4 ms·

The word excessive needs to be in the title. In 20 years of looking I've never seen a study that links recommended daily allowance amounts to anything harmful.

The word excessive needs to be in the title. In 20 years of looking I've never seen a study that links recommended daily allowance amounts to anything harmful. Yes 1000x RDA vitamins should be banned, but incendiary titles muddy people's thinking.

13years 9y ago
The reason people take 1000x plus etc is often due to absorption issue. Many people have problems absorbing B12. That's why they have a deficiency to begin with. In order for these people to get normal B12, it requires extreme doses just for their bodies to absorb normal amounts.
- myth_drannon 9y ago
  Yeah, the older you get the more likely you going to get absorption issues.
- phyzome 9y ago
  It's not just that -- there's an active and a passive pathway for absorption. The active pathway is limited to 1-2 µg per day by the quantity of "intrinsic factor" produced by the stomach even for people with no absorption disorder, but about 1% of oral B-12 can be absorbed through passive diffusion. If you're trying to remediate a deficiency, intramsucular shots or high oral doses are the correct approach. I think there's another limitation in how much the liver can capture and process per day, and I don't know what that limit is, but it's higher. In any event, once it is processed (and after excess is eliminated), it is highly conserved in your body -- a few micrograms can last years, IIRC.
saiya-jin 9y ago
I immediately checked my multivitamins that I take after every workout during work week (cca 4x/week). It contains practically all vitamins (100% RDA), plus around 15 minerals (30% RDA). I take 1/2 of tablet on any of those days, after lunch (so absorption with fats is +- ideal). For B12 it says RDA is 2.5 micrograms, so getting cca 1.25 micrograms. It is ridiculous to continuously heavily overdose oneself on various supplements and expect nothing will come out of it. Of course it is harmful, although cancer part surprised me (I would expect rather impaired liver, heart or similar effect).

13years 9y ago

The reason people take 1000x plus etc is often due to absorption issue. Many people have problems absorbing B12. That's why they have a deficiency to begin with. In order for these people to get normal B12, it requires extreme doses just for their bodies to absorb normal amounts.

myth_drannon 9y ago
Yeah, the older you get the more likely you going to get absorption issues.
phyzome 9y ago
It's not just that -- there's an active and a passive pathway for absorption. The active pathway is limited to 1-2 µg per day by the quantity of "intrinsic factor" produced by the stomach even for people with no absorption disorder, but about 1% of oral B-12 can be absorbed through passive diffusion. If you're trying to remediate a deficiency, intramsucular shots or high oral doses are the correct approach. I think there's another limitation in how much the liver can capture and process per day, and I don't know what that limit is, but it's higher. In any event, once it is processed (and after excess is eliminated), it is highly conserved in your body -- a few micrograms can last years, IIRC.

saiya-jin 9y ago

I immediately checked my multivitamins that I take after every workout during work week (cca 4x/week). It contains practically all vitamins (100% RDA), plus around 15 minerals (30% RDA). I take 1/2 of tablet on any of those days, after lunch (so absorption with fats is +- ideal). For B12 it says RDA is 2.5 micrograms, so getting cca 1.25 micrograms. It is ridiculous to continuously heavily overdose oneself on various supplements and expect nothing will come out of it. Of course it is harmful, although cancer part surprised me (I would expect rather impaired liver, heart or similar effect).