Higher folate levels recently linked to reduced risk of hearing loss

I have mentioned folate a lot in my blog posts but mainly in relation to women, especially pregnant women. However, recent research presented at the at the 2009 American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) Annual Meeting & OTO EXPO, in San Diego, CA(1) has found that high folate intakes in men may be associated with a 20% decreased risk of hearing loss.

The study(1) involved 3,559 cases of men with hearing loss. The study authors found that men over the age of 60 who have a high intake of foods and supplement high in folate had a 20% decrease in risk of developing hearing loss. The authors believe this is the largest study to delve into the relation between dietary intake and hearing loss. They also believe their findings could allow for greater education, prevention, and screening efforts in a bid to prevent hearing loss. Further studies would certainly be necessary as this study only shows an association and not cause and effect.

Ten years ago a small study in women (2) found that poor folate levels were associated with age-related decline in hearing. The study was conducted in 55 healthy women aged 60-71. The women were tested for hearing function and categorised into two groups – those with normal hearing and those with impaired hearing. Women with impaired hearing had a 31% lower blood level of folate than women with normal hearing. In addition to this study a couple of years ago a research team (3) found that folic acid supplementation seemed to slow the decline of low-frequency hearing in folate-deficient, older adults. The objective of this study was to determine whether folic acid supplementation slows age-related hearing loss. 728 men and women were involved. Subjects received daily oral folic acid (800 micro-grams) or placebo supplementation for 3 years. Folic acid supplementation slowed the decline in hearing of the speech frequencies associated with aging in a population (but did not affect the decline in hearing high frequencies). The authors note that the results need to be replicated in further larger studies but that folic acid supplementation seemed to slow the decline of low-frequency hearing in folate-deficient, older adults.

Folic acid may be playing a role in the prevention of age-related hearing loss by improving blood circulation to the artery that supplies blood to the cochlea of the ear. In addition, folic acid is also related to lowering elevated homocysteine levels. Elevated homocysteine could be related to age-related hearing loss. Most people are aware that high levels of homocysteine in the blood have been linked to an increased risk of heart problems. Recently high homocysteine levels have also been linked to poor bone health, poor eye health (such as age-related macular degeneration) and other health problems. To recap from my past blog posts: Homocysteine is produced when the amino acid (the building blocks of protein) methionine is broken down in the body. Normal levels of homocysteine are important to help build and maintain body tissues, however elevated concentrations in the blood can be harmful and have been associated with an increased risk of many disorders. At normal levels homocystein can be converted in the body into a harmless substance called cystanthionine. The conversion of homocysteine into this harmless substance depends upon various B vitamins (B6, B12 and folic acid). Having good levels of these B vitamins appears to be a very good way of preventing high homocysteine levels and low levels of B vitamins have been associated with raised homocysteine levels.

Foods particularly rich in folate include leafy vegetables such as spinach, asparagus, turnip greens, lettuces, dried or fresh beans and peas, fortified cereal products, sunflower seeds, yeast extract, liver and liver products. Vitamin B6 is mainly found in meat, fish and eggs. Vitamin B12 is found in liver, meats, eggs, milk and yeast extract.

Vegetarians and vegans and those who feel they are not eating a varied, balanced diet may wish to consider taking a multiple B vitamin supplement to ensure good levels of these important B vitamins

(1)American Academy of Otolaryngology — Head and Neck Surgery (2009, October 6). Higher Folates, Not Antioxidants, Can Reduce Hearing Loss Risk In Men. ScienceDaily. Retrieved October 6, 2009, from http://www.sciencedaily.com/releases/2009/10/091005161116.htm
(2)Houston DK et al. 1999. Age-related hearing loss, vitamin B-12, and folate in elderly women. American Journal of Clinical Nutrition. 69(3):564-571.
(3) Durga J et al. 2007. Effects of folic acid supplementation on hearing in older adults: a randomized, controlled trial. Ann Intern Med. 146(1):1-9.
Written by Ani Kowal