Scientists at the University of Warwick Medical School, Coventry, England have reported that the consumption of too much selenium can have adverse effects on cardiovascular health.
Selenium is a mineral which is necessary in the diet for optimal health and the body naturally obtains the selenium it needs from various food sources. Yet supplementing with selenium has recently become quite popular because of the mineral’s antioxidant properties, and due to the perception that selenium may reduce incidences of certain cancers – and especially prevent prostate cancer – which has recently been debunked.
While selenium certainly has many health benefits, if high blood levels of the trace mineral are associated with increased levels of serum cholesterol, people at risk for cardiovascular disease will want to monitor the levels of selenium in their diets.
According to the research team at Warwick University this is indeed the case.
The Warwick University study included 1042 participants (aged 19 to 64) from the UK’s National Diet and Nutrition Survey who were personally interviewed to assess various aspects of lifestyle, including eating and drinking habits. Blood was then drawn from each of the participants and analyzed.
Selenium Supplement Warning
The team of scientists reported that in those participants who had the highest levels of selenium – greater than 1.20 µmol per litre – an eight percent average increase in total serum cholesterol (lipids, or fats, within the blood) was observed.
The study also showed that LDL cholesterol, which is associated with heart disease, in these subjects was elevated by an average of 10%. Of the participants who demonstrated both high selenium levels and high levels of blood lipids, 48.2% reported regularly taking dietary supplements.
The leader of the study, Dr. Saverio Stranges, said that while high levels of selenium are not exclusively caused by people taking dietary supplements, the results of the study were of serious concern, given that the use of selenium as a dietary supplement has increased considerably in recent years due to the perception that selenium can reduce the risk of cancer and other diseases.
He went on to say that selenium’s use, “has spread despite a lack of definitive evidence on selenium supplements efficacy for cancer and other chronic disease prevention. The cholesterol increases we have identified may have important implications for public health. In fact, such a difference could translate into a large number of premature deaths from coronary heart disease.”
Dr. Stranges believes that the use of selenium supplements, or any other means of artificially increasing selenium levels above that which is normally required, is not advisable and he looks forward to further research which would examine the full impact of increased selenium levels on health.
Selenium in the Diet
In view of the Warwick study, people who are interested in lowering LDL cholesterol may want to monitor food sources of selenium in their diet. According to the U.S. National Institute of Health most people receive adequate amounts of selenium from their diets, and by the same token, it is possible to consume too much selenium without realizing it.
Foods High in Selenium
Some food sources of selenium can easily put a diet far beyond the recommended daily value of this important trace mineral.
- One ounce of Brazil nuts contains a whopping 540mcg of selenium (780% of the recommended daily value).
- Three ounces of light canned tuna contains 63mcg (95% DV).
- Only 3.5 ounces of beef provides 50% DV of selenium from only 35mcg.
Selenium Deficiency
Yet, even with such abundant sources of selenium available there are a few cases in which a doctor may recommend supplementation.
People who suffer from severe gastrointestinal disorders such as Crohn’s disease or who have had part of the stomach surgically removed may not absorb selenium in adequate amounts from diet alone. People with iodine deficiency and those who have experienced severe acute illnesses involving inflammation and widespread infection also will often show low levels of selenium in their blood.
In any such case a physician will evaluate the blood for its selenium content and determine whether there is a need for supplementation.
Disclaimer
The information in this article is presented for educational purposes only. No diagnosis should be made nor treatment undertaken without first consulting a Physician or other qualified health professional, as neither Suite101 nor the author will be responsible for readers' actions. Images are provided for illustrative purposes only.
Maria Blanco - Writer/Editor, Certified Family Herbalist, Naturopath, Holistic Nutritional Consultant
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