Food and Behaviour Research

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Sleep and Diet: Why Sleep Matters for Wellbeing and its Links with Nutrition - BOOK HEREE

Niacin skin test response in dyslexia

Cyhlarova E, Montgomery P, Ross MA, Richardson AJ. (2007) Prostaglandins Leukot Essent Fatty Acids 77(2): 123-8 

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The niacin skin test reflects a flush and oedema owing to the production of prostaglandin D2 from arachidonic acid. A diminished response may indicate abnormalities in the phospholipid metabolism, which has been shown in schizophrenia.

There is evidence that dyslexia might also involve phospholipid abnormalities, therefore we examined the skin response in 51 dyslexics and 45 controls. Four concentrations of aqueous methyl nicotinate were applied topically to the forearm. Flushing was rated using a seven-point scale at 3 min intervals over 21 min.

Repeated measures ANOVA for the four concentrations across all seven time-points showed no significant effect of subject group, but when analyses were confined to the first 9 min, flushing was reduced in dyslexics. Significant group differences were also found for the lowest niacin concentration (0.0001M) across six out of seven time-points. The results indicate a slightly reduced and delayed response to niacin in dyslexia.


The niacin skin test assesses the normal flushing response that occurs when niacin (Vitamin B3) is applied to the skin.  By using varying concentrations of niacin, and observing the responses every 3 minutes over a 21 minute period, an index of sensitivity to niacin can be obtained.

The skin flushing response to niacin depends on the conversion of Arachidonic Acid (AA) - a key Omega-6 fatty acid - to Prostaglandin D2 (PGD2) in the skin.  Reduced flushing would therefore be expected either if AA stores were unusually low, or if the metabolic pathway for converting AA to PGD2 were inefficient for any reason.

Reduced flushing to niacin has been reported in some patients with schizophrenia, consistent with reports of low blood AA in at least a subset of people with schizophrenia.

However, the significance of the current findings awaits further investigation, as very little is currently known about fatty acid status or metabolism in dyslexia and related conditions.