Mult-vitamins a must!

[El Greco]

Can you please point me to the actual studies ?

 

[BTox]

Can you please point me to the actual studies ?

These are the two recent studies most cited:

nejm serum retinol and fracture

jama vit A intake and fractures

 

[El Greco]

These are the two recent studies most cited:

nejm serum retinol and fracture

jama vit A intake and fractures

Ooops! Somehow I missed your answer. Sorry.

The studies you cited are large studies with a follow-up of many years. Very few variables are monitored during these years, mainly vit A intake and serum retinol. Well, let's see what's wrong with the interpretation of these studies:

1) There are other studies whith opposite results. Studies that show that a decrease in serum retinol is associated with osteoporosis. See Marked decrease in plasma antioxidants in aged osteoporotic women.
Also see Retinol, supplemental vitamin A and bone status.
2) Short-term studies have failed to find any relationship between vit A intake and bone turnover. See Short-term vitamin A supplementation does not affect bone turnover in men.

Such contradictions have led several scientists to question the validity of the interpretation of the studies you mentioned. See for example the Sigurdsson critique on one of the Michaëlsson studies.

So, what's really hapenning ? Can we dismiss such studies because of the apparent contradictions and limitations ?

Several theories and explanations have been proposed in order to explain such discrepancies. I could further elaborate on these, but for the moment let's focus on the most widely accepted theory: What contributes to the lower BMD is not the increased vit A intake or serum retinol, but the disruption of the Vit A to Vit D ratio. This could be a result of increased vit A intake or lower vit D levels.

Without going into many details, it seems that there are many reasons such a disorder may occur. On the biochemical level, there may be a connection between lower levels of retinol-binding protein and type-II osteoporosis (see Biochemical markers of nutrition in type-I and type-II osteoporosis. In any case, one proposed mechanism of why this imbalance can affect BMD is calcium response antagonizing. See Vitamin A antagonizes calcium response to vitamin D in man.

Sudies relating vit A intake to fractures have also been criticized because they have been conducted in northern climates, where sunlight exposure is low and therefore the findings could be attributed to lower levels of vit D. As Dr. Volpe points out:

CNN and various newspapers, including The New York Times and the Houston Chronicle, recently reported on a Swedish study (The New England Journal of Medicine, January 2003; 348: 287-294, 347-349) linking Vitamin A with an increased risk of fractures in aging men. These reports have led many people to wonder if supplements containing Vitamin A are safe, and many media outlets are advising readers against the use of any Vitamin A.

Since I often recommend cod liver oil (which does in fact contain Vitamin A) and other Vitamin A supplements, I was very puzzled by these reports and read the study in its entirety. I was surprised to see how little is known about the participants in the study. Basically all that was recorded was their level of Vitamin A in blood and the incidence of fractures over a thirty-year period. To conclude with certainty from this scant information that Vitamin A is dangerous seems quite a stretch to me.

Before we start thinking of Vitamin A as hazardous, let's remember that it plays many important roles, including in vision, cell differentiation, early fetal development, immunity, taste, appetite and growth. Vitamin A is an important antioxidant and may have anticancer and antiviral actions. Signs of deficiency include night blindness, acne and other skin conditions, reduced immunity, chronic viral conditions, complications from measles and, conceivably from the measles vaccine.

The US RDA (recommended daily allowance) for Vitamin A is 5,000 IU (international units) a day for adults and proportionately less for children. The most important recognized risk of Vitamin A is that doses exceeding 10,000 units a day in pregnant women were associated with a higher risk of certain birth defects in one study (Lancet 1988;1:236). However, another study found such doses to be associated with a reduction of the same type of birth defects (Lancet 1996;347:899-900). In total there have been fewer than 20 cases reported worldwide of birth defects possibly caused by Vitamin A overdose.

