Why do we need vitamins ???

bill5 said:

Some supplements can be beneficial, but again many have not been proven to be so, and some may even be harmful. But again, vitamins we get from natural sources are well-known to be beneficial, and none shown harmful. This may be in part due to how the body processes them, but also many researchers feel it's also because the value in vitamins isn't just from that isolated chemical compound itself, but in the overall plant (or animal) and how many things in that plant complement each other.

Click to expand...

The benefits from eating a healthy diet vs pure junk food and supplemental vitamins is not because the supplemental vitamins are not beneficial. They are. The benefit is that fruits and vegetables are lower in calories and salt than candy bars, potato chips, Cheetos, etc. Also, fruits and vegetables contain more fiber and antioxidants than the junk foods.

So, lower salt means lower blood pressure. Lower calories means less obesity. These are the benefits of fruits and vegetables; it's not that the vitamins in them work while the vitamins in vitamin pills don't.

As several people have pointed out, it is possible to overdose on the fat soluble vitamins and get immediate toxic effects from them. Yes, this happens when you get them "naturally" from food.

Folic acid (vitamin B9) from food can also have a negative effect, at least the breakdown products of folic acid can: birth defects. It is the balance between protection of folic acid from UV light vs synthesis of vitamin D by UV light that accounts for the variations of skin color among humans:
1 G Kirchwager, Black and white: the biology of skin color. Discover 22: 32-33, Feb. 2001.

bill5 said:

Yes, and that supplementation in your case is the sun. The cholesterol in our bodies can't make Vitamin D without it.

Click to expand...

"supplementation" meant getting the chemical in the diet.

No it doesn't. Note my links below. Have evidence to the contrary?

Click to expand...

Yes. All of biochemistry is evidence that the same chemical structure (and stereochemistry) gives the same effect. If the compounds are identical, then they behave identically.

Sorry I'm not allowed to post links, but if you google things like "vitamin supplement studies" you'll find lots (and some of these have links within them as well):

Click to expand...

I did the search. The first link up was this:
Vitamins - What Should You Eat? - The Nutrition Source - Harvard School of Public Health

That quotes lots of studies showing that supplemental vitamins are beneficial.

If what you say is true, we could just live on supplements.

Click to expand...

LOL! Vitamins are not all of what we need via diet. There's sugars, amino acids, and lipids. We need the sugars as substrates for oxidative phosphorylation (energy production) and as part of RNA and DNA. The amino acids are part of proteins. The lipids are for cell membranes among other things.

However, yes, theoretically we could live off a mixture of artificially made nutrients. It would be very expensive and not much fun, but it could be done.

lucaspa said:

"A vitamin is an organic compound required as a nutrient in tiny amounts by an organism." In other words, an organic chemical compound (or related set of compounds) is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. "

Click to expand...

Even if we assume wiki's definition is "the" definition, there is nothing in there that says "being syzthesized by an organism" is a requirement, but for the sake of argument, OK, fine, it's really not worth going round and round about.

LOL! Yes, having the same chemical compound does indeed make them the same.

Click to expand...

Pls re-read what I wrote about that. Yes the chemical compound itself is the same; I wasn't arguing that.

Where in the world did you get that information?

Click to expand...

By the fact that there is plenty of well-documented evidence to support the latter; little if any to support the former.

You do realize that milk is supplemented with synthetic Vitamin D, right? That health benefit in preventing rickets is well-documented.

Click to expand...

Yes. Note I said "few," not "none."

All the synthetic vitamins have been proven to be beneficial.

Click to expand...

No, they haven't, and no matter how many times you state it, it doesn't make it any more true, sorry. Where are you getting this?

They have to be, since they are IDENTICAL to the compounds that are found in food.

Click to expand...

One last time: it is not simply about the vitamin chemical compound itself.

Vitamins are regulated by the FDA.

Click to expand...

...so loosely that it means little, frankly, and certainly means nothing regarding whether they actually work. From the FDA site:

dietary supplements do not need approval from FDA before they are marketed. Except in the case of a new dietary ingredient, where pre-market review for safety data and other information is required by law, a firm does not have to provide FDA with the evidence it relies on to substantiate safety or effectiveness before or after it markets its products.

Click to expand...

aisy_Day said:

Water soluble vitamins are less likely to be harmful, while fat soluble A and E are more likely to cause harm.

Look up the effects of eating bear and seal liver.

Click to expand...

That's because those livers have such a high concentration of Vitamin A. If you ate a smaller amount of them, they would do no harm. I meant inherently harmful.

But in fairness and that said, that may be the case with supplements too, ie getting too much of something...I'll check the sources I saw on this. [/quote]

lucaspa said:

Yes. All of biochemistry is evidence that the same chemical structure (and stereochemistry) gives the same effect. If the compounds are identical, then they behave identically.

Click to expand...

You continue to ignore that the benefit from vitamins in food is not simply a function of that isolated chemical compound, so I see no point trying to discuss this further.

I did the search. The first link up was this:
That quotes lots of studies showing that supplemental vitamins are beneficial.

Click to expand...

Some supplements have been shown to be beneficial. Not all by any means.

LOL! Vitamins are not all of what we need via diet.

Click to expand...

No kidding; that isn't what I said.

theoretically we could live off a mixture of artificially made nutrients. It would be very expensive and not much fun, but it could be done.

Click to expand...

But theory does not equal reality, so that is merely an unproven claim.