Selenium and glucose metabolism

In our thinking about our diet and our fitness, scientific research must be our highest authority.  The results from randomized controlled studies are the best evidence for the possible existence of a cause-effect relationship between treatment with a selenium (or Coenzyme Q10) supplement and beneficial health outcomes.

Recently, I did a search of the Medline database on the subject of selenium supplementation and its effect or non-effect on glucose metabolism, insulin resistance, glycemic control, etc.  I limited my search to reports of data from randomized, controlled trials.

Altogether, the Medline search yielded 48 hits.  Reading through the abstracts of the 48 journal articles, I was able to eliminate 30 references from consideration.  These 30 eliminated studies were studies that included all of my search terms but did not actually measure the effect of an intervention with selenium on some aspect of glucose metabolism.

18 good selenium supplementation studies
I was left with 18 good intervention studies that met my search criteria.  I read these studies and separated them into three distinct categories related to the effect of selenium supplementation on glucose metabolism and insulin sensitivity:

  • Beneficial effect of selenium supplementation (n=6)
  • No effect of selenium supplementation (n=9)
  • Not beneficial effect of selenium supplementation (n=3)

Selenium supplementation beneficial for glucose metabolism
The six studies showing beneficial effects of selenium supplementation on glucose metabolism and/or insulin sensitivity enrolled a combined 402 patients.  All six studies were conducted on Iranian patients.

Basically, these six studies showed the following health benefits associated with the selenium supplementation:

  • decreased plasma glucose levels
  • decreased serum insulin levels
  • decreased plasma HOMA-B levels
  • decreased plasma HOMA-IR levels

Note:  The HOMA (homeostasis model assessment) measurements are based on plasma levels of fasting glucose and insulin.  HOMA scores have been validated for quantifying insulin resistance [Song].

Selenium supplementation with no effect on glucose metabolism
The nine studies showing no effect of selenium supplementation – neither positive nor negative – on glucose metabolism enrolled a total of 8568 patients, all of them study participants in the United Kingdom, the United States, or France.

In these nine studies, selenium supplementation was not associated with any significant changes:

  • in plasma or serum glucose levels
  • in insulin sensitivity measures
  • in bio-markers of insulin resistance

Selenium supplementation with non-beneficial effect on glucose metabolism
The three studies that showed an undesirable effect of selenium supplementation on glucose metabolism enrolled a total of 1315 patients and study participants.  The patients in two of the studies (n = 113) were of Iranian origin.  The participants in the third study (n=1202) lived in the United States.

  • One Iranian study (n=60) reported increased insulin resistance [Hosseinzadeh].
  • The other Iranian study (n=53) reported increased fasting plasma glucose [Faghihi].
  • The big American study (n=1202) was the post-hoc study by Dr. Saverio Stranges of the data from the Nutritional Prevention of Cancer (NPC) study.

The NPC study data show a strong association between daily supplementation with 200 micrograms of a high-selenium yeast preparation and significant reductions in total cancer mortality, total cancer incidence, and prostate cancer incidence [Clark].

Dr. Stranges reported finding an “exposure-response gradient” across tertiles of baseline plasma selenium concentrations.  He reported an increased risk for type 2 diabetes in the highest tertile only, the tertile with a baseline plasma selenium level greater than 121.6 micrograms per liter.

As limitations to his study, Dr. Stranges did note that diabetes was a secondary outcome in the NPC trial and that the diagnoses of diabetes were self-reported [Stranges].

U-shaped curve in the selenium-glucose metabolism relationship?
The relationship between selenium and glucose metabolism is clearly a complex one.  Professor Rayman, University of Surrey, Guildford, United Kingdom, has suggested that there may be a U-shaped relationship between the levels of certain selenoproteins and glucose metabolism or insulin resistance [Rayman].

In that case, it might be that both low levels of selenium and high levels of selenium over a longer period could have harmful effects.

The protective range for plasma selenium status seems to be 120-170 micrograms per liter [Hurst].

A systematic review and meta-analysis of five observational studies (note: not intervention studies) published in 2016 has also suggested a U-shaped relationship between selenium status and the risk of type-2 diabetes.  Populations with relatively low levels and relatively high levels of serum selenium were seen to be at increased risk [Wang].

Appropriate level of selenium supplementation
Given what we know about the beneficial effects of optimal selenium levels, I choose to get my blood serum selenium concentration tested.

