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Taking certain vitamin supplements may adversely affect people's lifespan, researchers have suggested.Millions worldwide use antioxidant supplements such as vitamins A and E, and beta-carotene.Looking at dozens of previous studies, Copenhagen University researchers suggested these appeared to raise, not lower, the risk of early death. The Copenhagen team reviewed more than 815 clinical trials into the benefits of vitamins A, E, and C, alongside beta-carotene and selenium - all commonly-used supplements.They selected 68 whose methods were more likely to produce an accurate picture of vitamin benefits, then added their results together to form one, large-scale study.This overview suggested that taking antioxidant supplements neither increased, nor reduced, the risk of early death.However, when the researchers eliminated a further 21 trials which had a slightly higher possibility of producing a skewed result, the picture changed considerably.While the risk of death was unchanged among selenium and vitamin C users, a statistically significant increase in risk emerged for the other three supplements.Beta-carotene produced an approximate 7% increased risk, vitamin E a 4% increase and vitamin A, a 16% increase. The researchers wrote: "Our findings contradict the findings of observational studies claiming that antioxidants improve health."Considering that 10% to 20% of the adult population in Europe and North America may consume the supplements, the public health consequences may be substantial."They said there were several different explanations for this increase in risk - and suggested that knocking out 'free radicals' might actually interfere with a natural defence mechanism within the body.The team called for more research into the effects of vitamin supplements on health.
Conclusions Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study.
Alice Lichtenstein, a professor of nutrition science and policy at Tufts University who was not involved with the research, said the study's main message is: "Rely on food to get your nutrients."
I would like to see if it is possible to locate anyone connected with the Shanghai report and find out if any further work or study was done in this area that we do not know about yet.
…In 1999 an italian doctor reads the article and decides to get more information writing a letter to the Author (who moved to USA in the meantime). He basically asks two questions: 1) are there further studies to confirm a protective effect of cod liver oil? 2) was the protective effect stronger in older children, suspected to develop leukemia after an overidden immune response to a common pathogen? (Mel Greaves’s hypothesis: “the final hit may be infectious”). He gets a kind reply from the Author in a short while, but the content is pretty dismal for human science as a whole.No further data are available to confirm those results: cod liver oil is not anymore commonly used. The over ten year old study is unfortunately “buried” in 5 inches diskettes and a detailed revision of those data is almost impossible.Tricky Note:The "Shanghai report" is almost unreachable by a rough search through Medline databases. A peculiar text-string: "cod liver oil containing vitamins A and D" makes it impossible to find it out just crossing "leukemia" and "vitamin d"...you have to go for cod liver.
Taking lots of multivitamins may increase the risk of deadly prostate cancer, say US researchers.Their study showed taking multivitamins more than seven times a week was associated with an increased risk of advanced and fatal prostate cancer.There was no link with early cancer or localised prostate cancer, the researchers wrote in the Journal of the National Cancer Institute.Experts advised men to eat a healthy diet to reduce their risk of cancer.The findings, based on data on nearly 300,000 men, indicated the risk of advanced prostate cancer is 32% higher in men who take multivitamins more than once a day than in those who do not take them at all.Risk of fatal prostate cancer was almost double. The correlation was strongest for men with a family history of the disease, and who also took selenium, beta-carotene or zinc supplements.It is unclear why the multivitamins may increase the risk of certain types of prostate cancer.Study leader Dr Karla Lawson from the US National Cancer Institute said: "The possibility that men taking high levels of multivitamins along with other supplements have increased risk of advanced and fatal prostate cancers is of concern and merits further evaluation."Because multivitamins contain so many different components and men taking a lot of them were more likely to be taking other supplements, the researchers were unable to tease out what was causing the association.In an accompanying editorial, European researchers said a high intake of fruit and vegetables has been shown to reduce the risk of cancer.But it is not clear which nutrients have a positive effect.AntioxidantsThere has been a lot of research into antioxidants such as vitamin C and E because it is believed they may protect cells against damage.However, some analyses have suggested that beta-carotene, vitamin A and vitamin E supplements may shorten life rather than extend it.The amounts of antioxidants needed to offer any potential protection are not known and may differ between individuals.Liz Baker, science information officer at Cancer Research UK, said: "It's still not entirely clear what factors can affect a man's risk of developing prostate cancer."And there is conflicting evidence on the pros and cons of vitamin supplements."These products don't seem to give us the same benefits as vitamins that naturally occur in our food."We encourage people wanting to reduce their risk of cancer to eat a diet rich in fibre, vegetables and fruit, and low in red and processed meat."Georgia Diebel, a specialist nurse at the Prostate Cancer Charity said: "With all vitamins, we recommend that men do not exceed the daily recommended dose stated on the bottle."People often think of them as something 'natural' and do not understand that they still have to be metabolised and used by the body - a study like this suggests they are not safe in larger quantities."Prostate cancer is the second leading cause of cancer death in men. It kills one man every hour in the UK.
Another similar report - but again, this is not from a specialist medical source but the general media:http://news.bbc.co.uk/1/hi/health/6657795.stmQuoteBecause multivitamins contain so many different components and men taking a lot of them were more likely to be taking other supplements, the researchers were unable to tease out what was causing the association.
Because multivitamins contain so many different components and men taking a lot of them were more likely to be taking other supplements, the researchers were unable to tease out what was causing the association.
...It is a much needed corrective to the promotionof so-called natural treatments by the integrativemedicine programs at some medical schools and by health care professionals who believe incorrectlythat herbal remedies and dietary supplementsareharmless. The book deserves a wide audience.
Vitamins 'could shorten lifespan'......may be they don't!I'll try to read the complete report, thenI might be able to comment on this.For now I just note that vitamin C didn'tdo bad things and vitamin D is not mentioned.ikod
Quote from: Mackay on 26/03/2009 05:17:44So what about Vitamin D3? The scientific evidence is stacking up that it can prevent cancer and a multitude of diseases and that middle aged and older folks just can't make enough from sun exposure.You name it!   A little help from the sun, probably working in the long run, in a limited number of patients...why not?It certainly wouldn't be such a "New!!!" discovery.http://www.thenakedscientists.com/forum/index.php?topic=4987.0
So what about Vitamin D3? The scientific evidence is stacking up that it can prevent cancer and a multitude of diseases and that middle aged and older folks just can't make enough from sun exposure.