Lung cancer is the number one cancer killer in the U.S., and a majority of those killed are smokers. New research suggests smokers who consumed the greatest variety of vegetables may have a decreased risk of developing lung cancer. Now, the benefits of multi-colored vegetables on your plate should not be overestimated: A mixed green salad smothered in fresh veggies is not going to cancel out that pack of Marlboros. So how could veggies help smokers fend off lung cancer? Different fruits and vegetables contain different bioactive compounds known as phytochemicals. Various pigments in vegetables, such as the red (lycopene) in tomatoes, may confer health benefits that differ from the blue (anthocyanin) in purple cabbage.
A study featured in the journal Cancer, Epidemiology, Biomarkers & Prevention, drew on data from the European Prospective Investigation into Cancer and Nutrition study (EPIC), in which 452,187 participants aged 25 to 70 were recruited from across Europe and followed for an average of 8.7 years. Participants filled out questionnaires at baseline in which they were asked to report how frequently they consume fruits and vegetables categorized into different subgroups (leafy greens, root vegetables, stalk vegetables, etc). The questionnaires also addressed other lifestyle factors, the most relevant one being smoking.
The researchers found that smokers who consumed the greatest variety of vegetables (at least one vegetable from each of eight identified subgroups in a two-week period) were 27 percent less likely to develop lung cancer than smokers who consumed the least variety of vegetables (vegetables from only zero to four identified vegetable subgroups in a two-week period). Interestingly, they found that the decreased risk was associated with variety of vegetable consumption independent of the quantity of vegetables consumed. It is important to note that these findings were only found to be valid for current smokers; a lower risk was not observed among former or non-smokers.
Additionally, the EPIC study focuses on the benefits of obtaining nutrients and antioxidants from natural, whole foods, as opposed to manufactured supplements. In contrast, other research has shown that supplementing with vitamin E (alpha-tocopherol) and vitamin A (beta carotene) did not prevent lung cancer in older men who smoke. The same research proved taking beta-carotene supplements may in fact increase the incidence of lung cancer. This does not, however, discount the findings of the current EPIC study; rather, it highlights that when it comes to nutrition, the effect of isolated, individual nutrients in pill form may not always be the same as the effect of these nutrients when consumed as part of whole foods.
This EPIC study, while conducted for a relatively long period of time in a very large cohort, does have its shortcomings. One of the major limitations with nutrition research is that information regarding dietary habits is often obtained by participant report. This is inherently flawed, as there is risk for under and over-reporting. Still, it offers a very valuable nutrition lesson: for optimal health, quality may be more important than quantity.
Eat a rainbow. The more colors you can get onto your plate, the better.
Again, we know that smoking is the leading cause of lung cancer. While this research suggests it may reduce the risk of cancer, a variety of fruits and vegetables does not negate the other harmful effects of smoking.