to produce glutathione – both of which are essential for regulating antioxidant systems in the body, providing significant protection against oxidative stress.