Breast cancer: Selenium levels in the blood predict 10-year survival

Having higher blood levels of selenium, an essential trace element, increases a breast cancer patient’s chances of 10-year survival, according to a Polish population study that is published in the science journal Nutrients. Also, earlier research has shown that supplementation with selenium yeast can lower the risk of contracting a variety of different cancer forms. The agricultural soil in Europe is very low in selenium and that is one of the reasons why selenium deficiencies are so common. The question is how much selenium we need to optimize levels in the blood.

Selenium supports around 30 different selenium-dependent enzymes called selenoproteins that are of vital importance to cellular energy metabolism and a number of other functions, several of which contribute to the following anti-cancer properties:

• To regulate cell growth
• To serve as powerful antioxidants (GPXs) that protect cellular DNA and mitochondria against free radical damage
• To repair DNA damage
• To prevent new blood vessels from forming in tumors (anti-angiogenesis)
• To support programmed self-destruction of cells (apoptosis)
• To contribute to a strong and well-functioning immune defense
• To counteract inflammation
• To neutralize environmental toxins like mercury

The selenium deficiency in Europe increases the risk of several cancers

Over the last decades, low selenium levels in the blood have been linked to an increased rate of different cancers. Moreover, low selenium increases your risk of dying of cancer. Selenium intake varies a lot from country to country. For example, people in the United States and Canada get a lot more dietary selenium than people in most European countries.
The researchers behind the new Polish study have reported earlier that low selenium blood levels are linked to an increased risk of laryngeal cancer, lung cancer, and colon cancer. A study of Swedish women with breast cancer has also demonstrated that the quartile with the highest blood levels of selenium (≤ 100 µg/L) had better odds of surviving than the quartile with the lowest levels (≥ 81 µg/L).
It turns out that the soil in Sweden, Denmark, Poland and other European countries contains very little selenium. As a result of this, the crops are low in selenium and that can affect the entire food chain.
In Poland, women’s average blood selenium levels are around 80-90 micrograms per liter, while the average blood selenium levels in American women are about 130 micrograms per liter. This is enormously important for our health and the numerous body functions that depend on the selenoproteins.

High selenium levels increase the odds of surviving with breast cancer for more than 10 years

The Polish scientists have already reported that low selenium levels in the blood negatively affect five-year survival in patients with laryngeal cancer, breast cancer, and lung cancer. The recent study looked exclusively at breast cancer patients from an earlier study and their odds of surviving for 10 years. The scientists collected blood samples from 538 women that had been diagnosed for the first time with invasive breast cancer during the period from 2008 to 2015. They all came from the Szcecin region of Poland. The blood samples were taken before their treatment was initiated. Levels of selenium in the blood were divided into quartiles, and the patients were followed from the time of their diagnosis until death or 10-year follow up, whichever came first. It turned out that, among the women from the quartile with the lowest blood selenium levels, the survival rate was 65.1. In comparison to this, the quartile with the highest selenium levels had a survival rate of 86.7%, which is a 20 percent difference.
The scientists say that more studies are needed to confirm that selenium and selenium supplements increase the chances of surviving with breast cancer. Their new study is published in the science journal Nutrients and supports earlier research that demonstrates anti-cancer properties with selenium and show that supplements can help prevent cancer in the breasts, prostate, colon, and lungs.

Even with a healthy diet it can be a challenge to get enough selenium

Selenium is mainly found in fish, shellfish, organ meat, eggs, dairy products, and Brazil nuts, but European crops lack selenium, as mentioned earlier. Even though fish and shell fish are considered good sources of selenium, research shows that you cannot get enough selenium even if you eat seafood five days per week. The research was conducted by Danish cancer scientists. Selenium supplements, however, can compensate for the low selenium intake. Stick with organic selenium yeast that contains a variety of different selenium compounds and provides the same variety of selenium species that you get from a balanced diet with many different selenium sources.

How much selenium do we need?

Selenoprotein P is an important selenium-containing protein that is used as a marker of the selenium status in blood. Studies show that the daily reference intake (RI) for selenium that is around 55 micrograms is too little to effectively saturate selenoprotein P. In order for this to happen, we need at least 100 micrograms and that is almost twice as much as the recommended intake level.
Most human studies have been conducted with a dose of 100-200 micrograms of selenium. The European Food Safety Authority (EFSA) has established a safe upper intake level for selenium of 300 micrograms per day.

References:

Mark Szwiec et al. Serum Selenium Level Predicts 10-Year Survival after Breast Cancer. Nutrients, 8 March, 2021

Rosewell Timmerman, Stanley Omaye. Selenium´s Utility in Mercury Toxicity: A Mini-Review. Scientific Research. 2021

Lutz Shomburg. Dietary Selenium and Human Health. Nutrients 2017

New Links between selenium and cancer prevention. HRB. December 2017

Clark LC et al: Effects of Selenium Supplementation for Cancer Prevention in Patients with Carcinoma of the Skin. JAMA: 1997.

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