Shedding Light on the Effect of Fish Oil Supplementation on Dark Adaptation Capabilities

Abstract:

Docosahexanoic acid (DHA) is a polyunsaturated fatty acid found in fish oils which is known to be present in high concentrations in the retina. Dark adaptation is the process the eyes go through when moving between environments with differing light levels. While the correlation between levels of DHA and the dark adaptation ability of dyslexic individuals has previously been investigated, a link between DHA and dark adaptation in the general population has not thus far been established.

In this study, 19 individuals took fish oil supplements for four weeks, then abstained for the following six weeks. DHA levels were monitored via GC-MS analysis of fingertip prick blood samples and showed the expected increase and subsequent decrease during the two phases. Dark adaptation ability was monitored using the Crime-lite Eye™ hand-held system; after the supplementation phase, dark adaptation ability was shown to improve in the majority of participants. Immediately following the wash-out period, dark adaptation ability effectively reverted back to its original level.

These data suggest that blood DHA levels can affect the ability of an individual to dark adapt, and confirms that any changes in  dark adaptation ability caused by the fatty acid are rapidly reversible when DHA levels are returned to normal