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Does caffeine make you lose or not absorb calcium, iron or any vitamins?

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#1 bbrubaker



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Posted 17 April 2010 - 01:49 PM

I seem to remember coaches in HS saying to stay away from soda because the caffeine would lead to more broken bones.

Is this the carbonation in soda?
Is it a myth?

TIA, wikipedia seems to of no use.
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#2 Mr Skeptic

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Posted 17 April 2010 - 06:27 PM

I think the problem is due to drinking soda instead of milk, not soda itself.

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#3 skyhook



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Posted 19 April 2010 - 03:49 AM

caffeine is in coffee and tea. soda has probably phosphoric acid, and the carbon dioxide in water cause carbonic acid or something.
I think caffeine may lead to calcium loss, as some articles regarding osteoporosis say it. I'm not sure about iron and vitamins.
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#4 CharonY


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Posted 19 April 2010 - 09:34 PM

I think there were studies around that supported the notion that large amount of caffeine intake may reduce calcium absorption. However, the effects were small and not reproduced in other studies (which claimed otherwise). If there is an effect, it is not a very pronounced one, apparently.
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#5 StacieJ247



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Posted 12 May 2010 - 04:43 PM

I think some confusion comes when nutritionists advise against drinking tea or coffee with vitamins. The interference in mineral absorption (particularly metals) is the tannins (in black tea and coffee) which chelate metals and prevent absorption.
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#6 Double K

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Posted 13 May 2010 - 11:46 PM

Caffeine is a diuretic, which means it causes you to urinate more frequently.
When you urinate you pass minerals that would normally remain in your system a bit longer allowing more absorption.
Minerals that can become depleted very easily include calcium, magnesium, sodium, phosphate and potassium.

There is speculation that caffeine inhibits iron and some A and B group vitamin absorption, although I can't say I've ever seen a study with results presented, which doesnt go to say that one doesn't exist, just that I've never seen it.

PS. you can also kill yourself with caffeine...more than 10 cups a day is becoming dangerous (depending on the individual)
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#7 CharonY


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Posted 14 May 2010 - 12:11 AM

A) studies have shown that coffee is not significantly more diuretic than other drinks (e.g. water). Caffeine alone has no obvious diuretic properties (up to normal consumption levels).

B) if you are talking about cups of coffee (as opposed to highly concentrated caffeine levels) then 10 cups are not acutely dangerous, though possibly unhealthy over a long time. The oral LD50 is around 192 mg/kg weight. Assuming a weight of, say 70 kg it would be around 13.44 grams. That would roughly require drinking around 100 cups in short time (without excretion). That is about 12.5 l. Even I would have trouble getting that much coffee in within a day, even disregarding elimination from the system.

What Stacie proposes makes a lot of sense, but I would have to look up details.

Edited by CharonY, 14 May 2010 - 12:17 AM.

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#8 Double K

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Posted 14 May 2010 - 03:51 AM

There does seem to be conflicting evidence surrounding this:

"Some research has shown that caffeine intake can also affect our fluid balance. In one study, 12 caffeine consumers were told to abstain from caffeine for five days and were then given 642 mg of caffeine in the form of coffee. Their urine output increased when given the caffeine. Another study done on eight men tested the effect of 45, 90, 180, or 360 mg of caffeine on urine volume. An increase in urine volume was seen only at the 360-mg dose of caffeine. One limitation to these studies is that they did not evaluate the impact of caffeine when consumed on a regular basis. A onetime dose may affect the body differently than daily consumption."

"Caffeine (in coffee, tea, and soft drinks) and theophylline in tea stimulate increased renal glomerular filtration and inhibit reabsorption of sodium (Na+) within nephrons, thereby stimulating an increased Na+ and water excretion."

(This is actually not a true diuretic, but theoretically should stimulate greater urination rates)

There are about 5 or 6 experiments listed in the article above in relation to caffeine acting as a "diuretic" and the article concludes that:

"The reader also should note that the hydration state, and the amount of fluid consumed during the previous 12 h, of test subjects was generally not controlled in these studies. This suggests that the negative values in Figure 1 (i.e., representing a net fluid loss) result from overhydration before experiments began, because even placebo trials resulted in a net fluid loss."

