(Reuters Health) - Another benefit of a healthy diet may be protection against age-related hearing loss, suggests a large study of U.S. women.
Researchers followed more than 80,000 women for 26 years and found those whose diets scored highest for health and quality were up to 47 percent less likely to experience moderate or severe hearing loss than women with the lowest dietary scores.
?Although hearing loss is thought to be an unavoidable companion to aging, findings from our research have highlighted a number of dietary factors that can be modified and may reduce the risk of hearing loss,? said lead author Dr. Sharon Curhan of the Channing Division of Network Medicine at Brigham and Women?s Hospital and Harvard Medical School in Boston.
Some 48 million people in the U.S. have hearing loss, Curhan and her colleagues write in The Journal of Nutrition. This loss can have devastating effects by diminishing a person?s ability to communicate, which often leads to social isolation. Hearing loss has also been tied to worsening work productivity and cognitive function, as well as depression, the authors note.
Past studies have suggested that vitamins, minerals or fatty acids might influence hearing health, the study team writes. But to see whether overall dietary pattern makes a difference, Curhan?s team analyzed data on 81,800 women who were between the ages of 25 and 42 when they enrolled in the Nurses? Health Study II in 1989.
The researchers focused on hearing assessments done in 2009 or 2013 and on dietary questionnaires the participants had completed every two years during the study period. The women?s diets were rated according to how closely they matched each of three healthy-eating criteria: the Alternate Mediterranean Diet (AMED), the Dietary Approaches to Stop Hypertension (DASH) and the Alternative Healthy Eating Index (AHEI).
All of these dietary guidelines provide a way of scoring diet quality. All three award points for diets high in vegetables, fruits, whole grains, nuts and legumes and low in processed meats, sugar and salt. The Mediterranean diet also emphasizes eating lots of fish and olive oil, while the DASH diet focuses on keeping sodium low and fiber intake high, the authors note.
Comparing women with the highest-scoring diets to those with the lowest scores, the study team found that high scorers on the AMED were 30 percent less likely to have moderate or severe hearing loss by the end of the follow-up period and high scorers on DASH had 29 percent lower risk. The researchers didn?t find a statistically meaningful difference with adherence to the AHEI over the full study period.
But when they analyzed a smaller group of 33,102 women who had data on medical conditions that could cause hearing loss, the importance of all three diet scores increased: high scores on AMED came with 47 percent lower risk of hearing loss, a high DASH score carried 46 percent lower risk and a high AHEI score carried 29 percent lower risk.
The researchers note that the information on both diet and hearing loss was reported by the study participants, rather than measured directly. The study was also not a controlled experiment designed to prove whether or how diet might affect hearing.
The authors note, however, that there are many possible mechanisms by which a healthy diet can be protective, including preserving blood vessel health and reducing inflammation, and certain nutrients might also directly protect auditory nerves.
?Having good, strong vascular health will keep blood flow to the inner ear and reduce oxidative stress,? said Dr. Christopher Spancovich, an auditory specialist at the University of Mississippi Medical Center in Jackson who was not involved in the study.
?And healthy diets rich in micronutrients help the ear defend itself against exposure to free radicals protecting the inner ear,? he told Reuters Health in a telephone interview.
Dietary health is important for our auditory health, which requires good blood flow to function normally, and foods contribute to this blood flow - for better or for worse, he said. ?How much of a role does diet play? We?re not sure just yet.?