Too much vitamin A is bad

[arcticpenguin]

http://www.cnn.com/2003/HEALTH/diet.fitness/01/23/vitamina.fractures.ap/index.html

In the study, about one-fifth, or roughly 465 of the men, were found to be at risk because they had the highest levels of vitamin A. The men were about 21/2 times more likely to break a hip and 65 percent more likely to suffer any fracture than those with lower levels of the vitamin in their blood.

Those in the 99th percentile were about seven times more likely to break a bone.

Louria said that people should not take fish oil supplements or eat liver more than once a week

I think somehow I'll be able to restrict my liver intake to less than once a week.

[zakur]

And remember, Polar bear liver contains toxic levels of vitamin A and should not be eaten.

[Andonyx]

Originally posted by zakur
And remember, Polar bear liver contains toxic levels of vitamin A and should not be eaten.

I was reading that in some science book. Apparently alaskan and Artctic explorers have to bury polar bear livers under ice to keep their sled dogs from getting into it.

Additionally, eating fatal doses of polar bear liver will make your SKIN PEEL OFF before you die.

As if the death part weren't enough?

[rwald]

I'll just point out that the study only shows correlation, not causation, and that people who take a lot of vitamine A may just naturally be the type of people who experience these health problems. After all, they could be taking vitamine A to cure ailment X, which is caused by the same thing which causes these health problems, and therefore vitamine A did not directly contribute to the illnesses.

I'm not sure if this is true; it just needs to be considered.

[espritch]

Years ago I read an account of an artic expedition attempting to reach the North Pole. They had been killing dogs for meat, but they didn’t like the dog meat much except for the livers. As a result they got vitamin A poisoning. Skin peeling off and all that nasty stuff. I don’t think it killed them though.

I'm of the opinion that anything in excess can harm you (with the possible exception of sex - not that I would know that from personal experience :( ).

[sickstan]

Not surprising. Retinoids have a crucial role in organogenesis in embryos and have multiple growth regulating effects in adults as well. I was actually not that surprised when the beta-carotene study came out suggesting that large doses caused certain cancers too. I believe it was Lucy, the australopithecus afarensis that had bony abnormalities normally associated with hypervitaminosis A (probably from having eaten some carnivore's liver).

[arcticpenguin]

Originally posted by espritch

I'm of the opinion that anything in excess can harm you (with the possible exception of sex - not that I would know that from personal experience :( ).
I think excessive amounts of vitamin c are safe. Pauling never proved that they cure cancer or anything else, but at least mega-doses of C didn't seem to hurt.

[zakur]

Originally posted by arcticpenguin
I think excessive amounts of vitamin c are safe. Pauling never proved that they cure cancer or anything else, but at least mega-doses of C didn't seem to hurt. There have been several studies that have shown that megadoses of Vitamin C can increase the risk of developing kidney stones in some people.

http://www.kidney.org/general/news/stones.cfm

[Frostbite]

I think too much of anything is bad...

[sickstan]

Originally posted by arcticpenguin

I think excessive amounts of vitamin c are safe. Pauling never proved that they cure cancer or anything else, but at least mega-doses of C didn't seem to hurt.

There's a plateau effect for every-increasing oral doses of ascorbic acid. That means you can only absorb a certain amount during a day. Now some scientists are proposing to give IV ascorbate to people just as so they can elevate serum levels to the millimolar range... yeah wait lemme volunteer not. They hope to achieve in vivo cytotoxicity vs. cancer cells.

[GreyWanderer]

Originally posted by arcticpenguin

I think excessive amounts of vitamin c are safe. Pauling never proved that they cure cancer or anything else, but at least mega-doses of C didn't seem to hurt.

Anyway, if you just eat varied you should be off fine. That way you don't have to keep up with all the research going on.

[Soapy Sam]

And remember, Polar bear liver contains toxic levels of vitamin A and should not be eaten.

Really? I thought this was vitamin "D". Hence the connection with sunlight / ricketts / arctic winters etc.
As for excess vitamin "C", my own research indicates that while a dosage of up to 40g per day does appear to stop an upper respiratory tract infection dead in it's tracks, it will also give you a quite astonishing dose of the squitters. I release these data into the public domain in the interest of science.