In numerous studies, doses far greater than the RDA were found to be both safe and effective. Doses of 400,000 units a day for 5 months in adolescents with acne were found to be effective and caused no side effects (Int J Dermatol 1981;114:1776 and Br Med J 1963;2:294). The short-term administration of doses of 200,000 to 400,000 units in small children were also studied, and were found to reduce the occurrence of complications from measles and pneumonia while enhancing immunity, again with no side effects reported. Incidentally, the benefits were documented both in children who were deficient in Vitamin A as well as in children who were not (J Trop Pediatr 2002;48(2):72-7, Clin Infec Dis 1994;19(3):489-99, Am J Epidemiol 1997;146(8):646-54, and many other published studies. You may e-mail me for a full list).

Interestingly, this most recent study linking Vitamin A with fractures in aging individuals was performed in Sweden, a country not known for its abundant sunshine. Since we know without a doubt that Vitamin D is associated with bone health and that much of our intake of Vitamin D comes from the sun, it is possible that Vitamin D deficiency is rampant in Sweden. This may explain why Scandinavians in general have higher rates of fractures in comparison to other Europeans.

One possible explanation of why fracture rates were higher in the study participants who had more Vitamin A in their blood is that vitamins A and D need to be balanced. Everything in nature is a matter of balance, and excessive intake of Vitamin A without enough Vitamin D may cause a relative Vitamin D deficiency, possibly leading to brittle bones.

Cod liver oil is apparently a very popular supplement in Sweden, and some experts suggested that the individuals with high levels of Vitamin A in their blood may have consumed ample doses of cod liver oil, over many decades, and this may have depleted them of Vitamin D.

Cod liver oil actually contains both vitamins A and D, but is tilted towards Vitamin A. It is plausible that consuming it without being exposed to sufficient sunshine or taking additional Vitamin D explains the results of this study. This theory may be the best we have, but is not entirely convincing since cod liver oil, in spite of its high Vitamin A to Vitamin D ratio, was used successfully in the 1800's to treat rickets, a childhood disorder of bone development caused by Vitamin D deficiency.

In my opinion, a normal intake of Vitamin A from cod liver oil or other sources within the RDA should not be of concern, especially if properly balanced with Vitamin D through sunlight exposure or supplements. In special cases much higher doses of Vitamin A can be greatly beneficial, but these doses should be taken only under the supervision of a trained professional, and this study clearly points out some of the risks of not doing so.

Well, this is a point I agree with. Cod liver oil supplementation does not disrupt the Vit A / Vit D balance.

But let's forget all of the above, and think of whether taking an EPA/DHA capsule will ensure that we get lower doses of vit A. Well, it doesn't. In most cases, EPA/DHA capsules are nothing more than fish oil in a different package. Not only that, but many EPA/DHA capsule manufacturers fail to specify the source of the oil and often do not provide any info as to the vit A content of the capsule. See this study which corroborates the above.

With the above in mind, I still think that cod liver oil is the prefered source of EPA/DHA, especially since it is so easy to find purified preparations of it with lower vitamin A content.

 

[BTox]

Well, this is a point I agree with. Cod liver oil supplementation does not disrupt the Vit A / Vit D balance.

As your studies suggest and as I mentioned, the association between high doses of vit A and fractures is not proven. The point was it is foolhardy to take any vitamin, especially fat soluble ones, at or above the upper tolerable limit, and most sources of cod liver oil at a dose of 15 mls per day do just that. As Dr. Volpe suggests, taking cod liver oil that delivers the RDA or less is fine.

But let's forget all of the above, and think of whether taking an EPA/DHA capsule will ensure that we get lower doses of vit A. Well, it doesn't. In most cases, EPA/DHA capsules are nothing more than fish oil in a different package. Not only that, but many EPA/DHA capsule manufacturers fail to specify the source of the oil and often do not provide any info as to the vit A content of the capsule. See this study which corroborates the above.

With the above in mind, I still think that cod liver oil is the prefered source of EPA/DHA, especially since it is so easy to find purified preparations of it with lower vitamin A content.

