If you’re looking for a natural way to boost your selenium intake, add beef organs to your diet and reap the benefits for thyroid function, immune health, and antioxidant protection.

A 2023 review found that beef liver and kidney meat contain much higher levels of selenium than muscle meat: “selenium concentrations in beef kidney, liver, and heart tissues are 4.5, 0.93, and 0.55 mg/kg, respectively, whereas muscle concentrations range between 0.2 and 0.55 mg/kg.”


Brown-white cows grazing on a lush pasture, grass-fed, pasture-raised New Zealand cattle

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The benefits of selenium

How much selenium do you need?

Selenium content in beef organs

Selenium concentration factors


It’s not just selenium; beef organs are packed with other minerals, vitamins, amino acids, fatty acids, and many other essential nutrients that your favorite steak just can’t match. 


What Are the Benefits of Selenium?


Selenium is a vital mineral that your body needs in small amounts. It's an essential nutrient for humans and animals because it plays key roles in many physiological processes. 

Selenium is a key component of powerful antioxidant enzymes that protect cells from oxidative damage caused by free radicals and reactive oxygen species (ROS). One such enzyme is glutathione peroxidase, which helps neutralize harmful peroxides (more unstable, reactive molecules). This enzyme prevents cell damage and reduces the risk of chronic diseases such as cancer and heart disease.

Here’s what makes selenium essential for human health:

  1. One of selenium's main tasks is to form selenoproteins. These compounds contain selenium in the form of the amino acid selenocysteine. Selenoproteins are essential for antioxidant defense, thyroid hormone metabolism, and many other vital functions.
  2. Selenium is essential for the production and metabolism of thyroid hormones, which regulate growth, development, and metabolic processes. A German study found that selenium aids in the conversion of T4 thyroid hormones to the more biologically active T3 form. Adequate selenium levels contribute to the optimal thyroid hormone metabolism and prevent thyroid disorders.
  3. Selenium supports healthy immune function, which is crucial for fighting off viral, bacterial, and fungal infections. It stimulates the production and activity of immune cells.  A 2013 study revealed that “Se is involved in regulating oxidative stress, redox, and other crucial cellular processes in nearly all tissues and cell types, including those involved in innate and adaptive immune responses.” 
  4. Its potent antioxidant properties may fight cancer. Some studies suggest that selenium may help reduce the risk of prostate, lung, and colorectal cancers.
  5. Selenium may lower the risk of heart disease. It lowers inflammation, prevents oxidative damage to blood vessels, and improves blood flow.
  6. Selenium can improve cognitive performance. It boosts memory, attention, and overall mental acuity. As a potent antioxidant, selenium protects brain cells from oxidative damage, reducing the risk of age-related cognitive decline and neurodegenerative diseases such as Alzheimer's and Parkinson's. 
  7. Selenium may have mood-regulating effects and manage symptoms of depression and anxiety. According to Benton and Cook, “the lower the level of selenium in the diet the more reports of anxiety, depression, and tiredness…” It aids in the production of “feel-good” neurotransmitters such as dopamine and serotonin. They are important for keeping your mood in check. Plus, its antioxidant powers shield your brain cells from damage that can contribute to mood disorders. 
  8. Selenium has important roles in male reproductive health
    1. It supports the production and motility of sperm
    2. It improves sperm quality
    3. It promotes better overall sperm morphology
  9. Selenium supports normal fetal growth and development. Adequate levels may reduce the risk of pregnancy complications such as preeclampsia, a serious condition characterized by high blood pressure and potential organ damage. 
  10. Selenium is a vital component of a healthy, youthful-looking skin. As an antioxidant, it protects skin cells from damage caused by UV radiation and other environmental stressors, which can lead to premature aging, wrinkles, and age spots. It also supports skin elasticity and promotes a healthy skin barrier, leaving your skin looking smooth, supple, and radiant.

Selenium deficiency can lead to many health issues, some of which include impaired thyroid function, weakened immune response, and increased oxidative stress. Over time, these issues may contribute to the development of chronic diseases and skin disorders. 

If you want to feel your best, make sure you’re getting enough selenium in your diet.


How Much Selenium Do You Need per Day?


