Adhering to healthy diets may prevent hearing loss, US research team finds

20 Nov 2019 --- Hearing loss is not just an inevitable part of the aging process, finds a longitudinal study conducted at Brigham and Women’s Hospital in Boston, US. Examining more than 3,000 women, the study found that changing lifestyle and dietary patterns may help reduce the risk of hearing loss. The researchers recommended adhering to a Mediterranean-style diet to include more direct sources of omega 3, protein and vitamins provided by higher consumption of fresh produce, legumes, whole grains and fish.

“In our research, we previously found that higher intakes of specific nutrients and certain foods, such as the carotenoids beta-carotene and beta-cryptoxanthin, folate, long-chain omega 3 fatty acids and fish, were associated with lower risk of self-reported hearing loss. These findings revealed that dietary intake could influence the risk of developing hearing loss,” Dr. Sharon Curhan, Physician and Epidemiologist at Brigham and Women’s Hospital, tells NutritionInsight.

This research found that people already in the 50s and 60s are experiencing hearing loss.Hearing damage can occur due to compromised blood flow to the cochlea, the main organ of hearing in the inner ear, injury from not receiving enough oxygen, oxidative damage, inflammation and neurodegeneration along auditory pathways, she explains.

Healthier diets may influence these processes and protect against hearing loss by a number of mechanisms. These include protection against oxidative damage, promotion of beneficial blood lipids, better endothelial function, lower blood pressure and less inflammation.

Research parameters
In a previous longitudinal study among around 71,000 women in the Nurses’ Health Study II (NHS II), study participants adhering to the Dietary Approaches to Stop Hypertension (DASH) and Alternate Mediterranean (AMED) diets and higher scores on the Alternate Healthy Eating Index (AHEI-2010) were associated with a nearly 30 percent lower risk of self-reported moderate or worse hearing loss. In tests conducted on higher frequencies, the odds were up to 25 percent lower. 

“These findings prompted us to investigate whether adherence to these healthy diets is related to longitudinal changes in pure-tone hearing thresholds measured by clinical audiometry, the gold standard of hearing assessment,” says Dr. Curhan. In this study, she and her colleagues found that adhering to these healthful diets were independently associated with a lower risk of a three-year audiometric hearing threshold decline.

The benefits of DASH, AMED and AHEI-2010 diets
Outside of the study’s research parameters, greater adherence to the DASH, AMED and AHEI-2010 diets are associated with a lower risk of major chronic diseases and mortality, besides hearing loss, Dr. Curhan emphasizes. The DASH diet is characterized by higher consumption of fruits, vegetables, nuts, seeds, legumes, lean meats, fish, poultry, low- or non-fat dairy and lower consumption of sweets, saturated fats, and sodium. The AMED diet recommends a hierarchy of food groupings, namely vegetables (excluding potatoes), fruits, nuts, whole grains and olive oil in particular, to form the base of the pyramid and biweekly fish consumption as well as regular but moderate alcohol intake. 

A Mediterranean diet consists of fresh fruits and vegetables, legumes, whole grains, nuts, moderate to high consumption of fish and extra virgin olive oil.Similar to AMED and DASH, the AHEI-2010 advocates higher intakes of vegetables, fruit, and lower intakes of sodium, added sugar, and saturated fat is a diet quality measure. This diet recommends a high consumption of whole grains, protein sources, alcohol intake and avoiding sugar-sweetened beverages. These factors combined provide a lower risk of cardiovascular disease, diabetes, cancer and other major chronic diseases. 

Research continues to provide science-backed evidence for the benefits of maintaining a Mediterranean diet. A recent study found that it is considered the most effective diet to prevent cognitive impairment. Other research has highlighted that the plant-based elements of a Mediterranean diet aid the biosynthesis of essential nutrients and the production of short-chain fatty acids, the main source of energy for cells lining the colon. A high intake of unrefined grains and legumes, extra virgin olive oil, fresh produce and regular fish consumption has also been found to support pregnant mothers reduce excessive weight gain reduction as well as their risk of gestational diabetes. 

Hearing decline over short periods of time
With the mean age of the women in the study reaching 59 years, Dr. Curhan notes that most participants were in their 50s and early 60s, a much younger age than when many people think about having their hearing checked. Moreover, she says she was “surprised” that so many women demonstrated hearing decline over such a relatively short period of time. 

Wearing protective gear when confronted with noise pollution helps prevent hearing loss and damage, says Dr. Cunhan.“After only three years, 19 percent had hearing loss in the low frequencies, 38 percent had hearing loss in the mid-frequencies, and almost half had hearing loss in the higher frequencies. Despite this considerable worsening in their hearing sensitivities, hearing loss among many of these participants would not typically be detected or addressed.”

How else can hearing loss be prevented?
Adhering to a healthy diet is not the only way patients can help support hearing health, says Dr. Curhan. “Our research has shown that maintaining a healthy weight, staying physically active, not smoking, limiting the use of over-the-counter pain relievers such as ibuprofen and acetaminophen and moderating the duration of use of oral post-menopausal hormone therapy, may also be helpful in maintaining hearing health.”

She also notes that several environmental factors can contribute to the development of hearing loss and hearing damage. As people are increasingly exposed to considerable noise pollution, it is imperative to raise awareness and support efforts to promote safe listening practices, she says. These include limiting earphone use to safe levels, moderating noise levels at sports and entertainment venues and using hearing protection when indicated.

By Anni Schleicher