From this and what I learned in college, the answer is in the ability of the body to buffer pH changes. When we are young, the body seems to have a strong buffering capacity. That is that it is able to neutralize excess acidity or alkalinity. Young people rarely get acid reflux, unless they are really abusing something.
Much of the buffering comes from ionic groups such ad bicarbonate and biphosphate. We all know about sodium bicarbonate, right? Baking soda ( not baking powder ) is a strong buffer. It neutralizes acids. Yep, some folks take baking soda for an acidic stomach and it works. Put it on a bee sting, rub it in to the puncture hole, and it will reduce the pain and swelling because bee stings are ??? formic acid.
So, take some sodium bicarbonate and put into a chamber with a small funnel at the top. Put some vinegar in the funnel and let it drip into the carbonate. Out comes carbon dioxide gas. You can use this to make things put-put around in the bath tub to keep the kids entertained.
Back to the buffering:
The body has plenty of reserves of both phosphate and carbonate in the bones. However, taking too much acid over the years can reduce the level of access to these reserves. That is that much of the easy to get to phosphates and carbonated have been removed. As a result, many people, as they age, develop soft weak bones, or even brittle bones. Note that this is not the only cause but can be a major contribution.
When we are young and consume lots of acidic substances, the bones provide an easy to use reserve so we really do not notice. Hey guys, lets drink a quart of phosphoric acid and carbonic acid every day for 20 years and see if we don't notice something eventually! The body will go to extremes to keep the blood pH at the proper level, otherwise, it could be deadly.
Understand this, the body will sacrifice major portions to keep the core alive and well. To either cold or heat, the body will attempt to sacrifice the limbs to preserve the core. To keep the pH at a safe level, the body will sacrifice bone.
As a point to this, the blood itself is not as badly damaged by a low pH as the core is. When pH drops to an low level, about 7.25 pH, which is still actually alkaline, the kidneys start to fail. They can not properly function when the blood pH gets that low. Remember, the kidneys are pumping out acidity much of the time. We also get some out through the lungs as carbon dioxide.
However, even more sensitive is the ability of immune cells to properly respond. Almost all of the immune cells have an optimum pH of about 7.38. Even a slight variation in either direction can have a dampening effect on the immune cells.
There were many studies done on this back in the 1920's and 1930's but you will rarely see anything published today, mostly because it is 'old hat'. If you want to find much on this topic you will have to dig way back in the archives.
It is sort of like the commercial "15 minutes can save you ...", yeah sure, if you are really being bilked (TIC). Oh!, yes, everybody knows that.
So, you commonly hear that there is a link, but no studies cited. Mostly because the studies are close to 100 years old. Why reinvent the wheel?
Sorry that I did not actually cite the studies, just don't have the time to dig through the archives.