New research sheds light on selenium’s cancer-fighting abilities

We have known for several decades that the mineral selenium has anti-cancer effects. But how it helps our bodies fight cancer is a bit of a mystery.

For instance, reams of research shows that broccoli and garlic—both of which contain selenium—are protective against cancer, as well having many other health benefits.

In addition, selenium is in the soil, and thus the amounts in drinking water, foods, and animal feed are determined by where you live. My own and other research shows that people who live in areas that have higher selenium content in the soil generally have lower cancer rates than people in lower-selenium areas.

In China 25 years ago, my colleagues and I designed an experiment to test the effectiveness of selenium at preventing liver cancer.

In the mouth of the great Yangtze River, new islands had formed in the delta from low-selenium soil that had washed down from a thousand miles away. During the Cultural Revolution, people were re-settled on these islands. As time progressed, these new settlers were found to have higher cancer rates than people living on either side of the river, where the selenium levels were higher.

My colleagues and I planned to supplement the island dwellers’ diets with selenium in order to lower cancer rates. Unfortunately, despite successful pilot studies using selenized salt and the amino acid selenomethionine, the U.S. government shut down our study, and all studies in China, following the protests at Tiananmen Square.

Early ideas about selenium’s cancer-fighting capabilities centered (as with most dietary constituents) on its role as an antioxidant, especially in combination with vitamin E. Now, more emphasis is being directed to selenium’s role in the immune system. After all, our immune systems are designed to remove cells not normally found in the body, including bacteria, viruses—and cancer cells.

But some cancer cells can actually overstimulate the immune system, making it impotent against those cells. Researchers have found that certain selenium compounds, such as those found in broccoli and garlic, block these cells from exhausting the immune system and causing it to collapse.

But while research into how selenium works is interesting, it doesn’t usually translate into real-world, practical advice. In other words, it doesn’t typically uncover the daily dose of selenium you should take to treat or reduce your risk of cancer.

Furthermore, these types of laboratory studies keep doctors guessing about how and why selenium really works. When what these doctors really should be doing is accepting that it does work. And, in turn, recommending it (along with other vitamins and minerals) in the right dosages and forms to their patients to help prevent or manage cancer.

Ideally, eating foods that contain many nutrients can help prevent cancer and many other health conditions.

But we also know that most people do not follow optimal diets, and that most foods no longer have optimal nutrient content.

That’s where the modern science of dietary supplementation comes in.

I recommend taking 100 mcg of selenium each day for optimal health. In addition, take 200 mg of magnesium, 5,000 IU of vitamin D3, 200 IU of vitamin E, and a high-quality B complex daily, along with 500 mg of vitamin C twice a day. And since most people don’t eat anti-cancer foods like broccoli and garlic every day, it’s also a good idea to supplement with some of the nutrients you get from these foods, including the carotenoids lycopene, lutein, and astaxanthin.