 A 2021 scoping review on the role of nutrition in the development and prevention of age-related hearing lost screened thousands of papers and concluded that diets rich in saturated fats and cholesterol have deleterious effects on hearing that could be prevented by lower consumption. The case of the Mabon noted before makes for a compelling story, but on what exactly are they basing their conclusion? It's true that in laboratory animals you can prove it, randomized rats to added saturated fat or chinchillas to added dietary cholesterol, scientists can show atherosclerosis-inducing diets exacerbate inner-ear damage and hearing loss, even without noise exposure. But that doesn't necessarily mean the same is true in people. There is coach in epidemiological data, for example, study of thousands of twins was able to draw significant length between a high-cholesterol diet and hearing impairment. In the Blue Mountains hearing study, which enrolled thousands of older men and women to study age-related hearing loss, dietary cholesterol was the nutrient component most associated with hearing loss. Those eating about two eggs worth of cholesterol a day had 34% greater odds of hearing loss compared to those only getting about a single egg's worth. Consistent with a vascular caused those on statins, and particularly those at higher doses, appeared to be at lower risk. The researchers suggested high cholesterol then taken to interfere with the circulation within the inner ear itself or atherosclerotic inflammatory changes could reduce blood flow to the tiny arteries feeding the inner ear. But how about looking inside the arteries to see if this is actually true? The extent and severity of coronary artery disease in the heart, as determined by Angiogram, was found to closely correlate to hearing loss, since atherosclerosis is a systemic disease affecting the entire arterial tree. This has relevance for the arteries feeding the inner ear. The same was found for the amount of atherosclerotic plaque found in the crotted arteries in the neck, the greater the plaque, the poorer the hearing, and the more plaque they found the greater risk of further hearing impairment, measured over the subsequent five years. Getting closer, but how about the arteries that directly supply the inner ear? Early autopsy data suggested sclerotic changes in the blood vessels of older ears contribute to inner ear degeneration, and these days, direct imaging studies correlate the degree of hearing loss with atherosclerotic narrowing of those inner ear arteries. Now all we need is an interventional trial to wrap it all up in a bow. Yes, high cholesterol and high saturated fat diets have been shown to kill off those critical inner ear cells and cause hearing loss in lab animals. But it's not like you can lock hundreds of people up for a few years and force them to eat different amounts of saturated fat and see what happens to their hearing. Oh, but you can, and they did. The Finnish Mental Hospital Study In 1960, one of two mental hospitals near Helsinki had their menus changed to decrease their intake of saturated animal fat. Then, after a few years, the two hospitals switched their menus over. It was one of the first interventional trials of its kind suggesting that you could decrease heart disease deaths by decreasing saturated fat intake. Ah, but what happened to their hearing? It followed the exact same pattern. As their heart disease got worse, so did their hearing. And then when the hospital switched, the reverse happened. And not just by a little. Those in their 50s in the lower saturated fat hospital ended up with significantly better hearing than the group in the control hospital that was 10 years younger. The researchers concluded our audiological studies lead us to conclude that diet is an important factor in the prevention of hearing loss.