Loughborough University researchers wanted to know if docosahexanoic acid (DHA), a polyunsaturated fatty acid found in fish oils, improves the ability to adapt to darkness – the process the eyes go through when adjusting to new light conditions.

DHA, which is found in mackerel, herring, tuna, and halibut, is known to be found in high concentrations in the retina, but is not synthesized in the body.

During the trials, a group of 19 participants were asked to identify a series of numbers of decreasing brightness that were displayed to them on a hand-held measuring device – the results were recorded.

They then took four omega-3 tablets a day for four weeks – each tablet contained 260 mg of DHA and 780 mg of EPA (another fatty acid that is converted into DHA).

After the one month dosing period, they revisited the labs and repeated the same test.

The researchers found that, on average, people could identify images that were 25% weaker the second time around – after the course of the fish oil.

Six weeks after completing the supplements, her night vision returned to its original level.

The main authors Dr. Paul Kelly and Dr. Jim Reynolds of the School of Science said that by analyzing blood levels before, during, and after the analysis, the team was able to directly link fatty acid levels in the body to changes in vision.

Dr. Kelly said:

This is the first time that dark adaptation has been linked to the fatty acids in fish oil by directly measuring the amounts that enter the blood.

The rise and fall in acid levels reflects the rise and fall in visual acuity.

You can imagine that this finding will benefit anyone who needs the best possible night vision – police, military personnel, forensic scientists looking for fluorescent evidence in the dark, for example.

The 25% figure represents a significant improvement in a person’s skills, especially given that it is done through a simple supplementation program.

Ideally, the next phase of this work is to expand the number of people tested in this way – in addition to placebos – to provide a larger data set for analysis.

It would also be interesting to investigate to what extent food, in contrast to dietary supplements, can provide enough of the acids required and whether the maintenance of the effects can be monitored via the simple hand-held measuring device, which reduces the need for blood tests. “

The paper that provides information on the effect of fish oil supplementation on adaptability to darkness is a pre-printed form and was published online at ChemRxiv.org.


Journal reference:

B. McMurchie et al. (2019) Shedding light on the effect of fish oil supplementation on the ability to adapt to darkness. ChemRxiv. https://chemrxiv.org/articles/Shedding_Light_on_the_Effect_of_Fish_Oil_Supplementation_on_Dark_Adaptation_Capabilities/11302613/1.


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