Written by Greg Arnold, DC, CSCS. Folic acid-deficient mice had hearing loss and inflammation in the inner ear while mice fed a standard diet containing folic acid had no hearing loss. Folic acid-deficient mice also had homocysteine levels that were 50% higher than standard diet-fed mice.
According to the World Health Organization, moderate-to-profound hearing loss affects over 360 million people worldwide (1) with a few reports suggesting a role for nutritional status in premature hearing impairment (2, 3, 4).
In a 2015 study (5), 130 2-month old mice were either a folic acid-deficient diet (< 0.1–0.2 milligrams per kilogram of bodyweight* as used in previous research (6, 7) = 65 mice) or a standard diet (65 mice) for 8 weeks after which those fed the folic acid-deficient diet “exhibited severe hearing loss” compared to the standard diet. Specifically, cell death (called “apoptosis”) was three time higher in ear canal tissue samples of the folic acid-deficient mice compared to the standard diet mice (p < 0.05). Cell death was greatest in an area of the ear called the cochlea (p < 0.001), an area of the inner ear shaped like a snail shell which transmits sound waves through the ear.
In addition, mice in the folic acid-deficient group also showed much more inflammation in the cochlea compared to the standard diet mice. Specifically, there were 50% higher homocysteine levels in the folic acid-deficient mice (p < 0.05).
For the researchers, “insufficient folic acid intake induces severe impairment of cochlear homocysteine metabolism, along with a profound [cell damage], ultimately leading to hearing loss” and that “targeting homocysteine metabolism by nutritional intervention could be a novel pathway to achieve therapeutic protection against hearing loss.”
* 0.15 mg/kg in mice is equivalent to 850 mcg for 154 lb person. The RDA is 400 mcg for adults.
Source: Martínez-Vega, Raquel, et al. “Folic acid deficiency induces premature hearing loss through mechanisms involving cochlear oxidative stress and impairment of homocysteine metabolism.” The FASEB Journal 29.2 (2015): 418-432.
0892-6638/15/0029-0001 © FASEB
Posted February 26, 2015.
References:
- Li-Korotky, H. S. Age-related hearing loss: quality of care for quality of life. Gerontologist 2012; 52:265–271
- Emmett, S. D., and West, K. P., Jr. Gestational vitamin A deficiency: a novel cause of sensorineural hearing loss in the developing world? Med. Hypotheses 2014;82:6–10
- Attias, J., Raveh, E., Aizer-Dannon, A., Bloch-Mimouni, A., and Fattal-Valevski, A. Auditory system dysfunction due to infantile thiamine deficiency: long-term auditory sequelae. Audiol. Neurootol 2012; 17:309–320
- Karli, R., G¨ ul, A., and U˘gur, B. Effect of vitamin B12 deficiencon otoacoustic emissions. Acta Otorhinolaryngol. Ital 2013; 33:243–247
- Martínez-Vega R Folic acid deficiency induces premature hearing loss through mechanisms involving cochlear oxidative stress and impairment of homocysteine metabolism. FASEB J. 2015 Feb;29(2):418-32. doi: 10.1096/fj.14-259283. Epub 2014 Nov 10
- Maestro-de-las-Casas, C., P´erez-Miguelsanz, J., L´opez-Gordillo, Y., Maldonado, E., Partearroyo, T., Varela-Moreiras, G., and Mart´ınez-´Alvarez, C. Maternal folic acid-deficient diet causes congenital malformations in the mouse eye. Birth Defects Res. A Clin. Mol. Teratol 2013; 97, 587–596
- Maldonado, E., Murillo, J., Barrio, C., del R´ıo, A., P´erez-Miguelsanz, J., L´opez-Gordillo, Y., Partearroyo, T., Paradas, I., Maestro, C., Mart´ınez-Sanz, E., Varela-Moreiras, G., and Martinez-Alvarez, C. Occurrence of cleft-palate and alteration of Tgf-b(3) expression and the mechanisms leading to palatal fusion in mice following dietary folic-acid deficiency. Cells Tissues Organs (Print) 2011; 194, 406–420
