Selenium protects the heart

Does selenium protect against arthrosclerosis and blood clots in the heart? This has long been debated. Researchers from John Hopkins University have recently attempted to create an overview of the countless studies into this question. In a so called meta-analysis, they went though a large number of population studies (where, for example, a large number of people were followed for many years to see who, an under what circumstances, had cardiac problems) as well as examining six accepted randomized studies.
Even though, as usual, the final judgement on selenium effectiveness has not been made, their results are encouraging.
In the first place, there is good reason to believe that selenium protects against atherosclerosis. It is perhaps most important that selenium is a component of the anti-oxidizing enzyme, glutathion peroxidase (GHSpx), which counteracts the oxidation of fats in the blood, which plays a crucial part in the development of atherosclerosis. We know that people who get too little selenium in the diet, which is the norm in Europe, produce more of this enzyme when they receive more selenium.
Another selenium protein (selenium protein P) is believed to protect the inner portion of the blood vessels against attacks form oxidized fats and free radicals. This should also prevent atherosclerosis. Selenium also binds very tightly to poisonous metals such as mercury, cadmium, and arsenic. These metals are believed to promote atherosclerosis. If one believes, like many experts, that the mercury given off by amalgam fillings can cause atherosclerosis or other illnesses, then it is logical that taking extra selenium can counteract these effects.
In good time
What does the study say? The population studies show that, when the selenium concentration in blood serum increases by 50%, the risk of heart attack (because of atherosclerosis) falls by 25%. This is something to remember. Typically (in northern Europe) a 100 mg selenium pill is enough to increase the amount of selenium in the blood by 50%.
Can one count on a single pill of selenium (there are no other forms of selenium supplements) if one wants to reduce one’s risk of heart attack by 25%?
The researchers answer “no” to this question. When they analyzed a more precise randomised study, the risk was only reduced by 11%. We also know that population studies can be wrong. For reasons unknown, they often show reality though rose coloured glasses.
Nevertheless, there are arguments against this objection. The population studies followed people who possibly received the same amount selenium daily throughout their lives. Concurrently, atherosclerosis occurs after a process that starts in the earliest days of youth. It is not reasonable to conclude that a selenium supplement taken for only a few years during a randomized study has the same effect. Typically the randomized studies analysed lasted about three years.
We therefore could conclude that it is important to get enough selenium, in good time.
Reference:
Flores-Mateo et al. Selenium and coronary heart disease: A meta-analysis. Am J Clin Nutr 2006;84:762-73