RESULTS: The available literature suggests that acute ingestion of caffeine in large doses (at least 250-300 mg, equivalent to the amount found in 2-3 cups of coffee or 5-8 cups of tea) results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. A profound tolerance to the diuretic and other effects of caffeine develops, however, and the actions are much diminished in individuals who regularly consume tea or coffee. Doses of caffeine equivalent to the amount normally found in standard servings of tea, coffee and carbonated soft drinks appear to have no diuretic action. CONCLUSION: The most ecologically valid of the published studies offers no support for the suggestion that consumption of caffeine-containing beverages as part of a normal lifestyle leads to fluid loss in excess of the volume ingested or is associated with poor hydration status. Therefore, there would appear to be no clear basis for refraining from caffeine containing drinks in situations where fluid balance might be compromised.

I stand corrected - although I can tell you I had a big bucket o' coffee this morning, and I need to pee!

Merged post follows:

Consecutive posts merged
Just to address the point regarding the amount of caffeine to kill you:

"Caffeine doses of 200 mg or higher can cause unpleasant symptoms including nausea, headache, and irregular heartbeat, while dose of 750 - 1000 mg can cause severe toxic symptoms. Severe caffeine intoxication can result in nausea, vomiting, anxiety, tremor, seizures, tachycardia, dysrhythmias, hypotension, hypokalemia, and metabolic acidosis.

Several fatalities resulting from caffeine overdose have been documented, but they are extremely rare relative to its widespread use. In the case of a massive caffeine overdose, vomiting often protects against fatal poisoning, but some deaths have still resulted.

Fatal dose range in humans is believed to be between 3 - 20 grams, approximately the amount of caffeine found in 20 - 130 cups of drip coffee or 15-100 common caffeine tablets (200 mg each). Blood caffeine levels greater than 80 ug/mL have been associated with death, but data is limited. It is difficult to ingest such high levels of caffeine accidentally, and many of the documented fatalities appear to be suicide attempts involving the ingestion of a large number of caffeine pills.

In one extreme case a 41-year-old woman was successfully resuscitated after ingesting 50 g of caffeine (see Holstege et al., 2003 below)."

Alstott RL, Miller AJ, Forney RB. Report of a human fatality due to caffeine. J Forensic Sci. 1973;18(2):135-7. [ Abstract ]
An individual (age unknown) died after consuming between 6.5 and 12 g caffeine.

Garriott JC, Simmons LM, Poklis A, Mackell MA. Five cases of fatal overdose from caffeine-containing 'look-alike' drugs. J Anal Toxicol, 1985; 9(3):141-3. [ Abstract ]
Mixed ephedrine and caffeine fatalities, showed blood levels of 130-344 mg/L caffeine and three also had 3.5-20.5 mg/L of ephedrine.

Holmgren P, Norden-Pettersson L, Ahlner J. Caffeine fatalities--four case reports. Forensic Sci Int, 2004; 139(1):71-3 [ Abstract ]
Four cases reported: 54 yr old male died after taking 100 x 100mg caffeine tablets resulting in 173mg/L in femoral blood. 21 yr old male died after ingesting 200 x 100mg caffeine tablets resulting in 210mg/L in femoral blood. 31 yr old male died after ingesting 100 x 100mg tablets resulting in 153 mg/L in blood sample. 47 yr old female died after ingesting 100 tablets containing both caffeine and ephedrine resulting in 200 mg/L of caffeine and 4.8 mg/L of ephedrine.

Kerrigan S, Lindsey T. Fatal caffeine overdose: two case reports. Forensic Sci Int, 2005; 153(1):67-9 [ Abstract ]
39 yr old female found dead with 192/mgL caffeine in femoral blood. 29 yr old male had taken 'a bottle of caffeine pills the day before' died while in hospital and had 567 mg / L caffeine in femoral blood.
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