According to the Harvard School of Public Health, the Recommended Dietary Allowance (RDA) for selenium is set at 55 micrograms per day for men and women over 19 years old. If you're pregnant or breastfeeding, you'll need a little extra: about 60 and 70 micrograms daily, respectively. 

The Tolerable Upper Intake Level (UL) for selenium is 400 micrograms daily for all adults. That's the highest amount you can consume without facing side effects and toxicity. When its levels in the body go over 400μg, selenium can interfere with the normal function of certain proteins and enzymes.

Acute selenium toxicity can cause symptoms such as:

  • Nausea and vomiting
  • Brittle nails
  • Nail discoloration
  • Teeth discoloration
  • Skin rashes
  • Fatigue and irritability
  • Mild nerve damage
  • Impaired coordination
  • Garlic breath odor

As long as you stick to the recommended range, you'll be giving your body the selenium it needs to thrive.

Speaking of giving your body what it needs to thrive, think about adding beef organ meat to your diet. They are a fantastic way to get plenty of selenium and other essential nutrients your body needs to perform at its best.

“Im enjoying the product a lot. I feel less anxiety and my cortisol levels are lower even though im still in a stressful situation. Overall I’m able to sleep better and my energy levels are more balanced throughout the day.”

Abbey Jaimes



Beef organ supplement bottle with 200 capsules of grass-fed beef liver, heart, spleen, kidney, and pancreas, packed with selenium and other essential nutrients



How Much Selenium Do Beef Organs Contain?


Beef organs, or offal, are an excellent source of selenium. Not all of them are super rich in this mineral, but many boast impressively high levels. According to the National Institute of Health (NIH), “foods that are high in protein tend to be the best sources of selenium.” The researchers list organ meats, particularly beef kidney, as one of the richest dietary sources of selenium.

The U.S. Department of Agriculture (USDA) provides the following amounts of selenium (shown in micrograms) per 100 grams of raw organ meat:


Beef kidney

Beef spleen

Beef liver

Beef pancreas

Beef heart

Beef thymus

Selenium content







% daily value







Among all organs, kidney meat is the richest source of selenium, providing an impressive 256% of the daily value in a single serving. This concentration makes kidney a great way to boost your selenium levels and reap its plethora of health benefits. The selenium found in beef kidney and other types of offal is highly bioavailable—your body can effectively absorb and use it. 

Organ meats contain organic selenium compounds such as selenocysteine and selenomethionine. These organic selenium forms are easily absorbed in the small intestine, while inorganic selenate and selenite have lower bioavailability. A 2019 study demonstrates a striking difference in absorption, with organic selenomethionine found in foods such as organ meats boasting a 96% gut absorption rate compared to 34–47% for inorganic selenite.

Harness the power of nature's ultimate selenium source with our beef kidney supplement. Packed with organic selenomethionine and selenocysteine, each capsule ensures optimal absorption of this mineral for unparalleled antioxidant protection and overall well-being.


One Earth Health's beef kidney supplement bottle is the richest source of selenium


Factors That Influence Selenium Content in Beef Organs


Here are some interesting facts and nuances about beef organ selenium:

  1. The animal’s diet influences selenium levels. Cattle raised on selenium-rich pastures have higher selenium concentrations. Selenium is easily absorbed from the plants and grains they consume and is stored in organs. That’s why we source our beef organ supplements from grass-fed New Zealand cattle.
  2. Selenium in plants depends on the mineral composition of the soil. Regions with selenium-rich soil (such as New Zealand) produce grass that is higher in selenium, resulting in higher levels in the cattle that graze there. 
  3. The selenium found in beef organs is organic (remember selenocysteine and selenomethionine?), which makes it more readily absorbed and utilized by the body.
  4. Beef organs are nutrient powerhouses, containing a synergistic blend of vitamins, minerals, and other beneficial compounds. This unique nutritional profile may enhance the absorption and utilization of organic selenium.
  5. The liver and kidneys play crucial roles in the animal’s metabolic processes, particularly detoxification and mineral storage. As a result, higher concentrations of essential minerals such as selenium accumulate in beef liver and kidney.

With such a remarkable confluence of factors contributing to their rich selenium content, do you need more reasons to include beef organs in your diet? These culinary delights will tantalize your taste buds with their rich, savory flavors and provide a unique combo of health-promoting nutrients.

