Recent research published in the American Journal of Clinical Nutrition suggests that vitamin D may protect against lung cancer in never-smoking postmenopausal women.
Researchers took a look at the Women’s Health Initiative, a cohort of 128,779 postmenopausal women. Among the entire cohort, 1,771 had lung cancer between the years of 1993-2010.
They found that for those who took more than 800 IU of vitamin D per day had a 63% decreased risk of developing lung cancer among never-smokers compared to those who took less than 100 IU/day.
Furthermore, the researchers looked at a specific portion of participants among the cohort that enrolled in a trial of taking 1,000 mg/day of calcium and 400 IU/day of vitamin D or daily placebos. There were about 38,000 participants in this subset trial.
While there was no benefit against lung cancer in taking calcium plus vitamin D in initial analysis, when the researchers only looked at participants that took less than 1,000 IU/day of vitamin A (retinol form), they did indeed find benefit in calcium + vitamin D. There was a 31% decreased risk of developing lung cancer if you took calcium and vitamin D and kept your retinol intake down compared to taking placebo and keeping your retinol intake down.
What does this mean? Researchers believe that if you take too much vitamin A in retinol form, it may negate any benefit in taking vitamin D and calcium, particularly for lung cancer.