  • beneficial effects on the prevention of cancer
  • beneficial effects on the prevention of thyroid disorders
  • beneficial effects on the strengthening of the immune system
  • beneficial effects on the prevention of heart disease

Then, with the test results in hand, I can decide which level of daily selenium supplementation – 50 or 100 or 200 micrograms daily – is appropriate for me.

Limitations of the available research
The randomized controlled studies that have been done on the effect of selenium supplementation on glucose metabolism have been done on samples with much heterogeneity with respect to age, gender, ethnic background, and medical condition.

Furthermore, most of the data come from studies in which the effect on glucose metabolism was not the primary outcome measured.

We need more and better studies.  However, we are not likely to see funding for large well-designed studies because selenium is not a substance that can be patented.  The best we can do is aim to keep our selenium status in the estimated protective range [Hurst].


Studies showing a beneficial effect:

Alizadeh, M., Safaeiyan, A., Ostadrahimi, A., Estakhri, R., Daneghian, S., Ghaffari, A., & Gargari, B. P. (2012). Effect of L-arginine and selenium added to a hypocaloric diet enriched with legumes on cardiovascular disease risk factors in women with central obesity: a randomized, double-blind, placebo-controlled trial. Annals Of Nutrition & Metabolism, 60(2), 157-168.

Asemi, Z., Jamilian, M., Mesdaghinia, E., & Esmaillzadeh, A. (2015). Effects of selenium supplementation on glucose homeostasis, inflammation, and oxidative stress in gestational diabetes: Randomized, double-blind, placebo-controlled trial. Nutrition (Burbank, Los Angeles County, Calif.), 31(10), 1235-1242.

Bahmani, F., Kia, M., Soleimani, A., Asemi, Z., & Esmaillzadeh, A. (2016). Effect of Selenium Supplementation on Glycemic Control and Lipid Profiles in Patients with Diabetic Nephropathy. Biological Trace Element Research, 172(2), 282-289.

Farrokhian, A., Bahmani, F., Taghizadeh, M., Mirhashemi, S. M., Aarabi, M. H., Raygan, F., & Asemi, Z. (2016). Selenium Supplementation Affects Insulin Resistance and Serum hs-CRP in Patients with Type 2 Diabetes and Coronary Heart Disease. Hormone and Metabolic Research, 48(4).

Jamilian, M., Razavi, M., Fakhrie Kashan, Z., Ghandi, Y., Bagherian, T., & Asemi, Z. (2015). Metabolic response to selenium supplementation in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial. Clinical Endocrinology, 82(6), 885-891.

Karamali, M., Nourgostar, S., Zamani, A., Vahedpoor, Z., & Asemi, Z. (2015). The favourable effects of long-term selenium supplementation on regression of cervical tissues and metabolic profiles of patients with cervical intraepithelial neoplasia: a randomised, double-blind, placebo-controlled trial. The British Journal of Nutrition, 114(12), 2039-2045.

Studies showing no effect:

Algotar, A. M., Hsu, C., Singh, P., & Stratton, S. P. (2013). Selenium supplementation has no effect on serum glucose levels in men at high risk of prostate cancer. Journal of Diabetes, 5(4), 465-470.

Algotar, A. M., Stratton, M. S., Stratton, S. P., Hsu, C., & Ahmann, F. R. (2010). No effect of selenium supplementation on serum glucose levels in men with prostate cancer. The American Journal of Medicine, 123(8), 765-768.

Czernichow, S., Couthouis, A., Bertrais, S., Vergnaud, A., Dauchet, L., Galan, P., & Hercberg, S. (2006). Antioxidant supplementation does not affect fasting plasma glucose in the Supplementation with Antioxidant Vitamins and Minerals (SU.VI.MAX) study in France: association with dietary intake and plasma concentrations. The American Journal of Clinical Nutrition, 84(2), 395-399.

Karp, D. D., Lee, S. J., Keller, S. M., Wright, G. S., Aisner, S., Belinsky, S. A., & Khuri, F. R. (2013). Randomized, double-blind, placebo-controlled, phase III chemoprevention trial of selenium supplementation in patients with resected stage I non-small-cell lung cancer: ECOG 5597. Journal of Clinical Oncology, 31(33), 4179-4187.

Lippman, S. M., Klein, E. A., Goodman, P. J., Lucia, M. S., Thompson, I. M., Ford, L. G., & Coltman, C. J. (2009). Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA, 301(1), 39-51.

Mao, J., Bath, S. C., Vanderlelie, J. J., Perkins, A. V., Redman, C. G., & Rayman, M. P. (2016). No effect of modest selenium supplementation on insulin resistance in UK pregnant women, as assessed by plasma adiponectin concentration. The British Journal of Nutrition, 115(1), 32-38.

