Food and Behaviour Research

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Docosahexaenoic Acid Explains the Unexplained in Visual Transduction

Crawford MA, Sinclair AJ, Wang Y, Schmidt WF, Broadhurst CL, Dyall SC, Horn L, Brenna JT, Johnson MR (2023) Entropy 25(11) 1520; 

Web URL: Read this paper via the Entropy journal here - Free full text is available online


In George Wald’s Nobel Prize acceptance speech for “discoveries concerning the primary physiological and chemical visual processes in the eye”, he noted that events after the activation of rhodopsin are too slow to explain visual reception.

Photoreceptor membrane phosphoglycerides contain near-saturation amounts of the omega-3 fatty acid docosahexaenoic acid (DHA). The visual response to a photon is a retinal cis–trans isomerization. The trans-state is lower in energy; hence, a quantum of energy is released equivalent to the sum of the photon and cis–trans difference.

We hypothesize that DHA traps this energy, and the resulting hyperpolarization extracts the energized electron, which depolarizes the membrane and carries a function of the photon’s energy (wavelength) to the brain.

There, it contributes to the creation of the vivid images of our world that we see in our consciousness.

This proposed revision to the visual process provides an explanation for these previously unresolved issues around the speed of information transfer and the purity of conservation of a photon’s wavelength and supports observations of the unique and indispensable role of DHA in the visual process.


This remarkable new study from Professor Michael Crawford and colleagues unlocks a longstanding scientific mystery, showing exactly

  • why omega-3 DHA is simply critical for vision (and brain signalling more generally), and
  • how this unique molecule enables the extraordinarily rapid AND accurate transmission required

This new article also complements another recent and equally important paper 

This summarises a wealth of data showing the critical importance of the long-chain omega-6 fat, Arachidonic Acid (known as AA or ArA). 

This omega-6 fatty acid is often unfairly 'demonised' in overly-simplistic messaging about the importance of dietary fats for health 
(because just some of its numerous derivates are involved in promoting inflammation, blood clotting and other vital functions which - in excess, i.e. relative to the long-chain omega-3 DHA and EPA - can contribute to many systemic physical and mental health conditions).


BOTH omega-3 DHA AND omega-6 AA are essential for healthy brain development and function (as well as physical health and development). The key issue is that we need them in the right balance.

The diets on which humans first evolved as 'Homo Sapiens' ensured adequate - and balanced - supplies of these essential fats, as well as other 'critical brain nutrients'. And so have all traditional or 'ancestral' diets ever since then (despite these varying in many other ways to suit different local environments) - until the industrialisation of our food supply.

By contrast, modern, 'western-type' diets lack omega-3 DHA in particular (although plant-based diets also lack omega-6 AA 'ready-made')

This new book by Crawford and Marsh explains the consequences, and the stark implications for the actual survival of humanity unless urgent steps are taken to ensure that the foods we eat actually meet the basic nutritional requirements of the human brain and nervous system: