MadSci Network: Neuroscience

Re: How does nutrition/junkfood affect the Myelin Sheath?

Date: Tue Jun 5 21:38:02 2001
Posted By: Dian Dooley, , Associate Professor, Food Science and Human Nutrition, University of Hawaii at Manoa
Area of science: Neuroscience
ID: 989988174.Ns

Aloha, Kiriana,

Thank you for asking such an interesting question.  First I think I need to 
say a few words about nutrition and 'junk food.'  I am a nutritionist at 
the University of Hawai`i at Manoa and teach many students each year in our 
introductory nutrition course.  I find it difficult to use the term 'junk 
food' because I don't believe that there really is such a thing (yes, it's 
OK to eat a candy bar now/then...and french fries occasionally are just 
fine).  There can be 'junk diets' because of choice and/or availibility of 
food.  In such a diet, there may be too little of some nutrients (such as 
the vitamins, minerals, protein) or too much of some nutrients (such as 
vitamins, etc.) OR too much of some and too little of is a 
question of balance. 

Now, on to your question.  As you probably already know, the myelin sheath 
is a fatty substance around the 'limbs' (or processes) that sprout off of 
nerve cell bodies, mainly in the brain, but also in the spinal cord.  The 
myelin sheath acts sort of like an insulator to keep messages from 
short-circuiting from one nerve pathway to another.

Since the myelin sheath is made up mainly of fatty tissue, mothers or 
caretakers need to take particular care with the food that they feed 
infants and small children to make sure that they get enough fat in their 
diets.  Did you know that human breast milk contains about 55% of its 
energy in the form of fat?!  That is a very high-fat diet.  What 'Mother 
Nature' is telling us is that infants need a lot of fat...partially to help 
the infant's body complete the development of the myelin sheath.  Babies 
are born with an incompletely developed nervous system, so fat in the diet 
is really important, especially for the first 2-3 years of life.

Now, I don't think any nutritionist, myself included, would recommend a 
diet of 'junk food' (whatever that means) for an infant (breast milk for 
the first 6 months is the recommendation).  But, what about a 
less-than-perfect diet for older children, adolescents and adults.  Will 
that affect the myelin sheath?  Once the sheath is formed, the body will do 
what it can to maintain that sheath. Also, your brain is quite well 
protected from outside influences.  Since it is essential to life, isn't 
this the way the body should be designed?...if you were doing the 

Thus, some fat in the diet is used to keep the myelin sheath healthy.  When 
the sheath starts to deteriorate, like in the disease multiple sclerosis, 
all kinds of strange things begin to happen to a person's ability to 
function.  However, there is little/no evidence that diet plays any major 
role in the development of multiple sclerosis.  We think that something 
goes wrong with the body's recognizing itself, in multiple sclerosis...and 
the body begins to destroy its own myelin sheath.

As a last comment, a nutritionally balanced and varied diet, with enough 
energy to allow growth is what we recommended.  What that means in terms of 
foods (we don't eat nutrients, really) is choosing well from an eating guide 
like the Food Guide Pyramid and eating according to when your body tells 
you to eat...when you're hungry...and stopping when your body tells you it 
has had enough.  For a growing, active young person, that allows for 
occasional treat foods that may be high in energy and even high in fat 
(like candy bars, french fries, chips, ice cream, etc.).

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