Where do vitamins come from?

[Swoop]

I don't mean within the food we eat, I mean in supplements and multi-vitamin form. Like if I buy a multi-vitamin that says it has 20mg of Vitamin B3 and 10mg of B6, how do I know? Where do they get/derive/extract the vitamins from? How do they mix them in the right levels? How do I know they're still at the right levels when I swallow the pill?
When I buy food that claims to be "vitamin enriched", how truthful is it? Do they just sprinkle magic health powder over everything and wam it's "enriched"? Are there any international standards as far as things like this go?

[curly chick]

Vitamins are biological chemicals so they are manufactured using standard processes based on organic chemistry, as you might expect to see in the petrochemical or pharmaceutical industry.

If your tablet has 20mg of Vitamin B3 and 10mg of B6, it means that if the tablet weighs 10g, then the rest of it is cellulose or starch of some description, this is the filler or carrier, used to hold the active vitamin ingredients together and present them to the user in a sensible size. A tablet which contained only 20mg of Vitamin B3 and 10mg of B6 would weigh 30mg and be pretty small. It would knock against other tablets in the bottle and bits of it would fall off, so the content of each tablet was would end up being less than 20mg of Vitamin B3 and 10mg of B6, with a lot of dusty vitamin powder in the bottom of the bottle.

The manufacturers of the tablets follow specific recipes and the Quality Control department carries out standard chemical tests on the raw materials, the mixture before it is made into the tablets and at various stages throughout the production process, as well as on samples of the finished tablet. So the recipe is mathematically devised to result in a 10g tablet with 20mg of Vitamin B3 and 10mg of B6, give or take an insignificant percentage error.

Vitamins in tablet form, taken within the expiry date on the bottle will not have degraded, so each tablet will still have its 20mg of Vitamin B3 and 10mg of B6.

Vitamins outside the expiry date may lose some of their potency, that is to say, there may be slightly less than 20mg of Vitamin B3 and 10mg of B6 in each tablet, but they will not suddenly turn into nasty toxic poisons.

Vitamin enriched is marketing lingo. If you enrich something you add something to it. When you get in your car and drive home, your car is Swoop enriched.
If, however, the food is marketed as having 10% more vitamin C than before, then that is what is has to have, by law.

[Swoop]

Thank you!

[bibliophage]

Several years ago, I came across an interesting recipe for how they synthesize (or used to synthesize) vitamin C in the laboratory. Dextrose is catalytically hydrogenated to d-sorbitol, which may then be fermented to l- sorbose. The sorbose is reacted with acetone in the presence of sulfuric acid to form diacetone sorbose. Alkaline solutions of the diacetone sorbose are oxidized with potassium permanganate or sodium hypochlorite to diacetone 2-keto-l-gulonic acid, which when hydrolyzed, yields 2-keto-l-gulonic acid. This acid may be esterfied with methanol and then transformed to vitamin C by the action of sodium methylate.Don't try this at home, kids.

[Dogface]

There are vitamin products that are extracts from plants. One is a vitamin C supplement extract from "acerola cherry". It's no different from synthetic vitamin C.

There is one vitamin that does differ between the natural and synthetic versions: Vitamin E. One of the two versions is racemic, the other is not.