Selenium is a trace element found in Brazil nuts, seafood, meats, cereals, and grains. It is a component of the antioxidant enzyme glutathione-peroxidase, which protects cells and DNA from damage. As a result, it has been investigated to prevent diseases caused or exacerbated by this type of cellular damage, such as cancer, heart disease, and rheumatoid arthritis. Selenium is also required for proper immune system function, but it is unknown whether higher-than-normal selenium levels can stimulate the immune system. Long-term selenium use may increase the risk of certain cancers. Chemotherapy drugs have little specificity, attack tumour cells, and also injure proliferative tissues. Understanding the functions of micronutrients has grown significantly, particularly of Selenium (Se), which has immunomodulatory and antitumor properties. Selenium can be found in a variety of chemical forms. In trace amounts daily. Its primary function is to be a component of the body’s most potent antioxidant enzyme. Selenium exists in various chemical forms, each with a unique biological activity. Since the late 1960s, a few observational studies have reported that people with high Selenium levels in their diet or body tissues have a lower risk of cancer, and Selenium has been shown in laboratory studies to inhibit growth. Cancer cells.

Importance of Selenium

While Selenium is necessary for protecting body cells and membranes from free radical damage, it also collaborates closely with vitamin E. These two potent nutrients work together to provide antioxidant and immune-boosting benefits. Selenium works well in conjunction with other antioxidants such as zinc, beta-carotene, and vitamin C. It also appears to be beneficial in the treatment of inflammatory conditions such as rheumatoid arthritis(Wallenberg et al., 2014).

How to take Selenium

Selenium (Selenium TR) should be taken as directed on the label or as directed by a doctor. Do not use in greater or lesser quantities or for a more extended period than recommended. Consult with your doctor before using herbal supplements—the doctor. You could also talk to a practitioner who is trained in the use of herbal/health supplements. If you choose to take Selenium, do so according to the package directions or as prescribed by a doctor, pharmacist, or another healthcare provider. Selenium use in longer-term doses greater than 400 micrograms (mcg) per day can result in serious medical problems or death. Use no more of this product than is specified on the label. The daily recommended intake is 55 micrograms, typically supplied by seafood, meat, and fortified grain products.

Mechanisms of Action:

Selenium is required for the antioxidant enzyme glutathione peroxidase, in which aggressive oxidation products and intracellular free radicals are converted into less reactive or neutral components .(IntechOpen – Page Not Found, n.d.) Other biological functions of Selenium include thyroid hormone regulation and vitamin C reduction status regulation. Selenium has been shown to cause a multi-targeted cell death process that consists of the induction of unfolded protein response, ER stress, and the formation of large cytoplasmic vacuoles and the formation of reactive oxygen species (ROS) (31). Excessive selenium consumption, on the other hand, causes hepatic insulin resistance via the opposite regulation of (ROS)


1.Cancer prevention and treatment

There is a lack of clear evidence. According to some research, it may increase the risk of aggressive and secondary cancers.

2.To lessen the side effects of chemotherapy

In young patients, Selenium may help reduce fatigue and nausea.

3.To reduce  lymphedema (swelling due to the accumulation of lymph)

According to a clinical trial, selenium supplementation can reduce swelling in patients who have had extensive surgery or radiation therapy. 

4.To avoid heart disease

Despite the fact that low blood selenium levels have been linked to Heart disease, general population studies have not supported the use of Selenium to treat heart disease. This application is still being debated.

5.Rheumatoid arthritis treatment.

Selenium deficiency has been discovered in rheumatoid arthritis patients. However, in a few clinical trials, selenium treatment for rheumatoid arthritis did not show any benefit.

Selenium and Hepatocellular carcinoma

Selenium is a micronutrient that has been linked to a lower risk of cancer. Hepatocellular carcinoma (HCC), a common and lethal cancer, needs new alternative treatment strategies to improve patient survival. Selenium has been studied for its anticancer properties in oxidative stress and inflammatory-related mechanisms that may contribute to HCC growth and metastasis as an essential trace element. An increasing number of studies have been conducted in recent decades, in vitro and in preclinical models, to investigate the potential role of Selenium in liver cancer, involving several major cancer-associated signalling pathways, metabolic pathways, and antioxidant defence systems. It was also discovered that the trend of developing novel selenium nanoparticles and selenium-containing inhibitors Selenium’s therapeutic efficacy and relative potency have improved. 

