Here is the article to read for analysis.This article is from the Science-Based Medicine group. It reports to show vitamins increase cancer risk and / or speed up growth. The authors cite 2 studies plus one of their own here. The main two studies include the SELECT prostate cancer study, and the Finnish ATBC study showing that Beta Carotene increased lung cancer rate in smokers and those exposed to abestos.
The SELECT study looked at the effects of vitamin E and selenium on prostate cancer. There is an article on this website that effectively deals with this SELECT study. The real result from the viamin E wing of the SELECT study should have reported that "the use of synthetic form of vitamin E slightly increases prostate cancer risk" and that form should not be consumed, at least not by itself. To look at differences between natural and synthetic vitamin E, go here. But this does not let natural vitamin E off the hook since the results may very well have been the same if a natural isolated form of vitamin E was used. In nature, there are 8 different forms of natural vitamin E as alpha, beta, delta, and gamma tocopherols and the same four as tocotrienols. The US Government only allows one of these to be called viamin E, alpha tocopherol. Look at this next result from a study on vitamin E forms: "In 2012, Yang & colleagues stated "that animal studies on colon, lung, breast, and prostate cancers found that gamma and delta tocopherols prevented cancer formation and growth...while the vitamin E form, d'alpha tocopherol, provided no such benefit."
Have Scientists been using the wrong vitamin E form(s)? Read this article, prepare to be shocked. And this next reference really tells a tall SELECT study tail. The SELECT study started a year after the publication of the last referenced study which mentioned different vitamin E forms should be used for prostate cancer research, but the SELECT only used just one, and a synthetic form, too. DID the SELECT study authors set out to FAIL?
The totality of research on vitamin E has many Scientists now questioning the past wisdom of FDA's decision about what is vitamin E.
There is a little recognized fact concerning vitamin E. It is used up faster in the body when diets are higher in omega fats and oils. These oils need to be protected from turning rancid, and vitamin E is the choice for preventing fat or lipid oxidation in the body.
The Finnish ATBC study on Beta Carotene and the CARET study in the United States
The Finnish study reported higher lung cancer risk with synthetic beta carotene consumption by smokers. Again, it is important for the results to be put into this perspective, only 1 more cancer per thousand, from 5-6, plus the amounts of the synthetic beta carotene were 5-10 times higher than normal dietary amounts of natural beta carotene which is a mixture of different forms. Synthetic beta carotene is only one form, the one thought to provide most of the action. The study of the different carotenoids is very complex and difficult to figure out. But until science does nail down, staying with the natural carotene forms appears to be wise. ref
Here is an article that explains what Scientists later discovered was happening here that changed the synthetic beta carotene from an anti-oxidant into a pro-oxidant. ref ref There is also a logical finding for the results that beta carotene in higher amounts should not be consumed in the synthetic form by smokers. Copied here from the above linked article is the result of a 2001 study, "beta-crytoxanthin levels were the only individual carotenoid family member related to a significant reduced risk of lung cancers in smokers. But together, higher total carotenoids exhibited a 37% reduction in lung cancer risks for smokers versus those with lower than normal total carotenoid amounts."
Eat vegetables and fruits. Beta-crytoxanthin is found in yellow apples, apricots, cantaloupe, lemon, mangoes, nectarines, papayas, oranges, tangerines, carrots, pumpkin, sweet potatoes, yellow tomatoes, and yellow winter squash.
This next reference looks at the lessons learned from the ATBC and CARET studies. ref Valuable points are raised, especially about how larger dosages of vital but synthetic nutrients can block out absorption of related nutrients. Or that influenced by conditions already present in the body, large doses of nutrients can change direction of reactions and exhibit opposite functions. Like an anti-oxidant turning into a pro-oxidant under an unbalanced redox system. ref The study that revealed antioxidant vitamins made colds last longer is one example. Body defences were trying to kill viruses by generating free radicals, but the antioxidant vitamins neutralized them before such actions. Another review with recommendations for vital points from Australian Government agency.