[sickstan]

Originally posted by Soapy Sam
Really? I thought this was vitamin "D". Hence the connection with sunlight / ricketts / arctic winters etc.

I would think the second part of this syllogism would be an opposite conclusion: It wouldn't be vitamin D as not enough would be produced to accumulate.

Vitamins A, D, E, and K are the fat-soluble vitamins, and can accumulate much more than can the water-soluble vitamins. I haven't heard much about vitamin E toxicity. Vitamin K can cause serious problems with people who are anticoagulated on coumadin. That's why people on coumadin are advised against drastically changing their diet to one heavy in kale or other green leafy vegetables.


As for excess vitamin "C", my own research indicates that while a dosage of up to 40g per day does appear to stop an upper respiratory tract infection dead in it's tracks, it will also give you a quite astonishing dose of the squitters. I release these data into the public domain in the interest of science.

Does the public domain have a donut-shaped seat over it?

[arcticpenguin]

Originally posted by Soapy Sam
And remember, Polar bear liver contains toxic levels of vitamin A and should not be eaten.

Really? I thought this was vitamin "D". Hence the connection with sunlight / ricketts / arctic winters etc.

Really. It's A.

[Soapy Sam]

Okay. I'll believe you. (In principle. I'll check too.) This is a bit of misinformation I have been carrying around for years. Can't recall where I picked it up.
The version I heard was that animals which winter over in the Arctic are adapted to store vitamin D , which (I believed) required the action of sunlight on the skin for humans to generate it. The attached urban story (I dunno yet that it's myth) was that with large scale Asian migration to Scottish latitudes, ricketts had made a reappearance due to the fact that asian kids (especially girls due to religious restraints) did not get enough exposure to sunlight. The story goes that chapati flour was supplemented with added Vitamin D.

If anyone can explain this mysterious sunlight mechanism (if it exists at all), I would be obliged.

And Sickstan-"Does the public domain have a donut-shaped seat over it?"- We are talking eye of a needle at twenty paces sir.

Edited to add-
Hmm- maybe I wasn't wholly misinformed.
http://www.cc.nih.gov/ccc/supplements/vitd.html#sun

but-

http://www.merck.com/pubs/mmanual/section1/chapter3/3c.htm

Lots of interesting stuff at the Merck site. Confirms the Vit A Polar bear thing and the Vit D Ricketts thing. So it seems I conflated two stories. We live and learn. Thanks people.

[sickstan]

Originally posted by Soapy Sam
And Sickstan-"Does the public domain have a donut-shaped seat over it?"- We are talking eye of a needle at twenty paces sir.


?? This is an odd conversation. I refer to your above post assuming the "squitters" is diarrhea. In that case, the donut-shaped seat would be a toilet, a parallel to your donation to the public domain. In short a play on words.

[Soapy Sam]

Correct. Fluid and apparently under some pressure.

The point is that self overdosing, even with something as apparently risk free as vitamin C, can have unexpected consequences. Particularly if you happen to be skiing at high altitude at the time.:)

[arcticpenguin]

Originally posted by Soapy Sam
Okay. I'll believe you. (In principle. I'll check too.) This is a bit of misinformation I have been carrying around for years. Can't recall where I picked it up.
The version I heard was that animals which winter over in the Arctic are adapted to store vitamin D , which (I believed) required the action of sunlight on the skin for humans to generate it.
If anyone can explain this mysterious sunlight mechanism (if it exists at all), I would be obliged.

Biochemistry, by Lubert Stryer, 2nd ed, C 1975 & 1981:
Cholesterol is the precursor of Vitamin D, which plays an essential role in the control of calcium and phosphorus metabolism. 7-dehydrocholesterol (pro-Vitamin D3) is photolyzed by ultraviolet light to pre-vitamin D3, which spontaneously isomerizes to Vitamin D3. Vitamin D3 (cholecalciferol) is converted into an active hormone by hydroxylation reactions occuring in the liver and kidneys.

