By Jimmy Downs

Wednesday Oct 3, 2012 (foodconsumer.org) -- A new study in Cancer Causes and Control suggests that non-smokers maintaining a high level of serum vitamin D can reduce risk of death from lung cancer.

T.Y. Cheng and M.L. Neuhouser of Fred Hutchinson Cancer Research Center in Seattle, WA conducted the study and found among non-smoking lung cancer patients, those who had high levels of vitamin D were less likely to die, compared to those who had low levels.

The researchers also found the apparently beneficial effect of high levels of vitamin D disappeared in individuals who had high serum levels of vitamin A and in those using a vitamin A/ß-carotene supplement.

This finding may not be too big of a surprise for those who read Dr. John Cannel's web site often.  Dr.  Cannel, director of Vitamin D Council said high levels of vitamin A may interfere with vitamin D metabolism.  Vitamin D deficiency has been linked to 17 types of cancer including lung cancer.

According to the authors of the current study, excess vitamin A may interrupt vitamin D-mediated transcription of genes related with vitamin D metabolism.  The study was intended to examine how vitamin D and A affects the death risk in lung cancer patients.

Cheng and Neuhouser found the associations after analysing data from 16,693 men and women in the Third National Health and Nutrition Examination Survey (NHANES III) between 1998 and 1994. Serum 25(OH)D, and vitamin A biomarkers including serum retinol, beta-carotene, and retinyl esters were measured.  Dietary information was surveyed through a self-report.

Overall, there was no association between serum vitamin D and lung cancer death risk. However, among non-smokers, those with 44 nmol/L or higher levels of vitamin D, compared to those with lower than 44 nmol/L vitamin D, had 47 percent reduced risk of dying from lung cancer.

However, the associations were not observed among study participants with higher circulating vitamin A (serum retinyl esters 7.0 µg/dL or greater or the ratio of retinyl esters to retinol equal to or greater than 0.08). No associations were found either in those taking vitamin A/ß-carotene supplements.

The researchers concluded "Serum 25(OH)D concentrations were inversely associated with lung cancer mortality in nonsmokers. The beneficial association was diminished among those with excess circulating vitamin A or vitamin A/ß-carotene supplement users."

Lung cancer is deadly.  It is often that the disease is diagnosed in a late stage.  The biggest risk factor for lung cancer or many other diseases is smoking although other factors can influence the risk of developing the disease and the outcomes (prognosis) of the disease.