Selenium is a trace mineral that offers a range of health benefits and is essential to the human body in small amounts; however, like all vital nutrients, it can be toxic at high levels. Let’s take a closer look at the potential health benefits of selenium, as well as the precautions necessary to ensure its safe and effective use.

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Weight Loss Benefits: 

Selenium plays a role in weight management. It is involved in the regulation of thyroid hormones, which are essential for maintaining a healthy metabolism. The thyroid gland requires selenium for the synthesis and activation of these hormones. In some cases, selenium deficiency may contribute to an underactive thyroid (hypothyroidism), which can lead to weight gain or difficulties in losing weight. By ensuring adequate selenium levels, you can support proper thyroid function and potentially facilitate weight loss efforts. 

However, it's essential to maintain a balanced approach to weight loss. While selenium may play a supportive role, it is not a magic solution on its own. A combination of a healthy diet, regular physical activity, overall lifestyle changes, adequate sleep, body detoxification, plus a correct diagnosis of hormonal imbalance and addressing that is crucial for sustainable weight loss.

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Anti-Cancer Benefits: 

Selenium has been studied for its potential role in cancer prevention and treatment. It acts as an antioxidant, helping to protect cells from damage caused by free radicals. Free radicals are unstable molecules that can contribute to the development of chronic diseases, including cancer. Research suggests that selenium may have a protective effect against certain types of cancer, such as lung, colorectal, prostate, and bladder cancer. It helps inhibit the growth of cancer cells and promotes their destruction through various mechanisms, including DNA repair, apoptosis (cell death), and modulation of cell signaling pathways.

However, it is important to note that while selenium shows promise in cancer prevention, it should not be considered a standalone treatment. Consult with a healthcare professional for personalized advice and treatment options if you have concerns about cancer.

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Additional Health Benefits of Selenium

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Immune Function Support: 

Selenium enhances immune response by supporting white blood cell function and cytokine production. Low selenium status has been associated with increased susceptibility to infections (Hoffmann & Berry, 2008).

Antioxidant Defense: 

• As part of the enzyme glutathione peroxidase, selenium protects against oxidative damage and cellular aging, contributing to long-term health.

Reproductive Health: 

• In men, selenium is essential for sperm motility and fertility. 
• In women, selenium supports ovarian health and may contribute to a healthy pregnancy.

Cardiovascular Health: 

• Adequate selenium levels have been linked to a lower risk of cardiovascular diseases by reducing inflammation and oxidative stress.

Cognitive Function: 

• Low selenium levels have been associated with cognitive decline and mood disorders. Its antioxidant properties may help protect brain cells and preserve.

Diabetes:

• Improved Insulin Sensitivity and Glucose Regulation: Some studies suggest that adequate selenium intake can improve insulin sensitivity and help regulate blood sugar levels.

Detoxification and Heavy Metal Binding: 

• Selenium helps neutralize and excrete heavy metals like mercury and cadmium, aiding in detoxification processes.

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Why is dietary Selenium important?

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In Nova Scotia and other parts of Canada, where the soil is naturally lower in selenium, this can lead to a deficiency in the local food supply. Studies have shown that pregnant women who consume foods high in mercury may have children with negative health outcomes. However, in areas where people eat ocean fish rich in selenium, which helps protect against mercury exposure, children tend to have better IQs.

Fish from regions with low selenium may be a concern, especially if they contain high levels of mercury. Ocean fish and seafood in Nova Scotia may be contaminated with mercury. To learn more, please follow the official advisory: Nova Scotia Fish Consumption Advisory.

Given these concerns, it may be beneficial for people to ensure they are consuming enough selenium, either through food or supplementation.

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How to supplement correctly with Selenium 

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Supporting Selenium Levels at Home:

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For general health and safe slenenium intake, it's best to obtain this essential mineral through natural food sources whenever possible. Below is a lost of selenium-rich foods you can incorporate into your diet

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Foods High in Selenium

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Brazil Nuts: 

• 2 Brazil nuts per day or every other day may provide sufficient selenium without the need for supplements

• Selenium: 68–91 mcg per Brazil nut (can vary widely by origin)
  
  • Note: Just 1–2 nuts can meet or exceed the daily requirement

Seafood

• Yellowfin tuna (cooked, 3 oz): ~92 mcg
• Sardines (canned in oil, 3 oz): ~45 mcg
• Shrimp (cooked, 3 oz): ~34 mcg
• Salmon (wild, cooked, 3 oz): ~26 mcg
• Halibut (cooked, 3 oz): ~47 mcg

Meats

• Beef liver (cooked, 3 oz): ~28 mcg
• Lean beef (cooked, 3 oz): ~33 mcg
• Pork (cooked, 3 oz): ~33 mcg
• Chicken (roasted, 3 oz): ~22 mcg
• Turkey (roasted, 3 oz): ~31 mcg

Dairy & Eggs

• Cottage cheese (1 cup): ~20 mcg
• Egg (1 large): ~15 mcg
• Milk (1 cup): ~8 mcg

Whole Grains & Legumes

• Brown rice (cooked, 1 cup): ~19 mcg
• Whole wheat bread (1 slice): ~10 mcg
• Lentils (cooked, 1 cup): ~6 mcg

Vegetables

• Spinach (cooked, 1 cup): ~11 mcg
• Mushrooms (shiitake, cooked, 1 cup): ~18 mcg

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Note: selenium content depends heavily on soil quality. While eating Brazil nuts and other foods can help boost selenium levels, the reality is that the selenium content can vary significantly, making it difficult to maintain consistent intake. Therefore, if you have a health condition that may be affected by selenium levels, it is recommended to consult a naturopathic doctor for personalized guidance.

