Too Much Selenium – Safe Dosage Range & Dangers of Toxicity

Getting too much selenium in the diet can cause selenium toxicity symptoms to develop.

In extreme cases, adverse effects can include hair loss, weight loss, irritability and fatigue.

The Natural Medicines Comprehensive Database (NMCD) states that selenium toxicity has also caused at least 9 deaths resulting from cardiac arrest.

However, at low doses this mineral is believed to be safe and has a number of potential health benefits. It is essential for proper functioning of several metabolic pathways in the body.

The US RDA for selenium is 55 mcg (micrograms) per day. That amount is purported to be easy for most people to obtain from the foods they eat commonly, even in areas where the selenium content of the soil is poor.

Selenium is important for reproduction, thyroid function, DNA repair and cellular protection from oxidation [1].

Some researchers believe that 55 mcg/day is not enough selenium to maintain optimal health in adult humans. The UL (upper safe limit) for selenium is 400 mcg/day.

Selenium

Essential Mineral

Anti-Oxidant

Immunity

Thyroid Function

How It Works:

• Cofactor for antioxidant enzymes
• Supports thyroid function & metabolism
• Promotes immune function & fertility

Dosage:

Up to 400 mcg per day

Safety:

Rated Likely Safe at Appropriate Dosages

Top Selenium Products* ❯

View User Ratings* ❯

How Much Is Too Much Selenium?

The biological effects of selenium vary according to the specific form of it used as a supplement.

Selenium is a trace chemical element (Se). Its atomic number is 34 on the Periodic Table of Elements.

Selenium is the major constituent of 25 different “selenoproteins”, which is any protein that includes a selenocysteine amino acid residue.

A study from Harvard University Medical School and the National Cancer Institute noted that selenoproteins are responsible for a large number of biological functions and molecular pathways in humans and other mammals. [2]

Some examples of selenoproteins include five glutathione peroxidase (GPX) enzymes and three thioredoxin reductase (TrxR/TXNRD) enzymes.

The effects of different selenoproteins and other selenium-based molecules continue to be explored in clinical studies.

Particular interest seems to be centered on how these chemicals might benefit cancer, cardiovascular disease, cognitive decline and thyroid disease. [1]

Currently, selenium has not been approved by the FDA as a medicine for preventing or treating any health condition or disease besides selenium deficiency.

Much more research is required to see how selenium supplementation might improve any medical condition in humans.

Too Much Selenium in the Diet

According to researchers from Cornell University, the amount of selenium found in foods depends largely on the amount of this mineral in the soil they are grown in.

Most countries have poor soil selenium content. In fact, only the United States, Canada, Japan and Norway have adequate soil levels. [1]

Still, selenium deficiencies are rare internationally. If someone does develop a deficiency in this important trace mineral, then they might experience symptoms like infertility – or a rare type of osteoarthritis called Kashin-Beck disease.

Selenium deficiency can also cause thyroid dysfunction. It may worsen the symptoms of those with hypothyroidism, especially if they also have an iodine deficiency.

This compound works with iodine in the thyroid gland to ensure adequate and efficient production of T3 and T4 thyroid hormones.

Even in selenium-poor geographic areas, most people still get enough of this trace element in the foods they eat to avoid developing a deficiency.

Those with HIV/AIDS and those undergoing kidney dialysis are the most likely to develop a selenium deficiency.

According to National Institutes of Health (NIH), some of the best foods to eat to avoid selenium deficiency are Brazil nuts, yellowfin tuna, halibut, sardines, bread, pasta and green leafy vegetables. [1]

Too Much Selenium in the Body

Selenium toxicity is more common than selenium deficiency. In most cases, this supplement is safe when it is used appropriately.

There are not any serious side effects associated with selenium when doses do not exceed the UL (400 mcg/day).

When selenium toxicity symptoms manifest, the most common are nausea, abdominal pain and vomiting. Other side effects of too much selenium include hair loss, weight loss, facial flushing and tremor.

Selenium Dosages to Prevent Toxicity

There is no established amount of selenium that causes fatality. Therefore it can be difficult to determine the best selenium dosage for an individual.

The following selenium dosages have been used in research as reported by NMCD:

• 100 – 200 mcg/day of selenized yeast has been used for arsenic poisoning.
• 200 mcg/day has been used for autoimmune thyroiditis.
• 100 – 300 mcg/day has been used for hypothyroidism.
• 100 – 300 mcg/day has been used for dyslipidemia.
• 200 mcg/day has been used for cancer prevention.

You should discuss the best selenium dosage for your health goals with your doctor before starting to avoid overdose.

Be sure to mention all medications and herbal supplements you sue, as well any pre-existing health conditions. This is especially important if you have an autoimmune disease, skin cancer, infertility and/or hypothyroidism.

Some of the drugs that selenium might interact with include antiplatelet/anticoagulant medications, barbiturates, contraceptives, immunosuppressants and warfarin.

Some of the herbal supplements selenium can interact with include angelica, clove, garlic, ginseng, dashen and astragalus. Selenium may also alter the metabolism of copper, omega-3 fatty acids, zinc and vitamin C.

Most people do not have to worry about getting too much selenium if they have healthy balanced diets based mainly with water-rich foods. [3]

Focusing food intake on plants, healthy fats, lean meats and plenty of water almost ensures proper selenium intake, without the risk of overdose.

Rate This Article

(1 votes, average: 5.00 out of 5, rated)