Rayman, M. P., Blundell-Pound, G., Pastor-Barriuso, R., Guallar, E., Steinbrenner, H., & Stranges, S. (2012). A randomized trial of selenium supplementation and risk of type-2 diabetes, as assessed by plasma adiponectin. Plos One, 7(9), e45269. doi:10.1371/journal.pone.0045269

Richie, J. J., Das, A., Calcagnotto, A. M., Sinha, R., Neidig, W., Liao, J., & El-Bayoumy, K. (2014). Comparative effects of two different forms of selenium on oxidative stress biomarkers in healthy men: a randomized clinical trial. Cancer Prevention Research (Philadelphia, Pa.), 7(8), 796-804.

Thompson, P. A., Ashbeck, E. L., Roe, D. J., Fales, L., Buckmeier, J., Wang, F., & Lance, P. (2016). Selenium Supplementation for Prevention of Colorectal Adenomas and Risk of Associated Type 2 Diabetes. Journal of The National Cancer Institute, 108(12), doi:10.1093/jnci/djw152.

Studies showing a non-beneficial effect:

Faghihi, T., Radfar, M., Barmal, M., Amini, P., Qorbani, M., Abdollahi, M., & Larijani, B. (2014). A randomized, placebo-controlled trial of selenium supplementation in patients with type 2 diabetes: effects on glucose homeostasis, oxidative stress, and lipid profile. American Journal of Therapeutics, 21(6), 491-495.

Mohammad Hosseinzadeh, F., Hosseinzadeh-Attar, M. J., Yekaninejad, M. S., & Rashidi, B. (2016). Effects of selenium supplementation on glucose homeostasis and free androgen index in women with polycystic ovary syndrome: A randomized, double blinded, placebo controlled clinical trial. Journal Of Trace Elements In Medicine And Biology, 3456-61.

Stranges, S., Marshall, J. R., Natarajan, R., Donahue, R. P., Trevisan, M., Combs, G. F., & Reid, M. E. (2007). Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial. Annals of Internal Medicine, 147(4), 217-223.

Other relevant studies:

Clark, L. C., Combs, G. J., Turnbull, B. W., Slate, E. H., Chalker, D. K., Chow, J., & … Taylor, J. R. (1996). Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group. JAMA, 276(24), 1957-1963.

Hurst, R., Armah, C. N., Dainty, J. R., Hart, D. J., Teucher, B., Goldson, A. J., & Fairweather-Tait, S. J. (2010). Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial. The American Journal of Clinical Nutrition, 91(4), 923-931.

Rayman, M. P., & Stranges, S. (2013). Epidemiology of selenium and type 2 diabetes: can we make sense of it? Free Radical Biology & Medicine, 65,1557-1564.

Song, Y., Manson, J. E., Tinker, L., Howard, B. V., Kuller, L. H., Nathan, L., & Liu, S. (2007). Insulin sensitivity and insulin secretion determined by homeostasis model assessment and risk of diabetes in a multiethnic cohort of women: the Women’s Health Initiative Observational Study. Diabetes Care, 30(7), 1747-1752.

Wang, X., Yang, T., Wei, J., Lei, G., & Zeng, C. (2016). Association between serum selenium level and type 2 diabetes mellitus: a non-linear dose-response meta-analysis of observational studies. Nutrition Journal, 15(1), 48

Disclaimer: The information reported in this article is not intended as medical advice and should not be used as such.

6 Replies to “Selenium and glucose metabolism”

  1. I was looking for an email address to send you this with no luck, so I will post here. I find reading about Coenzyme Q10 and Selenium, has fascinating possibilities for one’s health.

    I just started with Selenium (200 daily), to see if it will affect the antibodies that my immune system has apparently crested, to attack my Thyroid tissue; not serious but seems in early stages.

    I have the last two blood tests with Thyroid readings so will compare in the next two months.

    Although my Prostatitis Epididymitis Pain self help blog is for men (no advertising), I included some info on posts that women finding useful:

    “Sitz Bath – Hot Bath – Lymph Massage”
    “Yoga Exercise – Balasana – Fascia”

    1 / 7 Visitors = Avg 7 pages / 39 Mins

    1. Yes, amazingly, both selenium and Coenzyme Q10 get relatively little attention, and the biological inter-relationship between the two of them is scarcely known at all. I am glad that you are following along on both and


      1. My spelling mistake ↑ “crested” should be “created”

        Something interesting → I took Selenium (200 daily) for a week for my Thyroid antibodies; I also was jogging every day and lifting barbells because my red blood cell count had been low for the previous two blood tests.