So humans need ultraviolet light (e.g. sunlight) to naturally make their own Vitamin D from cholesterol. To ensure that people, especially children, get enough vitamin D regardless of light levels, it is added to food, especially milk.

I heard a similar story in the U.S. Breast-feeding has regained popularity in the last decade or so, and there was concern that breast-fed babies on the upper West coast might be short on Vitamin D because they are not drinking enriched milk and because the weather there does not allow much sunlight exposure for much of the year. I don't know how serious the problem was or what was done about it.

[Soapy Sam]

Thanks, AP.

Now is that GOOD cholesterol or BAD cholesterol that's the precursor...? I'm surprised McDonald's aren't using this in their advertising- "All our hamburgers contain Vitamin-D precursor!":D

[arcticpenguin]

Originally posted by Soapy Sam
Thanks, AP.

Now is that GOOD cholesterol or BAD cholesterol that's the precursor...? I'm surprised McDonald's aren't using this in their advertising- "All our hamburgers contain Vitamin-D precursor!":D
That is cholesterol, the chemical. "Good and Bad cholesterol" are actually complex amalgams of lipids, sterols and proteins in the bloodstream.

[arcticpenguin]

A recent article on this topic: http://www.cnn.com/2003/HEALTH/04/07/rickets.guidelines.ap/index.html

"Breast-fed infants need extra vitamin D"

because they are not drinking vitamin D-fortified milk.

[sadluxation]

Originally posted by arcticpenguin

Louria said that people should not take fish oil supplements or eat liver more than once a week

I think somehow I'll be able to restrict my liver intake to less than once a week.

I think I may have to cut down on my Liver Paté sandwiches and Fish Wellington intake?!!

[BillHoyt]

Some days the medical community really ticks me off with its lack of attention to science. What is happening here is that:

o Excessive melanoma scares are keeping people out of the sun, despite less-than-stellar evidence.
o Moms are not in the sun and not putting their babies in the sun. Neither the moms nor the kids get enough exposure to produce D.
o Dark-skinned moms, who need more sun to produce the same amount of D keep themselves and their kids out of the sun as well
o Half the cases of rickets identified by the CDC were in dark-skinned babies.
o So rather than recommend a bit more sun especially for dark-skinned moms and kids, now they tell everybody to get D supplements. And to be politically correct about it, they soft-pedal the fact that African-American and Latino kids are most at risk.

"The six children with rickets were male and age 8--21 months. Three children had skin complexions ranging from light to dark brown. The annual income level of two families was $30,000--$49,999; two families' income level was $10,000--$29,999; and the income level of two families was unknown. During this investigation, vitamin D deficient rickets was reported in a child aged 17 months who drank a soy beverage containing no vitamin D. This child also received a multivitamin supplement (30% of the recommended dose) 1 month before hospital admission. Six children received breast milk until age 8--20 months; none of the children received routine vitamin D supplementation while breast feeding. Two children were exposed to six and 21 hours of sunlight per week, respectively, one child "did not receive much sunlight," and two children received "minimal sunlight." Sun exposure was unknown for one child."

CDC study (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5012a3.htm)

Oy!

[Soapy Sam]

Bill, I find it interesting that only half the D deficient babies were dark skinned. The North of Scotland is not the sunshine capital of the world and ALL Scots have had little time to adapt to the latitude. (Most "natives" arrived here in the last 10,000 years, primarily the last 3000. The Pakistani arrivals really are little more recent in evolutionary timescales, but they are arriving equipped with tropical colouration and a cultural aversion to stripping off in the outdoors). Similar taboos were common in much of Scotland among the "native" population until within living memory.

Interestinh how culture changes can lead to misadaptation. We used to dry our washing out of doors too. It got whatever UV was around. Now we use bleach to achieve the same effect and tumble dry everything. The cost in energy is huge and I imagine there are biological effects we don't know about yet.

I advise more beach holidays and string bikinis.

[BillHoyt]

Originally posted by Soapy Sam
I advise more beach holidays and string bikinis.

:D