The brain and nervous system require the full complement of
essential nutrients and energy to develop and maintain their neurons
and supporting cells. A deficiency of any one of these essential
nutrients may impair the structure or functionality of the neurologic
system.
Stroke is the most common life-threatening neurologic disease. Other
neurologic conditions are, epilepsy, chronic headaches, and Alzheimer's
disease.
The brain metabolizes 100 g to 150 g of glucose per day. During starvation, it adapts and uses ketones, derived from the breakdown of body fat stores, for energy and thus spares blood glucose and conserves body protein.
Severe deficiencies of vitamins, especially the B-complex group,
impair nervous system function. Thiamin deficiency causes beriberi
neuropathy as well as a peripheral neuropathy and polyneuritis that
leads to paralysis of the eye muscles, loss of muscular coordination,
and memory loss, especially in long-term alcoholics. Inadequate niacin
intake causes pellagra, with symptoms that include intellectual
impairment and dementia. Deficiency caused by vitamin B12
malabsorption in untreated pernicious anaemia, or as a result of a long
term deficient vegetarian diet, can result in subacute degeneration of
the spinal cord, optic nerves, cerebral white matter, and peripheral
nerves. Severely deficient intakes of other vitamins of the B-complex
group also affect neurologic function. In the early stages, these
symptoms are readily overcome by increased dietary intake of the
appropriate vitamins, but nerve damage in later stages are irreversible.
Deficiencies of other nutrients relate to defects in the nervous
system function. Iodine deficiency during brain development causes
mental retardation and neuromotor abnormalities. Chronic iron
deficiency is associated with deficits in cognitive abilities. Vitamin
E deficiency can cause spinal cord, cerebellar, and peripheral nerve
degeneration with muscle wasting.
Stroke
Stroke is the sudden loss of brain function caused by thrombosis,
embolism, stenosis, atherosclerosis, or haemorrhage from rupture of a
cerebral artery. These events deprive the brain of oxygen and cause
tissue death and irreversible damage to nervous tissue. Symptoms range
from those too trivial for the victim to notice to major sensory
deficits, blindness, paralysis, speech loss, coma, and death.
Persons at greatest risk for stroke are those with hypertension and
diabetes, and those who smoke cigarettes and display impaired cardiac
function due to coronary heart disease, congestive heart failure, or
hypertensive heart disease. These major risk factorsfor stroke are
related to nutritional, dietary, and lifestyle factors.
Moderate sodium intake, high potassium intake, vegetarian diets,
calcium, weight reduction, and alcohol restriction all have been
suggested as factors associated with lowering the risk factor for
stroke in humans.
Headache
Headache is one of the most common complaints evaluated by
neurologists. The foods most frequently implicated contain tyramines
(eg. cheese, red wines), or phenylethylamine (eg. chocolates). The
"Chinese Restaurant Syndrome" is associated with numbness around the
mouth, tingling, flushing of the face, dizziness, and headache. This
syndrome could be attributable to the high quantity of monosodium
glutamate (MSG) used in the prepared foods.
Epilepsy
Low levels of magnesium can cause seizures, and the magnesium-deficient rat is used as a model of experimental epilepsy. [Buck,
D.R., Mahoney, A.W., and Hendricks, D.G.: Preliminary report on the
magnesium deficient rat as a model of epilepsy. Laboratory Animal
Science. 28(6),680-85, 1978.] Magnesium deficiency in humans most often results from kidney disease and is not a significant cause of epilepsy in people.
Vitamin Intake and Drug-Nutrient Interactions
Excessive intake of vitamin A causes reversible intracranial
hypertension, headache, blurred vision, seizures, end encephalopathy.
Excessive pyridoxine has been associated with peripheral nerve
deterioration.
Naturally occurring food-borne toxins also affect the mature nervous
system. Specific dietary constituents, such as heavy and trace metals,
may have adverse effects on the nervous systems of older adults.
Increased amounts of aluminum and calcium have been reported in brains
of patients with Alzheimer's disease.
Some of the drugs used to treat neurologic disease can lead to
vitamin deficiencies by changing the metabolism of vitamins, causing a
secondary impairment of brain function. Dilantin, used to treat
epilepsy, can increase folate requirements and cause vitamin K
deficiency. Hydralazine can cause neuropathy, tranquilizers such as
chlorpromazine and other phenothiazines may cause hyperphagia and
weight gain. Monoamine oxidase inhibitors can cause acute hypertensive
crises, including excruciating headaches or fatal intracranial
haemorrhages, when taken with foods or beverages high in tyramine.
Caffeine, found in foods and drugs, is an active pharmacologically
active agent that can enter the brain because of its lipid solubility.
Nutrition Programs and Services
Food Labels:Evidence related to the role of dietary
factors in stroke and other neurologic diseases supports the need for
sodium labeling of packaged food products.
Food Services:Food service programs should emphasize
diets low in sodium and calories to maintain ideal body weight and to
control obesity and diabetes. [The Surgeon General's Report on Nutrition & Health, 1988.]
