Healthier diets are associated  with a significantly 

lower risk of hearing loss,

and for all three diet quality scoring systems these researchers used,

avoidance of meat was most strongly associated with lower risk.

The Mabaan from my last video, who preserved their hearing into old age,

ate little meat, but also weren't eating sugary junk,

explaining their almost total absence of dental cavities.

A high glycemic diet of refined carbs

is also associated with developing age-related hearing loss.

If it's the blood sugar spikes, that would explain why diabetics

and prediabetics are also at higher risk.

Even among whole grains, sorghum, which is the center of the Mabaan diet,

has a particularly low glycemic index due to its resistant starch content,

causing about a 25 percent lower rise in blood sugar compared to whole wheat.

Impaired blood circulation may also explain how noise

damages the inner ear, as loud noises

cause constriction of the accompanying blood vessels.

This may also help clarify the link between obesity and hearing loss.

Excess weight may just be a proxy for unhealthier diets,

but the pro-inflammatory state of obesity can itself lead to vascular dysfunction.

Measures of systemic inflammation seem to directly correlate

with age-related hearing loss, as do measures of oxidative stress.

In my video on brain inflammation, I introduced

the antioxidant defense activator Nrf2,

called “guardian of healthspan and gatekeeper of species longevity.”

Those born with a genetic variant Nrf2 that doesn't encode as well

are significantly more likely to develop impaired hearing,

implicating the role of free radicals in the process of hearing loss.

You can look in the back of people's eyes and measure the amount of macular pigment—

the lutein and zeaxanthin antioxidants concentrated in greens—

and correlate that with superior hearing.

The population data on antioxidant intake and hearing loss is mixed, though.

Take vitamin C for example.

Some studies show that higher vitamin C intake is associated with better hearing,

but others failed to find any significant connection.

The only way to tell if antioxidants help or not—

you know the drill— is to put them to the test.

Adding antioxidants to the diets of rats

seems to help prevent age-related rat hearing loss,

but doing the same thing in mice doesn't appear to help.

The most exciting preclinical data may be a study

in which aged rats randomized to added blueberries

looked like they had a reversal in hearing deficits,

in fact ending up better than the young rats.

Wait, I thought hair cells don't regenerate?

Our ability to hear doesn't just have to do with our ears, but our brain.

As we age, our auditory cortex in the temporal lobe of our brain

loses some of its ability to discriminate and understand speech

even in a quiet environment.

We don't just need to sense sounds, but make sense out of them.

That's where blueberries seemed to come in,

reversing the age-related cognitive deficits in auditory processing.

But what about in people?

There are studies lacking control groups that documented improvements in hearing loss,

giving people antioxidant supplements like vitamins A, E, C, and alpha-lipoic acid.

But when properly put to the test in a randomized double-blind,

placebo-controlled trial of a whole list of antioxidants, the supplements flopped—

no effect on any of the measured hearing aspects.

Is there any supplement that has been shown to help with hearing in older adults?

Yes, folic acid, the supplement form of folate,

found concentrated in beans and greens.

Some observational studies had found that higher levels of folate

in the blood seem to correlate with better hearing,

but maybe that's just a marker of eating a healthier diet in general.

So, Dutch researchers set out on an ambitious three-year double-blind

placebo-controlled trial randomizing more than 700 older men and women

to take 800 μg of folic acid a day or an indistinguishable placebo.

Excitingly, those who had been taking the folic acid

suffered significantly less decline in hearing at speech frequencies.

The effect size was rather small, such that one might expect

the proportion of men, for example, who would be hearing aid candidates

at age 75 might drop from 33 percent to 22 percent

with folic acid supplementation.

Also note the study was done in the Netherlands, where, at the time,

the food supply was not fortified with folic acid.

In the U.S., where folic acid fortification

has been mandated in refined grain products for decades,

it's unclear how much additional benefit supplements might add.

Regardless, the healthiest sources are dark green leafy vegetables and legumes.

(A cup of cooked lentils has 90 percent of adult daily needs.)