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Information for patients, their families and helpers

Diet: Phytanic acid and phytol

These two substances are very important for adult Refsum's disease patients, so it's worth having a look at what the terms mean.

Phytanic acid

Phytanic acid is dangerous to adult Refsum's disease patients, because it accumulates in their bodies. Foods containing phytanic acid must be avoided in the diet.


Phytol is a chemical which can be changed into phytanic acid in the body - so it too can be dangerous to adult Refsum's disease patients.

However, when looking at diet it is important to distinguish between bound phytol and free phytol.

Bound phytol

Most phytol in food is bound - meaning that it is not absorbed by the human body, and so does not cause any harm. It has now been shown that the phytol in green foods, for example, is bound to chlorophyll and is not absorbed. This means that all fruits and vegetables can be eaten by adult Refsum's disease patients.

Free phytol

Free phytol can be changed into phytanic acid in the body, so adult Refsum's disease patients should avoid taking it in the diet. Little information on the free phytol in food has been available, but recent analyses of a range of foods have found none in meat and small amounts in foods of plant origin. Provided no one food is eaten in large quantities there are no grounds at present for avoiding any food because of its free phytol content.

(The previous section, 'Adult Refsum's disease - the facts', gives further information about phytanic acid and phytol.)

The rest of this section looks at what all this means in practise.

Next: Basic principles

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Page last updated 26 June 2006