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Updated 12 February 2016

Diet and your nervous system

The importance of a healthy diet in the maintenance of the brain and nervous system should not be underestimated. Read DietDoc's comments.

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The brain and nervous system are probably the most complex and sensitive physiological structures in the human body.

The importance of a healthy diet in the maintenance of these structures should not be underestimated, DietDoc warns.

It is logical to suppose that we need a healthy balanced diet and adequate intakes of all known nutrients to firstly develop a healthy nervous system before birth and also to maintain the delicate web of neurons and nerves during the entire course of life.

However, the complex effect of nutrition on brain function and the health of the central nervous system (CNS) is often a neglected field and most members of the public do not associate the foods they eat with the psychological conditions they develop.

Which nutrients are essential for normal brain and CNS function?
The answer to this question is: “All known nutrients in our diets can influence the function of our brains and CNS.”

Some of the most important nutrients, and how they can affect psychological health, are listed here:

1) Proteins and amino acids
Proteins and amino acids play an important role in normal brain function, particularly before birth when the concentrations in the blood of the developing foetus can be three times greater than in the mother.

We also tend to forget that most of the essential chemical substances in the brain and CNS – the so-called neurotransmitters, such as dopamine and serotonin – are produced in our bodies from amino acids. The following amino acids and their related neurotransmitters are vital for a healthy nervous system:

  • Gamma-amino-butyrate (GABA), glycine, aspartate, glutamate
  • Tyrosine - dopamine, adrenaline and noradrenaline
  • Tryptophan – serotonin
  • Adenosine, ADP, ATP and AMP
  • Arginine - nitric oxide
  • N-acetyl amino acids and peptides

It is, therefore, essential to ensure that the developing foetus, newborn infants and young children have an adequate supply of amino acids, which are derived from proteins.

If you are pregnant or breastfeeding, you need to eat protein foods with a high biological value, i.e. those proteins that contain all the so-called “essential” amino acids.

Protein foods that meet these requirements are: meat, fish, eggs, milk and dairy products.

If you are a vegan or a strict vegetarian, you may have to take an amino acid supplement to ensure that your baby obtains sufficient amino acids to develop a normal brain and CNS.

In adults, any condition that affects adequate protein intake (very low energy diets, vegan or macrobiotic diets, alcoholism, anorexia) or increases the requirement for protein when intakes may be inadequate (pregnancy, lactation, periods of growth, illnesses that exhaust protein supplies), can lead to an imbalance in the supply of amino acids to the brain and CNS. This can result in neurological fall-out and damage.

2) B vitamins
The B-complex vitamins, a large group of water-soluble vitamins, all play a role in healthy nerve and brain function. In this article, the three main B vitamins, namely thiamin, riboflavin and niacin, are considered.

2.1) Thiamin
A deficiency in thiamin (vitamin B1) can interfere with the production of certain neurotransmitter amino acids, such as glutamate and aspartate (see 1 above), as well as glucose metabolism, which the brain is highly sensitive to.

Pronounced vitamin B1 deficiency causes beriberi, which is characterised by oedema, shortness of breath and sensory disturbances with paralysis. Muscle weakness, irritability, loss of memory, convulsions and permanent brain damage may also develop.

Nowadays, outright thiamin deficiency is rare in populations that follow a western diet, but subclinical vitamin B1 deficiencies occur and certain conditions such as alcoholism (Wernicke-Korsakoff syndrome), and epilepsy treated with phenytoin, are known to be associated with a high risk of developing thiamin deficiency. The use of certain diuretics can also lead to higher losses of thiamin with associated deficiency.

Treatment of diet-deficiency-induced beriberi, thiamin-deficiency associated with alcoholism and drug-induced lack of B1, usually consists of B-complex injections or high doses of thiamin supplements.

Foods that are rich in thiamin include:

  • Unrefined, unsifted or minimally processed cereals and grains (brown rice, wholewheat or brown bread, crushed wheat, Maltabella, and all cereals and breads that are fortified with thiamin)
  • Organ meats (liver, kidneys), and pork
  • Nuts and legumes (dry beans, peas and lentils)

2.2 Niacin

Niacin (nicotinic acid) is another one of the B-complex vitamins that may be linked to neurological damage. Mild niacin deficiency is associated with weakness, tremor, anxiety, depression and irritability. In severe niacin deficiency the patient may develop delirium, dementia and death - the dreaded three D’s of pellagra, which is the deficiency disease caused by a severe lack of niacin in the diet.

Once again, severe niacin deficiency is rare in modern times, but sub-clinical niacin deficiency symptoms may be more prevalent than we suspect.

Immediate treatment of serious niacin deficiency is usually done by means of B-complex injections or high doses of niacin supplements.

The human body is capable of manufacturing niacin from the amino acid tryptophan. Thus patients with a niacin deficiency will benefit from adequate intakes of high-quality protein foods (see 1 above), as well as sources of niacin, such as:·

  • Meat - a good source of niacin and tryptophan
  • Unsifted cereals and grains, like oats, brown rice or crushed wheat, and maize treated with limewater (like the type used for making tortillas)

It is interesting to note that pellagra (niacin deficiency), which used to be common among populations that ate highly refined cereals combined with a low protein intake, did not occur in countries like Mexico, where the population was also mainly dependent on maize as their staple food.

The disease was relatively common among the black population of South Africa, which subsisted on sifted, white maize meal.

The reason for this is that the indigenous population of Mexico has always made tortillas by soaking the maize in limewater. The soaking process liberates the tryptophan (an amino acid) in the maize and makes it available for niacin production in the human body.

2.3 Riboflavin

A lack of riboflavin, or vitamin B2, can cause retarded growth of children and infants with typical symptoms such as anaemia, rash around the nose, cracks on the outer edges of the mouth and a red, inflamed tongue.

Diets deficient in riboflavin or conditions such as anorexia, malabsorption, chronic alcoholism and biliary atresia (narrowing or blockage of the gall duct leading to jaundice and death in the newborn), can cause riboflavin deficiency. It has also been suggested that there is a critical period during foetal development of the digestive system when a deficiency in the maternal diet may cause permanent damage.

The most important dietary sources of riboflavin are:

  • Dairy products - milk, yoghurt, cheese, maas
  • Meat, poultry, fish, eggs
  • Broccoli, spinach and asparagus
  • Cereals and bread fortified with vitamin B2

While a riboflavin deficiency is not as directly linked to neurological fallout and damage as thiamin and niacin, the anaemia associated with a lack of B2 can have neurological consequences.

In addition, the B-complex vitamins tend to work most efficiently when the intake of all these vitamins are at an optimum level. Treatments for thiamin and niacin deficiency will, therefore, usually also include an adequate supply of riboflavin. – (Dr I.V. van Heerden, DietDoc)

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Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.

 
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