Considerable research and studies are
underway on the need and benefits of selenium supplements. The subject of
recent study and debate is the role of selenium in cancer prevention.
Selenium is a trace material that is essential in several metabolic pathways. It is found in soil,
water and some foods. The mineral is incorporated into proteins to make
selenoproteins, an important antioxidant enzyme. This antioxidant helps prevent
cellular damage from free radicals, a by-product of oxygen metabolism that
contributes to the development of chronic diseases like cancer and heart
disease. Apart from playing an important role in the immune system,
selenoproteins also help regulate the thyroid function.
Selenium deficiency is rare in US. However, it is witnessed in other countries, especially in China, where soil concentration of
selenium is low. Selenium deficiency may lead to hypothyroidism, weakened
immune system. Evidences indicate that
selenium deficiency may lead to the following specific diseases in human.
- Keshan Disease that leads to enlarged heart and poor heart function, especially in selenium-deficient children.
- Kashin-Beck Disease, which results in osteoarthropathy
- Myxedematous Endemic Cretinism that results in mental retardation
The major causes for selenium deficiencies include gastrointestinal disorders and processed or refined foods.
Selenium deficiency is also seen in patients on total parenteral nutrition
(TPN) as their source of nutrition.
Uses of Selenium Supplements
Selenium supplements are useful to human race in a variety of ways. Few of them
are tested and proved with scientific evidence while others uses are unclear
for which the scientific studies still underway.
Uses with scientific evidence
As Antioxidan: Selenium is a key trace element that has antioxidant
properties in humans.
Prevention of Prostate Cancer: A study conducted by Nutritional Prevention of Cancer (NPC) suggests that selenium supplementation reduces the risk of prostate cancer among men with PSA
(prostate specific antigen) levels and low selenium blood levels. However, the
study indicates that selenium did not reduce the risk of lung, colorectal, or
basal cell carcinoma of the skin, rather increased the risk of squamous
cell skin carcinoma.
Unclear uses of Selenium that lack scientific evidence
Asthma: Few studies report that selenium supplements may help asthma symptoms. However, there is no clear
scientific evidence on the same.
Cancer Treatment: Physicians opine that people with cancer have low levels of selenium. However, the reason for
this deficiency is still a mystery. Studies are underway to determine the
effect of selenium on both cancer prevention and cancer treatment.
Cardiovascular Disease Prevention Research is underway to study the
antioxidant property of selenium, which should help in the prevention of heart
disease and other cardiovascular conditions.
Chemotherapy: A strong contradiction exists between selenium and chemotherapy. Because there are mixed opinions on the use of selenium supplements in patients undergoing chemotherapy for cancer.
Plant foods are rich in selenium, especially the ones that grow in selenium rich soil. For instance, researchers say that soil in the high plains of northern Nebraska and the Dakotas has high levels of selenium. The soil in certain parts of China and Russia has rather low levels of selenium. Meats and seafood are also rich sources of dietary selenium. Other foods that are rich in selenium
- Brewer's yeast
- Wheat gram
- Brazil nuts
- Sunflower seeds
- Cooked beef
- Cottage cheese
- Cheddar cheese
- Brown and white rice
Side effects of high selenium levels
People with high levels of selenium are at the increased risk of developing selenosis. Selenosis may lead to
Gastrointestinal troubles like nausea, vomiting, abdominal pain, diarrhea, garlic-like breath odor, and metallic taste.
- Neuromuscular-psychiatric disturbances including weakness/fatigue, lightheadedness, irritability, hyperreflexia, muscle tenderness, tremor, and peripheral neuropathy
- Dermatologic changes like skin rash, dermatitis, flushing, fingernail loss and hair loss.
- Liver dysfunction
- Kidney dysfunction
- Thrombocytopenia or low blood platelets
- Immune alterations or cell impairment
- Thyroid dysfunction
- Reduced sperm motility, or growth retardation.