For those who may not have acquired the taste for cooked organ meats or prefer a more convenient option, our beef organ supplements provide all the concentrated nutritional benefits of these powerhouse foods in an easy-to-consume capsule form. 


What Are the Effects of Selenium Deficiency?


With so many rich and naturally available sources of selenium, it's easy to obtain the recommended daily amount. Some people may still suffer from selenium deficiency, either because of inadequate dietary intake or problems with absorption. 

Selenium deficiency can have detrimental effects on bodily systems and functions. 

  • Immune function: selenium supports the immune system's ability to fight infections and diseases. Deficiency can weaken the body's immune response.
  • Thyroid function: selenium is essential for the production of thyroid hormones and keeping your thyroid function in check. Deficiency can lead to thyroid dysfunction, such as Hashimoto's thyroiditis or goiter.
  • Reproductive health: adequate selenium levels support optimal sperm motility in men. Deficiency has been linked to an increased risk of miscarriages and birth defects.
  • Cognitive function and brain development: selenium is involved in cognitive processes and brain development. Deficiency has been associated with cognitive impairment and an increased risk of neurological disorders.
  • Wound healing: selenium's antioxidant properties support the body's natural healing processes, and deficiency can impair wound healing capabilities.

Don't let your body starve of this essential mineral. Join the One Earth Health family and discover the power of selenium-rich beef organs.


About Our Beef Organ Supplements


Carefully crafted to harness the concentrated power of nature's most bioavailable selenium source, our supplements ensure you receive an optimal dose of this and other essential minerals and nutrients without compromising on quality or efficacy.

We source our beef organ products from New Zealand grass-fed, pasture-raised cattle to give you the highest quality, nutrient-dense superfoods. Beef organs are an excellent source of highly absorbable organic selenium compounds, along with a synergistic blend of vitamins B2, B6, B12, folic acid, zinc, iron, and other essential nutrients.

Purity and convenience are at the forefront of One Earth Health’s supplements. We've eliminated harmful additives, hormones, and antibiotics and focused on a clean, natural source of nutrients straight from nature's bounty. Our expertly crafted supplements offer a hassle-free way to harness the incredible health benefits of beef organs without acquiring an acquired taste for them. Say goodbye to the culinary challenges and embrace the concentrated goodness of these nutrient powerhouses in a convenient, easy-to-consume form.

Find guides, recipes, and tips in our free resource library to help you integrate these nutritional powerhouses into your daily routine effortlessly.

Shop our products and fuel your body with nature's most bioavailable nutrients.


Selenium in Beef Organs FAQ


Is 200 mg of selenium too much?


200 mg (2,000,000 μg) of selenium is excessively high and leads to toxicity. The recommended dietary allowance (RDA) is 55 μg a day, with an upper tolerable limit of 400 μg per day. Excessive selenium intake can cause nausea, fatigue, hair loss, nail brittleness, garlic breath odor, skin rashes, nerve damage, impaired coordination, and increased risk of diabetes and cardiovascular diseases.


What is the richest source of selenium?


Beef kidney is the richest dietary source of selenium. A 3.5-ounce (100g) serving provides 256% of the RDA—high, but nowhere near dangerous. This exceptional selenium content is attributed to factors such as selenium-rich animal feed, the presence of highly bioavailable organic selenium forms (selenocysteine and selenomethionine), and the kidney's role in nutrient accumulation and detoxification.

Other rich sources of selenium are beef liver, beef spleen, and beef heart.


What depletes selenium in the body?


The reasons for selenium depletion may include: 

  • Poor dietary intake of selenium-rich foods (organ meats, seafood, nuts, whole grains)
  • Digestive disorders (Crohn's, celiac)
  • Smoking
  • Excessive alcohol consumption
  • Certain medications (corticosteroids, antacids, chemotherapy)
  • Pregnancy or breastfeeding
  • Chronic diseases (HIV/AIDS, cancer, kidney disease)

    What organ is damaged by a selenium deficiency?


