What is Selenium Deficiency?
Selenium is a very important mineral that we need in small amounts to keep us healthy. Selenium exists mainly as selenoproteins, which play various roles in normal body functions and metabolism. One such protein, called glutathione peroxidase (G-Px), helps protect the body from harmful reactive oxygen and nitrogen species which can cause damage to our cells. Another important role of selenium is that it helps convert the inactive thyroid hormone (T4) into the active form (T3), a process that is important for our metabolism.
Selenium also affects our immune system and how it functions correctly. It even plays a role in how HIV develops into AIDS. Studies suggest that lacking enough selenium could increase the risk of various health problems, including heart diseases, infertility, muscle degenerative disorders, and problems with cognitive abilities or thinking skills.
Scientists are currently studying selenium’s potential role in treating cancer. Our knowledge about how selenium affects our health has grown a lot over the 200 years since it was first discovered in 1817. Despite once being considered a cancer-causing agent, we now know selenium to be an essential nutrient, but one that we only need in small amounts and that can be harmful in large amounts.
Historically, a lack of selenium was linked to a type of heart disease known as Keshan disease, first reported in China in the 1930s. By giving selenium supplements to people living in areas where Keshan disease is prevalent, the occurrence of the disease has been significantly reduced, highlighting the potential healing benefits of selenium.
What Causes Selenium Deficiency?
Selenium is a mineral that is naturally found in soil, which then affects the amount of selenium present in plants. Foods like Brazil nuts, green vegetables, shiitake and button mushrooms as well as certain seeds like young barley seedlings are great sources of selenium, provided that they are grown in areas where the soil has sufficient selenium levels.
Yeasty food, like bread, is also a significant source of selenium since selenium yeast is often used in their production. Additionally, animals that eat plants rich in selenium, including sea creatures like fish, and land animals like cows and chickens, are also valuable sources of selenium, provided they are fed in regions where the soil is rich in selenium.
It’s important to note that selenium in plant-based foods is found in a form called selenomethionine, which is about 90% available to be used by our bodies. Supplements of selenium usually contain it in a form like selenate or selenite and are equally ready to be used by our bodies.
Several things can affect the level of selenium in foods. These include the type of plant, the pH levels, soil composition, rainfall patterns, how active microbes are, and other factors related to the chemistry of the earth and living things. A selenium deficiency is not getting enough dietary selenium, usually because there aren’t enough sources of selenium in the area. If someone has a disease because of a lack of selenium, they often lack enough vitamin E too.
As of April 2000, the recommended daily amount (RDA) of selenium programmed is 70 micrograms (µg) for men and 55 µg for women to maintain good health. However, some studies suggest that these amounts might be low and that adults may need at least 90 µg per day. The World Health Organization (WHO) set a safe upper limit for adults 19 years and older to 400 µg or 5.1 micromoles per day. Taking more than this could be harmful.
Risk Factors and Frequency for Selenium Deficiency
A huge number of people worldwide, between 500 million to 1 billion, are affected by a lack of selenium in their diet. This deficiency is quite common in certain parts of the United States, such as the Northwest, Northeast, Southeast, and areas of the Midwest near the Great Lakes. The Great Plains and the Southwest however, generally have adequate selenium content.
People with certain conditions like phenylketonuria or other diet-related diseases are at a higher risk of selenium deficiency. This is mainly due to their dietary restrictions, which often prevent them from consuming enough foods that are rich in selenium.
Selenium intake in many parts of Europe is lower than in the United States, with Eastern Europe showing a lower average intake than Western Europe. Finland was able to increase their selenium intake by adding selenium to their fertilizers. In these countries, Brazil nuts are the main source of selenium, followed by crab, liver, other shellfish, and fish. However, the use of these sources is limited due to the presence of different kinds of selenium in fish and the presence of harmful substances like arsenic and mercury.
Low selenium intake has been extensively documented in countries such as China and New Zealand. In the Middle East, the intake varies greatly depending on a person’s socioeconomic status.
Signs and Symptoms of Selenium Deficiency
Checking for selenium deficiency involves a detailed process. This includes understanding the patient’s health history, performing physical checks, and recognizing any relevant symptoms. A severe lack of selenium can lead to issues with the heart muscles and joints. If the deficiency is moderate, it may increase the risk of male infertility, prostate cancer, and neurological problems. Therefore, it’s crucial to fully examine the range of symptoms related to selenium deficiency.
