WHAT IMPACT DOES NUTRITION HAVE ON THE BRAIN?
The food you eat has a direct impact on your brain’s overall health and function. According to the Harvard Medical School, the gastrointestinal tract produces about 95% of the body’s serotonin. In other words, your digestive system literally helps guide your mood and emotional well-being based on the foods you put in your body.
Your brain, especially, is reliant on good nutrition. Like all of our organs, the brain needs proteins, vitamins, and minerals from our food to perform at its best. Unfortunately, over-processed foods or those high in sugar can increase the amount of “oxidative stress” in the brain. (Oxidative stress is a byproduct of our brains’ natural oxygen use. These free radicals damage healthy cell. Plus, poor diet, diabetes, and a number of nutrition-related health issues exacerbate free radical issues.)
Ultimately, your diet impacts your overall cognition and mood. During a 2009 study, researchers at Tufts University determined that reducing calories alone is not enough to improve memory overall. In fact, while participants in the study reported less confusion and faster response times to attention vigilance tasks during their low-calorie diets, they also performed worse on tests designed to assess memory. Simply put, a low-calorie diet improved cognition, but not memory.
The effects of different foods on our behavior and cognitive performance have been known for years without needing to be examined closely – caffeine stimulates the brain; when kids have too much sugar, they turn “hyper”; and chocolate makes us all feel good. For centuries these experiences have been known and our dietary behaviors reflect this.
In recent years the idea of nutritional effects on the brain have been developed further and extensive research into effects of food on brain functions that are not clearly evident or observable have emerged. The effect of certain foods on brain development, mood disorders, cognition (thinking), disease states and ageing has promised to be an essential area of research, development, non-pharmacological treatment and preventative measures.
The brain is an extremely active organ which demands an extremely high percentage of the overall daily energy requirements supplied by food. PET scans and MRIs show which brain areas are utilizing the greatest amount of energy by monitoring the glucose utilization. This has enabled us to understand of brain development and maturation at different ages.
The effect of poor nutrition can lead to sub-optimal functioning indirectly by exacerbation of stress, sleep disturbances and fatigue. Although these states are not considered “diseases” they are daily stressors that effect psychological well-being. A flow-on effect exists between fatigue and sub-optimal cognitive functioning, in other words, our ability to think is affected. This in turn has a negative effect on self esteem and performance. This is a classic example of a psychological cycle. All aspects of the cycle impact psychological well-being which feeds lower self-esteem. It is becoming more necessary to evaluate the function of diet on these factors before turning to medicines.
Food and Cognition
Perhaps one of the greatest effects of nutrition on brain functioning is on our cognition (thinking). The effects of poor diet on sleeping patterns, energy and mood all indirectly affect day to day functioning of the brain at work or school. Cognition is also indirectly affected by the development of other brain functions, for example nutrition is essential for the development of the sensory systems such as hearing and vision and the integration of these processes, the sensorimotor system. Sensorimotor systems are the coordination between sensory functions and motor (movement) functions. An example of a sensorimotor function would be seeing a ball (sensory) and putting up hands to catch it (motor). These processes mature before cognition as they are essential components needed for learning and memory. Therefore without full and healthy development of these systems, optimal cognitive maturation is not achieved.
A lot of recent attention has been directed towards the effects of nutrition in neuro-degeneration. Neuro-degeneration can be thought of as the opposite of neuro-development. It is the breakdown of synapses and shrinkage of the brain (atrophy). Neuro-degeneration is an ageing process and is associated with dementia.
The lack of certain nutrients is thought to be toxic to the brain (neurotoxicity), especially in the elderly brain. Under-nutrition leads to processes which predispose the brain to shrinkage and neuro-degeneration such as uncontrolled neuron (brain cell) death, amyloid-beta toxicity, oxidative stress and mitochondrial dysfunction. Research has been focused on nutrients that may have the potential to protect the brain from oxidation and atrophy, such as EFA’s and folate.
Specific nutrient qualities
Different foods provide different nutrients which have different actions in development, maturation, growth and protection of the brain.
Dietary cholesterol from dairy products and egg yolks have been associated with brain functioning at all ages. Lipids make up 10% of the weight of the brain and are essential for the proper formation of membranes and myelin. Importantly though, excess cholesterol can build up in the blood leading to disease.