Food Sources

Whole wheat foods are high in Selenium; the wheat germ is exceptionally high in Selenium. Plant-based foods, in general, provide the most where the soil is rich in minerals. Oats – 56ug per 100g, Wheat germ – 111ug per 100g, Brazil nuts – 103ug per 100g and Bran – 63mg per 100g

Clinical Summary

Selenium, an essential dietary trace mineral, is a critical component in antioxidant systems such as glutathione peroxidase ([Minerals], 2013), which neutralise and protect against damage caused by free radicals and reactive oxygen species. It is also necessary for thyroid function. Selenium can be obtained from the diet by eating whole grains, meats, seafood, poultry, and nuts. It is sold as a supplement to boost immune function and prevent cardiovascular, rheumatic, and cancer diseases. Studies have been carried out to determine the role of Selenium in lowering the risk of cardiovascular disease, but the results have been inconclusive. Supplementation has been shown to reduce viral load in people infected with the human immunodeficiency virus (HIV)(Vinceti et al., 2018). In epidemiological studies and clinical intervention trials, the importance of selenium in cancer prevention has been documented. Data suggest that it may be beneficial in preventing gastrointestinal and lung cancers, though findings from bladder cancer research are contradictory (Amaral et al., 2010). In ovarian cancer patients undergoing chemotherapy, selenium supplementation reduced side effects such as hair loss, abdominal pain, and loss of appetite (Sieja & Talerczyk, 2004). It was found to be effective in the treatment of head and neck lymphedema. It aids in the reduction of diarrhoea associated with radiation therapy (24) in gynaecological cancer patients without affecting effectiveness or long-term survival (39), and may aid in reducing chemotherapy-induced fatigue and nausea in adolescents(Vieira et al., 2015). Selenium has been shown to cause a multi-targeted cell death process that includes the induction of unfolded protein response, ER stress, and the formation of large cytoplasmic vacuoles, as well as the formation of reactive oxygen species (ROS) (31). On the other hand, excessive selenium consumption causes hepatic insulin resistance via the opposite regulation of (ROS). Recent research indicates that the effects of dietary Selenium on the progression of malignant mesothelioma tumours are dependent on the redox metabolism of the arising cancer cells and tumours that can convert increased Selenium into a more substantial reducing capacity benefit from increased selenium intake.

Adverse Reactions:

1.Case study: A 75-year-old man died after ingesting 10 g of sodium selenite supplement for the treatment of prostate cancer (See et al., 2006)

2.Acute toxicity due to selenium poisoning has been reported with accidental or suicidal ingestion of gun bluing solution or sheep drench. Consuming gramme quantities of Selenium can cause severe gastrointestinal and neurological disturbances, acute respiratory distress syndrome, myocardial infarction, and renal failure.

3.Chronic selenosis (doses above 1000 mcg/day): Muscle weakness, fatigue, peripheral neuropathy, dermatitis, nail and hair changes/loss, garlic breath/body odour, irritability, growth retardation, hepatic necrosis.

4.Selenium poisoning has occurred due to either unintentional or suicidal ingestion of gun bluing solution or sheep drench. Ingestion of grammes of Selenium can result in severe gastrointestinal and neurological disturbances, kidney failure, acute respiratory distress syndrome,  and myocardial infarction (heart attack).

General Overview

Mineral nameSelenium
What’s it used for?Immunity; protection from age-related degenerative diseases
Best food sourcesBrazil nuts, whole wheat foods, brown rice, oats and turnips
How much do I need?NRV is 55ug per day*
Need to knowSelenium levels in plant-based foods are directly related to groups in the soil.


Selenium is a naturally occurring element that people are exposed to primarily through food consumption, though it can also be absorbed through the air, drinking water, and dietary supplements. Small amounts of Selenium are required for specific biological functions in humans. Still, slightly higher doses can be toxic, making Selenium an element with a narrow but undefined range of applications. Sparked widespread interest in selenium supplements and claims that taking them could help prevent cancer. Since then, many more observational studies have been conducted to compare cancer rates among people with high and low selenium exposure. Hence Selenium is a natural compound. It shows the promising outcome for cancer treatment but stills a clinical on the broader way is needed to test the exact mechanism and approach of Selenium to treat cancer.