During the patient’s medical history review, doctors gather information about pre-existing health conditions, current medication, and family incidents of selenium-related problems. They also study the patient’s diet, focusing on foods rich in selenium like nuts, seeds, seafood, and vegetables. They look for any dietary restrictions or significant changes in dietary habits. Geographical location also comes into play, as living in or visiting areas with selenium-deficient soil could contribute to the deficiency. Doctors also probe any symptoms associated with heart health, joint discomfort, male infertility, neurological issues, and any other relevant patient complaints.
Physical exams also form a part of the assessment process for selenium deficiency:
- Cardiovascular examination: This to check the functioning of the heart, such as the heart rate and rhythm, and to look for any signs of heart abnormalities.
- Musculoskeletal examination: The doctor examines the patient’s joints for any abnormalities. Symptoms such as rheumatoid arthritis or abnormal growth, particularly in children aged 5 to 13, may signal a selenium deficiency.
- Neurological examination: The patient’s sensory perception, reflexes, and coordination are evaluated to look for any signs of neurological disorders.
- Skin and nails: The doctor looks for skin texture changes, white spots on nails, or brittle nails—all signs of selenium deficiency.
- Reproductive health assessment: Doctors inquire about fertility issues and may conduct relevant examinations for men. Women are asked about any irregular periods or other reproductive problems.
- Growth assessment: This is especially important for children. Doctors monitor growth and watch out for any disorders.
- General physical health: A comprehensive physical exam is conducted to assess the overall health of the patient, with attention to signs indicative of selenium deficiency.
Testing for Selenium Deficiency
To check if you have a selenium deficiency, your doctor might use a combination of lab tests, x-ray images, and other clinical methods. However, it’s important to keep in mind that the protocols for evaluating a selenium deficiency are not universally standardized.
Here are some of the tests commonly used:
– Serum selenium levels: This test measures the amount of selenium in your serum, a component of your blood. In the U.S., the Institute of Medicine recommends that a healthy range is between 70 to 155 micrograms per liter of selenium.
– Plasma G-Px activity: This test helps doctors understand the state of your selenium levels by measuring the activity of an enzyme called G-Px that relies on selenium to function.
– Urinary selenium levels: This test measures selenium in your urine, which can indicate your recent selenium intake. However, interpreting the results can be tricky due to variations in how we excrete selenium in our urine.
Using imaging technologies, doctors can also check for signs of diseases related to selenium deficiency:
– X-ray imaging: X-rays can help identify deformities in your bones and joints that may indicate Kashin-Beck disease or other skeletal abnormalities due to selenium deficiency.
– Magnetic resonance imaging (MRI): If you have symptoms like joint pain or restricted movement, an MRI scan might be used to examine the condition of your joints and tissues.
– Bone density scans: Also referred to as dual-energy x-ray absorptiometry (DEXA) scans, these tests assess the health and density of your bones. A selenium deficiency can affect your bone structure and increase the risk of fractures.
Selenium deficiency is typically found in certain communities rather than occurring randomly in individuals. If you’re suspected to have this deficiency, your doctor might measure selenium levels in your serum or even in your hair or nails, as these are strongly correlated. In places where selenium deficiency is common, hair samples are often preferred over blood samples because they’re easier to collect, even by non-medical personnel.
Other tests may include measuring the activity of the G-Px enzyme in various blood components or determining the concentration of selenoprotein P (SePP), a protein that relies on selenium. These are additional effective ways to measure your selenium levels.
Treatment Options for Selenium Deficiency
Selenium deficiency, a lack of an essential mineral in your body, often tends to be a problem faced by whole communities rather than just one person. To tackle this, some strategies involve improving the quality of soil we use for farming, or adding selenium to the feed given to animals. When animals eat selenium-enriched food, products like their eggs, meat or milk also get enhanced with selenium. This way, when we consume these products, we get more selenium in our diet.
Sourcing selenium from food like selenium-enriched eggs, meat, and milk is a solution that has worked well for many countries. Another interesting strategy is to use tiny life forms like yeast, altering them to produce selenium, which can then also be consumed. This is all part of a big effort to deal with selenium deficiency and increase the overall health and nutrition of the public.
