antioxidant supplements differ--some may decrease chance of recurrence, some increase

[Lani]

Breast cancer patients who take antioxidants may have an increased or decreased risk of death or recurrent cancer, depending on which vitamin they use, a new study suggests.

Researchers found that among nearly 2,300 women with early-stage breast cancer, those who regularly used either vitamins C or E had a lower risk of cancer recurrence over five years than those who didn't use the vitamins.

On the other hand, women who regularly took a mix of carotenoids had a higher risk of dying from breast cancer, or any other cause, than women who did not take them.

Carotenoids include nutrients like vitamin A, beta-carotene and lutein.

The findings, reported in the journal Cancer, do not prove that any of the antioxidants are the reason for the effects seen.

But they do add to concerns about the risks of high doses of carotenoids, according to lead researcher Heather Greenlee, an assistant professor of epidemiology at Columbia University in New York.

"In my opinion," she told Reuters Health in an email, "our paper adds to the growing body of literature suggesting that dietary supplements containing high doses carotenoids may be harmful, and people should think twice before taking them."

Studies have found, for example, that giving beta-carotene supplements to smokers may actually raise their risk of lung cancer.

As for other antioxidants, Greenlee noted that the American Cancer Society and the American Institute for Cancer Research say that there's not enough evidence to recommend any dietary supplement for preventing cancer, or a cancer recurrence.

There is also concern about patients taking high doses of any antioxidant while on chemotherapy or radiation.

Antioxidants protect body cells from so-called oxidative damage. Cancer drugs and radiation work in part by creating oxidative damage. So in theory, high-dose antioxidants could diminish the treatments' effectiveness.

Still, studies show that women with breast cancer commonly use antioxidant supplements of some kind.

The current findings are based on questionnaires and case data from 2,264 U.S. women diagnosed with early-stage breast cancer.

Overall, 81 percent said they'd used at least one supplement containing antioxidants -- either within multivitamins or in the form of single-vitamin supplements -- in the two years after being diagnosed.

Over the next five years, the study found, women who'd reported using single supplements of either vitamin C or vitamin E six to seven days a week had a lower risk of cancer recurrence.

Of 540 women who took vitamin C, 15 percent had a breast cancer recurrence. That compared with 19 percent of the 1,072 women who did not use vitamin C supplements.

The differences were about the same when the researchers looked at vitamin E.

On the other hand, women who used any combination of carotenoids had a higher risk of dying from breast cancer, or from any cause. Of 89 women who used carotenoids six to seven days per week, 18 percent died of breast cancer; that compared with just under seven percent of women who did not use carotenoid combinations.

According to Greenlee, much of the benefit associated with vitamins C and E could potentially be explained by a "healthy user bias" -- that is, women who use dietary supplements tend to have healthier habits in general.

And that, she and her colleagues write, makes the increased risk of death linked to carotenoid use "even more striking."

The reasons for the different breast cancer outcomes linked to different antioxidants are not known, and the findings need to be confirmed in further studies, Greenlee said.

The most important point this study raises, she added, is that "antioxidant dietary supplements should not be assumed to all act in a similar fashion, as is a common perception in the general public."

"They are made up of different molecules," Greenlee said, "and likely have different effects."

On the other hand, the researchers found no evidence that breast cancer recurrence or deaths were linked to antioxidants taken within multivitamins -- which generally have more moderate doses of individual nutrients.

SOURCE: bit.ly/rkf6uw Cancer, online September 27, 2011.

[rhondalea]

I'm debating whether to buy the full article because the assertion that "Carotenoids include nutrients like vitamin A, beta-carotene and lutein" (a line included in the news stories but not in the journal abstract) may be misleading in the context of the study.

It is true that lutein is a carotenoid, but lutein--like several other carotenoids, including zeaxanthin, astaxanthin and lycopene--is not converted to retinol. If vitamin A is the problem, then non-vitamin A carotenoids should not be a problem.

I would really like to know which carotenoids they evaluated. I just need to decide if I want to know $35 worth.

Edited to add: Okay, now I want a differential study to distinguish between those carotenoids that convert to retinol and those that don't:

http://foodforbreastcancer.com/studies/7389

"The women completed a mailed questionnaire at baseline which collected data concerning the frequency of antioxidant supplement use since diagnosis (multivitamins with or without minerals, vitamin C, vitamin E, beta-carotene, lycopene, combination multiple carotenoids (vitamin A, alpha-carotene, beta-cryptoxanthin, beta-carotene, lutein, lycopene, zeaxanthin), selenium, zinc, coenzyme Q10, and soy), as well as factors known to influence breast cancer risk."

Of course, with all the googling, I found other studies to indicate lutein may contribute to the development of lung cancer. Lycopene, on the other hand, has been demonstrated to suppress prostate cancer.

The one supplement I really want to take--astaxanthin--seems not to have been studied in this context at all.

My aching head...

[ElaineM]

I agree. Things can get pretty confusing at times. That is why it is important to try to look for reliable sources of information that resulted from large studies that were funded by a source that did not benefit financially from the outcome of the studies.
Lutein is an important eye vitamin,especially for those with vision problems. It also can be found in dark leafy vegetables. In addition to the eyes dark leafy vegetables like kale, collard greens and spinach are great for several other parts of the body.
It seems we have to make some difficult choices about which part of our bodies we want to help the most.

I think vitamin c supplements is what its all about. I have a friend who took high dose vitamin c all of the time when she had cancer, she was impressed with the results to say the least. I don't know whether to believe science or just believe people's testimonials but I'm a believer which is why I take it daily for preventative measures. I buy it from http://www.livonlabs.com/ because that was where I first tried it and have had no reason to stray away.

[ElaineM]

I look up interactions between whatever conventional medicines I am taking and what supplements I am taking.
There are several places one can look on the internet, but I find that www.drugs.com has a pretty good database of conventional medicines and supplements.
All we have to do is to type in the names of the drugs and supplements we are taking and click. A list of possible interactions will come up along with possible food interactions.
It could be that vitamin C and vitamin E have different interactions with different drugs, therefore affecting the success or failure of those drugs and eventually affecting survival of the people who are taking those drugs and/or supplements.
Doctors should check for these things, but sometimes they don't know either. Pharmacists are sometimes better than doctors when it comes to checking for drug interactions or drug and supplement interactions.

[Ellie F]

Many thanks Elaine for posting this link. I am often concerned what herbs and supps I can take even though at present am just on herceptin. Sometimes I find myself munching a herb from the garden and aterwards wondering if there is any problem with it. Will now try to look it up first!
Cheers
Ellie