Carotenoids and flavonoids
These powerful antioxidants combat oxidative stress in the brain and this is believed to have a protective effect in the ageing processes. Carotenoids are found in yellow and orange fruits and vegetables especially but all fruits are good sources of flavonoids.
Micro-nutrients including iron, zinc, choline, selenium, iodine, magnesium, B vitamins, and vitamins A and C play key roles in energy metabolism as well as neurological enzymatic reactions and processes. Micro-nutrients are specifically involved in producing functional brain lipids, neurotransmitters, DNA and RNA.
This micro-nutrient is essential for the enzymatic formation of thyroxin, without which can lead to mental retardation any age, although it is especially influential during infancy.
Salt and seafood are the best sources of dietary iodine.
A deficiency of iron is common, especially in females. Fatigue, lethargy, irritability, inattention, decreased IQ and apathy are seen in iron deficient individuals and have been linked to the symptoms of ADHD in children. The inattentive symptoms may be explained by the cognitive maturation delay found in studies of animals deprived of iron in their diets. Furthermore the fluidity of membranes is hardened in iron deficient individuals.
Lean meat and fish are the best sources of iron but other protein rich alternatives also provide this mineral such as eggs, nuts and legumes.
Protein intake is essential for the production of vital neurotransmitters including; dopamine, noradrenaline, histamine and glycine. One such protein is tryptophan, a precursor for serotonin which has effects on mood and memory.
Protein is largely found in meat, fish, poultry, eggs, liver and kidney, legumes, nuts, sunflower seeds and sesame seeds.
Low levels of folate (also called folic acid or vitamin B9), a nutrient found largely in leafy green vegetables, are hypothesised to be toxic to the brain, causing brain atrophy. This is especially prevalent in the cerebral cortex of patients with Alzheimer’s Disease.
Folate levels have also been associated with positive effects on mood.
Vitamin B12 deficiency is related to brain atrophy. Lean beef, salmon and eggs are good sources of vitamin B12.
Vitamin D has recently been determined to be an important neurosteroid and its receptors are widespread throughout the brain. A deficiency of vitamin D is sometimes accompanied by depression, psychosis and anxiety. Accordingly vitamin D therapy has been shown to provide mood-elevating effects.
A vitamin D-rich diet has been associated with a reduced risk of multiple sclerosis (MS) and has been utilized as an adjunctive treatment in early MS patients. Epilepsy has also been associated with a deficit in vitamin D which suggests its use may be developed as a potential adjunctive treatment for the disease in the future.
Vitamin D is also thought to play a role in the regulation of behavior. The receptors for this micro-nutrient are widespread through areas of the brain known to be responsible for mediating behavior, such as the limbic system.
The best sources of vitamin D include fatty fish, eggs and margarine’s fortified with vitamin D.
Essential fatty acids
Essential fatty acides (EFA) cannot be synthesized by the brain and are therefore an “essential” part of our diets. Found largely in fish, EFA are necessary for the induction of myelination and providing components of the myelin sheath, which present these nutrients as important regulators of membrane fluidity. Animal studies have found that deficiency of fatty acids can lead to altered blood brain barrier functioning. EFA are also involved in producing neurotransmitters and other important peptides.
Importantly EFA are associated with auditory and visual development. Docosahexaenoic acid (DHA) is an essential omega-3 fatty acid necessary for normal neurogenesis and neurological function. DHA is specifically important for visual signalling pathways. Consumption of high levels of DHA during infancy are associated with better visual development.
The effect of EFA in neuropsychiatric diseases such as depression, bipolar disorder, schizophrenia and dementia are under investigation.
Many studies have focussed on the improved cognitive and mood elevating effects in adults who consume a Mediterranean diet; namely a diet primarily comprised of fish, fruits and vegetables. People who adhere to the diet describe better self-rated health which has been found to influence overall energy and vitality.
The importance of our diet
The body of evidence to support the positive effects of a healthy and varied diet is large and is an active area of research and development. It is important at all ages to focus on consuming a well rounded diet with all the essential nutrients. This is especially important for infants and children during times of neurodevelopment and then again during ageing when neurodegeneration can compromise health and vitality.
References: The Whole You 2020