Flax has been part of human history for over 30,000 years, used for feeding people and animals, weaving cloth, and even making paint. Now, researchers have found that it might now have a new use: protecting healthy tissues and organs from the harmful effects of radiation. In a new study, researchers found that a diet of flaxseed given to mice not only protects lung tissues before exposure to radiation, but also significantly reduce damage after exposure occurs.

The study’s findings, conducted by investigators from the Perelman School of Medicine at the University of Pennsylvania (Philadelphia, USA), were published June 24, 2011, in the journal BMC Cancer. “There are only a handful of potential mitigators of radiation effect, and none of them is nearly ready for the clinic,” said the lead investigator Melpo Christofidou-Solomidou, PhD, research associate professor of medicine, pulmonary, allergy, and critical care division. “Our current study demonstrates that dietary flaxseed, already known for its strong antioxidant and anti-inflammatory properties, works as both a mitigator and protector against radiation pneumonopathy.”

In several individual experiments, the researchers fed one group of mice a diet supplemented with 10% 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% of the irradiated control group survived, compared to 70% to 88% of the irradiated, flaxseed-fed animals. Various studies of blood, fluids, and tissues were conducted.

Dr. Christofidou-Solomidou and her colleagues found that 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 proinflammatory cytokine levels, and greatly reduced pulmonary inflammation and fibrosis.

The latter finding is especially exciting, because while radiation-induced inflammatory damage can be potentially treated with steroidal therapy [i.e., in radiotherapy patients], lung fibrosis is essentially untreatable. “There’s nothing you can give to patients to prevent fibrosis,” Dr. Christofidou-Solomidou pointed out. “Once a lung becomes “stiff” from collagen deposition, it’s irreversible. We have discovered that flaxseed not only prevents fibrosis, but it also protects after the onset of radiation damage.”

Dr. Christofidou-Solomidou and her colleagues are focusing additional research on the bioactive lignan component of flaxseed, known as SDG (secoisolariciresinol diglucoside), which is believed to confer its potent antioxidant characteristics. The lignan component also “regulates the transcription of antioxidant enzymes that protect and detoxify carcinogens, free radicals, and other damaging agents,” she stated.

Flaxseed has many other qualities that make it particularly attractive as a radioprotector and mitigator. “Flaxseed is safe, it’s very cheap, it’s readily available, there’s nothing you have to synthesize,” Dr. Christofidou-Solomidou noted. “It can be given orally so it has a very convenient administration route. It can be packaged and manufactured in large quantities. Best of all, you can store it for very long periods of time.” That makes it particularly interesting to government officials looking to stockpile radioprotective substances in case of radiologic disasters.

Coauthor Keith Cengel, MD, PhD, assistant professor of radiation oncology at Penn, explained that in such cases, “a big issue is the ‘worried well’”--all the folks who probably weren’t exposed but are concerned and want to do something.” Many potential radioprotectors, however, could have risky side effects. Dr. Christofidou-Solomidou added, “When you give something to four or five million worried well, you have people with preexisting medical conditions. You can’t give just anything to people with heart disease, for example. But this is absolutely safe. In fact, it is known to increase cardiovascular health, a finding shown by another group of Penn investigators a few years ago. It’s loaded with omega-3 fatty acids.”

Along with other researchers at the Perelman School of Medicine, the authors are conducting additional pilot studies on the potential of flaxseed for mitigation of lung damage in patients awaiting lung transplants and those undergoing radiation therapy for the treatment of intrathoracic malignancies. Dr. Christofidou-Solomidou is also conducting a pilot study for NASA on the benefits of flaxseed for astronauts on extended deep space missions. Long space exploration missions require that the astronauts perform extravehicular activities (EVAs) for repairs, during which they can face exposure to high levels of solar and galactic radiation with the added risk factor of breathing 100% oxygen. “Hyperoxia superimposed with radiation could potentially cause some lung damage and some reason to worry for the astronauts,” she said. “We are one of a handful of teams in the US that can study radiation in addition to hyperoxia. So now we’re adding another level of complexity to the one-hit, radiation damage studies; the double-hit model is something novel, nobody has done it before.”

The researchers are already convinced enough to incorporate flaxseed into their own routine. “I actually eat it every morning,” concluded Dr. Cengel, noting, “The potential health benefits are significant and there is no known toxicity--it just makes good sense to me.”

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