    Selenium deficiency primarily impacts the thyroid gland. Here are the reasons why: 

    • Selenium plays a crucial role in the conversion of the thyroid hormone thyroxine (T4) into its active form, triiodothyronine (T3). With inadequate selenium levels, this conversion is hindered, leading to hypothyroidism (underactive thyroid).
    • Low selenium levels have been associated with a higher risk of developing autoimmune thyroid diseases such as Hashimoto's thyroiditis (chronic inflammation of the thyroid) and Graves' disease (overactive thyroid).
    • In areas with severe selenium deficiency, the thyroid gland may enlarge or develop a goiter as the body attempts to compensate for the impaired thyroid hormone production by increasing its size.

      Can beef liver replace a multivitamin?


      While valuable, beef liver alone may not replace a multivitamin for everyone. Beef liver is incredibly nutrient-dense, packed with omega-3 fatty acids, coenzyme Q10, vitamins A, B12, riboflavin, folate, iron, zinc, and copper. Its high-quality protein and heme iron are readily absorbed. It may lack adequate amounts of certain vitamins like C, D, and some B-complex found in multivitamins.

      When choosing a supplement, take into consideration your individual needs, health conditions, and portion control (risk of vitamin A toxicity). Certain groups such as pregnant women, and those with iron overload, gout, vitamin A hypersensitivity, and kidney disease should limit liver intake. 


      Does steak have selenium?


      Steak does contain selenium, although in lower amounts than beef organs. Selenium is primarily concentrated in the muscle tissue and blood of animals. While a serving of steak can provide a decent amount of this essential mineral, beef organs such as kidney and liver are considered the richest dietary sources of highly bioavailable selenium.


      Are eggs high in selenium?


      Eggs are a good source of selenium, making them a valuable addition to a balanced diet to meet daily selenium requirements. One large egg can provide approximately 15.8μg of selenium, which accounts for a significant portion of the recommended daily allowance. The selenium content in eggs is primarily concentrated in the egg yolk, as it is an essential nutrient for embryonic development and growth. 


      Do beef organs increase testosterone?


      While there is no direct evidence that beef organs specifically increase testosterone levels, they do provide a concentrated source of essential vitamins and minerals that support overall hormonal health and bodily functions. Beef organs such as liver and kidney are rich in zinc, vitamin D, vitamin B12, and vitamin B6, all of which play crucial roles in testosterone production and regulation. Their high protein content, including essential amino acids, supports muscle mass and strength, which can indirectly influence testosterone levels.


      Does garlic have selenium?


      Garlic does contain small amounts of selenium. One clove of garlic provides approximately 0.6μg of selenium, which is a modest contribution to the recommended daily allowance. Garlic's selenium depends on the soil conditions where it is grown, as well as the variety and processing methods used.

      Regardless of its selenium content, garlic offers a wealth of other beneficial compounds, such as allicin and other sulfur-containing compounds, that promote heart health. It also has potent anti-inflammatory and antimicrobial properties.




      Sun, Y., Wang, Z., Gong, P., Yao, W., Ba, Q., & Wang, H. (2023). Review on the health-promoting effect of adequate selenium status. Frontiers in Nutrition, 10. https://doi.org/10.3389/fnut.2023.1136458

      Köhrle J. Selenium and the control of thyroid hormone metabolism. Thyroid. 2005 Aug;15(8):841-53. doi: 10.1089/thy.2005.15.841. PMID: 16131327.

      Hoffmann, P. R., & Berry, M. J. (2008). The influence of selenium on immune responses. Molecular Nutrition & Food Research, 52(11), 1273. https://doi.org/10.1002/mnfr.200700330

      Vinceti M, Filippini T, Del Giovane C, Dennert G, Zwahlen M, Brinkman M, Zeegers MP, Horneber M, D'Amico R, Crespi CM. Selenium for preventing cancer. Cochrane Database Syst Rev. 2018 Jan 29;1(1):CD005195. doi: 10.1002/14651858.CD005195.pub4. PMID: 29376219; PMCID: PMC6491296.

      Benton D, Cook R. The impact of selenium supplementation on mood. Biol Psychiatry. 1991 Jun 1;29(11):1092-8. doi: 10.1016/0006-3223(91)90251-g. PMID: 1873372.

      Selenium. (2023, March 7). The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/selenium/

      Office of Dietary Supplements - Selenium. (n.d.). https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/

      FoodData Central. (n.d.). https://fdc.nal.usda.gov/fdc-app.html#/food-search?query=&type=SR%20Legacy

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