Originally Posted by MachOneMustang
I know taking supplements with food promotes absorption (most, anyway), are there certain foods or drinks to steer clear of?
I heard ingesting caffeine could render some vitamins (Calcium mostly I think) useless. Is this true? If so, how long before or after are you allowed to have that cup of coffee, or tea.
Caffeine does impact absorption of some minerals and vitamins, but it doesn't necessarily render them useless. In the case of calcium it can cause more to be excreted in the urine and feces (e.g. every cup of coffee, roughly 150 mg of caffeine, will result in approximately 5 mg of calcium to be excreted in the urine). Waiting half an hour after coffee to have your calcium should fix this.
reduce the absorption of some minerals, such as manganese, zinc, & copper, as well as vitamins such as vitamin A & B complex.
Certain minerals and vitamins should be taken with food (your bottle should stipulate this) and many work best when taken together - calcium and magnesium often come combined because they work in tandem; calcium and vitamin D are another combination. Depending on the type of calcium you can take it w/o food or with (carbonate is hard on the tummy and should be taken with food; the others, citrate, malate, etc, are not and can be taken alone).
Grapefruit juice can increase absorption of many supplements (and medicines) so you should not take them with this. You should also not take a fibre supplement when taking any kind of mineral / vitamin or medicine, as it will slow their absorption. You need a window of 2 hours on either side when taking fibre.
Never take iron w/ calcium or with grapefruit juice - this also increases absorption.
If you're taking a vitamin E supplement you want to ensure there is some fat in your meal; vitamin E is a fat soluble vitamin and some fat is therefore necessary for it to be absorbed.
That's all I can think of off the top of my head this morning