Selenium can fight cancer, but what else can it do?

Mineral Medicine

New research shows supplementing with selenium and zinc may benefit patients with liver cancer and cirrhosis.1

But…in terms of real “news,” this is yet another case of “new” research that’s the same as what we found 30 years ago!

The question to be answered is,“What else can selenium do?”

It’s high time researchers and the government agencies that fund them, like the NIH, start looking outside the box. To thoroughly review the full evidence of what’s come before and to stop repeating the same studies.

For years we have been starving for research that will take integrative medicine into truly new directions to directly benefit patients, medical practice and the healthcare system. Like the study on selenium I shared in last month’s issue, which showed its potential for fighting diabetes.

In the meantime, here’s what we already know:

Yes, selenium can help prevent and fight cancer. But you must be careful to get the dosage right.

As with other minerals, selenium is found in the soil. Thus, selenium levels reflect the ground in which plants were grown for food and the plants that cattle eat.

As a result, there are marked regional variations in environmental selenium levels. In high selenium areas there’s a risk of developing selenium toxicity, which may lead to deformities of bones and teeth and other health problems.

In areas that are low in selenium, deficiency may develop. This condition can result in a cardiomyopathy (abnormality of the heart muscle) that leads to heart disease and heart failure.

Aside from these extremes of selenium deficiency and selenium toxicity, most of the research on selenium actually relates to its ability to prevent cancer.

Selenium is a powerful antioxidant, which means it helps protect against oxidative stress and free-radical damage. It is thought to work well in partnership with vitamin E. Selenium also supports your immune system, and plays a part in human growth and development.

Several studies show that the level of selenium in the food of a given population is related to their rate of cancer. The lower the selenium, the higher the risk. In over 27 developed countries, the overall cancer mortality rate as well as mortality rates from leukemia and cancers of the colon, rectum, breast, ovary, and lung all are related to average per capita intakes of selenium.

Within the United States, cancers of the breast, colon, rectum, and lung are inversely related to the amount of selenium found in blood samples.

Similar results are found in China, where they actually fortify their foods with selenium to help counter deficiency. In a study conducted in 24 locations in China, there was a significantly lower rate of death from cancer and with higher amounts of selenium in the blood. This research is of course related to overall dietary intake and population studies.

But in fact, I had the opportunity of serving as the principal co-investigator on a cancer prevention study using selenium in a county in China. This county (Qidong County, Jiangsu Province) had a high incidence of liver cancer. The areas that had low levels of selenium in the blood or in the locally available grains had a higher rate of liver cancer–and by giving selenium supplements it is possible to raise selenium in blood to levels that prevent cancer.

Supplementation has also been shown to be effective in blocking the formation of chemically-induced tumors in the gastrointestinal tract, liver, breast, skin, and pancreas in laboratory animals. And in human clinical trials, supplementation has been shown to prevent skin cancer and lower the risk of other cancers.

Other studies have clearly shown protective effects of this trace element even when given after carcinogen exposure. Such results suggest that selenium owes at least part of its effects to a decrease in the spread of any cancer cells that form.

Remember to use caution when it comes to dosage

The cancer protection offered by selenium is generally observed at concentrations greater than those known to meet the requirements for normal growth and metabolic activity (i.e. the RDA). And, as observed with other nutrients, continuous intake of selenium is necessary for maximum inhibition of cancer.

However, as I pointed out in last month’s issue, while selenium toxicity is rare, it is a real concern. To avoid side effects and potential toxicity, it’s best to keep selenium intake at or below 400 mcg per day. Organic forms of selenium, such as selenomethionine, are absorbed as well as sodium selenite salt, but can persist in the body longer and thus theoretically pose a higher risk of toxicity.

Citations: 1 “Effects of Mineral Supplementation on Liver Cirrhotic/Cancer Male Patients.” Biol Trace Elem Res. 2012 Sep 12. [Epub ahead of print]