Higher intakes of certain micronutrients may reduce a process called methylation which affects gene signaling. Many genes involved in critical cell functions, including cell division, are methylated in lung tumours, showing the potential of the micronutrients to reduce the risk of lung cancer, according to findings published online ahead of print in Cancer Research.
The role of micronutrients in smokers is controversial with some studies; most notably the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Trial, reporting that beta-carotene supplements may increase the risk of lung cancer.
The new study, supported by the US National Cancer Institute (NCI), part of the National Institutes of Health, showed that reduced gene methylation with the intake of multivitamin supplements that are rich in phytochemicals, such as vitamin C, carotenoids, lutein, folic acid, and vitamins A and K. Such micronutrients are also present green leafy vegetables.
“This is the first cohort-based study to identify dietary factors associated with reduced promoter methylation in cells exfoliated from the airway epithelium of smokers,” wrote the researchers, led by Steven Belinsky, PhD, from the Lovelace Respiratory Research Institute in Albuquerque.
“Novel interventions to prevent lung cancer should be developed based on the ability of diet and dietary supplements to affect reprogramming of the epigenome,” they added.
‘Impressive’ study
Commenting independently on the study, a spokesperson for ingredient supplier DSM told NutraIngredients that the study illustrates how complex micronutrient research is.
“It impressively shows, for example, that supplements containing beta-carotene, conceivably increasing the risk of lung cancer in heavy smokers when taken in extremely high doses over years, have the potential to reduce cancer risk even in smokers,” said the spokesperson.
“Additionally, the study is further evidence that nature-identical, synthetic micronutrients in multivitamins can be effective in disease risk reduction as micronutrients from vegetables and fruits.”
Study details
Just over 1,100 current and former smokers participating in the Lovelace Smokers Cohort submitted sputum samples and completed questionnaires regarding their dietary intake. The sputum samples were used to examine the degree of methylation of eight genes commonly silenced in lung cancer and associated with risk for this disease.
People who ate at least 12 servings of green leafy vegetables per month had a 17 per cent lower risk of methylation, while a daily folate intake of at least 750 micrograms was associated with a 16 per cent lower risk.
Current multivitamin users had a 43 per cent lower risk of gene methylation, added the researchers, although there was no association between the duration of use and methylation..
More research needed
Sudhir Srivastava, PhD, chief of the Biomarkers Research Group at the NCI called for additional research to independently validate the study’s observations, and also to help resolve contradictions between varying studies.
“This particular study used a well-planned design and can serve as a basis for future identification of the mechanistic targets of these dietary factors,” said Srivastava, who was not involved in the study.
“Such studies are important steps for the future success of chemopreventive strategies.”
Source: Cancer Research
Published online ahead of print, doi: 10.1158/0008-5472.CAN-09-3410
“Multi-Vitamins, Folate, and Green Vegetables Protect Against Gene Promoter Methylation in the Aerodigestive Tract of Smokers”
Authors: C.A. Stidley, M.A. Picchi, S. Leng, R. Willink, R. Crowell, F.G. Flores, H. Kang, T. Byers, F.D. Gilliland, S.A. Belinsky