Women taking 1,000 mg of vitamin C daily are 25% more likely to develop cataracts

[snagglepuss]

snip

Researchers followed 25,593 women, aged 49 to 83, for eight years and found that those who took 1,000 mg of vitamin C daily were 25 per cent more likely to develop cataracts than those who did not use supplements.

Among women 65 and older, vitamin C use increased the risk of cataract by 38 per cent. Taking vitamin C in combination with hormone replacement therapy or corticosteroid medication was associated with an even greater risk.

However, getting too little vitamin C may also contribute to cataracts, since vitamin C is a potent antioxidant, protecting from free radicals. Previous research has linked higher blood levels and dietary intakes of vitamin C with a lower risk of cataracts.

The new study showed that multivitamins containing a small amount of vitamin C (60 mg) did not increase cataract risk.



Read more at

http://www.theglobeandmail.com/life/health/high-dose-vitamin-c-can-increase-cataract-risk/article1445734/

[bemildred]

1. Now that's interesting. But don't tell Linus Pauling. nt

[snagglepuss]

3. If this is true so much for the notion that certain vitamins like C aren't

dangerous at high levels because they are water soluble.

[bemildred]

5. Dosage is everything with any drug.

Too little, you don't get the right effect, too much and it's toxic or you get extra unwanted effects. Even with the right dosage it is common to get extra unwanted effects. And most any isolated chemical nutrient can be viewed as a drug.

[semillama]

18. And that's why supplements need to be regulated

so a consumer can be confident they are getting the dose they want.

[bemildred]

21. As long as they don't start forbidding things, that would be good. nt

[Sanity Claws]

2. Taking any supplement in such a high dosage for eight years

probably causes nutritional imbalances.
Anything in excess is not good for the body, IMHO.

[newfie11]

4. well it did not cause cataracts on me.

Maybe I am the only one but I have taken 10 grams of Vit C for 20 years with no problems. I am 63, just saw my eye doctor for yearly exam and to refill my contacts. I always ask about cataracts as I have worked 40 years as an x-ray tech. 15 of those years as a specials tech standing over a c-arm with radiation coming up towards my face. Yes I had a lead apron and thyroid sheild but nothing for eyes.

So blast away. All I can say is it has not happened to me. Also I haven't been sick for many many years.

[snagglepuss]

6. Are you sure you don't have cataracts cause you seem to have missed

that this was seen in 25% of women who took that amount. Obviously you would be included among those 75% catagory who did not get cataracts.

[newfie11]

11. MEOWWW!!!!!

Just stating the facts!

[Sanity Claws]

12. This is one of the rudest forums in DU

and that is saying a lot.

[Chemisse]

15. It really is

And this thread is like a group hug compared to many others here.

[SidDithers]

17. Anecdote vs data...nt

Sid

[Dorian Gray]

20. This makes me laugh

can't people share their personal experience here? (Of course, it's not proof, though!) But why can't people share anecdotal information in regard to topics?

So what?

I take Vitamin C every day, too! So far, no cataracts. I will be sure to check for them, however, at my eye examinations.

Not proof of anything, but sharing my experience.

[Orrex]

22. Of course people can share anecdotes here

However, all too often (as in this case) the single-case anecdote is put forth as if it were a refutation to a formal study, and some readers are happy to latch onto the anecdote while disregarding the rest.

That's how the denial of global warming works, by the way: "We just had a big snow storm, so global warming must be bullshit."


People are welcome to share anecdotes as anecdotes, but they shouldn't be taken as a substitute for real evidence.

[hlthe2b]

7. There are a lot of potential confounding exposures that could

provide these findings... Without having the actual study available, it is hard to assess. If the women with cataracts were more likely to have these other risk factors, e.g, obesity, high blood pressure, sun exposure, other dietary issues, etc., etc. this could be erroneous. Nonetheless, I think there is a general truth that natural sources of vitamins/minerals are in most cases superior. Living at altitude in Colorado, the likelihood of NOT developing cataracts is actually pretty low--even if you are meticulous about wearing sunglasses and all the other factors... So the role of excess vitamin C is likely to be very minimal compared to other factors.

[frazzled]

8. 25% of what?

You always have to ask that. I hate these freaking "x% more likely" studies. They're like a cottage industry for getting published in newspapers. Causation, as opposed to correlation, is rarely proved.

I remember a study from some years back that found smokers were such-and-such percent more likely not to wear their seat belts. That doesn't mean smoking causes a person not to wear seat belts, fer chris'sake.

[snagglepuss]

9. It' s there in B&W. 25% of the 25,593 women, aged 49 to 83,

researchers followed for 8 years.

[frazzled]

10. It absolutely is not

"Researchers followed 25,593 women, aged 49 to 83, for eight years and found that those who took 1,000 mg of vitamin C daily were 25 per cent more likely to develop cataracts than those who did not use supplements."

Not 25% of them; 25% more likely. We need to know what the likelihood is of developing cataracts is in general to see how statistically significant the findings are.

[HysteryDiagnosis]

13. What about the guineau pigs?? Don't forget about the guineau pigs...

Preventive effect of ascorbic acid against glucocorticoid-induced cataract formation of developing chick embryos
Purchase the full-text article



References and further reading may be available for this article. To view references and further reading you must purchase this article.

Hideo Nishigori Corresponding Author Contact Information, Rume Hayashi , Jung W. Lee , Kazuo Maruyama and Motoharu Iwatsuru

Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan
Received 19 June 1984;
accepted 27 September 1984.
Available online 11 April 2004.

Abstract

Glucocorticoid administration to developing chick embryos is known to promote cataract formation with a decreasing level of glutathione in the lens. To gain further understanding of this process, the level of ascorbic acid, a biological antioxidant, in the lenses was measured during the course of glucocorticoid treatment. When 0·25 μmol of hydrocortisone hemisuccinate sodium (HC) were administered to 15-day-old chick embryos, the level of ascorbic acid in the lens began to decline after 30 hr and became around 40% of the control value at 48 hr after HC treatment. At this time about 90% of the lenses showed opacity in the nuclear region. However, the level of ascorbic acid in the cataractous lens recovered to the control level at 96 hr, a time when the lens has recovered from cataract formation.

A triple application of ascorbic acid (20 μmol/egg) at 3, 10 and 20 hr after HC treatment significantly prevented lens opacification. The administration of ascorbic acid prevented the decline of ascorbic acid content and partially that of glutathione content in the lens caused by HC.

Author Keywords: Author Keywords: glucocorticoid; hydrocortisone; cataract; chick embryo; ascorbic acid; lens; glutathione
Article Outline

[HysteryDiagnosis]

14. 77,000 nurses agree... lutein prevents cataracts.

http://www.luteininfo.com/eyelutein

Chasan-Taber and co-workers conducted a prospective study of 77,466 female nurses 45-71 years old, from 1980 through 1992. The results showed that nurses with the highest intake of lutein and zeaxanthin had 22 percent lower risk of cataract extraction compared to those in the lowest quintile of intake. This study also showed that high intake of spinach and kale, green vegetables rich in lutein, may reduce the risk of cataract extraction.** 3

[finn78]

16. It's the old too many vitamins debate

This kind of issue has been around for years. Some studies show that taking too many vitamins can cause problems whilst others say that the body will simply urinate out anything it doesn't need. However, the fact that experts can decide on the answer is in itself enough reason not to go crazy with high doses of vitamins. I always stick to a low dosage multi-vitamin and try to eat healthily.

[semillama]

19. That's the way to go

Eat healthy, take a multi for insurance.

Welcome to DU, by the way!