        Now, I had been jogging a few times a week for last couple of years → Once around large parking lot ~ 1 minute, shoulder exercises standstill, walk a bit and then repeat jogging cycle 1-2 times (interval training). Slightly winded after ~ minute jog.

        Interestingly, after taking 200 Selenium (took 100 night, and 100 hour before exercise), I discovered that my endurance had shot right up, to a point that I could now run easily 4X times around a very large parking lot. As matter of fact, I had to stop the first couple days at 6 times because I was concerned of pulling muscles that were not conditioned yet.

        I took a blood test on July 17th for another problem, and my red blood cell count was now in the acceptable lower range. I had to stop Selenium and barbell lifting in order to eliminate variables, in solving another reoccurring problem (Hematospermia can be caused by weightlifting).

        Still, after 4 weeks, my jogging endurance is still great!

        Googling about Selenium & endurance, I came across these two pieces:
        “Whole blood selenium concentrations in endurance horses” → An increase in blood Se concentration was observed following exercise and this warrants further study
        “Essential Nutrients for Endurance Athletes: 10 for the Road” → After cycling to exhaustion—durations ranged from 2.6 to 3.5 hours—the group that took selenium showed less cellular damage.

        Question: → Did or can Selenium have affected my endurance in any way? I only took it for my Thyroid antibodies, but consequently was surprised at my elevated energy and endurance levels.

        BTW, I had energy to tackle the barbells with additional attempts, but added strength is not part of the deal 🙂

        I noticed in your articles that endurance was not clinically tested. I had just read about:
        “Daily dose of beetroot juice improved endurance and blood pressure” → The team found that the daily dosing of beetroot juice improved aerobic endurance by 24 percent after one week, as compared to the single dose which produced no improvement.

        Would be interesting to compare Selenium in the same setting. Any thoughts to my comments?

        BTW, I have posted that Ragweed starts ~ August 16th → 1st frost (~Sept 21st)

        As I wrote in “Sitz Bath – Hot Bath – Lymph Massage” blog post

        Coating nostrils 2X daily w/ virgin coconut oil stops Fall Ragweed allergies (+Spring Pollen)

        → This is the second year that I have had great success with Virgin coconut oil and ragweed allergies. I am very happy as I sleep well, no allergy pill side-affects, and it’s cheap ( 2 tablespoons a week).
        Also, thanks for posting my comment so I could share my experience with Selenium with you. I am hoping to get back on the 200 a day dosage in a couple of weeks.

        Selenium I used was → Natural Factors 200 mcg Selenium (yeast) 60 tablets.

        1. Just to be accurate → One lap takes ~ 1 minute 40 seconds at a comfortable jogging pace.

          I did 2X 6 laps today, no fatigue.
          “Effect of erythropoietin therapy and selenium supplementation on selected antioxidant parameters in blood of uremic patients on long-term hemodialysis” → Treatment with EPO and supplementation with Se significantly increased the element concentration in whole blood and plasma, and GSH-Px activity in red cells
          “Low serum selenium is associated with anemia among older adults in the United States” → Low serum selenium is independently associated with anemia among older men and women in the United States
          “Factors affecting RBC count” → Erythropoietin: this is a cytokine for erythrocyte precursors in bone marrow (remember that cytokines are signaling molecules used in cellular communication).
          “The Interaction of Iron and Erythropoietin” → Evidence of the interplay between iron and erythropoietin has existed for a number of years.

          So can Selenium “Quickly” jump start the Erythropoietin process to signal the bone marrow to increase red blood cells, and sustained with constant exercise?

          Erythropoietin (EPO) misuse common with cyclists?

          1. Correction ► July 11th was my 2nd consecutive low RBC count; I then added 200 Selenium few days later. I altered dosage from 200 at night to 100 / 100 split as mentioned because of middle night anxiety surge.

            The endurance results were clearly visible already July 20th, and the consecutive blood test moving my RBC count into the lower acceptable range was July 28th, not July 17th as quoted (15 days).

            The 100 Selenium hour before exercise was just a coincidence since I would take it in the morning and jog shortly after. I kept the schedule because of positive results, and also because medications are suggested to be consumed an hour before Sitz baths, to maximize blood flow / painkillers effectiveness.

            Hope that clears my posts up 🙂

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