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Words of Caution on Selenium Supplementation

While selenium is an essential nutrient, it's important to be mindful of how much you're getting—too much can be harmful. Supplementation should be approached with caution, especially since selenium has a narrow margin between beneficial and toxic levels.

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Potential Risks of Excess Selenium Intake:

• Toxicity (Selenosis): Consuming too much selenium can lead to symptoms such as: nausea, hair loss, fatigue, muscle tenderness, irritability, gastrointestinal distress

• Risk of Diabetes: Excess selenium has been linked in some studies to increased insulin resistance and a potential rise in the risk of type 2 diabetes.
• Radiation Exposure from Brazil Nuts: Brazil nuts can contain naturally occurring radionuclides like radium-226 due to the deep root systems that absorb it from soil. This radium can be stored in bones and teeth similarly to calcium.
  
  • Children and adolescents are advised to avoid Brazil nuts to reduce the risk of long-term radiation exposure.
• Interaction with Supplements: If you're already taking a multivitamin or selenium supplement, consuming additional selenium-rich foods—especially Brazil nuts—could lead to unintentional overconsumption.
• Pregnancy Considerations: Pregnant and breastfeeding individuals should be especially cautious, as both deficiency and excess can affect fetal development.

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Safe Intake Tips:

• Limit Brazil nuts to no more than 1–2 per day.
  (Eating 50 Brazil nuts could give you over 5,000 mcg of selenium—far above the recommended upper limit of 400 mcg/day for adults!)
• Always check your supplement labels—selenium is often included in multivitamins, and it adds up.
• If you have a pre-existing health condition or are on a restricted diet, consult a healthcare provider (e.g., naturopathic doctor or registered dietitian) before starting selenium supplements.

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Final Note

As with any dietary considerations, supplementation, or concerns about nutrient status, it is important to seek guidance from a qualified healthcare professional. A Naturopathic Doctor can provide personalized, evidence-informed recommendations based on your individual health history, current conditions, and nutritional needs. This ensures that your approach to selenium—and overall wellness—is both safe and effective.

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Wirtten By: Dr. Mina Laura Moldovan, ND

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References: 

Cavedon E, Manso J, Negro I, et al. Selenium Supplementation, Body Mass Composition, and Leptin Levels in Patients with Obesity on a Balanced Mildly Hypocaloric Diet: A Pilot Study. Int J Endocrinol. 2020;2020:4802739. Published 2020 May 28. doi:10.1155/2020/4802739

Ventura M, Melo M, Carrilho F. Selenium and Thyroid Disease: From Pathophysiology to Treatment. Int J Endocrinol. 2017;2017:1297658. doi:10.1155/2017/1297658

Andrade GRG, Gorgulho B, Lotufo PA, Bensenor IM, Marchioni DM. Dietary Selenium Intake and Subclinical Hypothyroidism: A Cross-Sectional Analysis of the ELSA-Brasil Study. Nutrients. 2018;10(6):693. Published 2018 May 30. doi:10.3390/nu10060693

Lee SO, Nadiminty N, Wu XX, Lou W, Dong Y, Ip C, Onate SA, Gao AC. Selenium disrupts estrogen signaling by altering estrogen receptor expression and ligand binding in human breast cancer cells. Cancer Res. 2005 Apr 15;65(8):3487–92. doi: 10.1158/0008-5472.CAN-04-3267. PMID: 15833885.

Ouyang J, Cai Y, Song Y, Gao Z, Bai R, Wang A. Potential Benefits of Selenium Supplementation in Reducing Insulin Resistance in Patients with Cardiometabolic Diseases: A Systematic Review and Meta-Analysis. Nutrients. 2022 Nov 21;14(22):4933. doi: 10.3390/nu14224933. PMID: 36432623; PMCID: PMC9693215.

Hoffmann PR, Berry MJ. The influence of selenium on immune responses. Mol Nutr Food Res. 2008 Nov;52(11):1273–80.

Rayman MP. The importance of selenium to human health. Lancet. 2000 Jul 15;356(9225):233–41.

Kaur P, Bansal MP. Effect of selenium-induced oxidative stress on the reproductive system of male mice. J Biomed Sci. 2015;22:36.

Flores-Mateo G, Navas-Acien A, Pastor-Barriuso R, Guallar E. Selenium and coronary heart disease: a meta-analysis. Am J Clin Nutr. 2006;84(4):762–73.

Cardoso BR, Roberts BR, Bush AI, Hare DJ. Selenium, selenoproteins and neurodegenerative diseases. Metallomics. 2016 Jun;8(6):610–9.

Ralston NV, Raymond LJ. Dietary selenium’s protective effects against methylmercury toxicity. Toxicology. 2010;278(1):112–23.

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