Vitmain C synthetic vs. natural

As far as I know almost all studies on C were done on
isolated ascorbic acid, either buffered or not.

Just because it is isolated and concentrated it does not mean it is "synthetic".
If you eat the fruit you also get the bioflavanoids and other beneficial factors
that work in unison with ascorbic acid. These serve both to help absorb ascorbic acid, to buffer it, and to offset potential side effects throughout the metabolic process if the entire spectrum of needed co factors are not available to the body.

Most fruits are made this way. For example, apple seeds are great but if you eat a cup full, you could get sick from it, and there is one person in the medical records that has died from doing this. The apple itself has the cofactors that go along with the apple seed, and if you eat both, you won't get sick or toxic. This is true for most fruits.

Most C is isolated from corn. It is cheap because corn is cheap. Try to get non Genetically-Modified-Organisms corn. Some is isolated from beets. That is also cheap but not as cheap as corn. A few C supplements are isolated from fruits, or so the manufacturers claim. These are extremely expensive. If fact so expensive that the great majority of people could not obtain therapeutic amounts. It would cost $1000s per month to get the same doses as corn isolated ascorbic acid.

The fact is that what is isolated from beets, corn or fruit is the same...namely ascorbic acid. Most ascorbic acid powders/pills come with added bioflavonoids like those in rosehips. Of course this is not the same as the whole fruit but then neither is the fruit isolated ascobic acid!

What I do is I buy buffered ascorbic acid and drink it in fresh squeezed fruit juice. Inexpensive and the best compromise. Best would be to also get the skin of the fruit but that has pesticides so unfortunately that is something I feel I need to give up. Of course once the codex comes in this year, we will no longer be able to get vit c except by prescription and only in low doses. 100 milligrams/day.