Folic Acid Protects Hearing

WAGENINGEN, Netherlands—Folic acid supplementation helps retain hearing in folate-deficient older adults, according to new research from The Netherlands (Ann Intern Med, 146, 1:1-9, 2007). In a study coordinated through Wageningen University and University Hospital Maastricht, 728 older men and women (50 to 70 years old) with no middle ear dysfunction, unilateral hearing loss or pathologic ear conditions unrelated to hearing were recruited to receive 800 mcg/d folic acid or placebo for three years. Baseline measurements of homocysteine were 13 µmol/L or greater and vitamin B12 concentrations were at least 200 pmol/L; at the time of the study, there was no folic acid fortification of food in The Netherlands. Changes in hearing thresholds were assessed for low (0.5-kHz to 2-kHz) and high (4-kHz to 8-kHz) frequencies.

After three years, thresholds of the low frequencies increased by 1.0 dB in the folic acid group and by 1.7 dB in the placebo group; folic acid supplementation did not affect the decline in hearing high frequencies. The researchers concluded folic acid supplementation slowed the decline in hearing in a population without folic acid fortification of food.