How did they arrive at this conclusion? First, they did a preliminary analysis of the available research literature and found that antioxidant supplements seemed to reduce incidence of all-cause death when the supplements included selenium [Jenkins 2020].
Systematic Review of Supplements With and Without Selenium
Next, they did a systematic review and meta-analysis of randomized controlled trials to evaluate the effect of selenium supplementation alone and the effect of antioxidant mixtures with or without selenium on the risk of heart disease and all-cause mortality [Jenkins 2020].
In their study, the researchers analyzed the results from 43 studies, all of which were randomized controlled trials and all of which had a duration of 6 months or longer [Jenkins 2020].
Significant Effects on Disease Prevention With Selenium Added
Here is what the researchers found [Jenkins 2020]:
- decreased risk of death from heart disease with antioxidant supplements when selenium was part of the mixture but no such association when selenium was absent from the mixture
- decreased risk of death from all causes when selenium was part of the antioxidant supplement and a slightly increased risk when selenium was absent from the supplement
- no decreased risk of heart disease or all-cause death with selenium alone or with antioxidants minus selenium
What Were the Antioxidant Cocktails Tested in the Studies?
The researchers reported that they analyzed the results from studies that tested the efficacy of supplements containing two or more of the following antioxidants as composite supplements [Jenkins 2020]:
- vitamin A
- retinol
- β-carotene
- vitamin C
- vitamin E
- selenium
- zinc
- copper
Selenium and Zinc as Indirect Antioxidants
The researchers explain that selenium, zinc, and copper do not have direct antioxidant effects. Instead, they support the cells’ endogenous antioxidant system that involves the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase. These endogenous antioxidants are important for the neutralizing of harmful free radicals caused by normal everyday metabolic processes.
Serum Selenium Levels and Heart Disease
Bomer et al have published a study showing that heart failure patients with serum selenium concentrations below 70 micrograms per liter had impaired exercise capacity and a 50% higher mortality rate.
Interestingly, heart failure patients with serum selenium concentrations between 70 and 100 micrograms per liter had similar adverse associations, suggesting that serum selenium values below 100 micrograms per liter might be considered abnormal [Bomer 2019].
In a four-year randomized controlled trial of the effect of daily combined selenium (200 micrograms) and the antioxidant Coenzyme Q10 (2 x times 100 milligrams) on heart disease in senior citizens, Professor Urban Alehagen achieved an increase in the active treatment study participants’ serum selenium concentrations from a mean value of 67 micrograms per liter at baseline to a mean value of 210 micrograms per liter at 48 months. Serum selenium concentrations did not change in the placebo group [Alehagen ].
The senior citizens who took the selenium and Coenzyme Q10 supplements had significantly lower plasma concentrations of a known bio-marker for heart failure (NT‐proBNP) at 24 and 48 months and had improved heart function shown on echocardiograms. The senior citizens in the active treatment group had significantly lower risk of death from heart disease. It is entirely possible that there was a synergistic effect from combining selenium with Coenzyme Q10 [Alehagen 2013].
Bottom line: Importance of Selenium and Zinc
The Canadian researchers’ analysis suggests that selenium and zinc supplementation should be part of any antioxidant supplement mixture that is aimed at reducing the risk of heart disease [Jenkins 2020].
Their dose-response analysis showed a significant decrease in the risk of heart disease and the risk of all-cause death at supplemental intakes of 50 micrograms of selenium per day. At 100 and 200 micrograms per day, there was no statistically significant increase in benefit.
Selenium intakes and selenium status vary considerably from region to region. The best thing to do is have a blood test to see whether one’s serum selenium status is far below 100 micrograms per liter.
Sources
Alehagen U, Johansson P, Björnstedt M, Rosén A, Dahlström U. Cardiovascular mortality and N‐terminal‐proBNP reduced after combined selenium and coenzyme Q10 supplementation: a 5‐year prospective randomized double‐blind placebo‐controlled trial among elderly Swedish citizens. Int J Cardiol. 2013;167:1860–1866.
Alehagen U, Aaseth J, Alexander J, Johansson P, Larsson A. Supplemental selenium and coenzyme Q10 reduce glycation along with cardiovascular mortality in an elderly population with low selenium status – A four-year, prospective, randomised, double-blind placebo-controlled trial. J Trace Elem Med Biol. 2020 May 4;61:126541.
Bomer N, Grote Beverborg N, Hoes MF, Streng KW, Vermeer M, Dokter MM, IJmker J, Anker SD, Cleland JGF, Hillege HL, Lang CC, Ng LL, Samani NJ, Tromp J, van Veldhuisen DJ, Touw DJ, Voors AA, van der Meer P. Selenium and outcome in heart failure. Eur J Heart Fail. 2020 Aug;22(8):1415-1423.
Jenkins DJA, Kitts D, Giovannucci EL, et al. Selenium, antioxidants, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2020; 112(6):1642-1652.
The information presented in this review article is not intended as medical advice and should not be used as such.
15 January 2021