Selenium can also be consumed through supplements. There are two forms, organic and inorganic. Organic selenium supplements are absorbed more slowly by the body but are less likely to build up to toxic levels than inorganic selenium salts, which are absorbed quickly. The latter are often used when a swift response to selenium deficiency is needed. The target amount to consume from these supplements should generally be around 90 mcg per day for adults.
According to World Health Organization, the maximum amount of selenium an adult should take in a day is 400 µg. Any more than this could be harmful because of the risk of selenium toxicity. However, the best way to avoid selenium deficiency is simply to maintain a balanced diet. This will make sure your body gets all the selenium it needs without resorting to over-supplementation.
What else can Selenium Deficiency be?
Selenium is a key nutrient that affects many body functions. The following conditions may suggest a lack of selenium in the body:
- Addison disease
- Anemia
- Anovulation (lack of ovulation)
- Autoimmune thyroid disease and pregnancy
- Cardiac tamponade (pressure on the heart)
- Constipation
- Euthyroid sick syndrome (thyroid illness not due to thyroid disease)
- Goiter (enlarged thyroid)
- Hypothyroidism (low thyroid function)
- Nutritional cardiomyopathy (heart disease caused by poor nutrition)
- Pericardial effusion (fluid around the heart)
- Pituitary macroadenomas (large tumours in the pituitary gland)
- Prolactin deficiency (low levels of the hormone prolactin)
- Thyroid lymphoma (cancer of the thyroid)
- T4-binding globulin deficiency (a condition affecting thyroid hormone levels)
What to expect with Selenium Deficiency
The health outlook for not having enough selenium in your body can vary depending on things like how severe or long-lasting the deficiency is, the person’s health overall, and how effective treatments are. If selenium deficiency is not treated, it can lead to various health issues. These can include a weakened immune system, heart problems, issues with reproduction and fertility, a malfunctioning thyroid, signs related to your nervous system, and problems with your muscles and skeleton.
If a selenium deficiency is identified and treated promptly, the health outlook usually improves. Often, eating a diet with more selenium or taking supplements can fix a selenium deficiency. After the deficiency is fixed, many of the problems and health risks it caused can be reversed. But the extent of improvement and how quickly it happens can vary from person to person, depending on how severe the deficiency was and the person’s underlying health issues.
Even though a light to moderate selenium deficiency can usually be managed effectively, a severe or long-lasting deficiency could result in health complications that can’t be reversed. Importantly, a very low selenium level is linked on its own to a decreased ability to tolerate exercise, a 50% increase in the mortality rate, and a malfunctioning of what are called mitochondria (which are like your body’s cell “powerhouses”) within human heart cells in the lab.
Possible Complications When Diagnosed with Selenium Deficiency
A lack of selenium in your body can be linked to numerous health problems. These can include issues with your thyroid, heart muscle disease, infertility in both men and women, and heart failure. There can also be complications like miscarriage, preeclampsia (a condition in pregnant women that causes high blood pressure and damage to other organs like the liver and kidneys), restricted growth in fetuses, Keshan disease (a type of heart disease), and Kashin-Beck disease (an osteoarthropathy that can lead to deformities in the joints due to lesions in the cartilage). Additionally, selenium deficiency can result in cognitive decline, early labor, and gestational diabetes (a form of high blood sugar affecting pregnant women).
Issues related to Selenium Deficiency:
- Thyroid problems
- Cardiomyopathy (heart muscle disease)
- Infertility in men and women
- Heart failure
- Miscarriage
- Preeclampsia in pregnant women
- Fetal growth restriction
- Keshan disease (a heart disease)
- Kashin-Beck disease (a joint disorder)
- Cognitive decline
- Preterm labor
- Gestational diabetes in pregnant women
Preventing Selenium Deficiency
It’s important for individuals to understand the value of selenium, a vital tiny nutrient that plays a key role in our health. Selenium can be found in many different foods which makes it even more important. Foods high in selenium include meat, grain-based cereals, milk, egg yolks, Brazil nuts, garlic, mushrooms, and seafood. Eating a balanced diet containing these foods that are rich in selenium can help keep selenium levels in the body at their best and support overall health.
