More Discoveries About Vitamin A
More Discoveries About Vitamin A
As my regular readers are aware, I firmly believe that vitamin A is one of the most important nutrients, and that it is commonly deficient in people who do not eat liver (any kind of liver: cow, fish, chicken, lamb, goose, etc).
It is well established that “vitamin A is an essential nutrient required for vision, reproduction, cellular growth and differentiation, the immune response, and embryological development.”
Vitamin A, or retinoic acid (RA) as it is referred to in the scientific literature, is utilized, during fetal growth, for the proper development of the central nervous system (CNS), and either too much, or not enough, vitamin A causes a variety of defects in brain patterning.
The body has retinoid receptors in the tissue of a number of organs, including kidneys, liver, lung, spleen, and testes. And in the brain and spinal cord. Not only is vitamin A detected throughout the brain and spinal cord, it is present at relatively higher levels than in other target tissues, “suggesting a vital need for RA in the CNS”.
In fact, there is a higher proportion of RA in the CNS than in the other organs, and even though RA can enter the brain, it is not preferentially transported from the blood to the brain. “Because RA is not transported preferentially to the brain, this tissue likely synthesizes RA more efficiently than other target tissues.” (Study)
Vitamin A and Blue Light
A co-worker turned me on to the work of Dr. Jack Kruse and his thoughts on vitamin A (thanks Carmine). Dr. Kruse believes that vitamin A is designed to work with visible light from the sun only, and that these days it is being forced to work within the spectrum of blue light, due to our overuse of technological devices.
According to Kruse, “this creates massive optical signalling problems in cells. The major collateral damage is in how protons can operate in cells properly”.
Kruse believes that over-exposure to artificial, blue light, along with lack of exposure to sunlight, reduces vitamin A’s effectiveness at doing its jobs. Thus if a pregnant woman falls into this camp, it will have a negative effect on the development of the growing infant’s brain and central nervous system.
As a result (in a forum discussion on vitamin A), Kruse states that “kids with autism always have delayed speech onset”, going on to say, “vitamin A helps humans acquire speech”. (Source)
This concept about the importance of vitamin A in developing speech functions is based on bird studies, which suggest that “RA is not only required for the proper development of the CNS but continues to play a role in the adult CNS as well.”
“Songbird studies examine the effects of retinoid signalling on vocal/auditory learning and are uniquely suited to study the behavioural effects of Vitamin A Deficiency because the neural circuitry of the song system is discrete and well understood. Similar to human speech acquisition, avian vocal learning proceeds in well-defined stages of template acquisition, rendition and maturation. Local blockade of retinoic acid production in the brain or excess dietary retinoic acid results in the failure of song maturation, yet does not affect prior song acquisition. Together these results yield significant insights into the role of vitamin A in maintaining neuronal plasticity and cognitive function in adulthood.” (Study)
Furthermore, the above study also stated that “dietary vitamin A supplementation improves learning and memory in VAD rodents and can ameliorate cognitive declines associated with normal aging”.
And finally, we have a link “between the retinoid signalling pathway and the dopamine signalling pathway. This finding assigns to retinoids an important role in the control of gene expression in the central nervous system.” (Study) (Dopamine is our “feel good” neurotransmitter, and is involved in reward, motivation, memory, attention and even regulating body movements.)
So we need to ensure we have an adequate intake of vitamin A in order to help the developing fetus, and to protect our brains as we age. But we also need to minimize our exposure to blue light, and to increase our exposure to sunlight, in order for vitamin A to work effectively.
Increasing our exposure to sunlight is also an extremely important thing to do. Since I found Dr. Kruse’s material on the subject to be a bit too technical, I will provide this link to a layman’s guide to understanding the wide range of benefits to be gained from exposure to sunlight. (Article)
Vitamin A Deficiency Symptoms
Vitamin A is also essential for mammalian eye development, and is required for the normal functioning of the retina, dim-light vision, and colour vision. Thus, having inadequate amounts of vitamin A available to the retina can result in symptoms of impaired night vision, and reduced colour sensitivity. While impaired night vision is one obvious symptom of vitamin A deficiency, the most common symptom is over-sensitivity to bright light (e.g. squinting on a sunny day).
For those not deficient, I generally suggest ingesting about 50,000 IU of vitamin A weekly. This is roughly the amount found in a serving of cow liver, and thus is an amount that falls within the range of normal human intake.
Those showing symptoms of deficiency would benefit from taking 50,000 IU daily for a week, and then ingesting 50,000 IU per week thereafter (or start eating liver regularly). If they find their eyes again growing sensitive to sunlight, they should up the vitamin A dose until the sensitivity reduces.
For more on the subject of protecting us from the damaging effects of blue light see this previous newsletter of mine.
For a look at blue-blocking glasses and screen covers, check out this review.