Fibers Linked to Mesothelioma
Asbestos fibers are usually blamed as the cause of many lung diseases including malignant mesothelioma, lung cancer asbestosis, calcifications in the pleural cavity, and lung fibrosis. However, if antioxidant levels found in mesothelioma patients are high, it can stall the process of the development of cancer.
In the Cappadocia region of Central Anatolia, there’s another contaminant called erionite, which is found in volcanic tuffs. Erionite is a zeolite that is fibrous in nature, also causes pleural lining and lung diseases. The residents there use the white soil to make a whitewash or stucco to surface the walls, floors, and roofs of houses. They also use it as a substitute for baby powder.
Epidemiological and experimental studies dating back to the 1970s and ‘80s confirmed that erionite can cause malignant mesothelioma. Unfortunately, in villages where erionite is present, the incidence of malignant mesothelioma is up to 1000 times higher than the general population incidence elsewhere in the world.
In the 1980s, scientists believed that one determinant in the development of lung injury caused by fibers may possibly be the antioxidant capacity of the cells. Free radicals had been considered at that time to be the way that malignant mesothelioma developed, and antioxidant levels in the body are high then it’s possible that the disease process could be stalled. The antioxidants would interfere with the generation of the free radicals called reactive oxygen and nitrogen species.
Antioxidant Levels in Mesothelioma Patients Tested in Turkey
Scientists at different universities in Ankara, Turkey set out to discover whether or not there was a difference in antioxidant levels of those with and without mesothelioma. They had no problem finding volunteers for the study, and 42 patients with biopsy-proven mesothelioma along with 118 healthy subjects enrolled.
The researchers matched the meso patients to control subjects on the basis of age, sex, smoking status and lifestyle. The healthy subjects were divided into three groups, two of which were exposed to erionite and one that was not. The doctors took blood samples and tested for the antioxidant vitamins, vitamin E (alpha-tocopherol), vitamin C (ascorbic acid), vitamin A (retinol and beta-carotene).
Do Low Antioxidant Levels Precede Malignant Pleural Mesothelioma?
In this study, the serum levels of all antioxidants were significantly lower in mesothelioma patients than those in the control groups. Statistical analysis indicated that low levels of vitamin E and vitamin C in patients living in this area leads to a high risk of mesothelioma than the other antioxidants. Those who had low levels of vitamin A did not have a higher risk of mesothelioma.
The lower serum levels of antioxidants may be due to less frequent consumption of vegetables and fruits, which is rich in antioxidants normally.
The authors of the study commented that vitamin C has been shown to be strongly cytotoxic to different mesothelioma cell lines in 2011 and lab tests have shown that vitamin C works well with gemcitabine to kill the mesothelioma cell lines. Also, another study from Australia in 1998 that enrolled 1024 asbestos workers found that daily retinol was associated with a lower rate of mesothelioma compared with daily beta-carotene, which seemed to have no significant effect.
A study later in 2006 did not show any significant relationship between the plasma levels of vitamin E and beta-carotene with either mesothelioma or lung cancer. However, low levels of retinol were associated with a very modest increased risk of developing mesothelioma and lung cancer.
And as late as 2012, another experimental study revealed that dietary supplementation with vitamins A, E and selenium did not change the rate of development of mesothelioma in mice.
More studies on antioxidants need to be done to see whether or not there is an infallible connection between those with low levels and the development of mesothelioma who already are in an environment of exposure. But in the meantime, eating a good healthy plant-based diet high in fruits and vegetables and nuts and seeds may still be the best policy to stay healthy.
Emri, S., et al. Serum levels of alpha-tocopherol, vitamin C, beta-carotene, and retinol in malignant pleural mesothelioma. Asian Pac J Cancer Prev 2012;13(7):3025-9.
Ranzoto, E., et al. Selective ascorbate toxicity in malignant mesothelioma: a redox Trojan mechanism. Am J Respir Cell Mol Biol, 2011, Vol. 44, 108-17.
Martinotti, S., et al. In vitro screening of synergistic ascorbate-drug combinations for the treatment of malignant mesothelioma. Toxicol in Vitro, 2011, vol. 25, 1568-74.