I still disagree. That 15 year old study from Germany has no relevance to fish oil supplements sold in the U.S. today. FDA requires vitamin content must be accurately labelled on all supplements. Also, fish body oils, which compose most of the fish oil supplements sold in the U.S. today, as opposed to fish liver oils, have neglible amounts of vit A.

Bottom line is, I'll continue to use and recommend EPA/DHA fish oil concentrates for w-3 supplementation.

 

[El Greco]

Bottom line is, I'll continue to use and recommend EPA/DHA fish oil concentrates for w-3 supplementation.

Ok, then we just agree to disagree. My opinion is that current data show that cod liver oil is perfectly safe for chronic use. As I have already said I would prefer myself concetrated EPA/DHA capsules so that I would take less calories, but I do not trust most fish oil capsules because:

1) I can't always know the source of the oil
2) I can't always know whether it is liver or muscle oil
3) I can't always trust EPA/DHA content fish oil supplements. Their levels in capsules are currently NOT regulated by FDA. According to a ConsumerLab review, 6 out of 20 products failed their test because they didn't provide the claimed EPA/DHA. That is for supplements sold in the USA market.

And since:
1) you said yourself that "taking cod liver oil that delivers the RDA or less is fine", and such cod oil can be easily found
2) the cost in the case of capsules is ridiculously higher

...I cannot see why one wouldn't suggest cod liver oil.

Oh well... I think that if anyone is still reading this thread can draw his/her own conclusions by now.

 

[BTox]

Ok, then we just agree to disagree.

I agree!

My opinion is that current data show that cod liver oil is perfectly safe for chronic use. As I have already said I would prefer myself concetrated EPA/DHA capsules so that I would take less calories, but I do not trust most fish oil capsules because:

1) I can't always know the source of the oil
2) I can't always know whether it is liver or muscle oil
3) I can't always trust EPA/DHA content fish oil supplements. Their levels in capsules are currently NOT regulated by FDA. According to a ConsumerLab review, 6 out of 20 products failed their test because they didn't provide the claimed EPA/DHA. That is for supplements sold in the USA market.

I've read that study. And as you say that cod liver oil can be easily found with low vit A content, high quality fish oil/concentrates with proper levels of EPA/DHA can also be found. BTW, I would expect similar results with cod liver oils, some would also be lower in epa/dha than claimed.

And since:
1) you said yourself that "taking cod liver oil that delivers the RDA or less is fine", and such cod oil can be easily found

Yes, but I prefer to take a supplement with no additional vit A or D. Don't need more, why take it?

2) the cost in the case of capsules is ridiculously higher

Not really. I calculate a daily cost of fish oil concentrate caps at 50 cents vs 25 cents for cod liver oil by the tablespoon (both delivering the same amount of epa/dha). I'm not concerned with cost but even if I was I think the extra 25 cents/day is worth the convenience and palatability issues of taking a few caps vs a spoonful of cod liver oil. Not to mention the rancidity issue with bulk highly pufa oils - every time the bottle is opened oxygen is reacting with some of the epa, dha and other pufas - not good. Caps do not have this issue.

.

Oh well... I think that if anyone is still reading this thread can draw his/her own conclusions by now.

I think anyone once reading this thread has long ago fallen asleep

 

[joyrex]

Meat is NOT bad for you.

What would you say about this article, could meat have some kind of a negative impact on health after all? Funny that while being 2 and half years mainly vegetarian, I haven't had even a flu, cold or any kind of sickness. Maybe this is just coincidence, or something to do with (individual) immunology?

 

[Larspeart]

Centrum is one of the worst MV's on the market.

Reason? They are covered in a nasty shellac that not only inhibits dissolving, but isn't even healthy on the human system. (gf works as a pharm tech. the pharm was educating them on it last week)

Stick with the uncoated (and hence nasty-tasting and harder to swallow) ones. You'll get more out of them.