Could using dietary supplements help you survive the big C? According to a new study published in the International Journal of Cancer people who used dietary supplements before receiving a cancer diagnosis fared better in terms of survival. Is using dietary supplements to prevent cancer effective?

For this new study, researchers used questionnaires to evaluate the use of supplements among 68,518 women involved in the Norwegian Woman and Cancer study. They found cod liver oil to be the most commonly used supplement, followed by multivitamins and minerals. Those participants who used daily cod liver oil as a supplement within a year of their cancer diagnosis had their death rate cut by almost a quarter, while those with lung cancer had their death rate decreased by 44 percent. Use of other supplements was also associated with up to a 45 percent reduction in death risk among those diagnosed with lung cancer.

This study seems to suggest that using dietary supplements prior to receiving a diagnosis of cancer, particularly lung cancer, might prolong survival; but it’s unclear whether the effect is due to the supplements or whether supplement use is a marker for an overall healthier diet and lifestyle. The study did control for smoking habits, but not for dietary health habits.

It may be premature to be optimistic about the role of dietary supplements in cancer prevention and survival. A large scale study of 161,000 women published in the Archives of Internal Medicine this year showed that multivitamin use had no effect on the incidence of heart disease, stroke, or cancer. Several previous studies have also failed to show benefits of taking supplements for cancer prevention. Despite this around 40% of Americans take some form of multivitamin or supplement.

Some studies have even suggested that using some types of dietary supplements and vitamins could actually increase the risk of cancer. A 2004 study showed that smokers who used beta-carotene supplements appeared to be at a higher risk of developing lung cancer compared to those who didn’t. Other studies have shown that using dietary supplements in people who already have cancer could be associated with a more aggressive course. Men with prostate cancer who took selenium supplements, a supplement once believed to help with prostate cancer prevention, had a higher risk of a more aggressive type of prostate cancer.

It’s obvious that there are still unanswered questions about the use of dietary supplements and cancer.  The safest course of action may be to get vitamins and minerals through a healthy diet that emphasizes fruits, vegetables, and whole grain foods rather than processed ones. Many of the vitamins, minerals, and phytochemicals found in foods work better in synergy with one another, not used as a single ingredient in pill form. Two supplements that may be worth considering, since they’re hard to get through food sources, is vitamin D and fish oil. Always ask your doctor before taking any kind of supplement particularly if you’re on medications.