The intriguing proposal first came up at the recent Nutrition 2018 conference. During a carotenoid-centric symposium, University of Georgia (UGA) professor Dr. Billy Hammond made his case for lutein's beneficial effect on the hearing of humans.
Many studies have shown that carotenoids interact with the human eyes. In contrast, the body of scientific literature that covers their connection with the human ears is much more sparse.
Hammond is very familiar with lutein's effects on the brain. He is the author of a 2014 study that showed the optical density of macular pigments are linked to general cognition in people who suffer from mild cognitive impairment (MCI).
The macula are circular areas in the center of the retina of human eyes. They are responsible for visual acuity. They also contain plenty of pigments like lutein and zeaxanthin, which can be analyzed to measure the amounts of each carotenoid in the body.
Published in the journal Neurobiology of Aging, the 2014 study reported that low levels of these two carotenoids are linked to lower cognition in participants with MCI. Meanwhile, macular pigment optical density only affected visual-spational and constructional abilities in healthier adults. (Related: Lycopene is found in a variety of fruits, offering an array of antioxidant carotenoid benefits.)
Hammond also published another study about lutein and zeaxanthin in the 2017 issue of the journal Nutritional Neuroscience. His more recent paper investigated the possible connections between the two carotenoids and the human auditory system.
"This work began by noting that lutein is throughout the central nervous system," Hammond explained in an interview. "Early work looked at how much of it was in the retina, but then it was found throughout the brain, and also specifically in the auditory cortex."
The auditory cortex is the part of the brain that processes sounds and other auditory information. It can distinguish between signals and noise in order to interpret each individual sound. Some theories link this part of the brain to some forms of higher thinking, such as translating other languages.
This and other parts of the brain appear to be improved by dietary carotenoids. Improvements to visual acuity and brain power are apparently mediated by the amount of lutein and zeaxanthin in the macula and other important parts of the retina and brain.
Hammond theorized that the carotenoids raise the efficiency of neurons in the brain, making them significant factors in brain power. Lending support to his theory was the discovery that both lutein and zeaxanthin are found in the auditory cortex.
The findings of the 2017 study showed that the levels of lutein and zeaxanthin pigments are connected to the proper and optimal function of the auditory system.
Carotenoid specialist Dr. Elizabeth Johnson of Tufts University was at the symposium when Hammond made his presentation. She was excited about the unexplored region of new research on carotenoids that the UGA study uncovered.
Johnson said that she and her fellow researchers first studied carotenoids for their beneficial effects on visual acuity. Never did she think that her research would lead her to human cognition and now the auditory system as well.
If you want to know more about how carotenoids and other nutrients can improve your senses, visit Nutrients.com today.