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How fish could save your hearing

Eating omega-3 fatty acids and fish can reduce the rate of hearing loss.

Although we may joke about men’s selective hearing, the reality is that hearing loss is no joking matter; it’s second only to arthritis as a handicapping condition, according to a 2010 study in Hearing Research. Worse still, it increases the risk of death, according to a 2010 study in the Annals of Epidemiology. And chances are you know someone who has hearing loss, as about 30% of people over 65 have it.

We can’t halt ageing or avoid a genetic predisposition to hearing loss, but we can lower our risk of hearing loss by reducing our exposure to noise. What’s more, research evidence is emerging that a healthy diet may reduce the risk of hearing loss and of existing hearing loss worsening.

In the early 1990s the US Framingham study, which followed a cohort of 1662 adults, found a moderate association between cardiovascular disease events and hearing loss. Shortly after that, the Epidemiology of Hearing Loss Study (EHLS) in Beaver Dam, Wisconsin, reported that adults with cardiovascular disease were 52% more likely to have hearing loss. Exactly how cardiovascular disease might be related to hearing loss bears further explanation.

Most hearing loss in older adults is thought to originate from the cochlea in the inner ear. The cochlear is highly vascular – it has lots of blood vessels – and is supported by a single artery. However, in animal models disrupting the blood flow to the cochlea has been shown to damage it. Theoretically, then, a decrease in the blood supply to the cochlea as a result of cardiovascular disease could cause hearing loss.

Vascular health can be optimised by including fish in the diet. Longchain omega-3 fats, which fish are rich in, reduce the risk of heart disease by promoting a healthier blood-cholesterol profile and reducing inflammation, among other things. Australian researcher Vicki Flood, speaking in Queenstown in December at the Joint Scientific Meeting of the Nutrition Society of New Zealand and the Nutrition Society of Australia, explained that these properties of long-chain omega-3 fatty acids might also be beneficial for hearing, because they help ensure the cochlear gets the vascular supply it needs.

The Australian Blue Mountains Hearing Study, of which Flood is a team member, assessed dietary intake and measured hearing loss in a cohort of 2956 adults aged 50 and over from 1997-1999 and from 2002-2004. Around 32% of the cohort had, or developed, some degree of hearing loss. The Australian study found that both total dietary intake of omega-3 fatty acids and consumption of fish were associated with a reduced risk of developing hearing loss, with participants who consumed two or more servings of fish a week having a 42% lower risk of developing hearing loss, according to Flood, whose team published their findings in 2010 in the American Journal of Clinical Nutrition.

And for those with existing hearing loss, all may not be lost; the study also found that consuming one to two serves of fish a week was associated with a 47% reduced risk of hearing loss progressing – an important point, given existing hearing loss in older adults is highly likely to worsen with time.

Further research, including clinical trials, is required before we can definitively say that eating fish will help prevent hearing loss. Still, given the theoretical relationship between fish intake and hearing loss makes sense, and that including fish in a healthy diet will benefit heart health, why wait for more research? Why not make fish meals a weekly event in 2012?