Flaxseed Shows Protective Effects Against Radiation In Animal Models
Ionizing radiation produces deleterious effects in living organisms. People are exposed to ionizing radiation during diagnostic and therapeutic radiographic procedures, during air and space travel, background radiation from nuclear accidents and through the use of electronic devices. Researchers from the Perelman School of Medicine at the University of Pennsylvania have found that flaxseed may be effective at protecting healthy tissues and organs from the harmful effects of radiation.
In work by the laboratory of Melpo Christofidou-Solomidou, flaxseed and its bioactive lignan were found to be potent protectors against radiation-induced lung toxicity when given prior to radiation exposure (1). Specifically, dietary flaxseed decreased radiation-induced oxidative lung tissue damage, decreased lung inflammation and prevented lung fibrosis. This study was performed to determine whether dietary flaxseed can also be effective as a mitigator of radiation toxicity, i.e., when administered after radiation exposure to the lung.
A subsequent study (2) showed that a diet of flaxseed given to mice not only protects lung tissues before exposure to radiation, but can also significantly reduce damage after exposure occurs.
In separate experiments, the researchers fed one group of mice a diet supplemented with 10 percent flaxseed, either three weeks before a dose of X-ray radiation to the thorax or two, four, or six weeks after radiation exposure. A control group subjected to the same radiation dose was given the same diet but receiving an isocaloric control diet without the flaxseed supplement.
After four months, only 40 percent of the irradiated control group survived, compared to 70 to 88 percent of the irradiated flaxseed-fed animals. The flaxseed diet conferred substantial benefits regardless of whether it was initiated before or after irradiation. Mice on flaxseed displayed improved survival rates and mitigation of radiation pneumonitis, with increased blood oxygenation levels, higher body weight, lower pro-inflammatory cytokine levels, and greatly reduced pulmonary inflammation, and fibrosis.
Flaxseed may improve the efficacy of radiotherapy to reduce thoracic malignancy. Such treatment is significantly limited by radiation pneumonopathy which can cause cough, dyspnea on exertion and hypoxemia occurring within weeks to months after X-ray radiation therapy (XRT). Ultimately decreased lung function may result. Such radiation-induced effects are caused partly by chronic inflammation and oxidative stress. There is currently no effective pharmacologic therapy for the prevention of acute or chronic radiation pneumonopathy.
Thus, Christofidou-Solomidou (3) evaluated the lignan complex of FS (FLC) enriched in secoisolariciresinol diglucoside with respect to lung radioprotective and tumor radiosensitizing efficacy using a mouse model of thoracic radiation-induced pneumonopathy. Mice were fed 0% FS, 10% FS, 10% FLC or 20% FLC for 3 weeks, then subjected to XRT.
Irradiated mice fed 10% and 20% FLC diets displayed improved survival. The FLC diet reduced overall lung inflammation to levels comparable to those in nonirradiated mice. Flaxseed lignan complex up-regulated protein levels of protective antioxidant enzymes. Dietary FLC induced radiosensitizing effects in the XRT treated mice. Of note, the FLC protected normal tissue and did not affect tumor cell death by radiation treatment.
These studies demonstrate that dietary flaxseed, already known for its strong antioxidant and anti-inflammatory properties, works as both a mitigator and protector against radiation pneumonopathy.
References
- Lee JC, Bhora F, Sun J, Cheng G, Arguiri E, Solomides CC, Chatterjee S, Christofidou-Solomidou M. Dietary flaxseed enhances antioxidant defenses and is protective in a mouse model of lung ischemia-reperfusion injury. Am J Physiol Lung Cell Mol Physiol. 2008;294(2):L255
- Melpo Christofidou-Solomidou M, Tyagi S, Tan, KS, Hagan S, et al. Dietary flaxseed administered post thoracic radiation treatment improves survival and mitigates radiation-induced pneumonopathy in mice. BMC Cancer. 2011; 11:269.
- Melpo Christofidou-Solomidou M, Tyagi S, Pietrofesa R, Dukes F, et al. Radioprotective Role in Lung of the Flaxseed Lignan Complex Enriched in the Phenolic Secoisolariciresinol Diglucoside (SDG). Radiat Res. 2012; 178(6):568.